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 52nd 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 8.5m. This is a large
difference compared to 2003 WY25 which has an absolute magnitude of
about 21m! 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 20.06m and
20.73m depending on the filter. The comet was then about 21 AU from
earth and sun.
(IAUC 8479 subscription required)