Ison background

[MarkH]

Ok folks, last year I completed a moocs course with Curtin university Australia, on astronomy. One point that was emphasised was never ignore an anomoly in your data as it could yeild important information and not just data recording error. Today I received the latest edition of Sky at night mag with several SOHO images of Ison passing it's perihelion. In the background of  5 of the images to the 7 o'clock position is an object like a star with a line through it, now I'm pretty sure it's not Saturn, so any expanations anyone?

[Mike]

I can't see the image so can only guess. My guess is it's a CCD without anti-blooming technology and it's overloaded the cells. Or, it's just a diffraction spike.

[Rick]

Like this (composite) image --> http://sohowww.nascom.nasa.gov/hotshots/index.html/ISON_overlay.jpg

[MarkS]

I don't have Sky at Night but I do remember those SOHO images from the ISON pass. 
The bright light with a blooming line through it at 7 o'clock was a planet or bright star.  There was a description at the time but I don't remember where I read it.

[Rick]

A bit of playing with Starry Night suggests it might be Antares, and it's overloading the CCD. You'll see the opposing spikes on  bright objects seen by the SOHO C3 camera.

SOHO real time images: http://soho.esac.esa.int/data/realtime-images.html

SOHO "Hot Shots", at present showing a collection of ISON reports: http://soho.esac.esa.int/hotshots/index.html

[MarkH]

Yup Rick that's the one. So a blooming line is the accepted expanation then ?

[Rick]

Yeah, if you look through C3 images you'll often see that on bright objects. The camera's aim is to pick out diffuse CME activity, and bright objects push it over the edge. Some of the images of ISON show the same sort of artefacts. See http://soho.esac.esa.int/hotshots/index.html/ison_fades_c3.jpg for instance.

[MarkS]

A bit of playing with Starry Night suggests it might be Antares, and it's overloading the CCD.

Yes - Antares - see here:
http://www.skyandtelescope.com/observing/highlights/Comet-ISON-Updates-193909261.html