Mid-sequence abort - PHD2 error ASCOM driver disconnect

[Suzanne Beers]

During last night's imaging session (during a trip to Chile's Atacama Desert) my SGP sequence aborted in the middle of the capture.  PHD2 had an error at the top saying "ASCOM Camera 2_2 disconnected"  The last good subframe (3 minutes) was started at 00:42.  I discovered the abort when I went out to perform the meridian flip.  There was not an issue with the cable and the guiding before (and after I restarted) was very good with a nice tight pattern around the "bulls eye"

Can you tell me what you see from the logs that may have caused this issue?

It's disconcerting because of the randomness of it - in the middle of a mosaic tile data collect, two hours away from the meridian.  AND because I'm in Chile for a limited time and want to make the most of every available imaging minute!

Thanks for your help, here is the link to the log file from last night's session: https://openphdguiding.org/logs/dl/PHD2_logs_X8Ch.zip

[Bruce Waddington]

Hi Suzanne. The log shows that you started getting hard failures starting at 00:47, meaning that PHD2 couldn't connect to the camera at all.  This is different from the more common case where the connection is flakey and is lost intermittently.  This situation continued until 02:44 with SGP making repeated attempts about every 5 minutes.  I can't be sure, but it looks like SGP might have then parked the mount, moving it to a substantially different position from the one where the connection problems occurred.  When you restarted the session, the scope moved to the opposite side of the pier and you had no more connectivity problems.  So despite what you've said, this looks like a cable problem to me.  Because you were getting hard failures, it's possible that the camera may have been losing power, but of course I don't know how your setup is configured for both data and power connectivity.  Problems like this can be caused by issues at the connector ends of the cables or by damage to the cable which is often invisible to inspection.

That said, I'm baffled by the reported pointing positions even knowing that you're in the southern hemisphere.  Throughout the night, the mount was reporting a Dec position of about -60 degrees which is fine.  But the mount driver reported you started the night with the scope on the east side of the pier with an hour angle of -5.75 hours and a pointing altitude of only 22 degrees.  Taken at face value, this would usually mean that the scope was completely upside-down.  Were you imaging "below the pole" on this target?  This pattern continued with side-of-pier east associated with negative hour angles and side-of-pier west associated with positive hour angles - backwards from the normal situation.  Hour angle calculations are trivial - (LocalSiderealTime - RightAscension) - so they don't change depending on which hemisphere you're in.  Can you tell me what the physical orientation of the scope and mount was during the night?  I'm poking at this because very unusual pointing positions are often situations where cabling problems show up.

On an unrelated note, why are you doing so many calibrations?  This is really a waste of good imaging time and certainly isn't necessary in a permanent observatory setup.

Regards,

Bruce

[Suzanne Beers]

Bruce...

  Thanks for your quick and thorough reply.  

  I am in Chile (Southern Hemisphere), site coords are -22 degrees south latitude,  -68 degrees west latitude), I traveled here from Colorado for a week+ of imaging from the gloriously dark and clear skies of San Pedro de Atacama.  I had two completely successful imaging nights on 15Mar and 16Mar, with the same equipment set-up. 

  Let me give you the sequence of events last night..

.. I started the session at dark (~0850CDT), planning to image a 4-tile mosaic of the Southern Cross, when it was at about 24 degrees above the horizon at the start of the sequence (the telescope was on the west side of the pier, pointing SE at the target).

 .  I came back outside at 23:15 to watch the swap from Tile#1 to Tile#2.  The sequence was capturing frame #42, so I changed the number of frames on that tile to 42 (from 45), so I didn't have to sit outside and watch 3 more frames.  Between 23:15 and 23:20, the mount moved to Tile#2, plate solved, PHD2 calibrated, and the EAF ran.  Tile#2 started at 23:20.

  I came outside for the meridian flip at 02:45 (I've never been able to have PHD2 restart successfully after a meridian flip, so I always go out and do it "by hand" (disconnect the equipment from SGP, close down PHD2, recycle power on the mount, then reconnect and restart the sequence)) That was when I discovered that the sequence had aborted (the last 3-minute subframe captured was at 00:42).  I noticed the "ASCOM Camera2_2 disconnected" error in PHD2.  All the cabling seemed secure without any snags.  For good measure, I disconnected and reconnected (at the camera) the AG cable.  (I recently switched to an ASI120MM AG camera from the Orion SSAG Pro that I was having issues with - I always had to disconnect/reconnect the cable to the Orion SSAG Pro at the flip).  Everything started back up again correctly - plate solve, AG calibration, EAF - now with the telescope on the east side of the pier, pointing SW at the target.

  After I restarted the sequence after the meridian flip, I came back out at various points throughout the night because I was a little spooked by the random sequence abort (on frame #26/45 of Tile #2).  At 0430, I came out watched the switch from Tile #3 to Tile#4 - everything went fine.  Although, strangely on the plate solver, it was showing the imaging camera angle at 270degrees (vs. 90 degrees on the plan and the earlier plate solves)...but resolved just fine and started Tile #4 at 05:09.  I ended the sequence at 06:42, about partway through astronomical twilight.  

  The data I collected stacked well...but I would like to not lose any of the precious dark skies time during the rest of the nights that I'm here!  

On your comment on the calibration setting...I've always done it that way - I do not have a permanent observatory setup.  When home, I either image from my front patio (rolling the telescope outside on a trolly and setting it up anew each time or we go camping in dark skies locations, where I set up at the campsite.  Here, I transported my equipment from the states and set it up at the Atacama Lodge for the week.   Given that, do you recommend a calibration at the beginning of each night's imaging, then no more after that throughout the night?  If so, where do I change those settings?  

The attached picture is my set-up here at the SPACE Atacama Lodge...  My website's blog has entries with pictures from the front patio and out dispersed camping locations - if you're at all interested (www.beersastrophotography.com)

Thanks so much for your help and quick response. 

Suzanne

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[Bruce Waddington]

Ok, it sounds like you have a long-standing problem with meridian flip handling.  You probably don't want to fiddle with that during your Chile excursion but it would be good to get it sorted out when you return home.  I'm referring to this comment:

(I've never been able to have PHD2 restart successfully after a meridian flip, so I always go out and do it "by hand" (disconnect the equipment from SGP, close down PHD2, recycle power on the mount, then reconnect and restart the sequence)) 

This is horrible!   SGP is quite capable of doing automated imaging all night long and that's one of the big reasons to use a session manager.  Setting aside the mechanical considerations, there's nothing complicated about doing a meridian flip - this is what SGP or any other session manager app will do:

1.  Stop imaging and tell PHD2 to stop guiding at some reasonable time before the target crosses the central meridian.

2.  Wait until the target has crossed the central meridian + plus some configurable time/distance beyond that

3.  Slew the scope to the same target coordinates that were used at the start of the session

4.  Do whatever centering/plate-solving is needed to precisely re-center the target

5.  Tell PHD2 to start guiding

6.  Re-start imaging

So I think you should just set aside an evening at home and get this working.  I still suspect you probably have cable-routing problems, but that's just an educated guess.  Those kinds of problems could be cable wraps that occur close to the central meridian or a lack of strain-relief mechanisms where the cables plug into devices/ports.  If you encounter the problem again, look in the Windows Device Manager to see if the guide camera is shown.  

You currently have SGP configured to force a calibration every time you slew to a target, so you should eliminate that.  If you are setting up each night, you should use the PHD2 Calibration Assistant at the start of the nightly session and get one acceptable calibration.  Once you have it, don't do any more for the rest of the night unless things go seriously hay-wire.  You can often do this before it's completely dark, you just need a usable guide star (using auto-find).  In that case, you waste zero imaging time doing calibrations and you will be working with the most accurate calibration measurements.

Good luck and have fun down there,

Bruce

(Nice web site by the way, well done!)

[Suzanne Beers]

Thanks Bruce!  

 

 Yes, I was thinking exactly the same thing about NOT doing this while I'm in Chile! 

  I understand how the meridian flip is supposed to work - and everything typically works until step #5 - getting PHD2 to restart guiding.  I will try again when I get home - since I think that issue may have been a function of the old AG camera I had (Orion SSAG Pro).  It required a physical cable reset anytime the sequence stopped (for example for the meridian flip)...otherwise, the camera would not reconnect.  I have gotten so used to doing that sequence of events at the meridian flip (and I've had more than my fair share of issues with my new ASI6200MM mono camera leading up to this trip, that in mid-February, I cried Uncle and got myself back to a stable configuration (ASCOM 6.5) and process for the trip.  I've got a long list of "to-do after Chile" to resolve issues...I'll add the "courage to let the meridian flip happen" to it!

Thanks so much for your speedy response.  I'll let you know if I have issues tonight!

Suzanne

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[Suzanne Beers]

Bruce - 

  Everything went very well last night!

  I made sure that the AG camera cable was firmly inserted into the camera, perhaps, as you'd suggested that was what was going on... 

  I did uncheck the "recalibrate with new target" in SGP's autoguide equipment tab - so PHD2 did no calibration.  The guiding was good throughout the night.  

  I'm about 15 minutes away from darkness here tonight, so hopefully I'll have the same experience tonight!

  Thanks very much for your help.  Once I get home I'll look into working the Guiding Assistant into my workflow. 

Thanks,

Suzanne

[Bruce Waddington]

Glad things went better last night.  Just to be clear though, what I was urging you to use is the Calibration Assistant, not the same as the Guiding Assistant.  The User Guide has detailed instructions for how to use it although it's pretty intuitive if you let it do its thing.

Bruce

[Suzanne Beers]

Okay thank you...I will read through the guide!  Everything worked well again last night!!

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