Celestial Whale


Roland Christen
 

Had 3 good clear and steady nights which allowed me to capture the Whale galaxy (although it looks more like a Sardine to me).
Used the AP 10" F14.6 Mak-Cass with our simple CCDT67 telecompressor to attain F10 focal ratio.

The Mach2 mount was purposely polar misaligned so I could test my keypad's simple Drift Model. With drift compensation on, I used the guider to nudge the mount at very low aggressiveness for each of the 20 minute exposures. Average guiding varied between 0.15 to 0.25 arc sec RMS.

Could have gone an hour for each exposure, but the light pollution is overwhelming here. Trying to remove the gradients and the background sky light noise was a real challenge.

https://www.astrobin.com/xricwg/

--
Roland Christen
Astro-Physics


Dean Jacobsen
 

Nicely done!
--
Dean Jacobsen
Astrobin Image Gallery - https://www.astrobin.com/users/deanjacobsen/


Edward Beshore
 

This is quite impressive at only 70” across, resolving stars at the edge of the galaxy. Unguided! 

I  put my name on the list for a Mach 2 a couple of months ago. I’m going to have to start exercising to make sure I’m around to enjoy it… 


Roland Christen
 

Well, not totally unguided, rather it is nudge guided Smile It's like a horse that follows the trail but every once in a while you have to spur it along when it stops to eat grass off the side of the trail.

Rolando



-----Original Message-----
From: Edward Beshore via groups.io <ebeshore@...>
To: main@ap-gto.groups.io
Sent: Fri, May 14, 2021 8:02 am
Subject: Re: [ap-gto] Celestial Whale

This is quite impressive at only 70” across, resolving stars at the edge of the galaxy. Unguided! 
I  put my name on the list for a Mach 2 a couple of months ago. I’m going to have to start exercising to make sure I’m around to enjoy it… 

--
Roland Christen
Astro-Physics


Dean Jacobsen
 

Roland, I know that you have discussed nudge guiding here several times but have you posted a write up on your method somewhere on the AP site that we can copy and use as a reference?
--
Dean Jacobsen
Astrobin Image Gallery - https://www.astrobin.com/users/deanjacobsen/


Roland Christen
 

It's really simple. And it's a keypad thing, for the most part for people who set up in the field and don't want to spend a lot of time polar aligning.

So basically you pick your object at the beginning of your session, start guiding and start taking images. Just as you would normally do. Then, as the mount is guiding, you start the drift model and press Enter. Wait 5 to 10 minutes and press Enter again. Then exit the model and turn the model compensation on. Your drift model will begin adjusting the sidereal and Dec tracking rate so that the guide star basically stays put and all you need are occasional steering bumps with your guiding software. You can turn down the aggressiveness to around 3 or 4 and take longish guide exposures to avoid chasing the seeing.

After an hour or so you can repeat the process. Use "Add To Model" to establish another model term and just continue to image while the mount is gathering data for the model. You can add any number of points for any other objects during the night or during subsequent sessions as long as you don't disturb the mount setup.

Bump guiding is simply another way you can use the model tool.

Rolando



-----Original Message-----
From: Dean Jacobsen <deanjacobsen@...>
To: main@ap-gto.groups.io
Sent: Fri, May 14, 2021 11:06 am
Subject: Re: [ap-gto] Celestial Whale

Roland, I know that you have discussed nudge guiding here several times but have you posted a write up on your method somewhere on the AP site that we can copy and use as a reference?
--
Dean Jacobsen
Astrobin Image Gallery - https://www.astrobin.com/users/deanjacobsen/

--
Roland Christen
Astro-Physics


Worsel
 

Roland

That's amazing performance.  Do you have an idea how polar mis-aligned the setup was, even qualitatively?

Bryan


Roland Christen
 

I can't quantify it in terms of polar misalignment, but the Dec drift was about 2 arc sec per minute. That's about 10 times higher than what I would normally want.

Rolando

-----Original Message-----
From: Worsel via groups.io <bryancashion@...>
To: main@ap-gto.groups.io
Sent: Fri, May 14, 2021 1:49 pm
Subject: Re: [ap-gto] Celestial Whale

Roland

That's amazing performance.  Do you have an idea how polar mis-aligned the setup was, even qualitatively?

Bryan

--
Roland Christen
Astro-Physics


Jeff B
 

Yeah I'm curious too but I also imagine the software can tell you too.


On Fri, May 14, 2021 at 2:51 PM Worsel via groups.io <bryancashion=yahoo.com@groups.io> wrote:
Roland

That's amazing performance.  Do you have an idea how polar mis-aligned the setup was, even qualitatively?

Bryan


Roland Christen
 

MaximDL has no way to tell. However it has a nifty tool that I developed to get the drift to zero in just a few minutes.

Rolando



-----Original Message-----
From: Jeff B <mnebula946@...>
To: main@ap-gto.groups.io
Sent: Fri, May 14, 2021 2:02 pm
Subject: Re: [ap-gto] Celestial Whale

Yeah I'm curious too but I also imagine the software can tell you too.

On Fri, May 14, 2021 at 2:51 PM Worsel via groups.io <bryancashion=yahoo.com@groups.io> wrote:
Roland

That's amazing performance.  Do you have an idea how polar mis-aligned the setup was, even qualitatively?

Bryan

--
Roland Christen
Astro-Physics


Don Anderson
 

And what is that?

Don Anderson


On Friday, May 14, 2021, 02:01:23 p.m. MDT, Roland Christen via groups.io <chris1011@...> wrote:


MaximDL has no way to tell. However it has a nifty tool that I developed to get the drift to zero in just a few minutes.

Rolando



-----Original Message-----
From: Jeff B <mnebula946@...>
To: main@ap-gto.groups.io
Sent: Fri, May 14, 2021 2:02 pm
Subject: Re: [ap-gto] Celestial Whale

Yeah I'm curious too but I also imagine the software can tell you too.

On Fri, May 14, 2021 at 2:51 PM Worsel via groups.io <bryancashion=yahoo.com@groups.io> wrote:
Roland

That's amazing performance.  Do you have an idea how polar mis-aligned the setup was, even qualitatively?

Bryan

--
Roland Christen
Astro-Physics


Roland Christen
 

Start with my quick and easy daylight polar alignment (Park4, level etc.). Use your main imaging camera with H-a filter and send the mount to a bright star overhead. Use a wide field short FL scope (no SCTs). Have the camera aligned so that left-right is RA and up-down is Dec.

1) pull up the crosshair in MaximDL
2) Put the star on the crosshair and watch it drift for about 2 minutes. Use continuous mode and note the exact pixel where it ended up after 2 minutes.
3) Turn the azimuth adjuster until the star is at one end of your frame (left or right). Using your up-down slo-mo buttons, put the star back on the crosshair (not the center but at the edge).
4) Watch it drift for same exact amount of time. Note the exact pixel where it ended up.

Draw a line between the 2 end positions. Where it intersects the left-right crosshair is where you want to put this star using the azimuth adjusters.

I take two images of the star's positions and layer one on top of the other so that both stars can be seen. Then use a line tool to draw the line between them.

Rolando





-----Original Message-----
From: Don Anderson via groups.io <jockey_ca@...>
To: main@ap-gto.groups.io <main@ap-gto.groups.io>
Sent: Fri, May 14, 2021 5:56 pm
Subject: Re: [ap-gto] Celestial Whale

And what is that?

Don Anderson


On Friday, May 14, 2021, 02:01:23 p.m. MDT, Roland Christen via groups.io <chris1011@...> wrote:


MaximDL has no way to tell. However it has a nifty tool that I developed to get the drift to zero in just a few minutes.

Rolando



-----Original Message-----
From: Jeff B <mnebula946@...>
To: main@ap-gto.groups.io
Sent: Fri, May 14, 2021 2:02 pm
Subject: Re: [ap-gto] Celestial Whale

Yeah I'm curious too but I also imagine the software can tell you too.

On Fri, May 14, 2021 at 2:51 PM Worsel via groups.io <bryancashion=yahoo.com@groups.io> wrote:
Roland

That's amazing performance.  Do you have an idea how polar mis-aligned the setup was, even qualitatively?

Bryan

--
Roland Christen
Astro-Physics

--
Roland Christen
Astro-Physics


Don Anderson
 

Thanks Rolando! I'll try that with my Tele Vue NP127is using the .8X reducer (528mm f/l). I can use your procedure to fine tune the calibration on my RAPAS.

Don Anderson


On Friday, May 14, 2021, 06:15:18 p.m. MDT, Roland Christen via groups.io <chris1011@...> wrote:


Start with my quick and easy daylight polar alignment (Park4, level etc.). Use your main imaging camera with H-a filter and send the mount to a bright star overhead. Use a wide field short FL scope (no SCTs). Have the camera aligned so that left-right is RA and up-down is Dec.

1) pull up the crosshair in MaximDL
2) Put the star on the crosshair and watch it drift for about 2 minutes. Use continuous mode and note the exact pixel where it ended up after 2 minutes.
3) Turn the azimuth adjuster until the star is at one end of your frame (left or right). Using your up-down slo-mo buttons, put the star back on the crosshair (not the center but at the edge).
4) Watch it drift for same exact amount of time. Note the exact pixel where it ended up.

Draw a line between the 2 end positions. Where it intersects the left-right crosshair is where you want to put this star using the azimuth adjusters.

I take two images of the star's positions and layer one on top of the other so that both stars can be seen. Then use a line tool to draw the line between them.

Rolando





-----Original Message-----
From: Don Anderson via groups.io <jockey_ca@...>
To: main@ap-gto.groups.io <main@ap-gto.groups.io>
Sent: Fri, May 14, 2021 5:56 pm
Subject: Re: [ap-gto] Celestial Whale

And what is that?

Don Anderson


On Friday, May 14, 2021, 02:01:23 p.m. MDT, Roland Christen via groups.io <chris1011@...> wrote:


MaximDL has no way to tell. However it has a nifty tool that I developed to get the drift to zero in just a few minutes.

Rolando



-----Original Message-----
From: Jeff B <mnebula946@...>
To: main@ap-gto.groups.io
Sent: Fri, May 14, 2021 2:02 pm
Subject: Re: [ap-gto] Celestial Whale

Yeah I'm curious too but I also imagine the software can tell you too.

On Fri, May 14, 2021 at 2:51 PM Worsel via groups.io <bryancashion=yahoo.com@groups.io> wrote:
Roland

That's amazing performance.  Do you have an idea how polar mis-aligned the setup was, even qualitatively?

Bryan

--
Roland Christen
Astro-Physics

--
Roland Christen
Astro-Physics