Help Preventing Star Halos!

[iksose7]

Hi, i have noticed on my latest 3 images i have succumb to a really annoying star halo problem, i will include my latest image below which i have just stacked, no processing other than a histogram transformation and a crop.

I have never had this problem before, its kind of just appeared this year, and i really want it gone. Can anybody tell me what may be causing this or how i can fix it?

I am using a refractor, i know if it was a reflector flocking would be advised but i have never heard of this being done on fracs.

I seriously appreciate anybodys help here, thanks.

Callum

[ronin]

I assume you are using the 115 EDT, so that is a triplet.

Initial thought is moisture, but not sure about the distinct ending to the circle, would have expected it to fade more not stop.

Halo is off centre which could mean something is not sitting flat or orthogonal, but that would make circular halo's so not really a cure.

Is this occuring everytime or just the last few nights ??

Just the last few nights have been a bit odd and moisture in the atmosphere is most likely for that and you could be getting diffraction of the light from the bright stars through the atmosphere - it looks similar to a moon halo on "misty" nights. Stacking could be bringing out this diffraction.

As said it looks very similar to the brighter moon halo's that are not uncommon.

[iksose7]

Hi Ronin,

Yes it with the 115EDT and yes, just the last few times using it.

I may have an idea of whats causing it. I had a look down the scope before and it almost looks like the baffle at the bottom end of the scope has moved down, revealing a reflective surface at the bottom, perfect culprit for the halos i would say. Hopefully its not a serious problem that requires a long trip back to the UK for service. I will post some images when i get a chance. The scope is imaging right now but its cloudy the next few nights so that will give me a chance to take a proper look.

Callum

[ronin]

Makes some sense, if the baffle has moved at an angle then that could be why the slight off centre effect.

Sending it back is a pain but if in warrenty then dismantling it yourself is not a good idea.

[iksose7]

I will have to check what the status is on my warrenty as i bought the scope from Io Astronomy which ceased to exist within the past couple weeks i think.

Callum

[ollypenrice]

If it's at the bottom you'll only have to remove the focuser so you won't disturn the optics at all and it should be a painless and low risk process, I'd have thought.

Olly