Anyone else image M13 last night?

[jl694]

I took advantage of the beautifully clear evening yesterday to image M13 with 2-minute subs for just over an hour.

I stacked the individual frames this morning (kappa sigma clipping) and found something I can't explain. There is a prominent streak to the top left of M13 in the image:

(this image is excessively brightened to accentuate the streak)

I can't seem to find this in anyone else's pictures of M13, yet it appears in every one of my light frames in exactly the same place. I don't think this is a symptom of my imaging train since it doesn't appear in my dark frames or some flat frames I took but haven't stacked yet.

Did anyone else capture M13 last night? Can you confirm whether or not this streak is a real astronomical object or just down to my imaging setup in some way?

[Stub Mandrel]

Estimating the centre of that arc it could be flare from 65-Her which is mag 3.15.  I've had similar marks and they always line up with a bright star.

<edit> and if you draw the line further ... Vega.

[jl694]

Thanks for your reply. I'm not familiar with flare caused by bright stars. Would you be able to post any examples that you've captured?

[Stub Mandrel]

Ok, this took a bit of finding as I have either deleted or cropped images with that sort of mark.

This has no particular merit other than showing the sort of marks I mean, there are two at top left.

This is a complete fail to get an image of the pelican nebula (at right) and the two curved marks point towards Deneb. As you might be able to see the 'centre' of the curves is within the frame although Deneb is well outside it. This suggest to me that your fainter, less curved marks could be from a bright star quite far out of view. I wonder if they could be caused by reflection off a damp dew shield or similar?

[physicus]

I took advantage of the beautifully clear evening yesterday to image M13 with 2-minute subs for just over an hour.

I stacked the individual frames this morning (kappa sigma clipping) and found something I can't explain. There is a prominent streak to the top left of M13 in the image:

(this image is excessively brightened to accentuate the streak)

I can't seem to find this in anyone else's pictures of M13, yet it appears in every one of my light frames in exactly the same place. I don't think this is a symptom of my imaging train since it doesn't appear in my dark frames or some flat frames I took but haven't stacked yet.

Did anyone else capture M13 last night? Can you confirm whether or not this streak is a real astronomical object or just down to my imaging setup in some way?

These things come in colour too!  Prompted by your post I just checked various radii on Stellarium, and reckon in my case the star Sheliak is to blame.  This effect has spoilt all my long exposure attempts on M57  (there again, the whole thing is quite attractive too).  But I did wonder what it was at first.  Ollie suggested reflections from nearby stars.