Spectrophotometry of Comet P/Halley. I - Flux, column density and emission gradients within the coma in the emission bands and the continuum

Abstract

The authors made spectral scans of comet P/Halley using the scanner at the Cassegrain focus (f/13) of the 102 cm reflector at Kavalur. The scans cover generally the wavelength region from 3900 to 6200 Å and are at 40 Å resolution and on a few occasions in the blue region at 20 Å resolution. The f/13 beam provided an image of the coma with a scale of 15arcsec.5 mm-1. The authors have obtained scans on several consecutive nights in March and April, 1986 with a 25arcsec.9 entrance aperture of the scanner at discrete and systematically displaced locations within the coma in the anti-sunward direction as well as normal to it about the position of the nucleus. They have derived the brightness profiles of the neutrals and dust within the coma and have discussed the variations of the spatial gradients of the profiles.