Needed, advice/help creating mosaics in ASTAP and APP

[Varavall]

Hi

Below are 2 mosaics of M31 the top one from ASTAP and the bottom from APP. The subs are all luminance of 300s taken on the same night, then processed in ASTAP and APP. The resulting 6 panel mosaics show different issues. ASTAP has gaps between some of the panels, whereas APP shows different background luminosities for each panel. I guess there are two questions: 1. How best to eliminate the gaps in ASTAP; and 2. How to equalize the backgrounds in APP. I'm all ears for the solutions!

[tomato]

If it is the same dataset for each mosaic, and each program has registered the frames correctly, I can't see how one would create gaps between the frames and the other would not. I've never used ASTAP for mosaics, but in APP you need to experiment with the LNC and MBB settings at the integration stage. These algorithms even out the background levels between each panel and smooth the joins. I would try 1st or 2nd degree LNC with 3 or 4 iterations and 10% MBB as a starter. Make a note in the image filename of what settings you have used and experiment until you get the optimum result. 

Be prepared to be in front of your computer screen for quite a while...

Great M31 data BTW. 👍

[Varavall]

5 hours ago, tomato said:

Be prepared to be in front of your computer screen for quite a while

Yup, that seems to be my life since taking up astrophotography. Thanks for the pointers with APP, I'll give that a whirl and see what comes out. And yes, it's the same dataset used in each programme.

[Varavall]

On 09/09/2022 at 16:09, tomato said:

but in APP you need to experiment with the LNC and MBB settings at the integration stage.

Getting there after 5 hours computing time with a quad core i7 computer! I need a powerful gaming machine or a Cray for this malarkey.