I can't seem to find data about surface magnitude of galaxies in Simbad. I can easily find the apparent and absolute magnitude ... Should I just try to compute the surface magnitude, given the apparent magnitude, and galaxy diameter (arc sec)? Do you know how to find surface mag in Simbad, or NED , Vizier?

Will this give a reasonable estimate?:

SurfaceB = m + 2.5 * log10(AngularArea)

Aproximate Angular Area:

AngularArea = pi * (galaxyDiameter/2)^2
  • $\begingroup$ The reason there is no surface magnitude is due to the difficulty in defining it. A galaxy will have a bright core, and fade out to nothing, with features of various brighness in between. $\endgroup$ Aug 16, 2022 at 0:05
  • $\begingroup$ Ok, so I figure it's better to calculate a rough estimate $\endgroup$
    – Adrian
    Aug 16, 2022 at 8:34


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