Live stack frame alignment problem

[dasman]

Hello

I have a problem that has started, and I am not sure why. The other night I was live stacking, and it went well for about 30 minutes. I then went to another object and started live stacking again. The first image displayed, and every subsequent image was rejected. I did not have filter brightness or FWHM filters on. I also did not have sharpcap monitoring my guide camera. I tried exiting and restarting. I tried rebooting. I had a friend who has used sharpcap for years trying to help me figure it out. After 90 minutes we unchecked align frames to see if they would still get rejected. They did not, they stacked. We then re checked the box for align frames and live stacking started working again, go figure! Well tonight I set up to get the supernova in NGC 7331, and live stacking rejected everything after the first frame. I unclicked the box for aligning frames and it started stacking again. So after it stacked a few frames I re-checked the box for align frames and everything was rejected. I tried another object and had the same error. I should also add I had good focus and could see 50 to 100 stars at each object.

I then downloaded the latest version of sharpcap to see if it would help. It did not. Still get every image rejected after the 1st image. I copied the live stack log file for the last object I tried.


10:22:56 PM NOTE Live stacking activated
10:23:01 PM NOTE Initializing stacking
10:23:01 PM NOTE Clearing stack
10:23:02 PM INFO 0.0000% of pixels (0) not stacked due to sigma limits
10:23:16 PM INFO Detected 0 in the stacked image, mean FWHM is NaN
10:23:16 PM INFO Detected 0 stars in the frame image, mean FWHM is NaN
10:23:16 PM ERROR Less than 3 stars found in the frame image, cannot align
10:23:16 PM WARN Failed to align with the reference frame.
10:23:16 PM ERROR Failed to calculate alignment.
10:23:16 PM WARN Frame not stacked because : Could not align
10:23:30 PM INFO Detected 0 in the stacked image, mean FWHM is NaN
10:23:30 PM INFO Detected 0 stars in the frame image, mean FWHM is NaN
10:23:30 PM ERROR Less than 3 stars found in the frame image, cannot align
10:23:30 PM WARN Failed to align with the reference frame.
10:23:30 PM ERROR Failed to calculate alignment.
10:23:30 PM WARN Frame not stacked because : Could not align
10:23:45 PM INFO Detected 0 in the stacked image, mean FWHM is NaN
10:23:45 PM INFO Detected 0 stars in the frame image, mean FWHM is NaN
10:23:45 PM ERROR Less than 3 stars found in the frame image, cannot align
10:23:45 PM WARN Failed to align with the reference frame.
10:23:45 PM ERROR Failed to calculate alignment.
10:23:45 PM WARN Frame not stacked because : Could not align
10:23:59 PM INFO Detected 0 in the stacked image, mean FWHM is NaN
10:23:59 PM INFO Detected 0 stars in the frame image, mean FWHM is NaN
10:23:59 PM ERROR Less than 3 stars found in the frame image, cannot align
10:23:59 PM WARN Failed to align with the reference frame.
10:23:59 PM ERROR Failed to calculate alignment.
10:23:59 PM WARN Frame not stacked because : Could not align
10:24:14 PM INFO Detected 0 in the stacked image, mean FWHM is NaN
10:24:14 PM INFO Detected 0 stars in the frame image, mean FWHM is NaN
10:24:14 PM ERROR Less than 3 stars found in the frame image, cannot align
10:24:14 PM WARN Failed to align with the reference frame.
10:24:14 PM ERROR Failed to calculate alignment.
10:24:14 PM WARN Frame not stacked because : Could not align
10:24:29 PM INFO Detected 0 in the stacked image, mean FWHM is NaN
10:24:29 PM INFO Detected 0 stars in the frame image, mean FWHM is NaN
10:24:29 PM ERROR Less than 3 stars found in the frame image, cannot align
10:24:29 PM WARN Failed to align with the reference frame.
10:24:29 PM ERROR Failed to calculate alignment.
10:24:29 PM WARN Frame not stacked because : Could not align
10:24:43 PM INFO Detected 0 in the stacked image, mean FWHM is NaN
10:24:43 PM INFO Detected 0 stars in the frame image, mean FWHM is NaN
10:24:43 PM ERROR Less than 3 stars found in the frame image, cannot align
10:24:43 PM WARN Failed to align with the reference frame.
10:24:43 PM ERROR Failed to calculate alignment.
10:24:43 PM WARN Frame not stacked because : Could not align
10:24:58 PM INFO Detected 0 in the stacked image, mean FWHM is NaN
10:24:58 PM INFO Detected 0 stars in the frame image, mean FWHM is NaN
10:24:58 PM ERROR Less than 3 stars found in the frame image, cannot align
10:24:58 PM WARN Failed to align with the reference frame.
10:24:58 PM ERROR Failed to calculate alignment.
10:24:58 PM WARN Frame not stacked because : Could not align
10:25:12 PM INFO Detected 0 in the stacked image, mean FWHM is NaN
10:25:12 PM INFO Detected 0 stars in the frame image, mean FWHM is NaN
10:25:12 PM ERROR Less than 3 stars found in the frame image, cannot align
10:25:12 PM WARN Failed to align with the reference frame.
10:25:12 PM ERROR Failed to calculate alignment.
10:25:12 PM WARN Frame not stacked because : Could not align
10:25:27 PM INFO Detected 0 in the stacked image, mean FWHM is NaN
10:25:27 PM INFO Detected 0 stars in the frame image, mean FWHM is NaN
10:25:27 PM ERROR Less than 3 stars found in the frame image, cannot align
10:25:27 PM WARN Failed to align with the reference frame.
10:25:27 PM ERROR Failed to calculate alignment.
10:25:27 PM WARN Frame not stacked because : Could not align
10:25:41 PM INFO Detected 0 in the stacked image, mean FWHM is NaN
10:25:41 PM INFO Detected 0 stars in the frame image, mean FWHM is NaN
10:25:41 PM ERROR Less than 3 stars found in the frame image, cannot align
10:25:41 PM WARN Failed to align with the reference frame.
10:25:41 PM ERROR Failed to calculate alignment.
10:25:41 PM WARN Frame not stacked because : Could not align
10:25:56 PM INFO Detected 0 in the stacked image, mean FWHM is NaN
10:25:56 PM INFO Detected 0 stars in the frame image, mean FWHM is NaN
10:25:56 PM ERROR Less than 3 stars found in the frame image, cannot align
10:25:56 PM WARN Failed to align with the reference frame.
10:25:56 PM ERROR Failed to calculate alignment.
10:25:56 PM WARN Frame not stacked because : Could not align
10:26:11 PM INFO Detected 0 in the stacked image, mean FWHM is NaN
10:26:11 PM INFO Detected 0 stars in the frame image, mean FWHM is NaN
10:26:11 PM ERROR Less than 3 stars found in the frame image, cannot align
10:26:11 PM WARN Failed to align with the reference frame.
10:26:11 PM ERROR Failed to calculate alignment.
10:26:11 PM WARN Frame not stacked because : Could not align



Even though it says its not detecting stars, they were there. And on the 1st image I ran the new color calibration, and it worked saying it detected 80 stars. So, I'm at a loss. Help!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

[admin]

Hi,

the place to start here is to look at the 'alignment' tab in live stacking (see https://docs.sharpcap.co.uk/4.1/#Alignment%20Tab) - here you can see live information about the number of stars being detected and adjust the star detection settings to try to fix any problems (for instance, you might increase the sensitivity, reduce the noise reduction or use the 'optimize for faint stars' option to try to get more stars.)

One more thing to be aware of (although I don't think it is the problem in your case) is that if you get a bad first frame (blurred due to guiding issues,etc) then other frames may fail to stack because SharpCap cannot find stars in the first frame no matter what the settings - in this case resetting the stack usually fixes thing. However, your log is showing that each subsequent frame was also detecting zero stars, so I don't think that was the problem here.

Hope this helps,

Robin

[dasman]

Hi Robin thanks for your reply. I wanted to add that my sensitivity was already set to 97. Also there were a lot of stars on the 1st frame (over 50) and they were in focus. Also the counter for the exposure was running past zero into negative numbers. It's just strange that I had to check the box to optimize for faint stars, because it was a normal looking frame with lots of stars. This has now happened 2 outings in a row. I'm pretty sure something else is going on. I have updated my camera software as well.

Thanks again

Dave

[admin]

Hi Dave,

OK, interesting that the counter was going negative... A few seconds negative (particularly on a camera with high resolution when using long exposures) is OK - that is just the transfer time for the data to get from the camera to the computer. If it is going negative beyond 10s then the more likely cause is that frames are being lost before they get to the computer. SharpCap allows some extra time for the transfer time mentioned above, but if the frame is too late then it will give up on that one and try again, which sometimes works or could have the same result. Turning down the 'Turbo USB' or 'USB speed' can help cure this issue (or if you have a QHY camera, turning up the USB Traffic - that one works the other way).

The issue with the negative count is likely to be separate to the star detection problem though - in your first log we can see frames being discarded every 15s due to no stars being found, so when that was happening the frames must have been coming through OK.

Probably the thing to do is to set up live stacking raw frame saving to 'Save All' (and make sure your preferred still format is set to FITS in the settings) - that way you will get all the frames from the camera saved during the attempt to live stack and we can go back and look at those frames afterwards to see if we can work out what is going wrong.

cheers,

Robin

[dasman]

Thanks again for your reply Robin. I will save all of the images the next time I am out. As an FYI my camera is the MallinCam Dsc26tec.