Plate Solving in VPHOT

American Association of Variable Star Observers (AAVSO)
Thu, 12/10/2020 - 21:19

Why doesn't VPHOT ask for an lower and upper bound for the image scale?

It makes uploads faster.

American Association of Variable Star Observers (AAVSO)
No Reason To?


I assume you had an issue with the speed of the queue that prompted this question?

VPhot uses Pinpoint that needs an image scale so that it can plate-solve the images. Obviously, there is some uncertainty in this value. Pinpoint uses the defined image scale reported in your telescope settings and some error band in its calculation. IOW, it does not fail unless the image scale is significantly different from that value.

Therefore, a small amount of error does not slow the plate-solving process. If the image scale of your image is much different than the reported telescope setting, then VPhot tries three catalogs for 20 seconds each before failing/skipping to the next image. My own image scale is very stable. Do you think some images sent to VPhot are not?

IMHO, is not faster.