Help with SNR and check stars

[shbarr2001]

Hello,
In my latest runs with AIJ the Target, comparison, and check stars all come up with an SNR of "INFINITY".  The egain, readout noise, dark current are set.  Also and this may  be a factor of the missing SNR, the calculated magnitude of the check stars come up with the value I put in while selecting stars.  When I put Source_Sky_Cx into -2.5*log(flux1/flux2) I get reasonable answers but that calc doesn't appear to be performing for check stars.  

Anybody out there that can help?

Clear skies,
Steve

[karenacollins]

Hi Steve,

Could you please double check that all of the default checkbox settings shown below are set in the Aperture Settings > More Settings panel? All of them are not required, but it is a good starting place. If this check does not lead to a solution, please let us know which AIJ version you are running and which computing platform and OS you are using.


Karen

[shbarr2001]

Hi Karen,

Let me first thank you for the work that has been put into AIJ.  I currently use it for photometry, spectroscopy, and general astro photography.  I've recommended it many times and have received nothing but thank you's and kudos for your software.  I think this is only the second problem I've had with it and the first involved plate solving which was easily corrected.

Well, I'm perplexed.  I attempted setting all the parameters in the More Aperture Photometry settings and there was no joy.  Still Infinity in the SNR for the Target, Comparison, and check stars and no calculation of the magnitude of check stars.  

Actually, the data  I am working with is for RR Lyrae at the Okie Tex Star Party in 2024.  I'm developing a presentation on Intro to Photometry for the Scientific Special Interest Group of the Denver Astronomical Society and just for an example of how to calculate magnitude I selected one of the stars in the AAVSO photometry table as the target and a comparison and two check stars.  Sounds simple enough and the results for the target star were only 0.01m off the accepted value after averaging 10 frames.  Note the magnitude is being calculated for the target star, just not the check stars.  I can fill in the calculated magnitudes for the check stars using the equation in my last message, but can't fill in SNR for anything.  I often use SNR to eliminate images which are not within my threshold.  

The camera is a ZWO ASI2600mm and for this I used an 80mm APO with 0.8 reducer and V-band filter.  All the files were calibrated and as a matter of fact in my last run I recalibrated the files with Bias, Darks, and Flats and still no joy.  

I'm running on Windows 11 and the AIJ version is 5.5.1.00 which is probably quite old, but I haven't updated because if it's not broken why fix it.  I tried updating today and got a network error saying the server at the University of Louisville may be down.

As stated checking everything in the More Settings display didn't work.  I tried to insert both the settings displays into this message but couldn't get Insert Image to work.  My best guess is the problem is could be related to the CCD gain, readout noise, or dark current which are 0.777, 3.0, and 0.00098 respectively and haven't been changed for years.  

Currently I'm setup for spectroscopy but am considering changing scopes and cameras and getting brand new data for the RR Lyra area but we need a clear night and I don't have the dark skies that we did at Okie Tex.  

Clear skies,
Steve

[karenacollins]

Hi Steve,

It is difficult for us to work backwards and figure out if there was a related bug in 5.5.1. We need to get you migrated to latest 6.9 version. As mentioned in this pinned post, we migrated the hosting away from UofL due to UofL IT department issues, so the updates no longer work. You'll need to go to https://astroimagej.com, click the "Download Now" button at the top, and make sure an installation package for your OS is selected. Download and install that package and see if anything changes. I don't believe the issue is with an incorrect airmass, but there could be something else wrong that is affecting them both. It does sound like the WCS solution in the image header is incorrect, or AIJ interpreation of it is incorrect (but still problably not the underlying cause of your SNR calcuclation problem).

If the latest 6.x version does not solve your problem, I'll have to have you send me a backup of your AIJ_Prefs.txt file (use the menu item option near the bottom of the menu at Multi-Plot_Main > File. I'd also need one of your example images. You can send these to me at my email address listed at the top of this user forum.

It is fine to continue this thread on this forum, but if you have another problem in the future, please post on our new github-based discussions forum per this post.

Karen

[shbarr2001]

Hi Karen,
First I apologize about the message sent which included Airmass which was a red herring.  I was flailing around and attempted recalibration and must have made a mistake.  Tried to delete that post as a result but you must have seen it first.

Downloaded the new version of AIJ and the SNR problem is resolved, but still no calculation of the two check stars.  Thank you for that advice and I have what I need to proceed with my presentation on Thursday.  I will do is another run some evening with RR Lyra or something else visible and see if the check1 and check2 problem persists.  

Thanks again and clear skies,
Steve