Google earth, MS telescope and Sirius censorship, page 2
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reply posted on 3-12-2008 @ 04:57 PM by ngchunter
reply to post by MCoG1980



Those lines are due to diffraction around the spider vane of the telescope, they're common in astrophotography taken by telescopes with a central obstruction.



reply posted on 3-12-2008 @ 05:02 PM by RFBurns
reply to post by Manawydan



Dont worry there friend, as many MGS/MOC and Odyssey images I have poured over, and was even a part of the infamous "poof dirt city in cydonia" fiasco, I know exactly what it feels like to encounter censorship. To know there is something odd there but only to have another dataset come through that clearly was altered compared to the first dataset, it is very frustrating to see the "one hand shakes while the other pick-pockets" routine.



Cheers!!!!


reply posted on 3-12-2008 @ 05:02 PM by MCoG1980
reply to post by ngchunter



Thankyou for that, glad to hear someone has a scientific explanation.
The Sirious image has me baffled though - only one i found like it and looked very odd like it was CENSORED. Do you have any ideas on this one too, it looks puposley obscured?



reply posted on 3-12-2008 @ 05:56 PM by ngchunter
reply to post by imd12c4funn



If that were Nibiru, every serious amateur astronomer in the world would already know about it since it's sitting right on the ecliptic and is already bright enough to cause blooming in the CCD detector at near infrared wavelengths.


reply posted on 3-12-2008 @ 06:12 PM by ngchunter
Originally posted by MCoG1980
The Sirious image has me baffled though - only one i found like it and looked very odd like it was CENSORED. Do you have any ideas on this one too, it looks puposley obscured?

It's masked (whether it was done in the camera or in post is another matter), but once you realize what dataset it came from, the hubble guide star catalogue version two (GSC2), masking starts to make sense. The GSC is there so that hubble can keep its orientation perfectly as it takes long exposures of deep space. That requires knowing the precise position of at least one star in every possible field of view that hubble could have. If you have bad data on a star it might mess with hubble's guidance, so it makes sense to exclude stars that are poorly resolved due to glare from a nearby source, like Sirius. If it were censorship for a different reason they would have masked it from all sky surveys, not just one version of one made specifically made for hubble guide stars.

GSC1:
archive.stsci.edu...
GSC2:
archive.stsci.edu...

You can actually resolve more stars by masking Sirius. That must mean that they performed some of the masking in the telescope or camera because you can see how it's completely overexposed in GSC1 - there's no way to recover stars that are that washed out, but it's possible that they then edited the mask to be white instead of a black area. You can see dark fringes where the physical masking was done in the high resolution GSC2 view. Like I said though, that's the only source that has that masking, so it's not censorship, you can find plenty of other high resolution images of that area. As you can tell in the other images it ought to be washed out that close to sirius anyway so there's nothing that could be seen there in an exposure of this length.

[edit on 3-12-2008 by ngchunter]


reply posted on 19-2-2009 @ 07:13 PM by prevenge



reply posted on 19-2-2009 @ 07:18 PM by Phage
reply to post by prevenge



Works for me. It's an image of a section of the sky more or less completely washed out by something that I would assume is Sirius.


reply posted on 26-2-2009 @ 09:57 AM by Anonymous ATS
reply to post by ngchunter



Thanks for the logical explaination ngchunter, just wondering if you could help me make a bit of layman sense of the examples you posted.....

GSC1:
archive.stsci.edu... - Washed out and too much exposure for through the lense for the surrounding stars to come out defined... (i could understand this reason for using a mask)


GSC2:
archive.stsci.edu... - Mask helps the temperament of the exposure as suggested. I see there is a dark aura around the alleged mask (on the outskirts of the blob or filter). Why would that aura be as dark as it is? I can only imagine its a result of the mask

Apols if this is a silly question, cheers for reading

JC in London


reply posted on 13-3-2009 @ 10:52 PM by ngchunter
Originally posted by Anonymous ATS
reply to
post by ngchunter



Thanks for the logical explaination ngchunter, just wondering if you could help me make a bit of layman sense of the examples you posted.....

Sorry I missed this earlier

GSC2:
archive.stsci.edu... - Mask helps the temperament of the exposure as suggested. I see there is a dark aura around the alleged mask (on the outskirts of the blob or filter). Why would that aura be as dark as it is? I can only imagine its a result of the mask

Could be a diffraction artifact similar to what we sometimes see with coronagraphs. Could also be due to the fact that they were using large photographic plates rather than digital CCDs for that survey. I'm significantly less familiar with film anomalies since I've worked almost exclusively with digital when it comes to astrophotography.
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