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Reports from Geisei Observatory <October 6, 2010>

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

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.
Copyright (C) 2010 Tsutomu Seki.