White Stripe in Picture. What is it?

[CT08]

Hi everyone,

my name is Cedric and i'm from germany. I started Astrophotgraphy last year and since then i'm trying to improve my skills. I'm using PixInsight for quite some time now (awesome piece of software). Anyway my last picture showed some weird white stripe, after Stacking, and i can't figure out what this is. I checked my Scopes mirrors, the Sensor of my Camera, the coma corrector, the filter and found nothing strange. Just a few little pieces of dust on the telescope mirrors, Corrector and Filter. CCD Sensor is clean. It's no PI Stack Problem (I tried DSS as well and you can see a Stripe in every RAW Picture, but only very faint). The Weather here is actually quite bad at the moment, so i can't do another test run and see if it's a one time event. So i uploaded the Photo and maybe someone has an idea what this could be. Thanks for your time and i hope everyone understands what my problem is, im not writting that often in english. You can see the Stripe very clearly in the middle of the Picture, where the Dark Clouds are. It's visible from top to bottom. Target was NGC 281, the picture is not further processed. It's only the Stack with an applied STF.

Ah and my Gear: Camera Nikon D5200 Astromod, Skywatcher Explorer 200/1000, AZ-EQ6GT, MGen, Baader UHC-S Filter.63 x 5 Minute Subs at ISO 800, dithered,100 Bias,50 Flats, no Darks.

All the best and clear skies,

Cedric

https://goo.gl/photos/JmXdgGN8YYwQdmXr6

[NGC7789]

The stripe seems to follow the glow in the lower left corner (brightest at the bottom and then fading toward the top). Since you are using a newtonian my guess is that it's a diffraction spike cased by something bright just outside of the field of view. Could be a bright star or some local light. If I'm reading your image correctly Achird (Eta Cassiopeiae) may be close enough and bright enough. In fact if you look the stripe is parallel to the spikes on the stars.

[oldwexi]

Hi Cedric!
We establishing in Austria a tutorial collection in german language.
http://www.alrukaba.at/cms/upload/PI/Main_PI_tut_Mittetop.html
The correction of bad columns is already in there. Look at   SPALTEN KORREKTUR.
It is a simple PixelMath solution.

For more complex Solutions, which are not in the tutorial,  for example conic stripes here the link to the finished Project.
https://www.dropbox.com/s/2ogybkl0lin01nj/PixInsight_Schulung_remove_Conic_trail.zip?dl=0
Load the Project and step through to see how the conic Trail is removed.


Gerald

[CT08]

Hey NGC7789,

thanks for your fast reply. I never thought about that, but i think that makes sense. My grandma has mounted some small Solar-LED light in the garden, i ignored it the last time, because it wasn't very bright (never underestimate light pollution and small light bulbs  ), but maybe that is the cause of the spike. I will turn it off and then give it another try.

Hi Gerald,

also a big thank you to you, i'll check this out and will post my results. But i'm not sure, if i can test it today.

There's one more question (maybe a dumb one ;-)): As NGC7789 mentioned, it maybe a bright star, is there a way to avoid this?

Thanks again, it's awesome to see, that people here are trying to help!

All the best and clear skies!

Cedric

[NGC7789]

it maybe a bright star, is there a way to avoid this?

If it is a bright star, you may find that a slight change of image framing is sufficient to move the star far enough away to eliminate the spike or at least reduce the severity of it. Always turn off local lights under your control. They can never lead to good!

As for Gerald's always marvelous techniques, I would leave post-processing as a last resort. It's always best to get your capture as clean as you can.

[CT08]

@7789

Yes you're absolutely right about the lights (should have thought about that, before taking pictures) and the Post Processing, it's way better to get your shot a clean as possible! Okay, i'll try to change framing, and see what will happen. But i think i'm not able to take some photos the next few days. Very cloudy here.

@Gerald

I downloaded your Dropbox File, but i don't know how to open the files in the zip. Never heard about XOSM and SEAL fileformats. What kind of Software is needed to read this files?


Cedric

[msmythers]

Cedric

This is a PixInsight project. Just open from the file menu Load Project selection.

Gerald that is very nice. Learning a lot from that little project.


Mike

[CT08]

Hey Mike,

thanks for clarifying, wasn't aware of the Load Project Function, because i've never used it.

Cedric

[pfile]

just be aware that everything in your workspaces will be closed and replaced with what's in the project. so if you want to save what you've got going, first save a project containing all of your workspaces, then open the project uploaded here.

rob

[CT08]

Hi Rob,

yes i noticed that, thankfully no important Workspace was open. But it's not that easy to understand everything, that's used in this Project. Never used Pixelmath before.

Cedric

[oldwexi]

Hi Cedric!
In the same link i mentioned above there are also German Videos -
for example one about Basic functions of PixelMath  "GRUNDFUNKTIONEN"
This will bring you the very important and mighty process of PixelMath nearer!

Gerald

[CT08]

Hi,

here is a quick update, so i tried it again and the glow was gone. It was one of the little solar led lamps in the garden of my grandma and one of the street lamps that wasn't fully covered by a tree. So i switched positions and everything is fine now! Thanks for all your help and have a nice week!

cs

Cedric