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IAUC 8991: 29P

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IAUC number 

                                                  Circular No. 8991
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
CBAT@CFA.HARVARD.EDU (science)
URL http://www.cfa.harvard.edu/iau/cbat.html  ISSN 0081-0304
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COMET 29P/SCHWASSMANN-WACHMANN
     Y. R. Fernandez, University of Central Florida; B. E. A.
Mueller, Planetary Science Institute; and N. H. Samarasinha,
Planetary Science Institute and National Optical Astronomy
Observatories, report that they observed comet 29P with a CCD
camera on the Kitt Peak National Observatory 2.1-m telescope for
five consecutive nights on Sept. 25.5, 26.5, 27.5, 28.5, and 29.5
UT.  During this interval, R-band imaging of the comet's coma
showed manifestations of the outburst reported by Henriquez (IAUC
8978).  A shell of material is seen expanding outward at
approximately 0.1 km/s -- most prominent at p.a. about 60-290 deg.
There is also a second, expanding, partial shell of material,
closer to the nucleus and on the north side of the coma.  At least
three persistent radial jets can be discerned, at p.a. about 305,
355, and 40 deg.  A sample image is posted at website URL
http://www.physics.ucf.edu/~yfernandez/sw1.html.  Further
observations to watch the continuing development of 29P's intricate
coma morphology during the course of the current outburst are
requested.
     J. M. Trigo-Rodriguez, Institute of Space Sciences, Consejo
Superior de Investigaciones Cientificas and Institut Estudis
Espacials de Catalunya, reports that the present outburst
experienced by 29P is the brightest detected since Sept. 2004; for
more details see Trigo-Rodriguez et al. (2008, A.Ap. 485, 599),
where the outburst frequency of this comet was established to
average 7.3 outbursts/year, usually reaching a maximum magnitude of
13 or fainter.  A. Sanchez (Gualba, Spain, 36-cm f/6 Schmidt-
Cassegrain reflector) has obtained the following recent magnitudes
of 29P through a 10" aperture:  Sept. 13.158 UT, R = 14.1; 25.118,
R = 11.9; 29.155, V = 12.9, R = 12.4, I = 12.3; Oct. 1.154, V =
13.8, R = 13.4, I = 13.5.  On Sept. 29, an asymmetric 55"-wide
coma was visible, corresponding to a coma size of 255000 km; a
bright fan of material extended from the nuclear condensation in
p.a. 235 deg.
     Another bright outburst occurred last January (cf. IAUC 8910).
Additional total magnitude estimates, visual unless noted otherwise:
Jan. 27.89 UT, 11.6 (J. J. Gonzalez, Leon, Spain, 0.20-m reflector);
28.89, 11.2 (W. Hasubick, Buchloe, Germany, 44-cm reflector); Feb.
1.46, 11.2 (Y. Nagai, Gunma, Japan, 300-mm camera lens + CCD);
13.95, 11.6 (J. Qvam, Borrevannet, Horten, Norway, 0.10-m refractor
 + CCD + V filter); Mar. 1.92, 12.5 (Gonzalez); 26.87, 15.2 (Qvam,
0.46-m reflector + CCD + V filter); Sept. 23.08, 11.2 (V. Nevski,
Vitebsk, Belarus, 0.3-m reflector); 25.10, 10.9 (Gonzalez); 29.14,
10.7 (Gonzalez); Oct. 4.76, 10.4 (S. Yoshida, Gunma, Japan, 0.40-m
reflector).

                      (C) Copyright 2008 CBAT
2008 October 6                 (8991)            Daniel W. E. Green

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