posted on Jan, 3 2013 @ 12:19 PM
Originally posted by woogleuk
Reflection or glitch, can't remember which, but it has been discussed before, many many times.
edit on 3/1/13 by woogleuk because: (no reason
given)
Actually it's both a reflection of the optical system and a stitching error; the reflection is effectively cut in half by Google's panorama
stitching.
To recap for those unfamiliar with the source of the google sky image data, none of it comes from google; it's from pre-existing sky surveys, the
POSS2/UKSTU (identical Cassegrain telescopes in the northern and southern hemispheres that surveyed the entire sky a few decades ago - I usually just
call it POSS2 for short even though that's technically the northern half) in this case.
In this case, the optical reflection is being caused by a bright star recorded on the same film plate. The reflection is at the top of the film plate
and the bright star is at the bottom. The bright star is Canopus, the second brightest star in the night sky. The film plates that have the
reflection are the following:
S206
(01W3)
IS206
(A30W)
XS206
(A09M)
Those three monochromatic film plates are combined to make the color image of the reflection you see on google sky. The reflection is cut in half,
however, by a stitching artifact. Rather than showing the entire reflection all the way to the edge of the above film plates, the following plates
were used to stitch the sky together; the overlap the same coordinates, but in these plates the coordinates are at the bottom of the plate rather than
the top and allow the mosaic to continue on up. Because Canopus is far outside the field of view of these plates, no reflection is present there:
S255
(01VX)
IS255
(A329)
XS255
(A1KG)
To show you an example of this, here's the reflection region from plate XS206 (A09M):
i319.photobucket.com...
Here's the same coordinates from the corresponding plate XS255 (A1KG):
i319.photobucket.com...
No serious researcher uses google sky to retrieve sky survey data. The quality is lower (the native resolution of the above images is about 3 times
what photobucket will allow) and it's full of stitching errors like this. This reflection COULD have been avoided completely if they used more of the
second series of plates I listed; the overlap on those plates completely covers the region of the reflection (probably by design of the survey), but
when the google assembled their all-sky mosaic from the data, they didn't carefully curate it for problems like that. It's free, so you get what you
pay for. On the other hand, the original sky survey data is all publicly funded and also freely available and that is what you should be using. It's
much higher quality anyway. It's less "user friendly" than google sky because it's tailored for professional use, but that is proper research
technique; always check the primary source.
edit on 3-1-2013 by ngchunter because: (no reason given)