Observers: Glenda Denicolo, Miquel Serra-Ricart
Location: Teide Observatory, Canary Islands, Spain
Date: July 16-17, 1996
Images of Comet Hale-Bopp (C/1995 01) during the 1996 Observing Campaign
Six jets radiate from the nucleus of Comet Hale-Bopp. Nightly monitoring of Comet Hale-Bopp at Teide Observatory is continuing, providing an enormous archive of data. During the recent technical stand-down of the 82cm (IAC-80) Telescope the nightly observations were transferred to the 51cm University of Mons Telescope. This telescope has a Peltier-cooled STS-8 CCD camera and a broad band R filter.
The observations were taken by Glenda Denicolo and reduced by Glenda and Miquel Serra-Ricart. This image has a total exposure of 2700 seconds (45 minutes), made up of the combination of 180 exposures of 15 seconds taken over 6 hours on the night of July 16-17th 1996, with the comet at 2.78 AU from the Earth (416 million kilometers) and 3.746 AU from the Sun (561 million kilometers). At the time the comet was approaching the Sun at 19.1 kilometers per second and the Earth at 9.5 kilometers per second (the lower velocity towards the Earth is because, of course, the comet is not coming directly towards us, rather is sliding off to one side).
This image has been processed with a Laplacian filter to show faint structures close to the nucleus of the comet, hence its unusual form. The Laplacian filter enhances contrast by searching for edges in the low level contrast in the original frame. Because this is the superposition of many short exposures the stars show very long, faint straight trails across the image; these star trails are slightly inclined towards the top left hand corner of the image.
The images are completely different to those seen last year. The occasional spiral jets have now been replaced with a permanent kinked jet to the north which can be detected out to more than 250.000km from the nucleus. In addition to this main jet, we have detected on various occasions up to five other jets around the nucleus.
In the image from July 16th we see the permanent, very bright jet to the north, two moderately bright jets, one in PA 275 (almost due west), the other in PA 150 degrees (SSE). In addition, three fainter jets may be seen to the northwest, NNE and ENE. Some of the jets are straight, but the bright jet to the SSE is strongly kinked due to the rotation of the nucleus of the comet.
This image shows that the comet is extremely active now. It has been visible as a very faint naked-eye object since May 17th and is now about magnitude 5.5 and becoming easier to see without a telescope in the constellation of Ophiuchus. Latest predictions show that the comet is now brightening more slowly than previously, but should still reach magnitude -2.5 if it continues to brighten at the current rate. The observations confirm that this appears to be the second largest comet since 1450 and is only slightly inferior to the amazing Comet Sarabat of 1729.
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