ASI 1600 mm cool - Something Strange.

[Kaliska]

Just noticed this fixed pattern on my images tonight (light grey pixels). They are on every image so far and i have added a second image showing my last session (the usual mixed background pattern).

Any ideas?

Edited August 8, 2019 by Kaliska
Photos Added

[Demonperformer]

Are they still there when you apply your flats?

[Kaliska]

1 hour ago, Demonperformer said:

Are they still there when you apply your flats?

I'll be checking that tonight and I'll probably do a new set of Darks/Flats to see what happens.

 

[david_taurus83]

Are they on a dark frame of the same length?

[Kaliska]

10 minutes ago, david_taurus83 said:

Are they on a dark frame of the same length?

I've just managed to take 1 dark frame remotely (as I'm currently at work), but i dont have a viewer here, so I've just uploaded it here for now.

Iris Nebula_Lum_Dark_120sec_1x1_2019-08-08_80.8_.fit

[vlaiv]

Dark that you uploaded looks rather normal, except for the fact that I think your offset is set too low - you might want to increase it. It is probably set in range of 20-25. Raise it to something like 60ish.

Do this on a new target and do another set of darks that you will use after this setting change. Don't mix subs that you have now (with offset 20ish) with new subs that have offset 60ish (you can mix calibrated lights with one setting and new setting, each calibrated with corresponding darks / flats / etc, but don't "cross" use calibration frames - if you know what I mean).

Background in top image looks darker than background in bottom one - this is due to different level of stretch. But if you look at stats panel - bottom image is much "darker" in background than top image:

vs

They are either of different exposure time or upper image was shot in rather poor conditions - meaning low ALT for target and in direction of LP.

In any case, those specks might be artifact of stretching in SGP rather than true artifact of the image. In order to see what the actual sub looks like - it's best to have one calibrated light sub and examine that - maybe post one calibrated sub of above target here so we can run stats on it and see if there are unusual specks in the background or whatever.

[Kaliska]

10 minutes ago, vlaiv said:

It is probably set in range of 20-25

Yes, its at 21 right now, still getting to grips with these settings TBH.

I'll calibrate the image tonight with my current settings first, then change them after to your suggestion.