astronomer Takeshi Urata discovered Comet 112P on images taken by
Tsuneo Niijima on 1986 Oct 30th using a 0.30-m f/5.8 reflector, but
reported it as asteroidal. It was given the minor planet designation
1986 UD and mentioned on IAUC
4267 as a fast moving asteroidal object. At that time it was
moving at 2"/min in Aries, about 13' from the 11th magnitude
galaxy NGC 772.
Tsutomu Seki observing four day later from Geisei noticed a
"very faint and diffuse coma surrounding a central condensation"
and the true cometary nature of the object was announced in IAUC
4269 on 1986 Nov 05, together with the new name Comet
Urata-Niijima. Further observations, together with a pre-discovery
position from 1986 Oct 29 and an independent discovery by Miklos
Lovas from 1986 Nov 4th (IAUC
4270) allowed Brian Marsden at the Minor Planet Center to
determine that the comet was in a short period orbit with P = 6.4
years. The apparition was very favourable, with the closest approach
to Earth (0.48 AU) occurring three weeks before perihelion (1.449
AU) which was due on 1986 Nov 23.
A number of observatories followed the comet from 1986 November
through to 1987 January, with the 0.9-m Spacewatch telescope at Kitt
Peak recording the last images of it at the end of 1987 March as it receded
from both Sun and Earth and approached conjunction with the Sun.
Six years later, IAUC
5882 announced the recovery of the comet by Jim Scotti at Kitt
Peak with the 0.9-m Spacewatch telescope on 1993 Oct 20 & 21.
Three months past an unfavourable perihelion passage in 1993 July,
the comet was already 19th magnitude and fading fast as it pulled
away from the Sun. The Spacewatch telescope was the only facility to
report positions of the comet at this apparition with three further
nights of observations, the last being 1994 Apr 6th.
The next perihelion passage was in 2000 March and this was even
more unfavourable than 1993. The comet brightened on its way into
perihelion at far southerly declinations but spent the majority of
its time unobservable, very close to the Sun in the sky.
Photometry was obtained on 1999 July 14 with the 3.6-m NTT at La
Silla when the comet was at a declination of -46°, in
an effort to determine the absolute
nuclear magnitude, with the observed magnitude given as +21.3
and +21.4, but no astrometry appears to have been reported.
A single position of the comet taken on 1999 Sep 8 was made available
Hubble Space Telescope, obtained during an exercise
to determine the radius of the nucleus of selected comets.
positions from the night of 1999 Nov 13 were reported from Kitt Peak.
The 2006 return was almost as favourable as the discovery
apparition, with perihelion due on 2006 Oct 29 at a distance from
the Sun of 1.47 AU and closest approach to Earth due two weeks later
at a distance of 0.59 AU.
The comet was picked up from Great Shefford on 2006 Aug 2.1 UT in
the early morning sky at magnitude +20.7 about 14" from the
prediction. At that time it was 1.38 AU from Earth and 1.74 AU from
the Sun. It was observed again very faintly on 2006 Aug 10.1 UT with
a 45 minute exposure, despite the glare of the full moon some
distance away low on the horizon. The comet appeared asteroidal on
both occasions, without visible coma or tail.
The animation above was obtained
during the next dark of the moon by which time the comet had
brightened by about 1 magnitude. Confirmatory astrometry was
obtained from the Schiaparelli Observatory in Italy by Luca Buzzi
and Federica Luppi using a 0.60-m f/4.64 reflector on 2006 Aug 22.1
and 23.1 UT.