Hello,

I am trying to get the magnitudes for comets with Astronomical
algorithms p 216 but the results are different from those obtained in
Guide.

I used mag = H + 5*log delta + G * log r

H is first column after the equinox date (2000) and G is the second in
the file Soft02cmt.txt taken on Comet Observation Page

Does anyone knows the formula used in Guide to calculate the comet
magnitude ?

Thanks for your answers
Jean-François Coliac