Still having issues with Mosaics in APP

Hi Graham

Just posting here from our dialogue via email.  This looks to be related purely to your data, two of the panels have haze around the brightest stars, one is pretty bad in comparison to the other, and two of the panels do not have haze, this is likely caused by cloud.

Having loaded your frames up, rotated them to be the same orientation as the others, there's a clear difference between sky background quality, and whilst APP can account for some, I suspect this is so much of a difference that it's just not possible.  You can also see that there's a different gradient direction in each of the panels.

How much data makes up each of the panels?  I know you shot with an L-Pro, and the total for each panel is 1800s, I'd bet tempted to look through each of the individual frames and look at the quality of them, APP will provide you a graph of the frame quality also during stacking.

By the way, there's also an artifact in the same position of each of the mosaics, might want to take a look at your flats

APP is great for mosaics, I do lots of them, but the limiting factor will always be the quality of the data coming in, I have instances myself where a few "Problemtaic" frames cause the same thing you are getting.

Simon

@stastro Hi Simon,

What a comprehensive response, thank you so much for taking the time to respond.   I’ll analyse the individual frames to see if I can identify the rogue ones and also have another crack at the target when we get some skies again.   
There were 10 lights of 180 seconds in each panel. I also took flats, dark flats and darks.

I love APP but I do struggle with Mosaics - It’s a real learning curve !

One question, can you think why the gradients are in different directions, as they were all taken on the same night immediately after one another.   Could it be a light leak, or maybe the clouds throwing reflections about ? 

thanks again, Graham 

@grahamdevenishgmail-com Morning Graham

Your gradient could be different because of the orientation of the scope, I presume two of the frames were on the opposite side of meridian to the other two (the fact I had to rotate two of the frames), but there is a stark difference in the gradients, here they all are in their original rotation:

Of course sky quality will impact gradients as well, you did not mention what camera this is from (and it is not evident in the FITS header), tell us more about your imaging setup (Scope, Camera etc)

Regards

Simon

Hi @grahamdevenishgmail-com & @stastro,

Thank you Simon for your assistance here.

Graham, I understand that you have made mosaics before successfully with APP, so I think it will be best for me to have a good look at your data to understand what is going here. Maybe there is a problem with your optical train which is hard to see, but is causing the issues, or perhaps it is like Simon argues. The data might lack some consistency. Anyway, I can not tell for sure without seeing the data myself, so please upload it here:

https://upload.astropixelprocessor.com/

username: uploadData

password: uploadTestData

Please make a folder with your name and issue like: Graham-mosaic-issue

and upload your dataset there with all lights and all calibration files. Please separate the lights in different folders per panel if you can. FInally, let me know once uploaded and I will have a good look as soon as possible.

Mabula

Thanks Mabula.  I've uploaded the files as requested, and in each of the individual Light Panels I've separated out what I think were the bad lights where cloud was affecting the image - However, the Top Left panel was left blank and there were still faint lines separating the panels even with only using the Light frames cleaned up.  I will have another go at a Mosaic if we ever get a decent clear sky again......

I also accidentally created an additional folder which I'm unable to delete !

Here are the specs for the shot and the equipment used;

Astro Photography Data sheet

Subject;          M31 Andromeda

Date;               20 November 2024

Camera;          ZWO ASI2600MC Duo

Gain;               100

Temp;             -10 degrees

Filter;              Optylong L_Pro  

Scope;             Skywatcher PDS 200

Guiding;          ASI 220 (Built into Duo)

Mount;            Skywatcher NEQ6 Pro on a Pier

Data;

Light;              10x180 sec (x4 for a Mosaic) 20% Overlap

Dark;               20 x 180 sec as a Master Dark

Flats;               Auto Flats and Dark Flats (60 of each for a Master set)

Controlled by ASIAIR Pro

Thank you Mabula, and also Simon for his efforts so far !!

Regards

Graham