Mach2 APCC/APPM model for multiple nights in a mobile setting


mindspringtsai@...
 

I'm seeking advice on a multiple night mobile workflow to reuse an APCC/APPM pointing/tracking model created on the first for subsequent nights. 

Here are my observations from the most recent new moon:
Night 1:  Created 50pt model. Successfully imaged unguided throughout the night on a two objects in different parts of the sky.  Powered down mount and covered it during the day.

Night 2:  Powered up mount, ran APPM verify with 30pts and found pretty large pointing deltas, greater than several arcmin.  A quick test exposure seemed to show a little bit of star trailing, but I didn't not spend time to quantify or debugging it.  Since the object I was shooting had a limited window, I just ran another 50pt model and successfully imaged throughout the night again.  Powered down mount and covered it during the day.

Night 3:  Ran 50pt model and successfully imaged throughout the night. 

Running a 50pt model every night isn't a deal breaker for me because it only takes about 20min, but I'm interested in the experience of other mobile imagers. 

Other details that may or may not be relevant:  OTA is OS RH200 and camera is ASI6200.  

Cheers,
Curtis


Bill Long
 

Something is changing day over day that is enough to invalidate the mount model. You could try fixing the PA before each run and see if that has any effect. Maybe something is getting disturbed when you cover and uncover the gear? 


From: main@ap-gto.groups.io <main@ap-gto.groups.io> on behalf of mindspringtsai@... <mindspringtsai@...>
Sent: Tuesday, July 27, 2021 7:42 AM
To: main@ap-gto.groups.io <main@ap-gto.groups.io>
Subject: [ap-gto] Mach2 APCC/APPM model for multiple nights in a mobile setting
 
I'm seeking advice on a multiple night mobile workflow to reuse an APCC/APPM pointing/tracking model created on the first for subsequent nights. 

Here are my observations from the most recent new moon:
Night 1:  Created 50pt model. Successfully imaged unguided throughout the night on a two objects in different parts of the sky.  Powered down mount and covered it during the day.

Night 2:  Powered up mount, ran APPM verify with 30pts and found pretty large pointing deltas, greater than several arcmin.  A quick test exposure seemed to show a little bit of star trailing, but I didn't not spend time to quantify or debugging it.  Since the object I was shooting had a limited window, I just ran another 50pt model and successfully imaged throughout the night again.  Powered down mount and covered it during the day.

Night 3:  Ran 50pt model and successfully imaged throughout the night. 

Running a 50pt model every night isn't a deal breaker for me because it only takes about 20min, but I'm interested in the experience of other mobile imagers. 

Other details that may or may not be relevant:  OTA is OS RH200 and camera is ASI6200.  

Cheers,
Curtis


David Johnson
 

I often leave my equipment set up over multiple nights when the weather is favorable (as it is right now). I always do a quick polar alignment and redo mapping each night.  I don’t know if this is necessary, especially at shorter focal lengths, but I have seen issues, which I believe might be due to the tripod settling into the soil. It’s generally possible to finish both polar alignment and mapping before it’s dark enough to do serious imaging, so there’s little or no time lost. I understand that if the polar alignment is correct that I theoretically don’t need to remap, but polar alignment is never perfect, and mapping with APPM is quick and automated and accounts for PA errors. When I eventually get a permanent setup, I don’t think this will be necessary. 


Joseph Beyer
 

The process of covering and uncovering my equipment combined with ground movements, +/- tripod dynamics (it’s a Berlebach) changes my PA every night.  Once I correct the PA each night my model works fine for at least a week.  That’s on a Mach1 unguided.  


Eric Claeys
 

The ground could have shifted, causing the error.  I found this to be the case in SW NM on hard desert dirt.


mindspringtsai@...
 

Based on the comments, I reviewed the PA elevation and azimuth correction terms for each of the three nights and indeed these values changed upwards of 10 arcmins over the course of three nights. 

Thanks for your all your help!

Cheers,
Curtis