Group Stack freezes/hangs on final image after Photometry channel extraction (v2026.0519)

[Timothy Hager]

Hi Han,

I am encountering a persistent freeze/hang at the very end of my processing workflow during the group-stacking phase. It occurs across various batch sizes (tested from 6 files up to hundreds of frames).

My Environment: ASTAP Version: 2026.0519 (64-bit)OS: Windows 10 - 64 bit

Step-by-Step Workflow to Reproduce:
Load light images into the Lights tab of the stack menu .Run the routine to look for streaks and examine the detected images.

Load images into the Photometry tab and hit the + button to analyze.

Load appropriate dark images into the Dark tab. Load the appropriate flats and flat darks into their respective tabs.

Go back to the Photometry tab, select all, and choose Calibrate selected files.

Extract the Green channel (for eclipsing binaries) or Red/Green/Blue channels (for other stars).

Attempt to stack all files in groups using Mode: Average.

The Issue: At Step 8, the program consistently hangs/freezes on the very first image of the group stack. To make the stacking continue, I have to manually press the Esc key. Once bypassed via Esc, the stacking completes, but it leaves exactly one final image unstacked. Note: If I completely close ASTAP and reopen it right before Step 8, the group stack completes successfully with no freezing or missing files. This implies a background thread lock or file-handle leak is remaining active from the prior photometry/extraction steps.

Could you please look into why the file handle or background process isn't releasing that final image?

Let me know if you need any example FITS headers or my astap.cfg file. Thank you!

[Timothy Hager]

The subject is incorrect - it hangs on the first image.

[Timothy Hager]

Hi, any comment on this issue? Maybe I could use a different workflow to avoid having to shut ASTAP and open it up again?

[han.k]

Hi Timothy,

Sorry, I overlooked your previous postings. I will check if I can reproduce the problem. If not I will need some of your images.

cs, Han

[han.k]

I tested it here. Somehow the program goes in "pause mode" which can be solved by the esc button. (the stack button blinks pause) I will fix this weekend.

Once bypassed via Esc, the stacking completes, but it leaves exactly one final image unstacked.

If I have six images, and stack in groups of two, then I get 3 stacked images. Because 3x2=6
There will be a problem if I had five images. That would result in two stacked images and one left over.
How many images are you stacking in groups and could there be a left over?

cs, Han

[Timothy Hager]

Thank you for answering so quickly. I usually take sets of 10, 6 or hundreds. I undserstand when there is not an even integer number of images in the stacks leaving some or one unstacked at the end. But it always leaves the first image unstacked. I think that is the one that it pauses on before I hit esc. I have some images here yet to process and let me do that now. It seems to always happen after I extract the green channel or the red, green and blue channels and then stack.

I'll test again now. Okay I have 6 20 second images of AO Her taken with a Seestar S50. You know that's a one shot color camera.

I load the 6 images into the photometry tab, hit analyze and see that they are taken at 15C.

I load 6 darks taken at 15C into the dark tab. I already have a master flat in the flat tab.

I select all frames in the photometry tab, right click and click calibrate selected files.

After that is finished. I right click and select all again. I right click and click Extract Red, Green and Blue channels of Raw files. That extraction completes. I now have 18 files - 6 TB, 6 TG and 6 TR.

I right click again and stack ALL files in groups, mode average.

The program stops. Here is the log before I hit Esc:
5:11:40 PM Stack method Average
5:11:40 PM Analysing lights.
5:11:40 PM Grayscale stack (classify by light filter unchecked)
5:11:40 PM Stacking (Average), HOLD ESC key to abort.

I end up with no TB images stacked but the sixth TB image listed in the photometry tab not stacked and a stack of 6 TG images and a stack of 6 TR images.

Let me know if you need anymore information.

Tim

[han.k]

I have enough information. I will try to fix it the next days.

cs, Han

[han.k]

It is now fixed in the development version 2026-05-12 for Windows:
https://www.hnsky.org/astap_setup.exe

It happened only if calibration mode was used first prior to the stacking in groups. I will update the other versions later in the day

If you find anything else, please report. That helps.

Han

[han.k]

The last development version has a problem with the alignment I need to fix.

[han.k]

Fixed. Use the same link for version 2026.07-12a
https://www.hnsky.org/astap_setup.exe

[han.k]

The development version has a minor problem with detecting faint stars. I will fix that soon.

[han.k]

Fixed again. Use the same link for version 2026.07-13
https://www.hnsky.org/astap_setup.exe

Han

[Timothy Hager]

Hi Han,
I have finally gotten a chance to test your new update and it's great! It saves a lot of time for me. Is there any possiblity for actions to be scripted within ASTAP? I see the photometry command line which is great but can the calibration and debayering and stacking be scripted? The photometry takes no time at all. Thank you.

Tim

[han.k]

Hi Tim,

A few months ago. on request, I added the photometry command-line. As described here
https://www.hnsky.org/astap.htm#photometry_command-line

In the photometry tab there is check-mark option "calibration" which should do calibration automatic.

I have only briefly tested it and then left it.

I'm not doing much photometry myself. So it has never been full tested. You can have a look and see if it is workable. Report your finding and tell me what is missing.

cs, Han

[han.k]

This is the list. It looks like you can only report when you have a filter.

OBSERVED MAGNITUDE AND BAND
The observed magnitude (normally to a precision of 0.1 mag.) and the band in which the measurement was made. The observed magnitude can be given to 0.01 mag., where such precision is justified. The default magnitude scale is photographic, although magnitudes may be given in V- or R-band, for example. In the past for comets, the magnitude was specified as being nuclear, N, or total, T, but observers are now encouraged to provide the actual band used.

The current list of acceptable magnitude bands is: B, V, R, I, J, W, U, C, L, H, K, Y, G, g, r, i, w, y, z, o, c, v, u. Non-recognized magnitude bands will cause observations to be rejected. Addition of new recognised bands requires knowledge of a standard correction to convert a magnitude in that band to V. Conversion to V band used by MPC is located here.

The formerly-used "C" band to indicate "clear" or "no filter" is no longer valid for newly-submitted observations, but will remain on previously-submitted observations.