M51 Possible IFN? Help!

[Firas]

Hello! 

After what turned out to be a great astro-imaging night at Wim's @wimvb dark skies, north of Stockholm, I stacked the Luminance of 2 hours and 40 minutes of M51, taken with my 80 ED and Moravian G2 8300.  

As you see the integration yielded very nice results for that short integration time, thanks to the Bortle 4 skies. I knew that I should get something much better than my Bortle 8 skies in Stockholm city, but I was not anticipating such result in my wildest dreams. 

Anyways, the stack shows what I believe to be some sort of wisps of integrated flux nebula (IFN) that I never seen in any image before, in the lower left corner surrounding galaxy NGC 5229 which I haven't found any wide field image of it, that shows any hint of IFN. 

 

The pattern shows on all the subs frame and its signal grew stronger with stacking. Here is an inverted range selection mask that clearly shows it. 

But the question forces it self here, Is it truly an IFN or some sort of internal reflection in the tube? If it is the later why does it look like that and how to know for sure? 

I wish if the weather would allow me to image around galaxy NGC 5229 to see if the pattern stretches further or if I am all to optimistic and mistaken a light astray in my tube to be a new discovery ?

 

 

[dph1nm]

Nothing obvious in Pan-STARRS, SDSS or DECaLS surveys at this location.

NigelM

[coatesg]

I think this is something to do with Alkaid (at mag 1.84) which is exactly in that direction, about 2 degrees away. 

It sort of looks like some kind of reflection possibly off a circular shaped surface?

[Firas]

11 minutes ago, dph1nm said:

Nothing obvious in Pan-STARRS, SDSS or DECaLS surveys at this location.

NigelM

Intersting! 

 

8 minutes ago, coatesg said:

I think this is something to do with Alkaid (at mag 1.84) which is exactly in that direction, about 2 degrees away. 

It sort of looks like some kind of reflection possibly off a circular shaped surface?

Yes! Alkaid is about 2 degrees away. But that is really far fot its light to come near NGC 2559! Don't you think? 

[Knight of Clear Skies]

I'm fairly sure the parallel arcs are some kind of artifact, I've never seen anything as regular as that in an astronomical image. Looking on World Wide Telescope the IFN is very faint compared to the other end of Ursa Major (I've found a good correspondence between the SFD dust map and visible IFN in the past).

[Knight of Clear Skies]

1 minute ago, Firas said:

Yes! Alkaid is about 2 degrees away. But that is really far fot its light to come near NGC 2559! Don't you think? 

Could certainly happen if the tube is reflecting a little. Please bear in mind, we're talking about one of the brightest stars in the sky.

[Firas]

1 minute ago, Knight of Clear Skies said:

Could certainly happen if the tube is reflecting a little. Please bear in mind, we're talking about one of the brightest stars in the sky.

Wow! Never thought the light could stretch this far. Seems logical though. 

[Knight of Clear Skies]

Hopefully something like Gradient Xterminator can clean up the background. Your M51 and background fuzzies are looking really good.

[ollypenrice]

1 hour ago, Firas said:

Wow! Never thought the light could stretch this far. Seems logical though. 

Flare artefacts often get worse as the image moves away from their source. We have been fighting just this phenomenon in an attempt on NGC3227 and I remember the same thing with Deneb on a 9 panel North America Nebula project. The panel with Deneb near the middle was easy and flare-free. It was an adjacent panel which had a terrible flare coming from a very much off-shot Deneb.

Olly

[Firas]

4 minutes ago, ollypenrice said:

Flare artefacts often get worse as the image moves away from their source.

I see! I was not aware of the phenomena. But how a flare can stretch over 2 degrees or more?  

[coatesg]

20 minutes ago, Firas said:

I see! I was not aware of the phenomena. But how a flare can stretch over 2 degrees or more?  

The PSF from a star does not cut off at any point (in theory) - it fades such that it eventually can't really be detected, unless you stretch the thing to death. Eg I have images of a variable where I can see diffraction spikes from Alcor despite it being over a degree off field!

This isn't a PSF/diffraction however, and I don't think it's necessary for - might be a reflection - in which case it could reflect almost anywhere really. 

Do you have a lens shield, and do you have it flocked? Is there flocking/baffling in the drawtube? All places to look for culprits...

[don4l]

47 minutes ago, ollypenrice said:

Flare artefacts often get worse as the image moves away from their source. We have been fighting just this phenomenon in an attempt on NGC3227 and I remember the same thing with Deneb on a 9 panel North America Nebula project. The panel with Deneb near the middle was easy and flare-free. It was an adjacent panel which had a terrible flare coming from a very much off-shot Deneb.

Olly

I'm currently processing an Orion mosaic.  The panel with Betelgeuse wasn't as difficult as the panel below for some reason.  The problem extended a good 2.5 degrees from the star.

[wimvb]

Nice image, Firas. Next step is to process the colour frames.

I don't think you can get rid of the star flare/reflection with dbe, simply because it has a fine scale structure. You may need to create a mask and reduce its brightness.

[Firas]

14 minutes ago, wimvb said:

Nice image, Firas. Next step is to process the colour frames.

I don't think you can get rid of the star flare/reflection with dbe, simply because it has a fine scale structure. You may need to create a mask and reduce its brightness.

Or crop as intended ?