Re: APPM - offset when telescope is powered off and then powered on a day or later #APCC


Dan R Price
 

Thank you, Brian.  I've been using Polaris for testing.  Maybe Polaris is a bad choice for testing the performance of the APPM.  I seem to have come up with more questions and no clear answer.  In Stellarium 0.20.2 it shows for Polaris:
 
(J2000.0):  2h31m51.50s/+89d15m51.5s
(on date):  3h00m08.78s/+89d21m33.9s
 
Could Polaris have changed its location by approximately 28 minutes in just 22 years? 
 
Also, after using Sharpcap to perform a Polar Alignment and then running APPM/Verify for the first three points of the model (worst RA delta was -.273 arc-min, worst DEC delta was .347 arc-min) and then performing another go to to Polaris from TheSkyX, the Astro-Physics V2 ASCOM Driver went from
 
Before:    03:57:43/89:21:38
to 
After:       03:57:27/89:21:37
 
If this is RA/DEC why is it so far off from Stellarium and TheSkyX?  Is it because Polaris is so close to the earth's polar axis?  Do I have something set up wrong?  Also, as expected, another test image now shows Polaris is very close to the exact center of the image.  If it is an Epoch issue then that would mean APPM/Verify caused the Epoch used to be changed?  
 
Just to add another bit of confusion - TheSkyX lists for Polaris Topocentric:  03h02m11.2626s/89d21m16.859s, and 2000.0:  02h31m49.0837s/89d15m50.794s.  I could see confusing the two systems would cause the error, but then why would running APPM/Verify correct it?
 
Is it possible that APPM/Verify is introducing the 18 second difference between GPS and UTC?  And that this 18 seconds is being lost when the mount and computer are being shut down?  

I'll follow your suggestion and see what happens when I take TheSkyX out of the test and only use APCC.  Thank you!
 
Clear Skies,
Dan

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