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Re: APPC refraction correction question

Dean Jacobsen
 

On Fri, Jul 31, 2020 at 08:47 PM, Craig Young wrote:
Looks like 3 arcs works very well, do you know if 2 arcs works?
Craig, I have been using three lines only.
 
--
Dean Jacobsen
http://astrophoto.net/wp/
Image Gallery - http://astrophoto.net/wp/image-gallery/
Astrobin - https://www.astrobin.com/users/deanjacobsen/ 
Re: large alignment error with polemaster & mach2

Cheng-Yang Tan
 

Yes, I’ve used PM camera with SC. As long as SC can platesolve the image, it can calculate where to move the mount. 


Sent from Yahoo Mail for iPad

On Saturday, August 1, 2020, 8:41 AM, Andrea Lucchetti <andlucchett@...> wrote:

Hi, I Will check SC But it seems it works within a narrower fov. Did you try it with pole master camera right?
Thank you,
Andrea

Il giorno sab 1 ago 2020 alle 15:22 Cheng-Yang Tan via groups.io <cytan299=yahoo.com@groups.io> ha scritto:
PS, if you plan to use a guide scope rather than run unguided, SC works with your guide scope. And with higher magnification than the PM scope, SC should give an even better PA.


Sent from Yahoo Mail for iPad

On Saturday, August 1, 2020, 8:18 AM, Cheng-Yang Tan via groups.io <cytan299=yahoo.com@groups.io> wrote:

I’d suggest trying Sharpcap with the Polemaster camera. I’ve always found Sharpcap gives a better PA than the Polemaster software. An advantage of SC is that it gives an alignment error when you are adjusting alt and az which is absent in PM software.

Unfortunately, SC polar alignment costs $ and is an annual subscription, but it’s cheap.

As usual YMMV

cytan


Sent from Yahoo Mail for iPad

On Saturday, August 1, 2020, 7:51 AM, Andrea Lucchetti <andlucchett@...> wrote:

Hello,
I need to polar align my Mach 2 very quickly to save time on field.
I thought Polemaster would have been a good choice but I cant get a good alignment with it (I am ways off)
The procedure goes very well, till the end, including the precise alignment step, but I have drift in my images.
running the Polemaster twice results in a small change.


I am not using the refraction calculation , as I leave at 42 deg latitude: can this be one of the reason?

my aim is to shoot 10 min subs unguided (@790mm focal and 1,6 arcsec/pixel resolution).

I still don't have my OTA ready so it is difficult for me to check with the drift method for the time being ( I can borrow a dslr and C8)

Would the RAPAS be a better solution for my needs? 
I understand it can be mounted on the MACH2 using a dovetail, with repeatable accuracy.
Is the accuracy enough for imaging and how it compares to Polemaster?

Thank you,
Andrea

Re: large alignment error with polemaster & mach2

Dean Jacobsen
 

+1 for SharpCap.  I use it through my main imaging camera.

I had been using the RAPAS on the adapter for the Mach2 but i have been having trouble with getting repeatably consistent results.  Probably user error on my part.

SharpCap has been working well for me and it is quick.
--
Dean Jacobsen
http://astrophoto.net/wp/
Image Gallery - http://astrophoto.net/wp/image-gallery/
Astrobin - https://www.astrobin.com/users/deanjacobsen/ 
Re: large alignment error with polemaster & mach2

Andrea Lucchetti
 

Hi, I Will check SC But it seems it works within a narrower fov. Did you try it with pole master camera right?
Thank you,
Andrea

Il giorno sab 1 ago 2020 alle 15:22 Cheng-Yang Tan via groups.io <cytan299=yahoo.com@groups.io> ha scritto:
PS, if you plan to use a guide scope rather than run unguided, SC works with your guide scope. And with higher magnification than the PM scope, SC should give an even better PA.


Sent from Yahoo Mail for iPad

On Saturday, August 1, 2020, 8:18 AM, Cheng-Yang Tan via groups.io <cytan299=yahoo.com@groups.io> wrote:

I’d suggest trying Sharpcap with the Polemaster camera. I’ve always found Sharpcap gives a better PA than the Polemaster software. An advantage of SC is that it gives an alignment error when you are adjusting alt and az which is absent in PM software.

Unfortunately, SC polar alignment costs $ and is an annual subscription, but it’s cheap.

As usual YMMV

cytan


Sent from Yahoo Mail for iPad

On Saturday, August 1, 2020, 7:51 AM, Andrea Lucchetti <andlucchett@...> wrote:

Hello,
I need to polar align my Mach 2 very quickly to save time on field.
I thought Polemaster would have been a good choice but I cant get a good alignment with it (I am ways off)
The procedure goes very well, till the end, including the precise alignment step, but I have drift in my images.
running the Polemaster twice results in a small change.


I am not using the refraction calculation , as I leave at 42 deg latitude: can this be one of the reason?

my aim is to shoot 10 min subs unguided (@790mm focal and 1,6 arcsec/pixel resolution).

I still don't have my OTA ready so it is difficult for me to check with the drift method for the time being ( I can borrow a dslr and C8)

Would the RAPAS be a better solution for my needs? 
I understand it can be mounted on the MACH2 using a dovetail, with repeatable accuracy.
Is the accuracy enough for imaging and how it compares to Polemaster?

Thank you,
Andrea

Re: large alignment error with polemaster & mach2

Andrea Lucchetti
 

Thank you for the feedback
Andrea

Il giorno sab 1 ago 2020 alle 14:56 Michael Hambrick via groups.io <mike.hambrick=arlanxeo.com@groups.io> ha scritto:

I can't speak for the Polemaster, but I have a RAPAS that I bought with my 1100 mount and it is very reliable, quick, and accurate enough for imaging. I set my mount up and take it down every night, and I don't have time to do any kind of drift alignment.


Best Regards

Michael Hambrick
ARLANXEO
TSR Global Manufacturing Support
PO Box 2000
Orange, TX 77631-2000
Phone: +1 (409) 882-2799
email: mike.hambrick@...

Re: large alignment error with polemaster & mach2

Cheng-Yang Tan
 

PS, if you plan to use a guide scope rather than run unguided, SC works with your guide scope. And with higher magnification than the PM scope, SC should give an even better PA.


Sent from Yahoo Mail for iPad

On Saturday, August 1, 2020, 8:18 AM, Cheng-Yang Tan via groups.io <cytan299@...> wrote:

I’d suggest trying Sharpcap with the Polemaster camera. I’ve always found Sharpcap gives a better PA than the Polemaster software. An advantage of SC is that it gives an alignment error when you are adjusting alt and az which is absent in PM software.

Unfortunately, SC polar alignment costs $ and is an annual subscription, but it’s cheap.

As usual YMMV

cytan


Sent from Yahoo Mail for iPad

On Saturday, August 1, 2020, 7:51 AM, Andrea Lucchetti <andlucchett@...> wrote:

Hello,
I need to polar align my Mach 2 very quickly to save time on field.
I thought Polemaster would have been a good choice but I cant get a good alignment with it (I am ways off)
The procedure goes very well, till the end, including the precise alignment step, but I have drift in my images.
running the Polemaster twice results in a small change.


I am not using the refraction calculation , as I leave at 42 deg latitude: can this be one of the reason?

my aim is to shoot 10 min subs unguided (@790mm focal and 1,6 arcsec/pixel resolution).

I still don't have my OTA ready so it is difficult for me to check with the drift method for the time being ( I can borrow a dslr and C8)

Would the RAPAS be a better solution for my needs? 
I understand it can be mounted on the MACH2 using a dovetail, with repeatable accuracy.
Is the accuracy enough for imaging and how it compares to Polemaster?

Thank you,
Andrea

Re: large alignment error with polemaster & mach2

Cheng-Yang Tan
 

I’d suggest trying Sharpcap with the Polemaster camera. I’ve always found Sharpcap gives a better PA than the Polemaster software. An advantage of SC is that it gives an alignment error when you are adjusting alt and az which is absent in PM software.

Unfortunately, SC polar alignment costs $ and is an annual subscription, but it’s cheap.

As usual YMMV

On Saturday, August 1, 2020, 7:51 AM, Andrea Lucchetti <andlucchett@...> wrote:

Hello,
I need to polar align my Mach 2 very quickly to save time on field.
I thought Polemaster would have been a good choice but I cant get a good alignment with it (I am ways off)
The procedure goes very well, till the end, including the precise alignment step, but I have drift in my images.
running the Polemaster twice results in a small change.


I am not using the refraction calculation , as I leave at 42 deg latitude: can this be one of the reason?

my aim is to shoot 10 min subs unguided (@790mm focal and 1,6 arcsec/pixel resolution).

I still don't have my OTA ready so it is difficult for me to check with the drift method for the time being ( I can borrow a dslr and C8)

Would the RAPAS be a better solution for my needs? 
I understand it can be mounted on the MACH2 using a dovetail, with repeatable accuracy.
Is the accuracy enough for imaging and how it compares to Polemaster?

Thank you,
Andrea

Re: large alignment error with polemaster & mach2

Michael Hambrick <mike.hambrick@...>
 

I can't speak for the Polemaster, but I have a RAPAS that I bought with my 1100 mount and it is very reliable, quick, and accurate enough for imaging. I set my mount up and take it down every night, and I don't have time to do any kind of drift alignment.


Best Regards

Michael Hambrick
ARLANXEO
TSR Global Manufacturing Support
PO Box 2000
Orange, TX 77631-2000
Phone: +1 (409) 882-2799
email: mike.hambrick@...
large alignment error with polemaster & mach2

Andrea Lucchetti
 

Hello,
I need to polar align my Mach 2 very quickly to save time on field.
I thought Polemaster would have been a good choice but I cant get a good alignment with it (I am ways off)
The procedure goes very well, till the end, including the precise alignment step, but I have drift in my images.
running the Polemaster twice results in a small change.


I am not using the refraction calculation , as I leave at 42 deg latitude: can this be one of the reason?

my aim is to shoot 10 min subs unguided (@790mm focal and 1,6 arcsec/pixel resolution).

I still don't have my OTA ready so it is difficult for me to check with the drift method for the time being ( I can borrow a dslr and C8)

Would the RAPAS be a better solution for my needs? 
I understand it can be mounted on the MACH2 using a dovetail, with repeatable accuracy.
Is the accuracy enough for imaging and how it compares to Polemaster?

Thank you,
Andrea
Re: Planet Tracking and Imaging #Mach2GTO #APCC

thefamily90 Phillips
 

You do not need superb polar alignment/tracking to image the Moon and Planets. Using a webcam like ZWO and their firecapture software, you just get the image on your laptop screen and as long as you can keep the image somewhere on the screen while imaging(using the keypad at 1X) you have all you need. Then you stack the individual images in Registax or Autostakkert, use wavelets in Registax to sharpen the image and there you have it. Registax or Autostakkert will align the images no matter how much movement there is on the screen. Photoshop to polish it off.

Jim

Image.jpeg
Get Outlook for iOS
From: main@ap-gto.groups.io <main@ap-gto.groups.io> on behalf of Greg Vaughn <gregvaughn@...>
Sent: Friday, July 31, 2020 11:33:26 PM
To: main@ap-gto.groups.io <main@ap-gto.groups.io>
Subject: [ap-gto] Planet Tracking and Imaging #Mach2GTO #APCC
 
This is a question for Ray Gralak after watching his July 2016 video about Horizons again.  The question and/or response may be of interest to others as well.

Hi Ray,

in your Horizons video you mention downloading ephemeris data for Mars as an example of what Horizons can be used for - beyond tracking comets.  If I'm going to use the Mach 1 or Mach 2 to image Jupiter, Saturn or Mars, can I download ephemeris data for them in Horizons, do an APPM model and then reasonably expect to be able to track one of the planets with enough precision for good lucky (video) imaging.   Does it make a difference between the Mach 1 or Mach 2.   

I know there are some changes coming with the new keypad software, but the question is for an attempt to image the planets while they are still in my field of view and with a very long effective focal length (~5,700-11,400mm)  - using an 11in Edge HD and a barlow or PowerMate (2X-4X).  Using a ZWO ASI 174 OSC, the image scale would be about .212 to .106 arcsec/pixel while for the ZWO 1600MM it would be .138 to .069 - if I've calculated these correctly.  At any rate, they would need very accurate tracking during the length of the video which for Jupiter would be about 30sec if I remember correctly.

I've been focused on nebulae targets, but would like to shift scopes and catch the planets before they are gone. (I know I'm running a little late already.)

Thanks in advance for any insights from you on how best to leverage APCC for this task and any critiques on my thought process and setup.

Cheers,
Greg

p.s.  I'm limited in my views of the planets to the azimuthal range of about 110-185 deg true, so my APPM model is primarily an East model.

Re: APPC refraction correction question

Konstantin von Poschinger
 

Hi,

as I have tested a single line DEC arc is not working! I have done this night a 3 line one and got round stars eaven with 900 sec images!

Grüsse

Konstantin v. Poschinger


Hammerichstr. 5
22605 Hamburg
040/8805747
0171/1983476

Am 31.07.2020 um 21:43 schrieb Craig Young <craig.young.m8@...>:

I will give that a try on my next clear night.  First, I will create a new model with two DEC arcs, with the target DEC arc sitting between the two sample arcs.  That way the model straddles equally either side of the target arc.  Next, I will compare the tracking results: a) a single DEC arc model with refraction off, b) a single DEC arc model with refraction on and Offset error terms disabled, c) two DEC arc model with refraction enabled.  I'll come back here with the results after the test, hopefully soon.  If others are already doing this it would be good to add in their results to see which of these methods works best.  What we are looking for is the method providing the most accurate unguided imaging run, say a 1 hour run and looking at the quality of the stars (roundness) over that period (or tracking errors if using more analytic software like ATrack).

We can also use these test results as a benchmark for when Ray brings out the DEC arc feature in APPM.  So the more experience we can get from actual user experiences will help to evaluate the new feature and maybe provide some good feedback to Ray as he is designing the new feature.  The AP mounts are more than capable of reaching high performance unguided imaging over long periods of time with small plate scales.  What we need now is to perfect the methodology/software to match the hardware.

Craig

Re: [ap-ug] End of an era?

Michael Hambrick <mike.hambrick@...>
 

I have always been more into the imaging side of the hobby, but I will never forget the view through my 180EDT the night that Comet Shoemaker-Levy 9 impacted Jupiter. We had the scope out that night, but I had totally forgotten about the comet. I had just pointed the scope at Jupiter to give my wife something interesting to look at. When she looked through the eyepiece she asked what the black specs were in the clouds. At that point I immediately remembered about the comet. It was an amazing treat to be able to watch it "live".


Best Regards

Michael Hambrick
ARLANXEO
TSR Global Manufacturing Support
PO Box 2000
Orange, TX 77631-2000
Phone: +1 (409) 882-2799
email: mike.hambrick@...
Re: APPC refraction correction question

Craig Young
 

Hi Dean,
Thanks for sharing your tracking results using DEC arc modeling, this is very useful information for others looking to try it.  Looks like 3 arcs works very well, do you know if 2 arcs works?  Rolando is correct that it all comes down to the tracking error in arc seconds per minute x the plate scale:

Image Drift (pixels) = exposure time (seconds) x tracking error rate (arc seconds per second) / plate scale (arc seconds per pixel)

The greater the drift in the exposure (pixels) the more elongated the stars will appear.

Which means you can reduce stellar elongation by: a) reducing the exposure time, b) reducing the tracking error rate, or c) increasing the plate scale.

The new DEC arc modelling method does (b) which means for a given drift (star roundness in an image) you can now increase the image exposure time.  The equation also shows that putting a focal reducer into the optical path (increases the plate scale) can also reduce the image drift for a given exposure time and tracking error.

My plate scale is 0.5 arc seconds per pixel so you can see my system is about 4x more sensitive to tracking error than your system.

Craig
Re: End of an era?

Michael Hambrick <mike.hambrick@...>
 

Nice work Roland

Do you autograph all of the Stowaways ?


Best Regards

Michael Hambrick
ARLANXEO
TSR Global Manufacturing Support
PO Box 2000
Orange, TX 77631-2000
Phone: +1 (409) 882-2799
email: mike.hambrick@...
Planet Tracking and Imaging #Mach2GTO #APCC

Greg Vaughn
 

This is a question for Ray Gralak after watching his July 2016 video about Horizons again.  The question and/or response may be of interest to others as well.

Hi Ray,

in your Horizons video you mention downloading ephemeris data for Mars as an example of what Horizons can be used for - beyond tracking comets.  If I'm going to use the Mach 1 or Mach 2 to image Jupiter, Saturn or Mars, can I download ephemeris data for them in Horizons, do an APPM model and then reasonably expect to be able to track one of the planets with enough precision for good lucky (video) imaging.   Does it make a difference between the Mach 1 or Mach 2.   

I know there are some changes coming with the new keypad software, but the question is for an attempt to image the planets while they are still in my field of view and with a very long effective focal length (~5,700-11,400mm)  - using an 11in Edge HD and a barlow or PowerMate (2X-4X).  Using a ZWO ASI 174 OSC, the image scale would be about .212 to .106 arcsec/pixel while for the ZWO 1600MM it would be .138 to .069 - if I've calculated these correctly.  At any rate, they would need very accurate tracking during the length of the video which for Jupiter would be about 30sec if I remember correctly.

I've been focused on nebulae targets, but would like to shift scopes and catch the planets before they are gone. (I know I'm running a little late already.)

Thanks in advance for any insights from you on how best to leverage APCC for this task and any critiques on my thought process and setup.

Cheers,
Greg

p.s.  I'm limited in my views of the planets to the azimuthal range of about 110-185 deg true, so my APPM model is primarily an East model.
Re: [ap-ug] End of an era?

dvjbaja
 

Greatest scope ever from the AP line up.  Well done Roland! 


On Fri, Jul 31, 2020 at 5:58 PM Ben Lutch <procyon@...> wrote:

I hit 20 years on the Mark-Cass list earlier this month!

I found a used one many years ago; here's me using it in 2010:



On Fri, Jul 31, 2020 at 5:19 PM Harley Davidson <astrocnc@...> wrote:
Beautiful instrument Jim! I agree, just something about viewing the universe with your eyes.

tony

On 7/31/2020 6:46 PM, thefamily90 Phillips wrote:
Well, I have imaged the Moon and Planets with mine (earlier version) and could not be happier with its performance. I may be part of the end of the era of visual observations and am happy to say I have spent hours and hours at the eyepiece of telescopes. I can certainly image more detail on Jupiter with my 10??? than I can see but the longer I look the more I can see. And, in my opinion, very few images match the aesthetic beauty of Jupiter through the eyepiece of my telescope!

Jim Phillips??

Image.jpeg<main@ap-gto.groups.io> on behalf of Pete Lardizabal <p14@...>
Sent: Friday, July 31, 2020 6:32 PM
To: main@ap-ug.groups.io
Cc: main@ap-gto.groups.io
Subject: Re: [ap-gto] [ap-ug] End of an era?
??
WOW! Simply beautiful!

More rare than hens teeth...

????

Pete

On Jul 31, 2020, at 6:17 PM, Roland Christen via groups.io <chris1011@...> wrote:

???
Hi Astronuts,

Today I finished the last of the 10" F14.5 Maks, which will go to whoever is on our list. This is the last of my hand figured Maks that I plan to make of this size and focal length in production. It used to be that there was much more visual astronomy than there is today, probably because imaging was hard in the film days and for the first couple of years when we had small chips to do electronic imaging. Nowadays it is impossible to get visual views that remotely resemble what you can do with a few thousand bucks worth of electronic equipment.

That said, here is my last production Mak, aimed at a far distant telephone pole insulator which has a glint of sunshine that shows up as an artificial star. With a 5mm SPL ocular (737x) I see a tight high contrast Airy disc at focus. For those who don't know what that is - an Airy disc is the smallest resolvable spot from a distant point source that can be seen in any telescope. For a 10" it's approximately 4.5 arc seconds, and is surrounded by a few faint diffraction rings. With a scope like this I once saw the Sirius Pup in the Florida Keys when the separation was a mere 4 arc seconds.

<dummyfile.0.part>
Business end of the mighty Mak


<dummyfile.1.part>
Let there be light and minimal obstruction


<dummyfile.2.part>
The little Stowaway couldn't help hitching a ride on it's big sister
Re: [ap-ug] End of an era?

Ben Lutch
 


I hit 20 years on the Mark-Cass list earlier this month!

I found a used one many years ago; here's me using it in 2010:



On Fri, Jul 31, 2020 at 5:19 PM Harley Davidson <astrocnc@...> wrote:
Beautiful instrument Jim! I agree, just something about viewing the universe with your eyes.

tony

On 7/31/2020 6:46 PM, thefamily90 Phillips wrote:
Well, I have imaged the Moon and Planets with mine (earlier version) and could not be happier with its performance. I may be part of the end of the era of visual observations and am happy to say I have spent hours and hours at the eyepiece of telescopes. I can certainly image more detail on Jupiter with my 10??? than I can see but the longer I look the more I can see. And, in my opinion, very few images match the aesthetic beauty of Jupiter through the eyepiece of my telescope!

Jim Phillips??

Image.jpeg<main@ap-gto.groups.io> on behalf of Pete Lardizabal <p14@...>
Sent: Friday, July 31, 2020 6:32 PM
To: main@ap-ug.groups.io
Cc: main@ap-gto.groups.io
Subject: Re: [ap-gto] [ap-ug] End of an era?
??
WOW! Simply beautiful!

More rare than hens teeth...

????

Pete

On Jul 31, 2020, at 6:17 PM, Roland Christen via groups.io <chris1011@...> wrote:

???
Hi Astronuts,

Today I finished the last of the 10" F14.5 Maks, which will go to whoever is on our list. This is the last of my hand figured Maks that I plan to make of this size and focal length in production. It used to be that there was much more visual astronomy than there is today, probably because imaging was hard in the film days and for the first couple of years when we had small chips to do electronic imaging. Nowadays it is impossible to get visual views that remotely resemble what you can do with a few thousand bucks worth of electronic equipment.

That said, here is my last production Mak, aimed at a far distant telephone pole insulator which has a glint of sunshine that shows up as an artificial star. With a 5mm SPL ocular (737x) I see a tight high contrast Airy disc at focus. For those who don't know what that is - an Airy disc is the smallest resolvable spot from a distant point source that can be seen in any telescope. For a 10" it's approximately 4.5 arc seconds, and is surrounded by a few faint diffraction rings. With a scope like this I once saw the Sirius Pup in the Florida Keys when the separation was a mere 4 arc seconds.

<dummyfile.0.part>
Business end of the mighty Mak


<dummyfile.1.part>
Let there be light and minimal obstruction


<dummyfile.2.part>
The little Stowaway couldn't help hitching a ride on it's big sister
Re: APPC refraction correction question

Dean Jacobsen
 

So I guess I have tested my abbreviated all sky model at pixel scales of 2.47 to 1.48 arc seconds per pixel and every subexposure has looked good.
--
Dean Jacobsen
http://astrophoto.net/wp/
Image Gallery - http://astrophoto.net/wp/image-gallery/
Astrobin - https://www.astrobin.com/users/deanjacobsen/ 
Re: [ap-ug] End of an era?

Harley Davidson
 

Beautiful instrument Jim! I agree, just something about viewing the universe with your eyes.

tony

On 7/31/2020 6:46 PM, thefamily90 Phillips wrote:

Well, I have imaged the Moon and Planets with mine (earlier version) and could not be happier with its performance. I may be part of the end of the era of visual observations and am happy to say I have spent hours and hours at the eyepiece of telescopes. I can certainly image more detail on Jupiter with my 10??? than I can see but the longer I look the more I can see. And, in my opinion, very few images match the aesthetic beauty of Jupiter through the eyepiece of my telescope!

Jim Phillips??

Image.jpeg<main@ap-gto.groups.io> on behalf of Pete Lardizabal <p14@...>
Sent: Friday, July 31, 2020 6:32 PM
To: main@ap-ug.groups.io
Cc: main@ap-gto.groups.io
Subject: Re: [ap-gto] [ap-ug] End of an era?
??
WOW! Simply beautiful!

More rare than hens teeth...

????

Pete

On Jul 31, 2020, at 6:17 PM, Roland Christen via groups.io <chris1011@...> wrote:

???
Hi Astronuts,

Today I finished the last of the 10" F14.5 Maks, which will go to whoever is on our list. This is the last of my hand figured Maks that I plan to make of this size and focal length in production. It used to be that there was much more visual astronomy than there is today, probably because imaging was hard in the film days and for the first couple of years when we had small chips to do electronic imaging. Nowadays it is impossible to get visual views that remotely resemble what you can do with a few thousand bucks worth of electronic equipment.

That said, here is my last production Mak, aimed at a far distant telephone pole insulator which has a glint of sunshine that shows up as an artificial star. With a 5mm SPL ocular (737x) I see a tight high contrast Airy disc at focus. For those who don't know what that is - an Airy disc is the smallest resolvable spot from a distant point source that can be seen in any telescope. For a 10" it's approximately 4.5 arc seconds, and is surrounded by a few faint diffraction rings. With a scope like this I once saw the Sirius Pup in the Florida Keys when the separation was a mere 4 arc seconds.

<dummyfile.0.part>
Business end of the mighty Mak


<dummyfile.1.part>
Let there be light and minimal obstruction


<dummyfile.2.part>
The little Stowaway couldn't help hitching a ride on it's big sister
Re: APPC refraction correction question

Dean Jacobsen
 

That makes sense, thanks.  I literally learn something new every day by reading posts here.
--
Dean Jacobsen
http://astrophoto.net/wp/
Image Gallery - http://astrophoto.net/wp/image-gallery/
Astrobin - https://www.astrobin.com/users/deanjacobsen/ 
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