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Comet Hale-Bopp (September 13, 1996)
MPI/ESO 2.2-m + EFOSC II (May 14, 1996)
This is a summary of recent developments around this comet; the previous was published on the ESO Web on September 2, 1996. It is based on information received directly by email and also from IAU Circulars and on other Hale-Bopp WWW pages.
Richard M. West (ESO)
Munich, September 13, 1996; 16:00 UT
ESO Images from August
Some ESO images from August 1996 have now become available. More images from ESO of higher angular resolution will follow early next week.
These images show clearly the extraordinary activity, now visible around the cometary nucleus.
One of these images [False colour; GIF, 66k] was obtained by Stefano Covino (Osservatorio Astronomico di Brera, Milano-Merate, Italy) who observed with the 91-cm Dutch telescope on August 12, 1996. The exposure was 15 seconds through a V-filtre and the sky conditions were mediocre. The field measures about 3.8 arcmin square.
On August 18, Nick Thomas (Max-Planck-Institut fuer Aeronomie, Germany), Heike Rauer (Observatoire de Paris, France) and Hermann Boehnhardt (Universitaets-Sternwarte, Munchen, Germany) obtained a CCD image [GIF, 152k] of Comet 1995 O1 (Hale-Bopp) with the DFOSC multi-mode instrument on the Danish 1.54 m telescope at La Silla. The frame was taken at 04:20 UT using with an R filter and the integration time was 20 s. Bias subtraction and flat-fielding was performed and the frame was binned (4 x 4) to reduce the frame size to 512 x 512 pixels while still showing the entire CCD area.
Another CCD image [GIF, 176k] shows a smaller area of the first, but is unbinned and has otherwise received identical processing. Both images have a scalebar which is accurate to about +- 5 percent. At the time of these observations, Comet Hale-Bopp was 2.761 AU from the Earth and 3.392 AU from the Sun. At least 7 jet structures can be seen in the data. The appearance of these structures changed very little over a period of 3 nights suggesting a long rotation period. CN could be detected more than 1 million km from the nucleus.
Klaus Jockers and collaborators (IAUC 6468), working with the 2-m telescope (+ 2-channel focal reducer of the Max Planck Institute for Aeronomy, Katlenburg-Lindau) of the Centre AMEI, Kiev, at Mount Terskol, North Caucasus, have informed that they observed the ejection of a CO+ cloud into p.a. 130 deg on August 17. On the following nights, the CO+ tail gradually subsided.
On September 6, Martin Cartwright communicates that R- and B-band CCD observations taken at the 1.0-m Jacobus Kapteyn Telescope (Canary Islands, Spain) by Iwan Williams, Martin Cartwright and Alan Fitzsimmons over the preceding four nights have revealed a significant dust feature which has moved northwards from the nucleus a distance of approximately 30 arcseconds since Sept. 1st.
On September 13, Jun-ichi Watanabe (National Astronomical Observatory of Japan) informed that a H2O+ ion tail at Comet Hale-Bopp had now been detected at his observatory. However, it was later found, that this was an effect of a bright star just outside the field of view. Two representative images have been released at the observers' website: http://www.nao.ac.jp/whatsnew/index-e.html.
New, improved ephemerides , based on a new orbital calculation by Don Yeomans (JPL, Pasadena), have just become available.
Appulses of Comet Hale-Bopp to PPM Stars Ovidiu Vaduvescu of Astronomical Institute of the Romanian Academy has published a List of Appulses (near passages, as seen in the sky) of Comet Hale-Bopp to stars in the astrometric PPM catalogue.
Two new comets, Comet P/1996 N2 (Elst-Pizarro) and Comet 1996 R2 (Lagerkvist) , have just been discovered at ESO. More information will become available shortly.
Comet C/1991 A2 (ARAI) was detected in data obtained with the ROSAT Position Sensitive Proportional Counter during the ROSAT all-sky survey (IAUC 6472). The comet was observed from 1990 Nov. 18.09 to 21.43 UT (Delta = 1.2 AU, r = 1.5 AU), six weeks before it was discovered (IAUC 5157), when it would have had projected visual m1 about 12 (or fainter) and would be optically the faintest comet ever detected in X-rays. Back to ESO Hale-Bopp Homepage