Problem Running PhotometricColorCalibration

[Lee Dodge]

{Please move to appropriate forum topic.)

The idea behind PhotometricColorCalibration (PCC) seems great.  However, as an inexperienced PixInsight user, I cannot get it to work correctly.  I have an RGB image of Messier 33, with one-hour exposures through each of the three R,G, and B filters.  (I have not combined it with the 2-hour luminance image.)  I had trouble with version 1.8.6, so I downloaded the latest 1.8.7 version, and I have the same problem with it. 

My telescope setup is 1085 mm f/7, ZWO color filters, and a ZWO ASI1600mm-Pro camera.   

I am using fairly standard inputs of "Broadband," "Average Sprial Galaxy," "APASS" photometry index, etc.  I let it find the RA and DEC coordinates for M33.  I let the program read the dates and imaging details from one of the monochrome versions of the subs.  (It comes back with a focal length of 1000.0 mm, which I reset to 1085 mm.)  When I ask it to process the image, it works for a while, and includes messages such as:

2nd try
221 putative star pair matching
98 star pair matches in 145 RANSAC iterations
scale:  0.912
rotation:  +73.29 deg
dx:  +4049.81 px
dy:  -1490.71 px

Then it says "Running." but it continues running for at least 3 hours, and I have to do a Ctrl-Alt-Del to get the task manager and stop the PixInsight program in that way.  The computer is a new Dell laptop Inspiron 15 5000 Series - 5570.  I assume from the messages above that it successfully downloaded the photometry data, and that it did a match with my image.  Is that correct? 

Thank you for the help,
Lee

[andrewluck]

Hi Lee

There are two stages to this process, the first is a plate solve and this is then used for the photometry data. From your description it appears that the first stage is not completing.

At the end of this stage you should see something similar to the following in the log:

===============================================================================
Referentiation matrix (world[ra,dec] = matrix * image[x,y]):
 -3.75388403e-04  -6.14343469e-06  +8.14454864e-01
 +6.22449954e-06  -3.75303793e-04  +8.96487471e-01
WCS transformation ....... Linear
Projection ............... Gnomonic
Projection origin ........ [2129.961994 2424.024047] px -> [RA:  1 33 52.101  Dec: +30 39 01.53]
Resolution ............... 1.351 arcsec/px
Rotation ................. 0.950 deg
Observation start time ... 2019-10-08 21:41:10 UTC
Observation end time ..... 2019-10-31 01:55:45 UTC
Geodetic coordinates .....   0 50 44 E  52 32 11 N
Focal distance ........... 457.88 mm
Pixel size ............... 3.00 um
Field of view ............ 1d 35' 57.1" x 1d 49' 11.7"
Image center ............. RA:  1 33 52.097  Dec: +30 39 01.56
Image bounds:
   top-left .............. RA:  1 37 41.418  Dec: +31 32 35.83
   top-right ............. RA:  1 30 11.099  Dec: +31 34 12.17
   bottom-left ........... RA:  1 37 28.916  Dec: +29 43 28.03
   bottom-right .......... RA:  1 30 06.988  Dec: +29 45 02.60


* Process finished without errors.

It's quite normal for the focal length to differ slightly from the published figure for the telescope, especially if you're using a field flattener. If the solution never converges then the usual reason is that your initial parameters were incorrect. You don't say if you've used drizzle stacking but if so this will affect the value that you enter for the camera pixel size.

Regards
Andrew