Register to reply

Flux & apparent magnitude

by Schmetterling
Tags: apparent, flux, magnitude
Share this thread:
Schmetterling
#1
Dec6-12, 09:42 PM
P: 31
How to calculate the visual magnitude of a star having only the flux of such star?
The equation involves 2 magnitudes and 2 fluxes, corresponding to 2 objects a and b:

ma-mb= -2.5log10[itex]\left( \frac{F_a}{F_b}\right)[/itex]

but I just have Fa and I have to obtain ma.

Is it valid to take ma=-2.5log10 Fa?
Phys.Org News Partner Astronomy news on Phys.org
Exoplanet measured with remarkable precision
New star catalog reveals unexpected 'solar salad'
RXTE satellite decodes the rhythm of an unusual black hole
Simon Bridge
#2
Dec7-12, 05:22 AM
Homework
Sci Advisor
HW Helper
Thanks
Simon Bridge's Avatar
P: 12,739
the "b" indexed values would have to be some reference value that depends on the scale you are using.
http://en.wikipedia.org/wiki/Apparen...ference_Values
Schmetterling
#3
Dec7-12, 07:53 AM
P: 31
Ok, but in that table the values for "m" don't appear, only the fluxes :-s

Simon Bridge
#4
Dec7-12, 08:37 AM
Homework
Sci Advisor
HW Helper
Thanks
Simon Bridge's Avatar
P: 12,739
Flux & apparent magnitude

Ok, but in that table the values for "m" don't appear
... yes they do: right at the top of the 4th and 5th columns where it says "m=0". But you can use any reference values that make sense in terms of your coursework.
Specifically: you should not get your reference-values off wikipedia. You must have access to a library or a text book or something like that?
In a pinch - go to wikipedias primary source.


Register to reply

Related Discussions
Absolute and apparent magnitude General Physics 1
Calculating absolute magnitude and apparent magnitude Advanced Physics Homework 1
Apparent Magnitude Problem Astronomy & Astrophysics 1
Apparent Magnitude Astronomy & Astrophysics 3
Apparent magnitude Introductory Physics Homework 1