# Nebular Spectroscopy and extinction

After posting result related to Nebular Density Ratio of M42 “Orion Nebula” The results for Nebular Density Ratio without Interstellar Redding correction were c(Hb) = 0.0:
Ha/Hb = 5.17
Hy/Hb = 0.35
OIII5007/OIII4959 = 3.0
We have corrected data for interstellar extinction using formula:
c(Hb)= 3.08Xlog(I(Ha)-7.55, Ic=IoX10^(c*f).
We found c(Hb) equal to 0.81. In continuation, the paper said the IS extinction in between 0.0 to 1.6 for M42, but most of the places it is near to value 0.8.
The results for Nebular Density Ratio with Interstellar Redding correction c(Hb) = 0.81:
Ha/Hb = 2.79
Hy/Hb = 0.49
OIII5007/OIII4959 = 2.92
See paper link https://iopscience.iop.org/article/10.1086/301429/fulltext/
The corrected data are shown by dotted points:
If We follow paper given in link https://www.aanda.org/…/2011/01/aa14464-10/aa14464-10.html
and use IS extinction formula given by then
The results for Nebular Density Ratio with Interstellar Redding correction c(Hb) = 0.73:
Ha/Hb = 2.97
Hy/Hb = 0.48
OIII5007/OIII4959 = 2.93
Doing this exercise We guess, the slit was exposed in a place where IS extinction was in between 0.81 to 0.73.