Comet C/1995 O1 (Hale-Bopp)

Updated: 18 Mar 97

Since the beginning of 1996, comet Hale-Bopp has been performing rather consistently with r**-2.8 (considerably less than the default r**-4 assumed for the magnitude ephemerides) and absolute magnitude -0.4 (also considerably fainter than the -2 value used for the published magnitude ephemerides). With these values, the peak brightness would have been just barely a negative magnitude. Fortunately, over the past ten days, the comet has brightened by a half magnitude! With the predicted peak brightness another ten days away, if it can gain another half magnitude, it will reach -1, and there is always the possibility that thermal lag will cause the actual brightness peak to be shifted past perihelion (which is April 1). The comet is putting on a fine show; don't miss it! All you need is a clear view to the northeast (now) and northwest (next week).

The comet went through conjunction with the Sun about January 2. At the time, the motion of the Sun in right ascension exceeded that of the comet, so the comet appeared in our morning sky. As of around February 20, however, the acceleration of the comet caused its motion in right ascension to excced the Sun, so it started going back into conjunction. Fortunately, it has been going north at the same time, helping to maintain visibility in our [hawaiian] morning sky, though it is getting lower. Conjunction occurs on March 21, after which it technically becomes an evening object, though for northerly latitudes, it can be seen in both the morning and evening. Sunday, March 23, features a partial lunar eclipse in progress at sunset (you'll need a clear view of the eastern horizon to catch the maximum eclipse). Tuesday, March 25, will be the first night that moonlight will not interfere during the prime comet viewing time, which is about 7:30 p.m., when nautical twilight ends [again, for hawaii; actual time varies depending on your position in your time zone]. The comet will proceed to get higher in the sky for the next three weeks, though moonlight will begin to interfere again after two weeks. Those two weeks should represent the best viewing window. Don't miss it! Although the comet has been an easy target from the city, to appreciate it's full glory, get away from city lights. The azimuth will be almost due northwest, the altitude about 15 degrees (or about a fist and a half when held at arm's length) above the horizon during that prime viewing window [for Hawaiian observers. The higher is your latitude, the higher will the comet be].

David Tholen


Hale-Bopp in a nutshell

David J. Tholen

© IfA/UH (1997)
| Hale-Bopp @ IfA | IfA | Comments? |

Update: Wed Mar 19 17:17:29 1997 -- Hits: since created --- was 5056 on March 29 23:30