M101 what is this in the image? (OTA reflection?)

[B_ickringill]

HI SGL Folk, 

Here is a recent image of M101. The JPG is the output from batch processing in PI with an extreme STF applied.  Really pleased with the detail in the galaxy but confused what the streak is in the top left portion of the image. I blinked the sub frames and it is present in each frame. I noticed something similar but in a different position in my image of NGC4565;  it is in the lower right corner. The camera and filter (ATIK 314L and Astronomic 1.25" UV/IR cut) were in the same orientation for both images as they were taken on the same night without rotation of the camera. 

Any ideas as to what is causing this streak? Tube reflection? 

Many thanks, 

Brendan 

Edited April 23, 2023 by B_ickringill
Clarity title

[WolfieGlos]

Could it be a tiny hair caught somewhere? I once had a black line in the corners of my images, and I found an eyelash or something had got inside and wedged into the corner of the sensor of my DSLR.

[Chrissyfbpe]

1 minute ago, WolfieGlos said:

Could it be a tiny hair caught somewhere? I once had a black line in the corners of my images, and I found an eyelash or something had got inside and wedged into the corner of the sensor of my DSLR.

What is a DSLR??? Is it a big lens for a camera or is it a lens for a telescope?

[WolfieGlos]

It’s the camera itself, one that can use interchangeable lenses, I.e. that all landscape, wedding, animal and sports photographers use.

Most people who start astrophotography already have a dslr (or mirrorless) and opt to use it from the outset, instead of purchasing a dedicated astrocamera. 

[AMcD]

It might be a lens reflection caused by one of the bright stars that is just outside of your field of view.  I had a similar problem last year when imaging a nebula close to a bright star.  The bright star was not within the frame, but close enough to the target to cause reflections.

[B_ickringill]

Thanks for the suggestions. I'll have a close look for hairs. 

Also check how close any stars may have bee  to the FOV.

 

Thank you!