Stellar Halo's

[Clarkey]

I was recently processing a stacked image and during the star removal stage came across two odd 'halo's' on the starless version. I then went back and looked at the original and both halo's were round very red stars. It would be nice to think that they were the start of a new planetary nebula from a red giant - but I am sure the explanation is much more mundane. However, I have no other explanation. I do not believe they are optical aberrations as they are only on two stars - I have also not seen them before.

Anyone have any idea of the cause?

[Gfamily]

Can you give the RA/Dec ? 

[Gfamily]

Ok I've used astrometry to identify the three brightest stars as

HD199770

HD197407

HD197559

[Budgie1]

They look very much like the halo's created by a dual band filter, like L-eXtreme, L-eNhance or Askar Duo-Band. The only thing I'm not sure about is why the stars are red.

If they are a filter remnant, when you do star removal the halo's are normally left on the background image and can be removed using CloneStamp in PI.

[Clarkey]

10 hours ago, Budgie1 said:

They look very much like the halo's created by a dual band filter

Normally I would agree, but it does seem odd that it is only on two stars. There are hundreds of other red stars in the full image, but only these give the halo. I guess it is possible that these particular stars have a slightly unusual spectrum which is causing the effect. I have had halos on the filter (l-extreme in this case), but on the FMA180 the filter is on the dew shield, not in front of the camera. Previously these reflections have been on bright stars when the filter was near the camera.

I do not think these are any amazing new phenomenon, but they just struck me as odd. 

[Budgie1]

36 minutes ago, Clarkey said:

Normally I would agree, but it does seem odd that it is only on two stars. There are hundreds of other red stars in the full image, but only these give the halo. I guess it is possible that these particular stars have a slightly unusual spectrum which is causing the effect. I have had halos on the filter (l-extreme in this case), but on the FMA180 the filter is on the dew shield, not in front of the camera. Previously these reflections have been on bright stars when the filter was near the camera.

I do not think these are any amazing new phenomenon, but they just struck me as odd. 

I'm sure there's a scientific reason for the halo's these filters produce but they do seem to be on random stars and different numbers of stars on each image.  

If the filter is in dew shield then it's halo producing caricaturists maybe diluted by the other optics between it and the sensor?