Comet 1993a Mueller Target Name:   Comet Mueller Spacecraft:   Telescope Produced by:   Erich Meyer and Herbert Raab, Austria Date Released:  October 6, 1993

• Comet Introduction

This is a CCD image of comet 1993a "Mueller", taken on October 6, 1993, using SBIG's ST-6 CCD-camera and a 288mm f/5.2 Schmidt-Cassegrain telescope.The exposure lasted from 19:11 U.T. to 19:21 U.T. The field of view is 19.6' x 14.4'. The comet has a coma diameter of some- what more than 3' and a fan-shaped tail, up to 7' long, between P.A. 220o and P.A. 310o. (Sorry, I mixed that up in my posting last week: 1993a has a fan-shaped tail oriented around P.A. 270o, while 1993p shows a slender AN-tail pointing nearly exactly northward. However, this an-tail may not be visible any longer...)

The brightest star visible (PPM 7788) is of photographic magnitude 8.8. In this GIF-image, this star and the head of the comet appear to be nearly of the same brightness. However, a close inspection of the original CCD-image (which has a resolution of 16 bit per pixel rather than 8 bit for GIFs) shows that the star trail is satured at a value of 65535, while the brightest pixel in the comet's head reaches a value of only 15608. According to our measurements, the comet is of mag 10.5 in red light (where unfiltered, thick CCD's are most sensitive).Keep in mind that a comet has usually bright emissions in blue and green light, where our CCD is not that sensitive. (Courtesy Erich Meyer and Herbert Raab, Austria)