Re: BVR transformation and instrumental magnitude

Posted by chrismlt on May 02, 2024; 2:49pm
URL: http://astroimagej.170.s1.nabble.com/BVR-transformation-and-instrumental-magnitude-tp2430p2432.html

Helle again,

I've seen the same question was asked in 2017 :

http://astroimagej.170.s1.nabble.com/Instrumental-magnitude-td937.html

The process is discussed here (AAVSO) :

https://www.aavso.org/instrumental-magnitude

were instrumental is expected/needed to derive the transformation coeff in standard colors.

There is also this webpage :

https://en.wikipedia.org/wiki/Instrumental_magnitude

https://image-analysis.readthedocs.io/en/latest/06_photometry_intro/instrumental_mags_and_the_beauty_of_photometry.html

Most probably those values are already available in the measurement tables.
I initially thought about rel_flux_T1 C2 C3 ... but Source-Sky_T1 C2 C3 seems better candidates.


So I suppose, Source-Sky is the flux expressed in ADU. Then, it fits in the formula :
m=-2.5log 10 (f)

Then I've got the instrumental mag for each standard star of the serie.
It's only a matter of excel table and (big) patience.




I hope this will clarify.
Christophe