Dark vertical stripes on AstroArt stack

[AlistairW]

Hello,

I have been using AstroArt 6 to stack a red channel. Using Flats, Bias as Darks, and Bias as Flat Frame for Darks. I seem to be getting a lot of vertical banding after the stack, that does not exist on the subs. Any ideas, as I am using the default options apart from having Sigma (Average) as the Result Image.

Thanks

 

Alistair

[AlistairW]

Should a stacked bias of 30 frames look like this ?

 

[ollypenrice]

21 hours ago, AlistairW said:

Should a stacked bias of 30 frames look like this ?

 

It doesn't really look like that! What you're looking at there is a massively screen-stretched bias. Mouse over the image in AA while looking at the ADU values for the pixel you're mousing over. They appear on the bottom of the screen. That will tell you the real range of brightnesses in the bias. 

I can't see the banding you describe in your first post. Coulmd you post a good hard stretch?

Olly

[AlistairW]

Hi,

Thanks for the reply. I found what i was doing wrong - i was playing around with master bias for flat darks. But was putting the master in the wrong section - think i ended up subtracting the bias twice - hence introducing the noise. I will put it down to the learning curve and avoiding using darks at all. Next is to learn how to create a defect map ?

Thanks 

Alistair

 

[ollypenrice]

20 hours ago, AlistairW said:

Hi,

Thanks for the reply. I found what i was doing wrong - i was playing around with master bias for flat darks. But was putting the master in the wrong section - think i ended up subtracting the bias twice - hence introducing the noise. I will put it down to the learning curve and avoiding using darks at all. Next is to learn how to create a defect map ?

Thanks 

Alistair

 

It tells you in the instructions, which are pretty good in AA. I think I just took a master dark, went into Arithmetic and then Clip and clipped 2000 ADU off the dark.

Olly