Photograph of 103P/Hartley and returning Comet Crommein
0103P 2010 10 05.63021 01 37 06.90 +56 42 28.2 11.2 N 372
0103P 2010 10 05.63368 01 37 09.60 +56 42 31.2 11.2 N 372
Above are the results of astrometry by the 70cm reflector.
Only the magnitudes of the nucleus are provided due to the telescope's
slow optics (f/7). Observations with fast optics under dark skies will
result in unexpectedly brighter magnitude estimates. The result of visual
observation around the same time is given below:
2010UT m1 dia. DC Trans Seeing Inst. Obs.
Oct.5.65 7.1 10 6 4/5 4/5 7x50 B T.Seki
103P/Hartley
A composite of two 5-minute exposures at 1:20 and 1:26, October 6, 2010
70cm f/7 reflector, Nikon D700 at ISO 1600
Geisei Observatory, T. Seki
One hour before daybreak, I began searching the eastern sky
using 25x15cm binoculars. Fifty-four years ago this morning, I independently
discovered Comet Crommelin. I was using a 15cm f/6.3 reflector. It was
found in the Great Sickle of Leo glowing at 10th magnitude with a 5'-diameter
coma. It was in October, just 28 years after Mr. Yamasaki's discovery of
this comet. On October 11, 49 years ago, I discovered Comet Seki (1961
T1) near Beta Leonis. I was using a 9cm Namura lens. On October 1st 1940,
Comet Okabayashi-Honda was discovered also in the Sickle of Leo. Mr. Okabayashi
was using a 75mm refractor.
I concentrated on Leo. The rough position of an astronomical
object was easy to work out with the use of a "Navigator" (digital
setting circles). As long as I can narrow down the position within one
degree, I can rely on a sketch. When I don't have enough time, I use a
9cm refractor. Its field of view is 3.5 degrees. The image in the scope
is excellent and searching is made more efficient. Comet Crommelin with
a 28-year period is steadily approaching and returns to perihelion around
August 3, 2011.