Ha will not stack?

[Jkulin]

I wonder if anyone could help please?

I've got about 5 hours of M82, but only managed 5 x 600s of Ha because the clouds came in.

I've used the batchprocessing script and everything apart from the Ha stacks nicely.

I have tried a number of times to stack the Ha on it's own and it comes up saying it cannot find enough stars.

The files calibrated fine, and the image visually looks like it is all aligned.

Could it be because I'm using 3nm 2" unmounted Chroma filters that there just isn't enough data there to stack?

My masters were a bit old so I have spent the last couple of days recreating new superbias's and Master Darks.

I don't have any noisy subs with any of the other filters and my NB images during the winter have turned out really well.

I'm really at quite a loss and would welcome any ones thoughts.

I've uploaded a zip file of the master dark, superbias, Ha master flat and the 5 x 600s Ha lights, would anyone mind having a look and seeing what I am doing wrong: - https://drive.google.com/file/d/1Sh9ofzpDQhvmiRqrVU4WJyQmCvJERQyw/view?usp=sharing

Your help would be much appreciated.

[bulrichl]

The files calibrated fine, and the image visually looks like it is all aligned.

I disagree, the files didn't calibrate fine. The calibrated files contain a bunch of hot pixels. This strongly disturbs the StarAlignment process, and this is subsequently causing the trouble with ImageIntegration.

One possibility is that the used MasterDark is either too old or doesn't match the light frames (temperature, exposure time, if applicable gain and offset). In this case you would need to capture new dark frames and make a new MasterDark. However, since you didn't provide a single dark frame I cannot judge whether the conditions for the capturing of light and dark frames match.

If this is not the cause of the trouble, you will have to apply CosmeticCorrection after ImageCalibration. I tried this on your data and it succeeded without any problem. In CosmeticCorrection, I enabled 'Use Master Dark' and in the section 'Hot Pixel Threshold' checked 'Enable' with a Sigma of 3.0. This setting (which is not optimized, it was just a shot in the dark!) nicly removed the remaining hot pixels. Subsequently, StarAlignment and ImageIntegration worked flawlessly on the calibrated and cosmetic corrected light frames.

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One comment on your settings for ImageCalibration when calibrating the light frames. You don't use dark frame optimization. Nonetheless you are using these settings:

Section 'Master Bias': enabled, "superbias5.xisf", option 'Calibrate' enabled
Section 'Master Dark': enabled, "Master_Dark_600s.xisf", option 'Calibrate' enabled, option 'Optimize' disabled
Section 'Master Flat': enabled, "flat-FILTER_Ha-BINNING_1.xisf", option 'Calibrate' disabled

These settings effect that the superbias is subtracted from both the MasterDark and the light frame, then the resulting calibrated MasterDark is subtracted from the calibrated light frame. So the use of a MasterBias (or superbias) is completely unnecessary in this case. The same would be effected with these settings:

Section 'Master Bias': disabled
Section 'Master Dark': enabled, "Master_Dark_600s.xisf", both options 'Calibrate' and 'Optimize' disabled
Section 'Master Flat': enabled, "flat-FILTER_Ha-BINNING_1.xisf", option 'Calibrate' disabled

So you don't need a MasterBias (or superbias) for the light frame calibration at all. Of course, a MasterBias (or a MasterFlatDark) is needed for the calibration of the flat frames though.

I hope this helps.

Bernd

[Jkulin]

Bernd, Thank-you so much to take the time to reply, it truly is appreciated.

I'll work on your suggestions and let you know how I get on.

I have created new Superbias and Master darks for 600s prior to posting and I did try that but it failed.

My reason for thinking they had calibrated was because the batch pre-processing had created files in the calibrated folder and put a _c at the end of the file name.

The camera is a Moravian G2-8300 MkII and I have had some fantastic results with it combined with the Chroma LRGB and NB 3nm filters, so your help will really be of benefit to me.

BTW the Superbias is here: - https://drive.google.com/file/d/1CHzegnz8JoO9ORGA1F_RsNV-yXO8eaU3/view?usp=sharing

Here is the link to the Flat Ha: - https://drive.google.com/file/d/1naotoenQNQzxeJQ9Ubck1d79qyiyBNfm/view?usp=sharing

And here is the Master dark for 600s: - https://drive.google.com/file/d/1F5cB6ILJ-Mnizkh_RRLpX4Nv1I00X82R/view?usp=sharing

Once again thank-you so much

[Jkulin]

Hi Bernd,

I think I have tried what you suggested but it still failed, I've attached a txt file with the process details?

At my age I am probably being thick, but would welcome your though?