Re: APPC & Mach2: Dec Arc model results and RA drift connection? #APCC #Mach2GTO


Andrea Lucchetti
 

Thank you everyone for the helpful insights.
Next time I will play a bit with altitude/density.

In the long term I will also update the mirror cell from Orion UK to my design.
It should be a step further to control differential flexures.
a bit off topic but it is my baby :-)

Il giorno sab 19 nov 2022 alle ore 05:49 Bill Long <bill@...> ha scritto:
The modeling really is as good as people say it is. Here is a snip from my last OIII frame that just came in. This is 1:1 zoom, and as you can see these stars are excellent. 5 minute unguided subs, Mach 2 + Epsilon 160ED. Bravo to Ray and AP for making the best modeling and unguided experience there is in Astrophotography. 





From: main@ap-gto.groups.io <main@ap-gto.groups.io> on behalf of Bill Long <bill@...>
Sent: Friday, November 18, 2022 8:39 PM
To: main@ap-gto.groups.io <main@ap-gto.groups.io>
Subject: Re: [ap-gto] APPC & Mach2: Dec Arc model results and RA drift connection? #APCC #Mach2GTO
 
+1 for min altitude. Don't spend time on points in parts of the sky you will not be using for Dec Arc mode.



From: main@ap-gto.groups.io <main@ap-gto.groups.io> on behalf of Brian Valente <bvalente@...>
Sent: Friday, November 18, 2022 8:28 PM
To: main@ap-gto.groups.io <main@ap-gto.groups.io>
Subject: Re: [ap-gto] APPC & Mach2: Dec Arc model results and RA drift connection? #APCC #Mach2GTO
 
>>>Andrea, I am sitting out at my remote site right now running a 3-Dec line mapping run (2 degree Dec spacing and 5 degree RA spacing) as I am waiting for the temperature to stabilize and my object to get high enough.

nice update.

I would also point out setting an appropriate minimum altitude helps to minimize the number of mapping points. i used to do 30 degrees altitude until i realized i never really shot anything below 45 degrees

On Fri, Nov 18, 2022 at 8:23 PM Dean Jacobsen <deanjacobsen@...> wrote:
“Do you think that one single arc centred on the objects but very dense can work also better?
3 arcs for 3-5 degrees RA spacing is probably the best in terms of performance but time required is also important to me.
I'd like to keep the modeling within 30 minutes to maximize imaging time
In any case next time I will go for 3 arcs/5 deg spacing as suggested, so I can have also a good benchmark.
I will try to go unguided so any bias in the analysis can be eliminated.”

Andrea, I am sitting out at my remote site right now running a 3-Dec line mapping run (2 degree Dec spacing and 5 degree RA spacing) as I am waiting for the temperature to stabilize and my object to get high enough.  The run is nearly complete and it has been running for about 25 minutes.  The software/mount can map 3 points in a little over a minute - slew, settle, image and solve.  So it doesn’t really take very long.  I would just be sitting here waiting for it to get dark and for the scope to cool down anyway.  So no imaging time is lost.

 The big up side of going unguided for me is that I have eliminated the significant time overhead of the dither-settle cycle that happens when guiding.  For me it was 15 or 20 seconds, or more per dither.  That time starts to add up when you dither every image as I do.  With unguided imaging I just set the settle time to 3 seconds and the mount will dither, settle and start the next image in about 5 seconds or less.  Thus I can pack more subs into a given time period.

Last winter I was using my old school Takahashi MT-160 - f/6 1000mm fl - to take unguided images.  It works great.
--
Dean Jacobsen
Astrobin Image Gallery - https://www.astrobin.com/users/deanjacobsen/



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