Is that a star IN FRONT OF the Moon? (APOD 20 Mar 2007)

BMAONE23 · Post by **BMAONE23** » Wed Mar 21, 2007 5:27 pm

sounds like the ISS needs a new camera

mary · Post by **mary** » Wed Mar 21, 2007 5:39 pm

Interesting. The above image has a similar, even more dramatic "spot" at 1413/1215. The stripe below it is very clear and extends to the bottom of the image.

Yep! And there is a smaller one at 800/363. You can even detect these defect pixels
in the APOD that started the discussion.

Nice idea: with an appropriate program which analyzes a picture regarding this kind of
"fingerprints" one could easily identfy the affiliated camera...

Hehe, glad to still use good old analogue SLRs

Mary

NoelC · Post by **NoelC** » Fri Mar 23, 2007 1:40 pm

Yes, it is an imager defect - a hot pixel and a bad column below it.

What most folks don't realize is that virtually all cameras have these defects, and that (as implied above) the outer space environment is particularly harsh on camera equipment, in that energetic particles and radiation normally blocked by our atmosphere impact the imagers.

For example, every Hubble image you see has had literally HUNDREDS of these kinds of defects removed, both by calibration software and by hand by the people doing the image processing.

If this ISS APOD has not been processed to remove the defects then the camera truly is in GOOD shape.

-Noel

P.S., Mary, those "good old analog SLRs" will certainly show at least one dust or scratch mark in any scanned image.