Re: PlateSolve2 vs. TheSkyX Image Link for APPM Point Mapping


Greg thanks, A veritable lecture in an email that is a real keeper!!

On Sun, Jun 28, 2020 at 22:10 Greg Vaughn <gregvaughn@...> wrote:

Dean and Joe,


I normally watch this forum and learn from the experienced astronomers and imagers, but wanted to pass on a few thoughts about my developing experience with plate solving and APPM.


I was finally brave enough late last fall to dig into APPM and understand it well enough, after a few false starts, to make it work.    Despite understanding how to make it work now using at least three camera and telescope combinations and two different mount configurations, I still have an occasional issue - but I don’t think related to either APPM or my plate solver.   After successful use of APPM for several months with dedicated CMOS Astro cameras, a return to my Nikon D810A two weeks ago resulted in a failure to plate solve which resulted in an APPM failure.   Since then I’ve again had successful runs and my apparent failure to plate solve with the D810A is what I discuss in #5 below.


Just to level set everyone and to anticipate questions: I power up the mount, I use APCC to open the ASCOM driver, establish the virtual ports, and to run APPM.   For imaging I use SGP in concert with PHD2 and Focus Lynx software.   (I use SharpCap for planetary imaging, but use SGP to support APPM and auto focusing early in my sessions.)  I have been using Carte du Ciel planetarium software to slew to places other than those that I program into SGP for formal imaging runs (such as good locations for PHD2 calibration runs).   I have a Windows 10 Pro boot camp partition on a MacBook Pro with 16GB ram and an i5 processor.  I use a USB 3 router into which I plug; camera, guide camera, MGBoxV2 (GPS and environmental), USB to Serial cable for Mach 1 (CP4) or Mach 2 (CP5), and a Focus Lynx focuser.  I have the setup on my deck and run the operation from inside the house using UltraVNC remote desktop running on another laptop.  I use a variety of dedicated Astro cameras, ZWO and QHY, and a Nikon DSLR (D810A).   The only connection I ever have an issue with is the USB3 connection to the imaging camera.


Assuming  you are leveraging SGP for APPM, here are a few items that stand out in my mind as being worth trying or checking:


  1. After ‘connecting’ camera and mount on the APPM run page, make sure you have the proper imaging camera and plate solve settings, and they match, in both APPM and SGP prior to initiating your APPM run.  Critical items include binning (or ISO), exposure length, and Image Scale (must be correct for your current imaging train config in both places J).
  2. Remember to make sure in SGP that the selected image output format, under camera settings, is the FITS format.  My Nikon D810A choices in SGP are NEF, NEF and FITS, and FITS.   I have to choose ‘FITS’ – APPM will not work in ‘NEF and FITS’ and will deliver a ‘BAD IMAGE SCALE’ error.  (For my dedicated Astro cameras, I only have a choice of binning and FITS is automatically set.)
  3. I used platesolve2 for a long time as my plate solver in SGP.  As a result of a forum discussion (here as I remember)  about using ASTAP, I have switched to ASTAP (it was easy) and found that I can plate solve much faster and I think it works very well with APPM, returning points faster.    I like it better than platesolve2.   Consider switching to ASTAP if it seems slow with platesolve2.
  4. While this may be obvious, focusing your image train prior to running APM seems to improve my plate solve speed/reliability.   Even when I don’t mess with focus when I tear down and set back up, I still encounter different temperatures and could have bumped the focuser, so I do a focusing run.   (This may delay your mapping routine, but I like to try to do it.)
  5. My USB connection to the camera can be finicky – though not very often.  Most nights I have no issue.  When I do have an issue, sometimes it goes away with shutting down and restarting SGP, but sometimes it doesn’t resolve without shutting EVERYTHING down and starting completely over.   The only time that I’ve had issues with APPM in recent memory is when SGP shows that it’s connected to the camera and it’s downloading the plate solve image – but it really isn’t and it never completes the download.  The camera will show connected, but the image just will not complete a download to SGP.  This results in APPM timing out and reporting a failed plate solve, when clearly this was a camera/SGP issue.
  6. To make sure things are working properly before doing an APPM run, I usually do the focus run mentioned in #4 and I will do a ‘solve and sync’ in SGP to test the plate solver settings/connection and to start off on common ground.   These exercises will usually let me know if it’s a finicky night for my camera(s).   It also confirms that my exposure length and binning/ISO are sufficient to achieve a plate solve wherever I am in the transition to full darkness.


I’m sure that there are many other helpful items available to help you navigate APPM and plate solving, but the bottom line experience I’ve had is that APPM works well, but is usually unforgiving if your settings are mismatched between it and SGP and depends on SGP (in my case) delivering a plate solve.   I have SGP up in background and for the first couple points watch closely to make sure it goes through all the plate solve steps properly.   I’ve only had APPM stop one time after the first couple points were successful and that was due to a similar, but delayed, camera/image download issue which required attention on my part – independent of APPM.


Best of luck to everyone.  I have been very pleased with APPM and its impact.   I feel fortunate to have it to help compensate for having no view of Polaris from my deck and having a less than perfect polar alignment.


One last anecdote.   I only have about a 90deg azimuth sector available for imaging (~090-180) and a small slice overhead to the Northwest.   To cover that available sector, I did a 44 point map Thursday night and was able to track Jupiter in the early morning hours with a tiny ZWO ASI174 (in 640x480 mode) through an EDGE11 SCT with a Televue 4X Powermate connected to it - without guiding.   I had to make very minor 1X corrections with the virtual keypad about every fourth video capture to keep the planet absolutely centered - so I guess that’s a mild form of manual guiding) – but I was very impressed.    I had meant to ask Ray if the mapping would help tracking of the planets as well, but apparently it does.  (I should mention that this was with the Mach 2.)


Cheers, good luck, and clear skies!



p.s.  Ray helped me understand my failings in my first couple outings with APPM and I should also give credit to George who helped me set up APCC and the ASCOM driver for both the CP4 /Mach 1 configuration and the CP5/Mach 2 configuration.   Knowing that all that was good gave me additional confidence to dig into APPM.



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