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HellsKitchen
sage
Reged: 09/05/08
Posts: 356
Loc: Melbourne Australia
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I've been looking up galaxies in NED for their magnitudes, and I'm looking for Visual Magnitudes.
The list generated when I look up a galaxy's photometric data points includes these catogories, which I presume are visual magnitudes:
V(V_T^0), and
V(V_T)
these have differing mags listed. Which one is the actual visual magnitude?
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S 38º 00' E 145º20'
Custom 12" F/4.6 dob
10" GSO dob
Intes M500 Mak
4.5" Meade Newtonian
Set of Vixen LVWs + TV barlows + powermates
Astronomik 0III, UHC, H-beta filters
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BillFerris
Carpal Tunnel
Reged: 07/17/04
Posts: 2910
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Hi - the V(V_T) is the visual magnitude. If you read the notes on this and the V(V_T^0) magnitude, the V_T^0 mag is "(e)xtinction-corrected for internal and Milky Way and K-correction applied." It's the corrected brightness of the object if the intervening extinction factors are removed.
Accurate V_T mags have been determined for the brightest few thousand galaxies. For thousands more, B_T (blue) magnitudes have been measured. If you subtract 1 magnitude from a galaxy's B_T, you'll get an approximation of the visual magnitude. The J_total magnitude is a product of near-infrared photometry and a lot of near-IR data has been taken in the last decade. Add 2 magnitudes to the J_total get a ballpark approximation of the visual magnitude.
Regards,
Bill in Flag
Quote:
I've been looking up galaxies in NED for their magnitudes, and I'm looking for Visual Magnitudes.
The list generated when I look up a galaxy's photometric data points includes these catogories, which I presume are visual magnitudes:
V(V_T^0), and
V(V_T)
these have differing mags listed. Which one is the actual visual magnitude?
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Grand Canyon Adventure
Lowering the Threshold
18" Obsession
4.5" Meade 4500
10x50 Swift Audubon
Cosmic Voyage
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HellsKitchen
sage
Reged: 09/05/08
Posts: 356
Loc: Melbourne Australia
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Awesome, thanks for that Bill 
--------------------
S 38º 00' E 145º20'
Custom 12" F/4.6 dob
10" GSO dob
Intes M500 Mak
4.5" Meade Newtonian
Set of Vixen LVWs + TV barlows + powermates
Astronomik 0III, UHC, H-beta filters
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|
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