Ray Gralak



Regarding ASTAP plate solves, you can look at the APPM logs to see the command line arguments passed to APPM. If you set all of ASTAP values to zero in APPM’s plate solve tab and check the box to use the FITS header, then APPM will pass just the filename to APPM. If an image is not solving it’s likely a setting in ASTAP needs to be tweaked. APPM cannot predetermine which settings will best work with ASTAP, which is why it exposes controls to tweak command line parameters.


Regarding the 70 Mpix image not loading, I assume you are using the camera’s ASCOM Camera driver?  There are some VERY inefficient ASCOM drivers that require over 1 GB of ram for a 40 mpixel image. The maximum memory for APPM is 1GB so the image fails to load. If the manufacturers would create efficient ASCOM camera drivers then APPM would not have a problem. Binning or using a subframe will reduce memory size below 1GB and thus APPM can use the image.


Lastly, FOV is something ASTAP needs to reduce plate solve time. With the default values ASTAP will use the FITS header to calculate FOV.




From: [] On Behalf Of Worsel via
Sent: Tuesday, November 2, 2021 7:41 AM
Subject: Re: [ap-gto] APPM and ASTAP #APCC




Thanks for the new BETA  A few comments follow.  Your insight IS appreciated.    I hope these are helpful to others.

·        Program installed without issue. (1100 GT non-AE)

·        Following using

o   FOV = 135’ x 90’

o   Image scale = 1.1”/pxl

o   70 MP fits file.   No need to bin.   APPM would not read the original file. Cropped to 1/4x1/4.  Cropped image also downloads faster and solves fast.  No brainer there.

·        Initially, (local install) would solve, but ASTAP and, hence, APPM would not.

·        Took significant fiddling with gain, exposure, etc to come up with images that will solve.  Some images that would solve in ASTAP directly would not solve in APPM. 

·        Finally got everything lined out sufficiently to build a 227 pt model (Large Map default) with only 3 Solve Fails and those point were on the horizon.   Using this model, I was able to capture up to 15 minute subs un-guided.  I did not test beyond 15 minutes.

·        I also solved images from following train

o   FOV = 27 x 18’

o   Image scale = 0.4’/pxl

o   22 MP fits.  Uncropped, no need to bin.

·        Tips (at least these helped me)

o   Getting the image close is key (Ray says this in the documentation as well.)

o   However, setting Image scale tolerance to 50% gave me more latitude. May increase solve time, but only by small amounts.

o   Solve button will work when Blind Solve does not on the same image.

o   The initial RA and Dec only needs to be accurate to 1 hour and 1 degree, e.g. 3 50 will solve an image with center at

§  3h 23m 15s

§  49d 43m 36s

One comment.  People mention ‘setting’ the FOV.   As near as I can determine, there is no place to set the FOV directly.  APPM can calculate FOV from the sensor parameters, which is supplied from FITS header, and image scale, which is set in APPM and sent to FITS header.  Is this correct?



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