Sudden run-away during imaging run #APCC #Guiding


Endymion
 

I was imaging this evening and suddenly the stars started streaking across the image (after about 2 hours running fine).  It wasn't a fast slew and I watched it continue across several images (150s exposures) before I stopped it.  I wasn't anywhere near limits in the axis positions.   The software configuration is  NINA->PHD2->AP ASCOM->APCC.   I am connected via USB (short) to the AP1100 control box.   I have the PHD and APCC logs.   How do I go about debugging this? I certainly don't want it to happen when I'm not watching the session.

Thanks,
John


Ray Gralak
 

Hi John,

Were you using a pointing model?

-Ray

-----Original Message-----
From: main@ap-gto.groups.io [mailto:main@ap-gto.groups.io] On Behalf Of Endymion
Sent: Thursday, November 11, 2021 1:15 AM
To: main@ap-gto.groups.io
Subject: [ap-gto] Sudden run-away during imaging run #APCC #Guiding

I was imaging this evening and suddenly the stars started streaking across the image (after about 2 hours
running fine). It wasn't a fast slew and I watched it continue across several images (150s exposures) before I
stopped it. I wasn't anywhere near limits in the axis positions. The software configuration is NINA->PHD2-
AP ASCOM->APCC. I am connected via USB (short) to the AP1100 control box. I have the PHD and
APCC logs. How do I go about debugging this? I certainly don't want it to happen when I'm not watching the
session.

Thanks,
John


Endymion
 

No model being used.  Encoders on.


Roland Christen
 

If the mount stopped tracking the stars will run across your chip at 15 arc sec per second. Maybe the mount didn't run away, just stopped tracking due to any number of external commands.

Roland

-----Original Message-----
From: Endymion <john.creigh@...>
To: main@ap-gto.groups.io
Sent: Thu, Nov 11, 2021 3:49 pm
Subject: Re: [ap-gto] Sudden run-away during imaging run #APCC #Guiding

No model being used.  Encoders on.

--
Roland Christen
Astro-Physics


Endymion
 

I agree that the mount stopping could explain what I saw. The only commands being sent to the mount were from PHD2.  


Roland Christen
 

Without digging thru logs, no way to deduce anything. i doubt that the mount would stop on its own unless there was a power glitch or low battery.

Rolando

-----Original Message-----
From: Endymion <john.creigh@...>
To: main@ap-gto.groups.io
Sent: Thu, Nov 11, 2021 6:04 pm
Subject: Re: [ap-gto] Sudden run-away during imaging run #APCC #Guiding

I agree that the mount stopping could explain what I saw. The only commands being sent to the mount were from PHD2.  

--
Roland Christen
Astro-Physics


Endymion
 

Thanks Roland.   A  power glitch might be possible as I have just switched to everything tied to a single power supply instead of having the mount on its own supply.   It's a Powerwerx 30 amp supply so I thought it should handle the load; however, di/dt might be high enough to kick a large spike.   I'll go back to the mount on its own supply in the future.   In the meantime I may be able to find a PHD expert who can decode the log for me in case I have a software issue somewhere.

John 


 

Hi John 

>>>I agree that the mount stopping could explain what I saw. The only commands being sent to the mount were from PHD2.  

PHD doesn't start or stop tracking, so it's unlikely that was the cause, but i'm happy to look at your PHD logs


Endymion
 

Thanks Brian!   Attached are the logs.   The event occurred around 23:27.

Regards,
John


 

Hi John

My best guess is your dither at 23:29 resulted in PHD guiding on a hot pixel, so it would definitely mimic something like your scope "not moving"
image.png
in subsequent guiding, it no longer was on a hot pixel

Couple things to mention in your PHD settings to avoid this (and also some thoughts on your settings in general):
set your minimum HFD to at least 2 pixels
image.png


not sure why you are bin 2? you can bin 1 and still have a good image scale for guiding

i also suggest increasing your exposure to the 2-3 second range. at 1 second you are chasing seeing. Your graphs look pretty choppy so I suspect that's the case here. 



On Thu, Nov 11, 2021 at 11:55 PM Endymion <john.creigh@...> wrote:
Thanks Brian!   Attached are the logs.   The event occurred around 23:27.

Regards,
John



--
Brian 



Brian Valente


Endymion
 

Brian,
  Thank you very much for the analysis.   I'll definitely set the minimum star HFD to avoid guiding on hot pixels.   I was on bin2 since when I first set up this image train several months ago I was having problems finding guide stars and bin2 seemed to work.  I'll go back to bin1  and see how it goes.   I normally guide with an exposure of 3 seconds; not sure why I had 1 second in that series.  

Greatly appreciate the help.

Regards,
John