C/Hale-Bopp (1995 O1) prediction

Last updated 1996 Sep 16

Hale-Bopp will occult PPM 200723 on 1996/10/05 at 02:56:11.3 UTC (geocentric)

GIF (13kb), Postscript (308kb), Prediction details.

Comet Hale-Bopp (1995 O1) will occult the 9th magnitude star PPM 200723 early on 1996 Oct 5 (UT). This prediction is based on catalog positions for the star and Don Yeomans' ephemeris #41 which includes observations of Hale-Bopp thru 1996 Sep 10.

Due to uncertainty in the ephemeris and in the catalog position of the star, the actual location of the ground track is still uncertain. In addition, it is not known how far from the nucleus diminution of the starlight will be detectable.

Successful observation of this event will require relatively high speed photoelectric or CCD photometry; the comet has a sky plane velocity of 5.1 km/sec or 0.092 arcsec/sec. At the time of the appulse, the comet will be observable througout western North America and northern Mexico.

The catalog coordinates of the star are ra=17:29:59.845, dec=-04:48:09.45, J2000.

We are planning last minute direct CCD imaging to get the comet and star on the same image. This will be possible starting Tuesday night (10/1) from USNOFS (Naval Observatory, Flagstaff). Updated predictions will be made and posted each night prior to the event, weather permitting.

The image on the left was taken with our occultation field system, a Celestron 14" telescope with a CCD camera attached. This image is 11.7 by 7.8 arcmin field near the occultation star (marked with a pair of arrows). Other nearby stars are marked 1 through 5 and may be useful for on-chip reference stars during the occultation.

Star/Object                  R-band      --no filter--
                          mag   ph/sec    mag   ph/sec
PPM 200723, SAO 141696    8.26  33,400    6.84 124,000
Star #1                  12.45     706   11.11   2,410
Star #2                  12.72     550   11.39   1,880
Star #3                  13.30     321   10.89   2,970
Star #4                  12.05   1,020   10.47   4,350
Star #5                   9.59   9,850    8.25  33,700
Hale-Bopp 1996 Sep 23.2   8.51  26,700    7.16  92,000

All the above measurements were made using an 10-pixel radius aperture (24 arcsec diameter), including the comet. The seeing in these images is not all that great at about 8-9 arcsec FWHM.

Here is a scanned portion of the POSS1 print around the field. Superimposed on the image is a rectangle showing the FOV of our instrument. (GIF image, 494kb),

This prediction was computed by Larry Wasserman at Lowell Observatory based on ephemerides from Don Yeomans (JPL) and data from the US Naval Observatory, Flagstaff Station.