M13 wide field - 1 April 2012 - Blainville-Sur-Mer, Manche

[The Thing]

Canon 350Da, Skywatcher AT80, HEQ5 - no guiding. 20x120s @iso800.

Pretty awful image but does anyone know what the red ring shaped object is? I can't find it anywhere - it may be an artefact.

[Mike]

There is nothing I can find on any of my charts. It is either a weird looking artefact or you have discovered a newly popped planetary nebula.

[Mac]

Its definatly an artifact,
have a look at the exact same position on the other photo,
M81 & M82

http://forum.orpington-astronomy.org.uk/index.php?topic=8320.0;topicseen

the same red rings appear there as well, although stacked.

Mac.

[Mike]

Maybe an out of focus image of a reflection of a nearby LED ?

[The Thing]

There can't have been any LED's that high unless my laptop took flight or it's on a geostationary satellite! The OTA has been flocked though the draw tube and dew shield haven't. There was no CLS-CCD filter in the Canon. There is a possibility that the right angle finder I had on the Canon which was always pointed down during exposures so as not to catch torch light was pointed at an LED, but the two images are in different parts of the sky so it was pointing differently for each target. The only LED's around apart from the mount were 2 green ones (power slab and cigar plug) as I had a very cut down set of kit - no DSC fairy lights - and the laptop which has blue or yellow illumination and was in a cardboard box anyway.

There is a mystery...

Here is a full size crop.

[Mac]

have you checked on the darks?
assuming that you have not used your library set?

Might be worth while creating a dark to have a look at,
could be a tiny light leak somewhere.

Mac.

[The Thing]

I used a master dark created by DSS a while back since I wasn't after quality as such. The dark has no such artefacts.

However the flat has a big black blob at that location! The 350s CCD is filthy. It's a know factet that DSS doesn't process flats well. QED.

The same flats were used for both images as the subs were taken at the same time with the same setup,

[Mac]

Ahh, maybe its not a black blob, but a green and blue one, and the colour that has been left is red.

have you checked the individual RGB layers to see if the blob is on all of them,

could be an answer.

Mac.