Central Bureau for Astronomical Telegrams
IAUC 8349: C/2001 Q4; 2004by
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Circular No. 8349
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://cfa-www.harvard.edu/iau/cbat.html ISSN 0081-0304
Phone 617-495-7440/7244/7444 (for emergency use only)
COMET C/2001 Q4 (NEAT)
J. Lecacheux, LESIA, Meudon Observatory; and E. Frappa,
St-Etienne Planetarium, write: "We have observed the concentric
dust shells of comet C/2001 Q4 with the Pic-du-Midi 1.05-m
reflector during six 3-hr sessions from May 14 to 19, around the
time of perihelion. Direct measurement of the radial expansion on
consecutive exposures yields 163 +/- 20 m/s. From the measured
12000-km shell interval, a first approximation of P = 20.5 +/- 3 hr
can be inferred for the period of nucleus rotation, suggesting the
exclusion of any value shorter than 17-18 hr. Then by blinking
images of the inner shell taken at 1-day or several-day interval(s),
and assuming constant expansion velocity, we obtain a refined
probable period P = 23.2 +/- 0.25 hr. We also followed a small
dust jet rotating counterclockwise (facing the sun) on May 14; its
estimated angular motion of about 16 deg/hr agreed with the above
period. Fibrous-like features, not more 300 km wide, appear within
the brightest shell at 10000-15000 km from the nucleus; they show a
pure radial expansion and no other morphology change in 3 hr, and
they recur in the following shell 0.9 day later. In fact, we
observe a complex of 3 or or 4 muddled components (sub-shells),
issued from so many active regions and with slightly different
expansion rates."
Further visual total-magnitude estimates: May 19.87 UT, 4.2
(V. Znojil, Brno, Czech Republic, naked eye); 22.91, 4.5 (M. Meyer,
Ursenbach, Germany, naked eye); 24.91, 4.7 (A. Diepvens, Balen,
Belgium, 20x50 binoculars); 27.90, 5.0 (A. Amorim, Florianopolis,
Brazil, 7x50 binoculars); 30.92, 5.4 (J. J. Gonzalez, Asturias,
Spain, 7x50 binoculars).
SUPERNOVA 2004by IN NGC 7116
M. Armstrong, Rolvenden, U.K., reports his discovery of an
apparent supernova (mag 18.9) on unfiltered CCD images taken on May
24.102 and 28.026 UT with a 0.35-m reflector. SN 2004by is
located at R.A. = 21h42m41s.88, Decl. = +28o56'50".6 (equinox
2000.0), which is approximately 16" east and 1".9 north of the
center of NGC 7116. Nothing was visible at this position on his
images taken on 2001 July 15 and 2003 Dec. 17 (limiting mag about
19.5) and on Palomar Sky survey red and blue plates. M. Mobberley,
Cockfield, U.K., confirmed the new object on an unfiltered CCD
image taken on May 27.951 with a 0.35-m reflector.
(C) Copyright 2004 CBAT
2004 May 31 (8349) Daniel W. E. Green
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