Thread: How deep ?
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  #6  
Old 01-01-2009, 07:45 AM
Dennis
Dazzled by the Cosmos.

Dennis is offline
 
Join Date: May 2005
Location: Brisbane
Posts: 10,919
One difficulty in determining the magnitude of fainter stars is that the USNO-A2.0 Catalogue (a catalogue of 526,280,881 stars) “only” goes down to around mag 19. It was a 6Gb+ download!

To go dimmer than mag 19, I use the USNO Flagstaff Station Integrated Image and Catalogue Archive Service which is based on the POSS-I (1st epoch Palomar Obs. Sky Survey) and POSS-II (2nd epoch Palomar Obs. Sky Survey). The data lists the Red and Blue magnitudes.

Cheers

Dennis
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