[IAUC] IAUC 8793: C/2006 P1 [25139-2007/05-R1]

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                                                  Circular No. 8793
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
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COMET C/2006 P1 (McNAUGHT)
     K. Battams, Interferometrics, Inc., and Naval Research
Laboratory, reports that images of comet C/2006 P1 obtained on Jan.
11 with the SECCHI/HI-1B instrument on the NASA STEREO-B (Behind)
spacecraft are available at the following website URL:
http://ares.nrl.navy.mil/sungrazer/index.php?p=latest_news.  The
images show a curved, striated dust tail some 7 degrees long, the
bright coma being heavily saturated due to its brightness.
     J. N. Marcus writes that forward-scattering brightness
enhancement should peak in C/2006 P1, as viewed from the earth, on
Jan. 14 at a level approximately 2.3 magnitudes brighter than what
would be predicted by a standard power law (model details in Marcus
2007, ICQ, submitted).
     Selected visual total-magnitude, coma-diameter, and tail-
length/p.a. estimates made with the comet at low altitude (all
magnitudes were corrected by the observers for atmospheric
extinction) and in nautical or civil twilight unless otherwise
noted:  2006 Dec. 29.28 UT, 3.9, 1'.5, -- (B. H. Granslo,
Fjellhamar, Norway, 0.10-m refractor); 2007 Jan. 2.30, 2.7, 1'.5,
0.1 deg in p.a. 0 deg (J. J. Gonzalez, Leon, Spain, 25x100
binoculars); 3.28, 1.5, 1'.7, 0.2 deg (H. Dahle, Fjellhamar,
Norway, 9x63 binoculars); 4.64, 1.0:, --, -- (Dahle, Blindern/Oslo,
Norway, naked eye); 5.72, -0.5:, --, -- (D. Moore, Dublin, Ireland,
naked eye); 6.28, 0.2:, 1', 1 deg in p.a. 0 deg (Granslo, Tryvann/
Oslo, Norway, 7x50 binoc.); 7.30, 0.0:, 1', 0.4 deg (N. Biver,
Meudon, France, 7x50 binoc.); 7.48, -0.5:, about 1', < 1 deg (D. W.
E. Green, Rowley, MA, U.S.A., 7x35 binoc.); 8.25, -1.2:, 3', 0.5
deg (K. Hornoch, Vranov, Czech Republic, naked eye); 8.65, -0.8:,
--, 1.5 deg (O. Skilbrei, Honefoss, Norway, naked eye); 8.93, -1.5:,
about 1', -- (J. E. Bortle, Stormville, NY, U.S.A., naked eye);
9.68, -2.0, --, -- (W. Hasubick, Buchloe, Germany, naked eye); 9.71,
-2.2:, 1', 1.5 deg (Biver, naked eye); 9.98, -2.9:, --, short (J. N.
Marcus, St. Louis, MO, U.S.A., naked eye); 10.30, -2.2:, --, 1.0
deg in p.a. 15 deg (T. Karhula, Vaesteraas, Sweden, naked eye);
10.34, -2.2:, --, 0.3 deg in p.a. 15 deg (S. Yoshida, Toride,
Ibaraki, Japan, 10x70 refractor); 10.66, -2.7:, 5', 2 deg in p.a.
25 deg (K. Hornoch, Krasensko, Czech Rep., 10x50 binoculars); 10.68,
-3.2, 2', 2 deg (T. Scarmato, Calabria, Italy, 7x50 binoc.); 10.83,
-2.5:, --, short (R. A. Keen, Mt. Thorodin, CO, U.S.A., 7.6-cm
reflector; broad daylight; comparison with Venus); 10.92, -2.5:,
about 1', 1 deg (Bortle); 10.95, -2.9:, 1', 1.6 deg in p.a. 15 deg
(P. Creed, New London, OH, U.S.A., 10x50 binoc.); 11.34, -2.8,
about 3', 1 deg (Y. Nagai, Gunma, Japan, 7x35 binoc.); 11.68, -3.5,
3', about 2 deg (Scarmato, naked eye); 11.75, -3.5:, --, 1 deg (A.
Pereira, Cabo da Roca, Portugal, naked eye).

                      (C) Copyright 2006 CBAT
2007 January 11                (8793)            Daniel W. E. Green