News - February 2005

2005 February 24

Further SOHO comets: C/2005 B3 (SOHO) (X. Leprette) is a member of the Kreutz group and C/2005 B4 (SOHO) (B. Zhou) is the 52^nd member of the Meyer group. Official SOHO comets: 904. (MPEC 2005-D18)

2005 February 13

An Apollo-type minor planet, 2003 WY₂₅, discovered in November 2003, by the Catalina Sky survey seems to be identical with one long-lost periodic comet. One year ago, M. Micheli (Italy) suggested the possible identity of this minor planet with comet D/1819 W1 (Blanpain) based on backward integration which, however, still showed differences in the argument of perihelion up to 17 degrees. Now P. Jenniskens (NASA Ames Research Center) has also suggested this identity based on his own backward integration which showed only 0.2 degrees difference in the argument of perihelion. Computations by B. G. Marsden (Harvard-Smithsonian Center for Astrophysics) which also reexamined the data of 1819 and 1820, confirmed a best-fit gravitational linkage with the above mentioned difference. He also showed that the differences for all angular elements can be reduced to 0.01 degrees by using a slightly adjusted set of elements for 2003 WY₂₅. Backward integration of this set only shows a difference in T of about -4.3 days and fits 10 of the 13 historic astrometric positions within 90 arcsec.
Comet D/1819 W1 (Blanpain) was discovered on Nov. 28, 1819, by J. J. Blanpain (Marseille, France). The comet was then a large object, without tail and a small central condensation which obviously was absent in the later part of its apparition. It was last observed on Jan. 25, 1820, and the estimated absolute magnitude may have been about 8.5^m. This is a large difference compared to 2003 WY₂₅ which has an absolute magnitude of about 21^m! The minor planet approached earth in Dec. 2003, at 0.025 AU but did not show any sign of a coma.
The comet is also suspected of being the origin of the one-time meteor stream of the Phoenicids of 1956, with a ZHR of over 100 meteors per hour. (IAUC 8485 subscription required, Cometography II)

2005 February 11

Further SOHO Kreutz comets: C/1997 E2 (SOHO) (X. Leprette), C/2004 Y12 (SOHO) (T. Hoffman), C/2005 A2 (SOHO) (Y.-S. Tsai), C/2005 A3 (SOHO) (H. Su), C/2005 A4 (SOHO) (H. Su) and C/2005 A5 (SOHO) (R. Kracht), Official SOHO comets: 902. (MPEC 2005-C38)

2005 February 08

IAUC 8479 reports observations of comet C/1995 O1 (Hale-Bopp) by A. Rivkin and R. Binzel (MIT) on Jan 08, 2005, with the Magellan Observatory's Clay 6.5-m telescope and SDSS g', r', and i' filters. There was a tail of at least 8.5" length. The brightness in 4.2" aperture ranged between 20.06^m and 20.73^m depending on the filter. The comet was then about 21 AU from earth and sun. (IAUC 8479 subscription required)