Imaging in the Wind


W Hilmo
 

I've been doing a bunch of experimenting to transition from guided imaging with an SCT, to unguided imaging with a first class refractor.  Coincident to this, I'm imaging in a particularly windy area, which I moved to a few months before I received my AP130GTX.  Previously, I lived in an area with lots of overcast, but little wind.  It was also sheltered by being completely surrounded by forest.  My current location is wide open and completely unsheltered from the wind.

As mentioned, the scope is an AP130GTX.  The mount is an AP1600 with Absolute Encoders.  I'm finding that on calm nights (which are rare this time of year), I get nice, round stars at 10 minutes unguided.  With our typical winds, which are around 30mph over night, I get blobby and elongated stars.  Last night was windy, so the subs were all soft, with poor eccentricity.  I'm trying to determine how much of my soft stars are the the result of turbulence higher up, versus the mount and scope getting buffeted by the wind.

When I was blinking through the subs, I found the image that I've attached below.  It's interesting because there are crossing satellite trails at very different angles, that show signs of significant vibration.  I am guessing that what is happening here, is that the system is getting buffeted by winds, and the jaggies are due to the absolute encoders trying to quickly make corrections.  But I would be interested in other thoughts.

For tonight, I'm going to image the same field, but I've parked my motorhome up wind of the mount to act as a block.  The motorhome is parked 90 degrees to the prevailing wind, and is as close as I can get it while still keeping the roof at about 20 degrees elevation from the scope.  We are forecast for similar winds tonight, and the wind today seems consistent with yesterday.  I'll be curious to see if the results improve.  I'm not sure yet if turbulence as wind goes over and around the motorhome will be more than offset by sheltering the mount.

I am planning for an observatory, and have been thinking all along of a roll-off roof.  I suppose that if tonight's data looks good, perhaps I should be thinking about a dome.  Since I'm not planning on building the observatory until next year, I am also planning on experimenting with different wind blocks (presuming I can find something less than the motorhome, which can stand up to our winds on a regular basis).

If anyone else has dealt with this, I would be interested in how people have dealt with this.  I suppose that I could switch to only wide field imaging during the windiest times of the year, but if possible, I would like to mitigate things.

-Wade


Roland Christen
 

You can unplug the encoders and see what you get.

I got 30mph wind gusts here last couple of days with my 175 refractor on a 1600 encoder mount. Got round stars. Was watching the autoguider graph and saw only 1 arc sec or so deviations during a gust.

Rolando


-----Original Message-----
From: W Hilmo <y.groups@...>
To: main@ap-gto.groups.io
Sent: Tue, Jul 20, 2021 1:25 pm
Subject: [ap-gto] Imaging in the Wind

I've been doing a bunch of experimenting to transition from guided imaging with an SCT, to unguided imaging with a first class refractor.  Coincident to this, I'm imaging in a particularly windy area, which I moved to a few months before I received my AP130GTX.  Previously, I lived in an area with lots of overcast, but little wind.  It was also sheltered by being completely surrounded by forest.  My current location is wide open and completely unsheltered from the wind.

As mentioned, the scope is an AP130GTX.  The mount is an AP1600 with Absolute Encoders.  I'm finding that on calm nights (which are rare this time of year), I get nice, round stars at 10 minutes unguided.  With our typical winds, which are around 30mph over night, I get blobby and elongated stars.  Last night was windy, so the subs were all soft, with poor eccentricity.  I'm trying to determine how much of my soft stars are the the result of turbulence higher up, versus the mount and scope getting buffeted by the wind.

When I was blinking through the subs, I found the image that I've attached below.  It's interesting because there are crossing satellite trails at very different angles, that show signs of significant vibration.  I am guessing that what is happening here, is that the system is getting buffeted by winds, and the jaggies are due to the absolute encoders trying to quickly make corrections.  But I would be interested in other thoughts.

For tonight, I'm going to image the same field, but I've parked my motorhome up wind of the mount to act as a block.  The motorhome is parked 90 degrees to the prevailing wind, and is as close as I can get it while still keeping the roof at about 20 degrees elevation from the scope.  We are forecast for similar winds tonight, and the wind today seems consistent with yesterday.  I'll be curious to see if the results improve.  I'm not sure yet if turbulence as wind goes over and around the motorhome will be more than offset by sheltering the mount.

I am planning for an observatory, and have been thinking all along of a roll-off roof.  I suppose that if tonight's data looks good, perhaps I should be thinking about a dome.  Since I'm not planning on building the observatory until next year, I am also planning on experimenting with different wind blocks (presuming I can find something less than the motorhome, which can stand up to our winds on a regular basis).

If anyone else has dealt with this, I would be interested in how people have dealt with this.  I suppose that I could switch to only wide field imaging during the windiest times of the year, but if possible, I would like to mitigate things.

-Wade


--
Roland Christen
Astro-Physics


W Hilmo
 

Interesting.  If I can get tracking like you are seeing, that would be great.  If I unplug the encoders, I’ll either need to set up guiding or program a PEM curve.

 

Out of curiosity, what you are using for a pier?  I am using the portable field pier, and if the whole thing is shaking, perhaps I could tighten the turnbuckles a bit.


Oh, and one other thing that may be interesting, or may be nothing, I never get tight stars that are elongated.  I either get tight, round stars, or I get big elongated blobs.  I also get satellite lots and lots of satellite trails, and they are generally straight lines.  I was thinking that these satellites just happened to coincide with some strong gusts.

 

-Wade

 

From: main@ap-gto.groups.io <main@ap-gto.groups.io> On Behalf Of Roland Christen via groups.io
Sent: Tuesday, July 20, 2021 4:32 PM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Imaging in the Wind

 

You can unplug the encoders and see what you get.

 

I got 30mph wind gusts here last couple of days with my 175 refractor on a 1600 encoder mount. Got round stars. Was watching the autoguider graph and saw only 1 arc sec or so deviations during a gust.

 

Rolando

-----Original Message-----
From: W Hilmo <y.groups@...>
To: main@ap-gto.groups.io
Sent: Tue, Jul 20, 2021 1:25 pm
Subject: [ap-gto] Imaging in the Wind

I've been doing a bunch of experimenting to transition from guided imaging with an SCT, to unguided imaging with a first class refractor.  Coincident to this, I'm imaging in a particularly windy area, which I moved to a few months before I received my AP130GTX.  Previously, I lived in an area with lots of overcast, but little wind.  It was also sheltered by being completely surrounded by forest.  My current location is wide open and completely unsheltered from the wind.

As mentioned, the scope is an AP130GTX.  The mount is an AP1600 with Absolute Encoders.  I'm finding that on calm nights (which are rare this time of year), I get nice, round stars at 10 minutes unguided.  With our typical winds, which are around 30mph over night, I get blobby and elongated stars.  Last night was windy, so the subs were all soft, with poor eccentricity.  I'm trying to determine how much of my soft stars are the the result of turbulence higher up, versus the mount and scope getting buffeted by the wind.

When I was blinking through the subs, I found the image that I've attached below.  It's interesting because there are crossing satellite trails at very different angles, that show signs of significant vibration.  I am guessing that what is happening here, is that the system is getting buffeted by winds, and the jaggies are due to the absolute encoders trying to quickly make corrections.  But I would be interested in other thoughts.

For tonight, I'm going to image the same field, but I've parked my motorhome up wind of the mount to act as a block.  The motorhome is parked 90 degrees to the prevailing wind, and is as close as I can get it while still keeping the roof at about 20 degrees elevation from the scope.  We are forecast for similar winds tonight, and the wind today seems consistent with yesterday.  I'll be curious to see if the results improve.  I'm not sure yet if turbulence as wind goes over and around the motorhome will be more than offset by sheltering the mount.

I am planning for an observatory, and have been thinking all along of a roll-off roof.  I suppose that if tonight's data looks good, perhaps I should be thinking about a dome.  Since I'm not planning on building the observatory until next year, I am also planning on experimenting with different wind blocks (presuming I can find something less than the motorhome, which can stand up to our winds on a regular basis).

If anyone else has dealt with this, I would be interested in how people have dealt with this.  I suppose that I could switch to only wide field imaging during the windiest times of the year, but if possible, I would like to mitigate things.

-Wade


--
Roland Christen
Astro-Physics

Attachments:


Robert Chozick
 

You can build a temporary shelter with electrical conduits and tarps.  I have used this at star parties.  It is usually 8x8.  I have a friend that sells the connectors and tarps and you supply the electrical conduit. You could also just build an 8x8 or 9x9 fence enclosure.  My observatory at my Northwest Texas land is really just a 9x12 fence and it is all I need.  I take the equipment down when I leave.   No need for a roll off.  I keep the equipment in the container cabin at 85 degrees when not in use.  I leave the tripod and will be soon building a metal and concrete pier.  It just takes 30 minutes to set back up and do a quick polar align with Polemaster.  I just have to tweak it a bit each time.  I never do remote imaging.  I get wind gusts up to 60 mph and almost always at 15-20 mph minimum. 



Robert

On Jul 20, 2021, at 6:44 PM, W Hilmo <y.groups@...> wrote:

Interesting.  If I can get tracking like you are seeing, that would be great.  If I unplug the encoders, I’ll either need to set up guiding or program a PEM curve.
 
Out of curiosity, what you are using for a pier?  I am using the portable field pier, and if the whole thing is shaking, perhaps I could tighten the turnbuckles a bit.

Oh, and one other thing that may be interesting, or may be nothing, I never get tight stars that are elongated.  I either get tight, round stars, or I get big elongated blobs.  I also get satellite lots and lots of satellite trails, and they are generally straight lines.  I was thinking that these satellites just happened to coincide with some strong gusts.
 
-Wade
 
From: main@ap-gto.groups.io <main@ap-gto.groups.io> On Behalf Of Roland Christen via groups.io
Sent: Tuesday, July 20, 2021 4:32 PM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Imaging in the Wind
 
You can unplug the encoders and see what you get.
 
I got 30mph wind gusts here last couple of days with my 175 refractor on a 1600 encoder mount. Got round stars. Was watching the autoguider graph and saw only 1 arc sec or so deviations during a gust.
 

Rolando

-----Original Message-----
From: W Hilmo <y.groups@...>
To: main@ap-gto.groups.io
Sent: Tue, Jul 20, 2021 1:25 pm
Subject: [ap-gto] Imaging in the Wind

I've been doing a bunch of experimenting to transition from guided imaging with an SCT, to unguided imaging with a first class refractor.  Coincident to this, I'm imaging in a particularly windy area, which I moved to a few months before I received my AP130GTX.  Previously, I lived in an area with lots of overcast, but little wind.  It was also sheltered by being completely surrounded by forest.  My current location is wide open and completely unsheltered from the wind.

As mentioned, the scope is an AP130GTX.  The mount is an AP1600 with Absolute Encoders.  I'm finding that on calm nights (which are rare this time of year), I get nice, round stars at 10 minutes unguided.  With our typical winds, which are around 30mph over night, I get blobby and elongated stars.  Last night was windy, so the subs were all soft, with poor eccentricity.  I'm trying to determine how much of my soft stars are the the result of turbulence higher up, versus the mount and scope getting buffeted by the wind.

When I was blinking through the subs, I found the image that I've attached below.  It's interesting because there are crossing satellite trails at very different angles, that show signs of significant vibration.  I am guessing that what is happening here, is that the system is getting buffeted by winds, and the jaggies are due to the absolute encoders trying to quickly make corrections.  But I would be interested in other thoughts.

For tonight, I'm going to image the same field, but I've parked my motorhome up wind of the mount to act as a block.  The motorhome is parked 90 degrees to the prevailing wind, and is as close as I can get it while still keeping the roof at about 20 degrees elevation from the scope.  We are forecast for similar winds tonight, and the wind today seems consistent with yesterday.  I'll be curious to see if the results improve.  I'm not sure yet if turbulence as wind goes over and around the motorhome will be more than offset by sheltering the mount.

I am planning for an observatory, and have been thinking all along of a roll-off roof.  I suppose that if tonight's data looks good, perhaps I should be thinking about a dome.  Since I'm not planning on building the observatory until next year, I am also planning on experimenting with different wind blocks (presuming I can find something less than the motorhome, which can stand up to our winds on a regular basis).

If anyone else has dealt with this, I would be interested in how people have dealt with this.  I suppose that I could switch to only wide field imaging during the windiest times of the year, but if possible, I would like to mitigate things.

-Wade


-- 
Roland Christen
Astro-Physics 

Attachments:



Roland Christen
 


Out of curiosity, what you are using for a pier?

A good pier is very important, and is the foundation of the entire shebang. I use an ATS pier here. I have used the lighter weight 10" pier also and it generally works well also, but never had it in 30mph winds.

Rolando

-----Original Message-----
From: W Hilmo <y.groups@...>
To: main@ap-gto.groups.io
Sent: Tue, Jul 20, 2021 1:44 pm
Subject: Re: [ap-gto] Imaging in the Wind

Interesting.  If I can get tracking like you are seeing, that would be great.  If I unplug the encoders, I’ll either need to set up guiding or program a PEM curve.
 
Out of curiosity, what you are using for a pier?  I am using the portable field pier, and if the whole thing is shaking, perhaps I could tighten the turnbuckles a bit.

Oh, and one other thing that may be interesting, or may be nothing, I never get tight stars that are elongated.  I either get tight, round stars, or I get big elongated blobs.  I also get satellite lots and lots of satellite trails, and they are generally straight lines.  I was thinking that these satellites just happened to coincide with some strong gusts.
 
-Wade
 
From: main@ap-gto.groups.io <main@ap-gto.groups.io> On Behalf Of Roland Christen via groups.io
Sent: Tuesday, July 20, 2021 4:32 PM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Imaging in the Wind
 
You can unplug the encoders and see what you get.
 
I got 30mph wind gusts here last couple of days with my 175 refractor on a 1600 encoder mount. Got round stars. Was watching the autoguider graph and saw only 1 arc sec or so deviations during a gust.
 
Rolando

-----Original Message-----
From: W Hilmo <y.groups@...>
To: main@ap-gto.groups.io
Sent: Tue, Jul 20, 2021 1:25 pm
Subject: [ap-gto] Imaging in the Wind
I've been doing a bunch of experimenting to transition from guided imaging with an SCT, to unguided imaging with a first class refractor.  Coincident to this, I'm imaging in a particularly windy area, which I moved to a few months before I received my AP130GTX.  Previously, I lived in an area with lots of overcast, but little wind.  It was also sheltered by being completely surrounded by forest.  My current location is wide open and completely unsheltered from the wind.

As mentioned, the scope is an AP130GTX.  The mount is an AP1600 with Absolute Encoders.  I'm finding that on calm nights (which are rare this time of year), I get nice, round stars at 10 minutes unguided.  With our typical winds, which are around 30mph over night, I get blobby and elongated stars.  Last night was windy, so the subs were all soft, with poor eccentricity.  I'm trying to determine how much of my soft stars are the the result of turbulence higher up, versus the mount and scope getting buffeted by the wind.

When I was blinking through the subs, I found the image that I've attached below.  It's interesting because there are crossing satellite trails at very different angles, that show signs of significant vibration.  I am guessing that what is happening here, is that the system is getting buffeted by winds, and the jaggies are due to the absolute encoders trying to quickly make corrections.  But I would be interested in other thoughts.

For tonight, I'm going to image the same field, but I've parked my motorhome up wind of the mount to act as a block.  The motorhome is parked 90 degrees to the prevailing wind, and is as close as I can get it while still keeping the roof at about 20 degrees elevation from the scope.  We are forecast for similar winds tonight, and the wind today seems consistent with yesterday.  I'll be curious to see if the results improve.  I'm not sure yet if turbulence as wind goes over and around the motorhome will be more than offset by sheltering the mount.

I am planning for an observatory, and have been thinking all along of a roll-off roof.  I suppose that if tonight's data looks good, perhaps I should be thinking about a dome.  Since I'm not planning on building the observatory until next year, I am also planning on experimenting with different wind blocks (presuming I can find something less than the motorhome, which can stand up to our winds on a regular basis).

If anyone else has dealt with this, I would be interested in how people have dealt with this.  I suppose that I could switch to only wide field imaging during the windiest times of the year, but if possible, I would like to mitigate things.

-Wade


--
Roland Christen
Astro-Physics
Attachments:

--
Roland Christen
Astro-Physics


W Hilmo
 

I just wanted to follow up and say that using the motorhome as a wind block made a huge difference.

 

Based on the below results with the 175 refractor, I assume at this point that the mount itself is probably not the issue.  I have the rig set up on ground that is quite solid, and am using the 10” diameter portable field pier.  The pier height is 32” from the ground.

 

I’m wondering if the issue is that I leave the mount set up on the pier all the time.  In the last couple of weeks, our temperature has varied between 45F and 115F.  I suspect that the thermal cycling may affect the turn buckles.  It seems like they could be tighter than they are (although I find that if I tighten too much, it bends the hooks at the end of the turn buckles so that they open up).  I don’t adjust them often because I have a really good APPM model, and would need to recreate it each time.

 

I have plans for an observatory with a proper pier with a deep underground footing, but that won’t be until sometime next year at the earliest.  I’m going to need to find a temporary solution for between now and then. 

 

From: main@ap-gto.groups.io <main@ap-gto.groups.io> On Behalf Of W Hilmo
Sent: Tuesday, July 20, 2021 4:44 PM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Imaging in the Wind

 

Interesting.  If I can get tracking like you are seeing, that would be great.  If I unplug the encoders, I’ll either need to set up guiding or program a PEM curve.

 

Out of curiosity, what you are using for a pier?  I am using the portable field pier, and if the whole thing is shaking, perhaps I could tighten the turnbuckles a bit.


Oh, and one other thing that may be interesting, or may be nothing, I never get tight stars that are elongated.  I either get tight, round stars, or I get big elongated blobs.  I also get satellite lots and lots of satellite trails, and they are generally straight lines.  I was thinking that these satellites just happened to coincide with some strong gusts.

 

-Wade

 

From: main@ap-gto.groups.io <main@ap-gto.groups.io> On Behalf Of Roland Christen via groups.io
Sent: Tuesday, July 20, 2021 4:32 PM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Imaging in the Wind

 

You can unplug the encoders and see what you get.

 

I got 30mph wind gusts here last couple of days with my 175 refractor on a 1600 encoder mount. Got round stars. Was watching the autoguider graph and saw only 1 arc sec or so deviations during a gust.

 

Rolando

-----Original Message-----
From: W Hilmo <y.groups@...>
To: main@ap-gto.groups.io
Sent: Tue, Jul 20, 2021 1:25 pm
Subject: [ap-gto] Imaging in the Wind

I've been doing a bunch of experimenting to transition from guided imaging with an SCT, to unguided imaging with a first class refractor.  Coincident to this, I'm imaging in a particularly windy area, which I moved to a few months before I received my AP130GTX.  Previously, I lived in an area with lots of overcast, but little wind.  It was also sheltered by being completely surrounded by forest.  My current location is wide open and completely unsheltered from the wind.

As mentioned, the scope is an AP130GTX.  The mount is an AP1600 with Absolute Encoders.  I'm finding that on calm nights (which are rare this time of year), I get nice, round stars at 10 minutes unguided.  With our typical winds, which are around 30mph over night, I get blobby and elongated stars.  Last night was windy, so the subs were all soft, with poor eccentricity.  I'm trying to determine how much of my soft stars are the the result of turbulence higher up, versus the mount and scope getting buffeted by the wind.

When I was blinking through the subs, I found the image that I've attached below.  It's interesting because there are crossing satellite trails at very different angles, that show signs of significant vibration.  I am guessing that what is happening here, is that the system is getting buffeted by winds, and the jaggies are due to the absolute encoders trying to quickly make corrections.  But I would be interested in other thoughts.

For tonight, I'm going to image the same field, but I've parked my motorhome up wind of the mount to act as a block.  The motorhome is parked 90 degrees to the prevailing wind, and is as close as I can get it while still keeping the roof at about 20 degrees elevation from the scope.  We are forecast for similar winds tonight, and the wind today seems consistent with yesterday.  I'll be curious to see if the results improve.  I'm not sure yet if turbulence as wind goes over and around the motorhome will be more than offset by sheltering the mount.

I am planning for an observatory, and have been thinking all along of a roll-off roof.  I suppose that if tonight's data looks good, perhaps I should be thinking about a dome.  Since I'm not planning on building the observatory until next year, I am also planning on experimenting with different wind blocks (presuming I can find something less than the motorhome, which can stand up to our winds on a regular basis).

If anyone else has dealt with this, I would be interested in how people have dealt with this.  I suppose that I could switch to only wide field imaging during the windiest times of the year, but if possible, I would like to mitigate things.

-Wade


--
Roland Christen
Astro-Physics

Attachments:


Robert Chozick
 

A simple fence enclosure model would help greatly. 

Robert 


On Jul 22, 2021, at 1:04 PM, W Hilmo <y.groups@...> wrote:



I just wanted to follow up and say that using the motorhome as a wind block made a huge difference.

 

Based on the below results with the 175 refractor, I assume at this point that the mount itself is probably not the issue.  I have the rig set up on ground that is quite solid, and am using the 10” diameter portable field pier.  The pier height is 32” from the ground.

 

I’m wondering if the issue is that I leave the mount set up on the pier all the time.  In the last couple of weeks, our temperature has varied between 45F and 115F.  I suspect that the thermal cycling may affect the turn buckles.  It seems like they could be tighter than they are (although I find that if I tighten too much, it bends the hooks at the end of the turn buckles so that they open up).  I don’t adjust them often because I have a really good APPM model, and would need to recreate it each time.

 

I have plans for an observatory with a proper pier with a deep underground footing, but that won’t be until sometime next year at the earliest.  I’m going to need to find a temporary solution for between now and then. 

 

From: main@ap-gto.groups.io <main@ap-gto.groups.io> On Behalf Of W Hilmo
Sent: Tuesday, July 20, 2021 4:44 PM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Imaging in the Wind

 

Interesting.  If I can get tracking like you are seeing, that would be great.  If I unplug the encoders, I’ll either need to set up guiding or program a PEM curve.

 

Out of curiosity, what you are using for a pier?  I am using the portable field pier, and if the whole thing is shaking, perhaps I could tighten the turnbuckles a bit.


Oh, and one other thing that may be interesting, or may be nothing, I never get tight stars that are elongated.  I either get tight, round stars, or I get big elongated blobs.  I also get satellite lots and lots of satellite trails, and they are generally straight lines.  I was thinking that these satellites just happened to coincide with some strong gusts.

 

-Wade

 

From: main@ap-gto.groups.io <main@ap-gto.groups.io> On Behalf Of Roland Christen via groups.io
Sent: Tuesday, July 20, 2021 4:32 PM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Imaging in the Wind

 

You can unplug the encoders and see what you get.

 

I got 30mph wind gusts here last couple of days with my 175 refractor on a 1600 encoder mount. Got round stars. Was watching the autoguider graph and saw only 1 arc sec or so deviations during a gust.

 

Rolando

-----Original Message-----
From: W Hilmo <y.groups@...>
To: main@ap-gto.groups.io
Sent: Tue, Jul 20, 2021 1:25 pm
Subject: [ap-gto] Imaging in the Wind

I've been doing a bunch of experimenting to transition from guided imaging with an SCT, to unguided imaging with a first class refractor.  Coincident to this, I'm imaging in a particularly windy area, which I moved to a few months before I received my AP130GTX.  Previously, I lived in an area with lots of overcast, but little wind.  It was also sheltered by being completely surrounded by forest.  My current location is wide open and completely unsheltered from the wind.

As mentioned, the scope is an AP130GTX.  The mount is an AP1600 with Absolute Encoders.  I'm finding that on calm nights (which are rare this time of year), I get nice, round stars at 10 minutes unguided.  With our typical winds, which are around 30mph over night, I get blobby and elongated stars.  Last night was windy, so the subs were all soft, with poor eccentricity.  I'm trying to determine how much of my soft stars are the the result of turbulence higher up, versus the mount and scope getting buffeted by the wind.

When I was blinking through the subs, I found the image that I've attached below.  It's interesting because there are crossing satellite trails at very different angles, that show signs of significant vibration.  I am guessing that what is happening here, is that the system is getting buffeted by winds, and the jaggies are due to the absolute encoders trying to quickly make corrections.  But I would be interested in other thoughts.

For tonight, I'm going to image the same field, but I've parked my motorhome up wind of the mount to act as a block.  The motorhome is parked 90 degrees to the prevailing wind, and is as close as I can get it while still keeping the roof at about 20 degrees elevation from the scope.  We are forecast for similar winds tonight, and the wind today seems consistent with yesterday.  I'll be curious to see if the results improve.  I'm not sure yet if turbulence as wind goes over and around the motorhome will be more than offset by sheltering the mount.

I am planning for an observatory, and have been thinking all along of a roll-off roof.  I suppose that if tonight's data looks good, perhaps I should be thinking about a dome.  Since I'm not planning on building the observatory until next year, I am also planning on experimenting with different wind blocks (presuming I can find something less than the motorhome, which can stand up to our winds on a regular basis).

If anyone else has dealt with this, I would be interested in how people have dealt with this.  I suppose that I could switch to only wide field imaging during the windiest times of the year, but if possible, I would like to mitigate things.

-Wade


--
Roland Christen
Astro-Physics

Attachments:


Dale Ghent
 

How often do you PA? Do you spot check it at all?

I leave mine out for days at a time, and the tri-pier (it's an A-P Eagle) sits on pavers that are sunk into the ground. The ground swells and subsides subtly from day to day; at least the surface of it does. This means I need to touch up my PA every night before imaging as the PA can be off by several arc minutes depending on whether was a large enough rain or drying cycle since the last time I imaged. Soil type and other factors influence how much of a problem this is for any given person. This issue is noticeably worse in the winter when there's a freeze/thaw cycle going on.

On Jul 22, 2021, at 14:04, W Hilmo <y.groups@hilmo.net> wrote:

I just wanted to follow up and say that using the motorhome as a wind block made a huge difference.

Based on the below results with the 175 refractor, I assume at this point that the mount itself is probably not the issue. I have the rig set up on ground that is quite solid, and am using the 10” diameter portable field pier. The pier height is 32” from the ground.

I’m wondering if the issue is that I leave the mount set up on the pier all the time. In the last couple of weeks, our temperature has varied between 45F and 115F. I suspect that the thermal cycling may affect the turn buckles. It seems like they could be tighter than they are (although I find that if I tighten too much, it bends the hooks at the end of the turn buckles so that they open up). I don’t adjust them often because I have a really good APPM model, and would need to recreate it each time.

I have plans for an observatory with a proper pier with a deep underground footing, but that won’t be until sometime next year at the earliest. I’m going to need to find a temporary solution for between now and then.

From: main@ap-gto.groups.io <main@ap-gto.groups.io> On Behalf Of W Hilmo
Sent: Tuesday, July 20, 2021 4:44 PM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Imaging in the Wind

Interesting. If I can get tracking like you are seeing, that would be great. If I unplug the encoders, I’ll either need to set up guiding or program a PEM curve.

Out of curiosity, what you are using for a pier? I am using the portable field pier, and if the whole thing is shaking, perhaps I could tighten the turnbuckles a bit.

Oh, and one other thing that may be interesting, or may be nothing, I never get tight stars that are elongated. I either get tight, round stars, or I get big elongated blobs. I also get satellite lots and lots of satellite trails, and they are generally straight lines. I was thinking that these satellites just happened to coincide with some strong gusts.

-Wade

From: main@ap-gto.groups.io <main@ap-gto.groups.io> On Behalf Of Roland Christen via groups.io
Sent: Tuesday, July 20, 2021 4:32 PM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Imaging in the Wind

You can unplug the encoders and see what you get.

I got 30mph wind gusts here last couple of days with my 175 refractor on a 1600 encoder mount. Got round stars. Was watching the autoguider graph and saw only 1 arc sec or so deviations during a gust.

Rolando

-----Original Message-----
From: W Hilmo <y.groups@hilmo.net>
To: main@ap-gto.groups.io
Sent: Tue, Jul 20, 2021 1:25 pm
Subject: [ap-gto] Imaging in the Wind

I've been doing a bunch of experimenting to transition from guided imaging with an SCT, to unguided imaging with a first class refractor. Coincident to this, I'm imaging in a particularly windy area, which I moved to a few months before I received my AP130GTX. Previously, I lived in an area with lots of overcast, but little wind. It was also sheltered by being completely surrounded by forest. My current location is wide open and completely unsheltered from the wind.

As mentioned, the scope is an AP130GTX. The mount is an AP1600 with Absolute Encoders. I'm finding that on calm nights (which are rare this time of year), I get nice, round stars at 10 minutes unguided. With our typical winds, which are around 30mph over night, I get blobby and elongated stars. Last night was windy, so the subs were all soft, with poor eccentricity. I'm trying to determine how much of my soft stars are the the result of turbulence higher up, versus the mount and scope getting buffeted by the wind.

When I was blinking through the subs, I found the image that I've attached below. It's interesting because there are crossing satellite trails at very different angles, that show signs of significant vibration. I am guessing that what is happening here, is that the system is getting buffeted by winds, and the jaggies are due to the absolute encoders trying to quickly make corrections. But I would be interested in other thoughts.

For tonight, I'm going to image the same field, but I've parked my motorhome up wind of the mount to act as a block. The motorhome is parked 90 degrees to the prevailing wind, and is as close as I can get it while still keeping the roof at about 20 degrees elevation from the scope. We are forecast for similar winds tonight, and the wind today seems consistent with yesterday. I'll be curious to see if the results improve. I'm not sure yet if turbulence as wind goes over and around the motorhome will be more than offset by sheltering the mount.

I am planning for an observatory, and have been thinking all along of a roll-off roof. I suppose that if tonight's data looks good, perhaps I should be thinking about a dome. Since I'm not planning on building the observatory until next year, I am also planning on experimenting with different wind blocks (presuming I can find something less than the motorhome, which can stand up to our winds on a regular basis).

If anyone else has dealt with this, I would be interested in how people have dealt with this. I suppose that I could switch to only wide field imaging during the windiest times of the year, but if possible, I would like to mitigate things.

-Wade



--
Roland Christen
Astro-Physics
Attachments:

• wind_gust.jpg


Joseph Beyer
 

This brings up an interesting point. My setup is similar to Dale’s in the respect that I leave the gear/tripod out for a couple weeks at a time. The soil is nearly all clay and continues to move all summer long. On first setup I polar align as closely as possible with Smart Cap then run a 60 point APPM routine.  I’ve always assumed the model will always be valid as long as I polar align to a similar level of precision each night before imaging.  My results tend to support this. 


Adjusting the tension of the turn buckles on the pier before imaging should have no more effect that my yard’s clay soil.  As long as the mount is polar aligned to a level close to where it was when a model was run should have little impact on guiding, correct?


W Hilmo
 

I am taking 10 minute, unguided exposures at 0.88 arc seconds per pixel, so I expect that my polar alignment is good – or at least consistent with the tracking model.

 

I’ve only recently switched to unguided imaging, and I’ve only checked the polar alignment a couple of times and made a new model after adjustment.  Prior to this spring, I was using a different scope and guiding.  In that case, I checked the polar alignment periodically.  Certainly, during the winter with freeze/thaw cycles, I doubt that I could productively do unguided imaging with this setup as is.

 

On a whim, I did some guided imaging a few weeks ago, and got the exact same results as I get unguided (good results up to about 15-20mph wind, but poor results with 30+ and gusting).  I suspect that if the rig is vibrating in the wind, the frequency is far too high for the guider to deal with.

 

My soil is a combination of rock and clay, and seems to be pretty stable.  It is noticeably more stable than the ground at my previous property.

 

 

From: main@ap-gto.groups.io <main@ap-gto.groups.io> On Behalf Of Joseph Beyer
Sent: Thursday, July 22, 2021 11:55 AM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Imaging in the Wind

 

This brings up an interesting point. My setup is similar to Dale’s in the respect that I leave the gear/tripod out for a couple weeks at a time. The soil is nearly all clay and continues to move all summer long. On first setup I polar align as closely as possible with Smart Cap then run a 60 point APPM routine.  I’ve always assumed the model will always be valid as long as I polar align to a similar level of precision each night before imaging.  My results tend to support this. 


Adjusting the tension of the turn buckles on the pier before imaging should have no more effect that my yard’s clay soil.  As long as the mount is polar aligned to a level close to where it was when a model was run should have little impact on guiding, correct?


W Hilmo
 

I think so, too.

 

The problem is that my wife would prefer if I not sink fence posts into concrete for a temporary solution.  My fear is that without a really solid anchor, our wind would simply blow it away.  We’ve been seeing 30ish mph for the last couple of weeks, but it can get significantly higher than that with little warning.

 

Also, if the fence were upwind, which is would need to be to function, any wind strong enough to move it, would blow it right into the scope.

 

From: main@ap-gto.groups.io <main@ap-gto.groups.io> On Behalf Of Robert Chozick via groups.io
Sent: Thursday, July 22, 2021 11:25 AM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Imaging in the Wind

 

A simple fence enclosure model would help greatly. 

Robert 

 



On Jul 22, 2021, at 1:04 PM, W Hilmo <y.groups@...> wrote:



I just wanted to follow up and say that using the motorhome as a wind block made a huge difference.

 

Based on the below results with the 175 refractor, I assume at this point that the mount itself is probably not the issue.  I have the rig set up on ground that is quite solid, and am using the 10” diameter portable field pier.  The pier height is 32” from the ground.

 

I’m wondering if the issue is that I leave the mount set up on the pier all the time.  In the last couple of weeks, our temperature has varied between 45F and 115F.  I suspect that the thermal cycling may affect the turn buckles.  It seems like they could be tighter than they are (although I find that if I tighten too much, it bends the hooks at the end of the turn buckles so that they open up).  I don’t adjust them often because I have a really good APPM model, and would need to recreate it each time.

 

I have plans for an observatory with a proper pier with a deep underground footing, but that won’t be until sometime next year at the earliest.  I’m going to need to find a temporary solution for between now and then. 

 

From: main@ap-gto.groups.io <main@ap-gto.groups.io> On Behalf Of W Hilmo
Sent: Tuesday, July 20, 2021 4:44 PM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Imaging in the Wind

 

Interesting.  If I can get tracking like you are seeing, that would be great.  If I unplug the encoders, I’ll either need to set up guiding or program a PEM curve.

 

Out of curiosity, what you are using for a pier?  I am using the portable field pier, and if the whole thing is shaking, perhaps I could tighten the turnbuckles a bit.


Oh, and one other thing that may be interesting, or may be nothing, I never get tight stars that are elongated.  I either get tight, round stars, or I get big elongated blobs.  I also get satellite lots and lots of satellite trails, and they are generally straight lines.  I was thinking that these satellites just happened to coincide with some strong gusts.

 

-Wade

 

From: main@ap-gto.groups.io <main@ap-gto.groups.io> On Behalf Of Roland Christen via groups.io
Sent: Tuesday, July 20, 2021 4:32 PM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Imaging in the Wind

 

You can unplug the encoders and see what you get.

 

I got 30mph wind gusts here last couple of days with my 175 refractor on a 1600 encoder mount. Got round stars. Was watching the autoguider graph and saw only 1 arc sec or so deviations during a gust.

 

Rolando

-----Original Message-----
From: W Hilmo <y.groups@...>
To: main@ap-gto.groups.io
Sent: Tue, Jul 20, 2021 1:25 pm
Subject: [ap-gto] Imaging in the Wind

I've been doing a bunch of experimenting to transition from guided imaging with an SCT, to unguided imaging with a first class refractor.  Coincident to this, I'm imaging in a particularly windy area, which I moved to a few months before I received my AP130GTX.  Previously, I lived in an area with lots of overcast, but little wind.  It was also sheltered by being completely surrounded by forest.  My current location is wide open and completely unsheltered from the wind.

As mentioned, the scope is an AP130GTX.  The mount is an AP1600 with Absolute Encoders.  I'm finding that on calm nights (which are rare this time of year), I get nice, round stars at 10 minutes unguided.  With our typical winds, which are around 30mph over night, I get blobby and elongated stars.  Last night was windy, so the subs were all soft, with poor eccentricity.  I'm trying to determine how much of my soft stars are the the result of turbulence higher up, versus the mount and scope getting buffeted by the wind.

When I was blinking through the subs, I found the image that I've attached below.  It's interesting because there are crossing satellite trails at very different angles, that show signs of significant vibration.  I am guessing that what is happening here, is that the system is getting buffeted by winds, and the jaggies are due to the absolute encoders trying to quickly make corrections.  But I would be interested in other thoughts.

For tonight, I'm going to image the same field, but I've parked my motorhome up wind of the mount to act as a block.  The motorhome is parked 90 degrees to the prevailing wind, and is as close as I can get it while still keeping the roof at about 20 degrees elevation from the scope.  We are forecast for similar winds tonight, and the wind today seems consistent with yesterday.  I'll be curious to see if the results improve.  I'm not sure yet if turbulence as wind goes over and around the motorhome will be more than offset by sheltering the mount.

I am planning for an observatory, and have been thinking all along of a roll-off roof.  I suppose that if tonight's data looks good, perhaps I should be thinking about a dome.  Since I'm not planning on building the observatory until next year, I am also planning on experimenting with different wind blocks (presuming I can find something less than the motorhome, which can stand up to our winds on a regular basis).

If anyone else has dealt with this, I would be interested in how people have dealt with this.  I suppose that I could switch to only wide field imaging during the windiest times of the year, but if possible, I would like to mitigate things.

-Wade


--
Roland Christen
Astro-Physics

Attachments:


Joseph Beyer
 

Thinking about the sailing on SF Bay in a stiff wind, I’m wondering if the cables on the pier are a big part of the problem.  Given a high enough wind velocity they would likely vibrate as the mast stay cables do on a sailboat. In that case blocking the wind as you’re already attempting to do should help the problem.  


Robert Chozick
 

The temporary conduit solution works very well and is anchored with stakes and ropes. We use this at the Okie Tex star party and get gusts close to 60 miles an hour all the time setting up for a weeks time. You can set up the conduit and tarp shelter in less than an hour and it’s stores in a small area. I will find some pictures and send them. 

Robert 


On Jul 22, 2021, at 3:40 PM, W Hilmo <y.groups@...> wrote:



I think so, too.

 

The problem is that my wife would prefer if I not sink fence posts into concrete for a temporary solution.  My fear is that without a really solid anchor, our wind would simply blow it away.  We’ve been seeing 30ish mph for the last couple of weeks, but it can get significantly higher than that with little warning.

 

Also, if the fence were upwind, which is would need to be to function, any wind strong enough to move it, would blow it right into the scope.

 

From: main@ap-gto.groups.io <main@ap-gto.groups.io> On Behalf Of Robert Chozick via groups.io
Sent: Thursday, July 22, 2021 11:25 AM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Imaging in the Wind

 

A simple fence enclosure model would help greatly. 

Robert 

 



On Jul 22, 2021, at 1:04 PM, W Hilmo <y.groups@...> wrote:



I just wanted to follow up and say that using the motorhome as a wind block made a huge difference.

 

Based on the below results with the 175 refractor, I assume at this point that the mount itself is probably not the issue.  I have the rig set up on ground that is quite solid, and am using the 10” diameter portable field pier.  The pier height is 32” from the ground.

 

I’m wondering if the issue is that I leave the mount set up on the pier all the time.  In the last couple of weeks, our temperature has varied between 45F and 115F.  I suspect that the thermal cycling may affect the turn buckles.  It seems like they could be tighter than they are (although I find that if I tighten too much, it bends the hooks at the end of the turn buckles so that they open up).  I don’t adjust them often because I have a really good APPM model, and would need to recreate it each time.

 

I have plans for an observatory with a proper pier with a deep underground footing, but that won’t be until sometime next year at the earliest.  I’m going to need to find a temporary solution for between now and then. 

 

From: main@ap-gto.groups.io <main@ap-gto.groups.io> On Behalf Of W Hilmo
Sent: Tuesday, July 20, 2021 4:44 PM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Imaging in the Wind

 

Interesting.  If I can get tracking like you are seeing, that would be great.  If I unplug the encoders, I’ll either need to set up guiding or program a PEM curve.

 

Out of curiosity, what you are using for a pier?  I am using the portable field pier, and if the whole thing is shaking, perhaps I could tighten the turnbuckles a bit.


Oh, and one other thing that may be interesting, or may be nothing, I never get tight stars that are elongated.  I either get tight, round stars, or I get big elongated blobs.  I also get satellite lots and lots of satellite trails, and they are generally straight lines.  I was thinking that these satellites just happened to coincide with some strong gusts.

 

-Wade

 

From: main@ap-gto.groups.io <main@ap-gto.groups.io> On Behalf Of Roland Christen via groups.io
Sent: Tuesday, July 20, 2021 4:32 PM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Imaging in the Wind

 

You can unplug the encoders and see what you get.

 

I got 30mph wind gusts here last couple of days with my 175 refractor on a 1600 encoder mount. Got round stars. Was watching the autoguider graph and saw only 1 arc sec or so deviations during a gust.

 

Rolando

-----Original Message-----
From: W Hilmo <y.groups@...>
To: main@ap-gto.groups.io
Sent: Tue, Jul 20, 2021 1:25 pm
Subject: [ap-gto] Imaging in the Wind

I've been doing a bunch of experimenting to transition from guided imaging with an SCT, to unguided imaging with a first class refractor.  Coincident to this, I'm imaging in a particularly windy area, which I moved to a few months before I received my AP130GTX.  Previously, I lived in an area with lots of overcast, but little wind.  It was also sheltered by being completely surrounded by forest.  My current location is wide open and completely unsheltered from the wind.

As mentioned, the scope is an AP130GTX.  The mount is an AP1600 with Absolute Encoders.  I'm finding that on calm nights (which are rare this time of year), I get nice, round stars at 10 minutes unguided.  With our typical winds, which are around 30mph over night, I get blobby and elongated stars.  Last night was windy, so the subs were all soft, with poor eccentricity.  I'm trying to determine how much of my soft stars are the the result of turbulence higher up, versus the mount and scope getting buffeted by the wind.

When I was blinking through the subs, I found the image that I've attached below.  It's interesting because there are crossing satellite trails at very different angles, that show signs of significant vibration.  I am guessing that what is happening here, is that the system is getting buffeted by winds, and the jaggies are due to the absolute encoders trying to quickly make corrections.  But I would be interested in other thoughts.

For tonight, I'm going to image the same field, but I've parked my motorhome up wind of the mount to act as a block.  The motorhome is parked 90 degrees to the prevailing wind, and is as close as I can get it while still keeping the roof at about 20 degrees elevation from the scope.  We are forecast for similar winds tonight, and the wind today seems consistent with yesterday.  I'll be curious to see if the results improve.  I'm not sure yet if turbulence as wind goes over and around the motorhome will be more than offset by sheltering the mount.

I am planning for an observatory, and have been thinking all along of a roll-off roof.  I suppose that if tonight's data looks good, perhaps I should be thinking about a dome.  Since I'm not planning on building the observatory until next year, I am also planning on experimenting with different wind blocks (presuming I can find something less than the motorhome, which can stand up to our winds on a regular basis).

If anyone else has dealt with this, I would be interested in how people have dealt with this.  I suppose that I could switch to only wide field imaging during the windiest times of the year, but if possible, I would like to mitigate things.

-Wade


--
Roland Christen
Astro-Physics

Attachments:


Robert Chozick
 


Picture of wind shelter 
Robert 


On Jul 22, 2021, at 5:45 PM, Robert Chozick via groups.io <rchozick@...> wrote:

The temporary conduit solution works very well and is anchored with stakes and ropes. We use this at the Okie Tex star party and get gusts close to 60 miles an hour all the time setting up for a weeks time. You can set up the conduit and tarp shelter in less than an hour and it’s stores in a small area. I will find some pictures and send them. 

Robert 


On Jul 22, 2021, at 3:40 PM, W Hilmo <y.groups@...> wrote:



I think so, too.

 

The problem is that my wife would prefer if I not sink fence posts into concrete for a temporary solution.  My fear is that without a really solid anchor, our wind would simply blow it away.  We’ve been seeing 30ish mph for the last couple of weeks, but it can get significantly higher than that with little warning.

 

Also, if the fence were upwind, which is would need to be to function, any wind strong enough to move it, would blow it right into the scope.

 

From: main@ap-gto.groups.io <main@ap-gto.groups.io> On Behalf Of Robert Chozick via groups.io
Sent: Thursday, July 22, 2021 11:25 AM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Imaging in the Wind

 

A simple fence enclosure model would help greatly. 

Robert 

 



On Jul 22, 2021, at 1:04 PM, W Hilmo <y.groups@...> wrote:



I just wanted to follow up and say that using the motorhome as a wind block made a huge difference.

 

Based on the below results with the 175 refractor, I assume at this point that the mount itself is probably not the issue.  I have the rig set up on ground that is quite solid, and am using the 10” diameter portable field pier.  The pier height is 32” from the ground.

 

I’m wondering if the issue is that I leave the mount set up on the pier all the time.  In the last couple of weeks, our temperature has varied between 45F and 115F.  I suspect that the thermal cycling may affect the turn buckles.  It seems like they could be tighter than they are (although I find that if I tighten too much, it bends the hooks at the end of the turn buckles so that they open up).  I don’t adjust them often because I have a really good APPM model, and would need to recreate it each time.

 

I have plans for an observatory with a proper pier with a deep underground footing, but that won’t be until sometime next year at the earliest.  I’m going to need to find a temporary solution for between now and then. 

 

From: main@ap-gto.groups.io <main@ap-gto.groups.io> On Behalf Of W Hilmo
Sent: Tuesday, July 20, 2021 4:44 PM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Imaging in the Wind

 

Interesting.  If I can get tracking like you are seeing, that would be great.  If I unplug the encoders, I’ll either need to set up guiding or program a PEM curve.

 

Out of curiosity, what you are using for a pier?  I am using the portable field pier, and if the whole thing is shaking, perhaps I could tighten the turnbuckles a bit.


Oh, and one other thing that may be interesting, or may be nothing, I never get tight stars that are elongated.  I either get tight, round stars, or I get big elongated blobs.  I also get satellite lots and lots of satellite trails, and they are generally straight lines.  I was thinking that these satellites just happened to coincide with some strong gusts.

 

-Wade

 

From: main@ap-gto.groups.io <main@ap-gto.groups.io> On Behalf Of Roland Christen via groups.io
Sent: Tuesday, July 20, 2021 4:32 PM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Imaging in the Wind

 

You can unplug the encoders and see what you get.

 

I got 30mph wind gusts here last couple of days with my 175 refractor on a 1600 encoder mount. Got round stars. Was watching the autoguider graph and saw only 1 arc sec or so deviations during a gust.

 

Rolando

-----Original Message-----
From: W Hilmo <y.groups@...>
To: main@ap-gto.groups.io
Sent: Tue, Jul 20, 2021 1:25 pm
Subject: [ap-gto] Imaging in the Wind

I've been doing a bunch of experimenting to transition from guided imaging with an SCT, to unguided imaging with a first class refractor.  Coincident to this, I'm imaging in a particularly windy area, which I moved to a few months before I received my AP130GTX.  Previously, I lived in an area with lots of overcast, but little wind.  It was also sheltered by being completely surrounded by forest.  My current location is wide open and completely unsheltered from the wind.

As mentioned, the scope is an AP130GTX.  The mount is an AP1600 with Absolute Encoders.  I'm finding that on calm nights (which are rare this time of year), I get nice, round stars at 10 minutes unguided.  With our typical winds, which are around 30mph over night, I get blobby and elongated stars.  Last night was windy, so the subs were all soft, with poor eccentricity.  I'm trying to determine how much of my soft stars are the the result of turbulence higher up, versus the mount and scope getting buffeted by the wind.

When I was blinking through the subs, I found the image that I've attached below.  It's interesting because there are crossing satellite trails at very different angles, that show signs of significant vibration.  I am guessing that what is happening here, is that the system is getting buffeted by winds, and the jaggies are due to the absolute encoders trying to quickly make corrections.  But I would be interested in other thoughts.

For tonight, I'm going to image the same field, but I've parked my motorhome up wind of the mount to act as a block.  The motorhome is parked 90 degrees to the prevailing wind, and is as close as I can get it while still keeping the roof at about 20 degrees elevation from the scope.  We are forecast for similar winds tonight, and the wind today seems consistent with yesterday.  I'll be curious to see if the results improve.  I'm not sure yet if turbulence as wind goes over and around the motorhome will be more than offset by sheltering the mount.

I am planning for an observatory, and have been thinking all along of a roll-off roof.  I suppose that if tonight's data looks good, perhaps I should be thinking about a dome.  Since I'm not planning on building the observatory until next year, I am also planning on experimenting with different wind blocks (presuming I can find something less than the motorhome, which can stand up to our winds on a regular basis).

If anyone else has dealt with this, I would be interested in how people have dealt with this.  I suppose that I could switch to only wide field imaging during the windiest times of the year, but if possible, I would like to mitigate things.

-Wade


--
Roland Christen
Astro-Physics

Attachments:


W Hilmo
 

Thanks for that.

 

It looks like all of the rigidity is from guy wires, correct?

 

From: main@ap-gto.groups.io <main@ap-gto.groups.io> On Behalf Of Robert Chozick via groups.io
Sent: Thursday, July 22, 2021 4:26 PM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Imaging in the Wind

 

 

Picture of wind shelter 

Robert 

 



On Jul 22, 2021, at 5:45 PM, Robert Chozick via groups.io <rchozick@...> wrote:

The temporary conduit solution works very well and is anchored with stakes and ropes. We use this at the Okie Tex star party and get gusts close to 60 miles an hour all the time setting up for a weeks time. You can set up the conduit and tarp shelter in less than an hour and it’s stores in a small area. I will find some pictures and send them. 

Robert 

 



On Jul 22, 2021, at 3:40 PM, W Hilmo <y.groups@...> wrote:



I think so, too.

 

The problem is that my wife would prefer if I not sink fence posts into concrete for a temporary solution.  My fear is that without a really solid anchor, our wind would simply blow it away.  We’ve been seeing 30ish mph for the last couple of weeks, but it can get significantly higher than that with little warning.

 

Also, if the fence were upwind, which is would need to be to function, any wind strong enough to move it, would blow it right into the scope.

 

From: main@ap-gto.groups.io <main@ap-gto.groups.io> On Behalf Of Robert Chozick via groups.io
Sent: Thursday, July 22, 2021 11:25 AM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Imaging in the Wind

 

A simple fence enclosure model would help greatly. 

Robert 

 




On Jul 22, 2021, at 1:04 PM, W Hilmo <y.groups@...> wrote:



I just wanted to follow up and say that using the motorhome as a wind block made a huge difference.

 

Based on the below results with the 175 refractor, I assume at this point that the mount itself is probably not the issue.  I have the rig set up on ground that is quite solid, and am using the 10” diameter portable field pier.  The pier height is 32” from the ground.

 

I’m wondering if the issue is that I leave the mount set up on the pier all the time.  In the last couple of weeks, our temperature has varied between 45F and 115F.  I suspect that the thermal cycling may affect the turn buckles.  It seems like they could be tighter than they are (although I find that if I tighten too much, it bends the hooks at the end of the turn buckles so that they open up).  I don’t adjust them often because I have a really good APPM model, and would need to recreate it each time.

 

I have plans for an observatory with a proper pier with a deep underground footing, but that won’t be until sometime next year at the earliest.  I’m going to need to find a temporary solution for between now and then. 

 

From: main@ap-gto.groups.io <main@ap-gto.groups.io> On Behalf Of W Hilmo
Sent: Tuesday, July 20, 2021 4:44 PM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Imaging in the Wind

 

Interesting.  If I can get tracking like you are seeing, that would be great.  If I unplug the encoders, I’ll either need to set up guiding or program a PEM curve.

 

Out of curiosity, what you are using for a pier?  I am using the portable field pier, and if the whole thing is shaking, perhaps I could tighten the turnbuckles a bit.


Oh, and one other thing that may be interesting, or may be nothing, I never get tight stars that are elongated.  I either get tight, round stars, or I get big elongated blobs.  I also get satellite lots and lots of satellite trails, and they are generally straight lines.  I was thinking that these satellites just happened to coincide with some strong gusts.

 

-Wade

 

From: main@ap-gto.groups.io <main@ap-gto.groups.io> On Behalf Of Roland Christen via groups.io
Sent: Tuesday, July 20, 2021 4:32 PM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Imaging in the Wind

 

You can unplug the encoders and see what you get.

 

I got 30mph wind gusts here last couple of days with my 175 refractor on a 1600 encoder mount. Got round stars. Was watching the autoguider graph and saw only 1 arc sec or so deviations during a gust.

 

Rolando

-----Original Message-----
From: W Hilmo <y.groups@...>
To: main@ap-gto.groups.io
Sent: Tue, Jul 20, 2021 1:25 pm
Subject: [ap-gto] Imaging in the Wind

I've been doing a bunch of experimenting to transition from guided imaging with an SCT, to unguided imaging with a first class refractor.  Coincident to this, I'm imaging in a particularly windy area, which I moved to a few months before I received my AP130GTX.  Previously, I lived in an area with lots of overcast, but little wind.  It was also sheltered by being completely surrounded by forest.  My current location is wide open and completely unsheltered from the wind.

As mentioned, the scope is an AP130GTX.  The mount is an AP1600 with Absolute Encoders.  I'm finding that on calm nights (which are rare this time of year), I get nice, round stars at 10 minutes unguided.  With our typical winds, which are around 30mph over night, I get blobby and elongated stars.  Last night was windy, so the subs were all soft, with poor eccentricity.  I'm trying to determine how much of my soft stars are the the result of turbulence higher up, versus the mount and scope getting buffeted by the wind.

When I was blinking through the subs, I found the image that I've attached below.  It's interesting because there are crossing satellite trails at very different angles, that show signs of significant vibration.  I am guessing that what is happening here, is that the system is getting buffeted by winds, and the jaggies are due to the absolute encoders trying to quickly make corrections.  But I would be interested in other thoughts.

For tonight, I'm going to image the same field, but I've parked my motorhome up wind of the mount to act as a block.  The motorhome is parked 90 degrees to the prevailing wind, and is as close as I can get it while still keeping the roof at about 20 degrees elevation from the scope.  We are forecast for similar winds tonight, and the wind today seems consistent with yesterday.  I'll be curious to see if the results improve.  I'm not sure yet if turbulence as wind goes over and around the motorhome will be more than offset by sheltering the mount.

I am planning for an observatory, and have been thinking all along of a roll-off roof.  I suppose that if tonight's data looks good, perhaps I should be thinking about a dome.  Since I'm not planning on building the observatory until next year, I am also planning on experimenting with different wind blocks (presuming I can find something less than the motorhome, which can stand up to our winds on a regular basis).

If anyone else has dealt with this, I would be interested in how people have dealt with this.  I suppose that I could switch to only wide field imaging during the windiest times of the year, but if possible, I would like to mitigate things.

-Wade


--
Roland Christen
Astro-Physics

Attachments:

Attachments:


Robert Chozick
 

Yes. 

Robert 


On Jul 22, 2021, at 7:24 PM, W Hilmo <y.groups@...> wrote:



Thanks for that.

 

It looks like all of the rigidity is from guy wires, correct?

 

From: main@ap-gto.groups.io <main@ap-gto.groups.io> On Behalf Of Robert Chozick via groups.io
Sent: Thursday, July 22, 2021 4:26 PM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Imaging in the Wind

 

 

Picture of wind shelter 

Robert 

 



On Jul 22, 2021, at 5:45 PM, Robert Chozick via groups.io <rchozick@...> wrote:

The temporary conduit solution works very well and is anchored with stakes and ropes. We use this at the Okie Tex star party and get gusts close to 60 miles an hour all the time setting up for a weeks time. You can set up the conduit and tarp shelter in less than an hour and it’s stores in a small area. I will find some pictures and send them. 

Robert 

 



On Jul 22, 2021, at 3:40 PM, W Hilmo <y.groups@...> wrote:



I think so, too.

 

The problem is that my wife would prefer if I not sink fence posts into concrete for a temporary solution.  My fear is that without a really solid anchor, our wind would simply blow it away.  We’ve been seeing 30ish mph for the last couple of weeks, but it can get significantly higher than that with little warning.

 

Also, if the fence were upwind, which is would need to be to function, any wind strong enough to move it, would blow it right into the scope.

 

From: main@ap-gto.groups.io <main@ap-gto.groups.io> On Behalf Of Robert Chozick via groups.io
Sent: Thursday, July 22, 2021 11:25 AM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Imaging in the Wind

 

A simple fence enclosure model would help greatly. 

Robert 

 




On Jul 22, 2021, at 1:04 PM, W Hilmo <y.groups@...> wrote:



I just wanted to follow up and say that using the motorhome as a wind block made a huge difference.

 

Based on the below results with the 175 refractor, I assume at this point that the mount itself is probably not the issue.  I have the rig set up on ground that is quite solid, and am using the 10” diameter portable field pier.  The pier height is 32” from the ground.

 

I’m wondering if the issue is that I leave the mount set up on the pier all the time.  In the last couple of weeks, our temperature has varied between 45F and 115F.  I suspect that the thermal cycling may affect the turn buckles.  It seems like they could be tighter than they are (although I find that if I tighten too much, it bends the hooks at the end of the turn buckles so that they open up).  I don’t adjust them often because I have a really good APPM model, and would need to recreate it each time.

 

I have plans for an observatory with a proper pier with a deep underground footing, but that won’t be until sometime next year at the earliest.  I’m going to need to find a temporary solution for between now and then. 

 

From: main@ap-gto.groups.io <main@ap-gto.groups.io> On Behalf Of W Hilmo
Sent: Tuesday, July 20, 2021 4:44 PM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Imaging in the Wind

 

Interesting.  If I can get tracking like you are seeing, that would be great.  If I unplug the encoders, I’ll either need to set up guiding or program a PEM curve.

 

Out of curiosity, what you are using for a pier?  I am using the portable field pier, and if the whole thing is shaking, perhaps I could tighten the turnbuckles a bit.


Oh, and one other thing that may be interesting, or may be nothing, I never get tight stars that are elongated.  I either get tight, round stars, or I get big elongated blobs.  I also get satellite lots and lots of satellite trails, and they are generally straight lines.  I was thinking that these satellites just happened to coincide with some strong gusts.

 

-Wade

 

From: main@ap-gto.groups.io <main@ap-gto.groups.io> On Behalf Of Roland Christen via groups.io
Sent: Tuesday, July 20, 2021 4:32 PM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Imaging in the Wind

 

You can unplug the encoders and see what you get.

 

I got 30mph wind gusts here last couple of days with my 175 refractor on a 1600 encoder mount. Got round stars. Was watching the autoguider graph and saw only 1 arc sec or so deviations during a gust.

 

Rolando

-----Original Message-----
From: W Hilmo <y.groups@...>
To: main@ap-gto.groups.io
Sent: Tue, Jul 20, 2021 1:25 pm
Subject: [ap-gto] Imaging in the Wind

I've been doing a bunch of experimenting to transition from guided imaging with an SCT, to unguided imaging with a first class refractor.  Coincident to this, I'm imaging in a particularly windy area, which I moved to a few months before I received my AP130GTX.  Previously, I lived in an area with lots of overcast, but little wind.  It was also sheltered by being completely surrounded by forest.  My current location is wide open and completely unsheltered from the wind.

As mentioned, the scope is an AP130GTX.  The mount is an AP1600 with Absolute Encoders.  I'm finding that on calm nights (which are rare this time of year), I get nice, round stars at 10 minutes unguided.  With our typical winds, which are around 30mph over night, I get blobby and elongated stars.  Last night was windy, so the subs were all soft, with poor eccentricity.  I'm trying to determine how much of my soft stars are the the result of turbulence higher up, versus the mount and scope getting buffeted by the wind.

When I was blinking through the subs, I found the image that I've attached below.  It's interesting because there are crossing satellite trails at very different angles, that show signs of significant vibration.  I am guessing that what is happening here, is that the system is getting buffeted by winds, and the jaggies are due to the absolute encoders trying to quickly make corrections.  But I would be interested in other thoughts.

For tonight, I'm going to image the same field, but I've parked my motorhome up wind of the mount to act as a block.  The motorhome is parked 90 degrees to the prevailing wind, and is as close as I can get it while still keeping the roof at about 20 degrees elevation from the scope.  We are forecast for similar winds tonight, and the wind today seems consistent with yesterday.  I'll be curious to see if the results improve.  I'm not sure yet if turbulence as wind goes over and around the motorhome will be more than offset by sheltering the mount.

I am planning for an observatory, and have been thinking all along of a roll-off roof.  I suppose that if tonight's data looks good, perhaps I should be thinking about a dome.  Since I'm not planning on building the observatory until next year, I am also planning on experimenting with different wind blocks (presuming I can find something less than the motorhome, which can stand up to our winds on a regular basis).

If anyone else has dealt with this, I would be interested in how people have dealt with this.  I suppose that I could switch to only wide field imaging during the windiest times of the year, but if possible, I would like to mitigate things.

-Wade


--
Roland Christen
Astro-Physics

Attachments:

Attachments:


Len Fulham
 

I would like to make a comment re wind barrier and effectiveness.  With a impervious barrier such as a metal fence or tarp, there can be quite high forces applied to the structure and a lot of turbulence in the air as wind rolls in behind the barrier. It is my understanding that a barrier with perforations suppresses wind and reduces the turbulence effects and lowers the forces acting on the structure. Coarsely applied, this can be seen in canvas signs which often have holes cut in them. I have seen good effects from shade cloth and fly screen used in this role.

If anyone is making a tarp based barrier for portable use it is a simple process to try the fly mesh or a fairly open shade cloth instead of a tight material like a tarp. If the purpose is mainly as a light barrier then a opaque sheet would be preferred of course.

Just another idea to make your choices harder!

Len.


Robert Chozick
 

We have found that the smaller the structure the less this effect you mention applies.   8x8 seems to be optimal.   Light is always a concern for me.   


On Jul 23, 2021, at 7:53 AM, Len Fulham <lfulham@...> wrote:

I would like to make a comment re wind barrier and effectiveness.  With a impervious barrier such as a metal fence or tarp, there can be quite high forces applied to the structure and a lot of turbulence in the air as wind rolls in behind the barrier. It is my understanding that a barrier with perforations suppresses wind and reduces the turbulence effects and lowers the forces acting on the structure. Coarsely applied, this can be seen in canvas signs which often have holes cut in them. I have seen good effects from shade cloth and fly screen used in this role.

If anyone is making a tarp based barrier for portable use it is a simple process to try the fly mesh or a fairly open shade cloth instead of a tight material like a tarp. If the purpose is mainly as a light barrier then a opaque sheet would be preferred of course.

Just another idea to make your choices harder!

Len.


W Hilmo
 

Thanks again for the suggestions.

 

I’m thinking that I’ll probably build an 8x8, 6’ tall barrier that surrounds most of the site where I’m currently setting up.  I was already thinking about going with some kind of screen, instead of impermeable tarps.

 

I’m also thinking about the earlier comment about the turnbuckles in the wind.  I grew up sailing in the Seattle area, so I am very familiar with what happens to the rigging on the boat.  I’ve been thinking that wind hitting the scope was the problem, but it’s certainly possible that the wind is getting the turnbuckles to vibrate.

 

From: main@ap-gto.groups.io <main@ap-gto.groups.io> On Behalf Of Robert Chozick via groups.io
Sent: Friday, July 23, 2021 7:14 AM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Imaging in the Wind

 

We have found that the smaller the structure the less this effect you mention applies.   8x8 seems to be optimal.   Light is always a concern for me.   



On Jul 23, 2021, at 7:53 AM, Len Fulham <lfulham@...> wrote:

I would like to make a comment re wind barrier and effectiveness.  With a impervious barrier such as a metal fence or tarp, there can be quite high forces applied to the structure and a lot of turbulence in the air as wind rolls in behind the barrier. It is my understanding that a barrier with perforations suppresses wind and reduces the turbulence effects and lowers the forces acting on the structure. Coarsely applied, this can be seen in canvas signs which often have holes cut in them. I have seen good effects from shade cloth and fly screen used in this role.

If anyone is making a tarp based barrier for portable use it is a simple process to try the fly mesh or a fairly open shade cloth instead of a tight material like a tarp. If the purpose is mainly as a light barrier then a opaque sheet would be preferred of course.

Just another idea to make your choices harder!

Len.


John Love
 
Edited

I have found my SkyBox to be a real "game changer" since I built the first one in 2008.  I am often imaging at windy star parties after everyone else has given up and gone to bed.  Screen tarps would reduce wind loading on the structure but the frame is quite rigid when the tarps are installed and the tied downs keep the structure anchored to the ground.  I prefer the regular tarps to block stray light as well as wind.  During a recent trip to my dark site my 6x10x6H SkyBox withstood a 53 mph wind gust and sustained winds of about 45 mph.   The next night I took this image of NGC5033 with 25 mph wind with a 10" RC @ 2000mm / ASI-533MCp on my AP900.