ZetaTalk: Hale-Bopp sci.astro debates: European Southern Observatory

Comet Hale-Bopp: Observations of dust
19 January 1996

It has now been confirmed that a diffuse image found on a UK Schmidt plate obtained in April 1993 (IAUC 6198, 6202) is indeed of this comet (IAUC 6287). This shows that the dust production must have started already when the comet was at heliocentric distance 13 AU or possibly even before. This appears very unusual, and only a few comets have ever shown activity at this large distance (e.g. P/Halley at 14 AU). However, all such cases occurred after the perihelion passage; in fact, only comet Hale-Bopp has been observed at this large distance before perihelion.

C/1995 01 (Hale-Bopp)
5 February 1996

A look at the observations made during the first few days after discovery indicated the comet was between magnitude 10.5 and 11. It had some condensation and a short tail or elongation toward the north. The coma was reported as about 1 or 2 arc minutes in diameter.

On September 24, Gary W. Kronk (Illinois) determined the magnitude as 10.1 (13.1-inch reflector). The coma was 1.5' across. On September 28, Kronk determined the magnitude as 10.3 (13.1-inch reflector). On October 1, R. Keen (Colorado) determined the magnitude as 10.6 (0.32-m reflector). On October 13, Daniel W. E. Green (Massachusetts) determined the magnitude as 9.8 (0.25-m reflector). On October 22, C. S. Morris (California) determined the magnitude as 10.0 (0.26-m reflector). On October 28, Morris determined the magnitude as 10.0 (0.26-m reflector). On November 11, Hale determined it as 10.1 (0.41-m reflector). On November 14, Hale determined the magnitude as 10.0 (0.41-m reflector). On November 17, Morris determined the magnitude as 9.6 (0.26-m reflector). On November 19, Morris determined the magnitude as 9.7 (0.26-m reflector). On November 21, P. Camilleri (Australia) determined the magnitude as 10.0 (0.20-m reflector). On November 24, Hale estimated the magnitude as 9.8 (0.20-m reflector).

Hale-Bopp Recovered
9 February 1996

Speaking of Hale-Bopp, observers have recovered this comet in the predawn sky after it spent a couple of months in conjunction behind the Sun. It appears brighter than 9th magnitude, which is good news considering that it's still farther away than the orbit of Jupiter. Terry Lovejoy spotted it with a 10" reflector on the morning of February 2nd and reports a small fan-shaped tail.