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Never tried it myself, but have you tried adding a pedestal? My guess is that if the flats over correct, they have too much dynamic range (contrast). You can decrease contrast by adding a value. Btw, division by a constant shouldn't work.

General / Re: GOES Belt Satellite Trails: Best rejection?
« Last post by pfile on Today at 22:10 »
GOES as in the weather satellites?

the large scale rejection might be able to take care of them. another thing that rickS has mentioned is to open each sub and use pixelmath to draw a white line over each satellite trail, thus making them super-duper outliers and more easily rejected. i think adam block also recently posted a different method; it may have been based on LS rejection. can't remember offhand.

Gallery / M33 HaLRGB
« Last post by rdryfoos on Today at 22:00 »
32 10 min red
31 10 min Green
24 10 min Blue
18 20 min Lum
8 30 min Ha
TOA 130 at F7.7 and STT-8300
I used the new photometric colorcaliobration tool.

You can use cosmetic correction after calibration but before debayering (assuming this is from an osc/dslr camera). During image integration, you decrease the rejection parameters, to get more aggressive hot pixel rejection. This should help you get rid of them.

Open your calibrated, registered images with the blink tool. Zoom in on the area where one of the streaks is and run through the images one by one. My guess is you'll see a hot pixel that follows the direction of the lines.
I have an odd problem, my flats seem to be overcorrecting and I can't seem to fix it. They are Sky Flats (morning twilight) taken on the same day as the lights.

However, when I apply them they seem to somehow overcorrect the data.
I aimed for an ADU of 30k, but they're closer to 40k. Might be slightly overexposed, but not tremendously I think?

Flat (XISF, dropbox)
Light (XIFS, dropbox)

Any thoughts on whats wrong with my flats, and how to avoid this problem in the future (or ideally, somehow "fix" the flat?). I tried subtracting a fixed value from the flats (e.g. a pedestal) but I couldn't seem to get it right.

Note that this problem is /much/ worse with narrowband data, even though the flats were also shot with that filter.

SII Flat
SII Light

Full stack of flats (~700MB, very large!). And, also master bias for good measure. For NB data it seems that working without flats is preferred over using them in this setup, but I'm stumped as to why.


I'm new to PixInsight and AP.

I processed the attached image with 25 lights, 5 darks (I know too few) and no flats or biases  (maybe should have had them)

But I'm stumped as to what the "trails" of red, green and blue pixels are.

What are they? And did I miss a step?  Were they because of not having flats and biases?

I don't want these on all my photos.

General / GOES Belt Satellite Trails: Best rejection?
« Last post by Terry Danks on Today at 18:49 »
I am processing an image with numerous GOES trails. I have 22 lums and have selected Linear Fit Clipping as Rejection 1 in the Image Integration tool. No idea about Rejection 2, 3 or Large Scale Rejection settings. Have tried Winsorized Sigma as well.

Trails are substantially muted . . . but still present.

Is there a better way to suppress these evil things?
Or maybe your CPU voltage is set higher than needed.
Buying a new faster PC is also a good option ;) (at least 6 cores should about double your speed.)
You have an 9 year old 130W CPU.... (45 nm, They make them on 14nm now)

Thanks OldSkyEyes,

My nephew is a computer guru so I'll get him to check the voltage of the CPU and to look at Rob's suggestion about uderclocking it in the bios. (All Greek to me).

Regarding getting a new machine (I wish), unfortunately that is not in the budget for the time being.... must make due with existing gear.

Best regards,
you can set the # of threads to something lower than your machine actually has - Global Preferences > Parallel Processing and Threads > untick allow using all available processors, set box to # of threads, apply global (round button at bottom of preferences screen). that might keep the temperature down a little bit.

but any application could potentially do this to your CPU so you might investigate underclocking your CPU from the bios or a better cooling solution...


Thanks Rob,

That was just what I was looked for... it worked perfectly!

Best regards,
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