A correction factor for Gaussian deconvolution of optically thick linewidths in homogeneous sources

Profiles of optically thick, non-Gaussian emission lines convolved with Gau ssian instrumental profiles are constructed, and are deconvolved on the usu al Gaussian basis to examine the departure from accuracy thereby caused in 'measured' linewidths. It is found that 'measured' linewidths underestimate the true linewidths of optically thick lines, by a factor which depends on the resolution factor r equivalent to Doppler width/instrumental width and on the optical thickness tau(0). An approximate expression is obtained for this factor, applicable in the range of at least 0 less than or equal to t au(0)less than or equal to 10, which can provide estimates of the true line width and optical thickness.