# Which is more realiable: NED or SIMBAD?

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1. Sep 14, 2015

### Earnest Guest

I'm doing some research on M33. NED lists the luminosity as 6.27. SIMBAD gives it as 5.27. First, it looks odd to me that the difference is exactly 1. Second, I've seen other differences comparing identical extragalactic bodies, so which database is more reliable?

Note: it appears I misread the band data. NED and SIMBAD show the same value for the B band magnitude. However, the question still remains: is there a preference between the two for Z or luminosity values?

Last edited: Sep 14, 2015
2. Sep 14, 2015

### tfr000

Depends. How do they integrate the brightness over the surface of an extended object, like M33? There are probably as many answers as there are databases.