Comet Tuttle-Giacobini-Kresak is a periodic comet with the
designation 41P. Most of these old periodic comets were discovered visually
by comet hunters. This is a short period comet of a 5-year orbital period
and first appeared in 1858 . After having escaped several attempts to recover,
it was found in April 1951 in the constellation of Leo in the evening sky
as a 10th-magnitude comet by Dr. Kresak during his comet search at Skalnate
Pleso Observatory in Czechoslovakia@(present Slovakia). It was a discovery
by 10cm binoculars and immediately reported as a new comet to the Central
Bureau for Astronomical Telegrams in Copenhagen. It was many decades later
that it was confirmed to be Comet Tuttle reappearing after 50 years. In
fact, Tanakami Astronomical Circular-Letter issued in June 1951 reported
that Comet Kresak was Comet Tuttle 2.
Since then the comet has been recovered mostly with a regularity.
However, at its apparition of May 1973 something unusual happened. It was
predicted to become 15th magnitude, but in June it suddenly brightened
to 4th magnitude. It became a substantial comet with a trailing tail and
faintly visible to the naked eye. Dr. Kresak, the third discoverer of the
comet, observed this phenomenon and said that this comet had lost most
of its energy after two outbursts at this apparition, suggesting that he
was pessimistic about its next apparition.
The next apparition was predicted to be 5 years later in
December 1978. Dr. Marsden of BAA predicted the magnitude of its nucleus
to be fainter than 20, perhaps considering Dr. Kresak's view. What's more,
the comet would appear under the worst observing conditions: it would be
close to the sun and less than 20 degrees in altitude in the beginning
morning twilight. Under these conditions, the recovery would be impossible
and no observatories in the world would try to search for it. The "lost"
Comet Tuttle-Giacobini-Kresak would quietly turn around the sun and head
back toward distance space without being seen by anybody.
At 5 am of November 9 ,1978, Geisei's 40cm reflector captured
the comet right on the spot. Venus at the greatest west elongation was
blazing less than one degree from the comet swamping its feeble light.
But the comet was bright enough to be barely detectable at 17th magnitude.
In spite of Dr. Kresak's concern, the comet made an impressive
return shining at the normal total magnitude. There were no observations
at this apparition other than Geisei's. Geisei continued to track the comet
until January 1979. What is presented here is one of the photographic plates
exposed during the observation of this comet. Numerous scratches are the
reminiscence of the passing of time since the recovery, but the plate is
now restored to an extent that it is presentable. The comet on the plate
is hazy like fog without a nucleus.
16-minute exposure from 5:10, December 12, 1978, J.S.T.
40cm f/5 reflector, 103a-O photographic plate
Copyright © 2010 Tsutomu Seki.