[BAA 00403] Comet 2009 F6 (Yi-SWAN)

[Rick]

BAA electronic bulletin No. 00403 -- http://www.britastro.org/

On April 4 Rob Matson reported a possible 9th magnitude comet seen in SOHO-SWAN images between March 29 and April 4. This was soon confirmed as a comet by ground based astrometrists. Following the initial IAUC, the CBAT received a message that a comet had been discovered by Dae-am Yi of Korea on DSLR images that he had taken on March 26. Orbital calculation showed that the two objects were identical. The comet is at perihelion in early May at 1.3 AU. Located in Cassiopeia it should be readily observable from the UK, although it looks as if a series of depressions and full moon may give limited observing opportunities over the next few days.  It is unfavourably placed on the far side of the Sun near perhelion and will not change much in brightness over the next month.  It becomes too close to the Sun for observation after late May.  It is the first comet to be named for a Korean observer.

With such a bright object it is surprising that patrol images did not pick it up earlier. One reason is its location in the Milky Way, which is often avoided by the professional search programmes and its orbit is almost exactly along the plane of our galaxy. At least one amateur imager did locate the comet, so if you have taken widefield images of the Milky Way in Cygnus, Lacerta or Andromeda over the last month there is a chance that you will have recorded the comet as it was probably brighter than 10th magnitude throughout.

For an ephemeris see the section web page at http://www.ast.cam.ac.uk/~jds, which also has information on all the other currently observable comets.

Jonathan Shanklin

Bulletin transmitted on  Wed Apr 8 15:22:03 BST 2009
(c) 2009 British Astronomical Association