DSC October - Actual astrophotography?

[JonH]

Who has been chopping and changing the threads, confused much!

I think possibly my biggest problem was to use the merge_hdr command you first need to create a text file saved as a .lst which contains the different file names to combine and a number which defines the difference in exposures between the files.
I wasn't sure if that meant exposure per individual sub which is what I have used so far, but now thinking about it is very unlikely to be the correct number since the subs have been stacked into groups making this number rather irrelevant now, or the accumulated difference in exposure between the different groups of subs, FAR more likely to be the correct number.
Except I have a big variable to deal with being that the different groups of subs were taken from different locations with very different levels of light pollution thus again making this number most likely to give me a poor result.
BUT I have just discovered you can used the desc_hdr command in Iris which will look at an area defined by you of the different stacks, calculate the difference in exposure and create the .lst file for you. Thus giving you the correct numbers to use!

Progress is being made!  

[JonH]

Ahhh, thanks Mark that might just save me some considerable time as a full re-stack might yet be on the cards to tease out every last bit of detail!
I'm going to need every scrap of data I can find to stop my attempt at M31 falling into insignificance next to what you have on the way, which it will probably do anyway!