VPhot Stack just produced a completely black image

I tried loading other previously stacked images and the source images and these all look as they should.
When I load the sequence the star images seem to be identified.
Very odd . Never seen this before.

I just repeated the calibration and got the same result.
I tried stacking in ASTAP and the stacked image looks normal.
Annoying because I wanted to upload this quickly as RU was reported active this night.
Another clue. The last 3 observations of my session are all the same.
Nothing looks different on the raw images or the calibrated images.
I’m stumped. Any advice as to what to try next please?

PS I just tried VPHOT stack on obs from the following session and stack looks normal.

There is a menu item at upper right I believe, where you can set the ADU plotting range so as to make a black image look normal.
It will do the photometry on a black image. Kind of like setting the image scale in MaxIm.

Ray

Thanks Ray,
I think you mean ASTAP. (Correct me if I’m wrong)
The ASTAP images are fine.
It’s the VPhot images in which I can’t see anything.
I can’t see how to adjust the plotting range in VPhot.
Something seems to be different about the last three obs of the session. As stated the next session obs seem fine so far.
Kevin

Share one of those black images with TRE. I’ll take a look at it.

Upper right hand menu:
Tools–>Image Display
Make the high setting 1600.
Nice image though.
I get B-Mag 10.871. Sound about right?

Ray

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Ray,

Thanks for the great advice! I uploaded a stacked 64-bit FITS image to vPhot with some obnoxiously high ADU (1.5 hours of exposure for something really faint). I too was presented a black image in vPhot. I’ll have to try this again with a higher ADU setting!

Brian

Aha! Thanks Ray. We were probably taught that in the VPhot course but I’m darned if I remember…
I wonder why Vphot chose those display numbers (or did it?).
Have used VPhot many hundreds of times and never seen this happen.
I got transformed B mag of 10.73 and 10.86 for non-T.
Reassuring.
Many thanks again
Kevin