Flats from different sessions
Stacking program, astrometric (plate) solver, fits file viewer
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Han,
Ive read the updates in manual , thankyou
I will download the latest version and try it once I get some clear skies again , this may take a while
Martin
Han,
Ive been thinking about my Flat Darks which again are captured just after my Flats on each different night session over a period of weeks or longer where my camera is removed and re installed. My Flat Darks match my Flats with respect to exposure time, temperature and Gain. However my Flats are never the same expousure time for each different night on same filter.
Question : For example lets take the Ha filter data sets captured over 3 different nights , If I load all my Lights , Darks ( tick both create Master Dark and Classify by date for master creation ) , Flats ( tick both create Master Flat and Classify by date for master creation ) and Flat Darks , how does ASTAP know which of the 3 loaded nights of Flat Darks with different exposures to use with each nights Flats ? Should I have to tick Classify by exposure at the bottom in the Flat Darks tab ?
I just want to understand the ASTAP process to match Flats Darks with Flats captured over many different nights on the same filter and slightly different exposure times.
Hope my question is understood
Sorry for going over the same ground , just want to get the settings correct for ongoing testing the updated version
Thanks
Martin
Hi Martin,
Discussing helps with designing ASTAP so that is good.
That should all work except for the selection of the flat-darks. For your setup ideally they should match with the flats for both date and exposure duration. The match for exposure duration is missing. You could fix it by making the master flats in steps but I will add an new check-mark "classify by flat & flat-dark exposure duration".
The check-mark "classify by dark exposure time" works for both dark creation and selection of lights with darks. It doesn't work for flats & flat-darks. So the new check-mark mentioned above should be added.
I will also change the term "time" to "duration".
Han,
Thanks for understanding the issue I have for correct calibration using Darks , Flats and Flat Darks captured over different nights with same filter and slightly different exposure times for Flats and matching Flat Darks
Yes , adding a new check mark - Classify by Flat and Flat Dark exposure duration would solve that issue .
Im quite surprised that nobody else has raised this issue in the past across the world and asked for appropriate changes to ensure correct calibration process when capturing data over multiple different nights on the same filter using Flats and Flat Darks with subtle differences in exposure times.
I await your confirmation of these updated changes
Thankyou again
Martin
For flats you most likely will not notice difference in gain, temperature and exposure duration for flats and flat-darks. Anyhow I put it all in a tables:
http://www.hnsky.org/astap#lights_tab
Putting in tables was a good exercise.
Next version with these changes will be ready in maximum one hour.
Han
Try this development version for Windows:
http://www.hnsky.org/astap_setup.exe
Thanks Han
Im away visiting family for a week so will download this latest dev version when im back
Clear Skies
Martin
No problem. Also my weekend is busy.
When you have time then download again a fresh version and test the new option "Star colour smooth". Should fix colour smoothing for most very bright stars. See attached.
Thanks
I use Startools which requires stacked data set to be clean with no tweaks or adjustments for both OSC and Mono
https://www.startools.org/links--tutorials/starting-with-a-good-dataset/recommended-astap-settings
Martin
Han,
I downloaded the development version and tried it on my latest aquisition IC 4628 Prawn Nebula which was captured over 4 nights during May. I captured Flats and Flat Darks for each night on each filter. ( total SHO integration 14 hours ) Camera was removed and re installed each night for the 4 nights.
I tried 2 options ......
Option 1 - Loaded all Lights , Matching Darks from library then created a Master Dark , all Flats and corresponding Flat Darks then created a Master Flat , same procedure for each filter , SHO ( Used the Classify by date and exposure for master creation check boxes )
Sii stacked image was clean , evenly illuminated, no vignetting and no dust motes
Ha stacked image was clean , evenly illuminated, no vignetting and no dust motes
Oiii stacked image was clean , evenly illuminated , no vignetting and no dust motes
Option 2 - Loaded all Lights , Matching Darks from library then created a Master Dark, used only 1 night Flats and corresponding Flat Darks for each filter, SHO ( did not use Classify by date and expoure for master creation )
Sii stacked image was clean , evenly illuminated, no vignetting and no dust motes
Ha stacked image was clean , evenly illuminated, no vignetting and no dust motes
Oiii stacked image was clean , evenly illuminated , no vignetting and no dust motes
Obviously Option 2 where I only took 1 set of Flats and Flat Darks for each filter and used for all 4 nights Lights saves so much time moving forward
I dont know whether I should persist in capturing new Flats and Flat Darks for each filter over each nights capture even when I remove and te install camera as Option 2 proved otherwise.
The latest Development version worked perfect.
Clear Skies
Martin
Good it worked fine.
As long no significant dust is visibile, I would skip taking flats & flat-darks for each night.
Clear skies, Han
Han,
Ive just realised that my filter wheel ( ZWO EFW 2" x7 ) is permanently fixed to my camera ( ZWO2600MM ) and therefore my sensor to filter orientation always remains the same for each filter. My TS Optics GPU coma corrector is permanently fitted to my Filter wheet adapter ring so removing this complete (camera / filter / coma corrector fixed imaging set up ) from the focuser each night session does not change the filter / sensor orientation at all , therefore only one (1) set of Flats are required per filter per object ( irrespective of how many nights data I capture )
Re fitting the camera / filter fixed imaging set up in the focuser each night session may only changes the rotation of the field slightly if its not perfectly aligned in the focuser each time.
Why didnt I think of this from the start ??
This is going to save an immense amount of time , time I can spend capturing more data
Clear Skies
Martin
Yes good plan. I see no problems.
Even with the filter removed it will work fine in most cases unless you have a large dust particle suddenly occur on the camera window or filter. Dust particles on a filter are typical less influential due to the larger distance. (but for the ZWO filter the distance is relative short)
Clear skies, Han