Combining HOO with drizzle doesnt work

Posted by: @digitaliz-se

Extracting Ha and OIII from Optolong L-extreme works fine, but not if I do Bayer Drizzle.

It wont Align properly. Is it not suppose to work or is it a bug?

 

/Stefan

Hi Stefan @digitaliz-se,

I think you mean that aligning the Ha and OIII stack does not work well when the stacks are created with Bayer Drizzle? The registration of the single frames for the Ha and OIII stack should not be affected by the Bayer Drizzle itself.

If aligning/registering the stacks does not work, you might have too much drizzle artefacts on the stars, preventing a good registration. Maybe you need to increase the drizzle droplet size a bit for it to work? Have you tried this?

Have you zoomed in on the stars to see if there are clear artefacts? Maybe you can show some screenshots of the data where we can see the pixels clearly?

Mabula

Sorry, 

I get this kind of result after if I use Bayer drizzle. Ive tried Doplet size 0.75 and Scale 1.5 as well as Dropley size 1 and Scale 1. Both will give me this strange result.

If I simply use the Ha-OIII Color algorithm and drizzle, everything works fine.

Here are the extracted Ha and OIII using the Ha-OIII Extract Ha and OIII

https://www.dropbox.com/s/7bjrn77iqgi2t0p/2021-08-31_-_Wizard_Nebula_NGC7380_A7III_FS_L-extreme_5min_EQR6_10_grader_800mm_Drizzle_OIII.fits?dl=0
https://www.dropbox.com/s/q91vere4rqieuli/2021-08-31_-_Wizard_Nebula_NGC7380_A7III_FS_L-extreme_5min_EQR6_10_grader_800mm_Drizzle_Ha.fits?dl=0

/Stefan

Ive tried seveal settings now. But in vain, but I think I have found a workaround. If I use the Ha-OIII color algorithm and use drizzle, then if I load the fits as a light, I can split the channels into RGB and then recombine them into HOO by using red channel as Ha and the other two as OIII. Not really the same, but yields ok results.

/Stefan

@digitaliz-se Good that you found a workaround. What is it that you hope to achieve by using drizzle in the first place?

Ive found that drizzling is not just for making better star shapes, but also supressing noise in space.

Hi Stefan @digitaliz-se,

Also happy to hear that you found a work around, but.... Just to make sure that I understand what is happening and it will work in the next release, can you upload your light frames and calibration masters here:

https://upload.astropixelprocessor.com/

username and password: upload

Please make a folder with your name and let me know once uploaded 😉 I will make sure it is fixed.

Mabula

@mabula-admin

Uploaded