Electronic Telegram No. 3675
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
CBAT Director:  Daniel W. E. Green; Hoffman Lab 209; Harvard University;
 20 Oxford St.; Cambridge, MA  02138; U.S.A.
e-mail:  cbatiau@eps.harvard.edu (alternate cbat@iau.org)
URL http://www.cbat.eps.harvard.edu/index.html
Prepared using the Tamkin Foundation Computer Network


COMET C/2012 X1 (LINEAR)
     [Editor's note:  this text replaces that on CBET 3674]
     Having passed conjunction with the sun in August at elongation < 25 deg,
this comet (cf. CBET 3340) had been following a slow, steady brightness
increase according to H_10 = 8.0 from discovery until the last astrometry in
June (several months ago, when it was around total mag 16.5, according to
CCD astrometrists; cf. MPEC 2012-N23).  Now pulling slowly away from the
sun (elongation 35-40 deg), H. Sato (Tokyo, Japan) has reported an outburst
in brightness of this comet comet from a 60-s CCD exposure taken on Oct.
20.507 UT with a 0.51-m f/6.8 astrograph (+ luminance filter, which is
essentially a wide-band clear filter) near Mayhill, NM, U.S.A.; the comet
shows a morphology similar to the outburst of comet 17P in 2007, showing a
disk-like coma 85" across of total mag 8.5 (as measured within a circular
aperture of diameter 85".2) with a brighter center about 10" across.  The
predicted H_10 magnitude would be around 14 now.
     K. Kadota, Ageo, Japan (0.25-m reflector + CCD) reports a disk-like
inner coma of diameter 1'.6 and an outer coma diameter of 5' with total
magnitude 8.2 on Oct. 20.82 UT.  Kadota has posted his image at website
URL http://members.jcom.home.ne.jp/kenic-k/comet/2012X1-20131020.jpg.
     Quanzhi Ye, University of Western Ontario; Xing Gao, No. 1 Senior High
School of Urumqi, China; and Man-To Hui, Guangzhou, China, report on their
imaging of an expanding coma of the comet, taken with the 0.35-m SASP
telescope at Xingming Observatory at Oct 21.96 UT.  The unprocessed data
show a highly circular coma with a radius measured to be 90"; processing
with an azimuthal median model reveals a bright fan extending from p.a. 90
to 225 deg, together with two fainter jet-like structures at p.a. 20 and 80
deg.  No features ejection are identified in the anti-sunward direction
(p.a. 225 to 360 deg).


NOTE: These 'Central Bureau Electronic Telegrams' are sometimes
      superseded by text appearing later in the printed IAU Circulars.

                         (C) Copyright 2013 CBAT
2013 October 21                  (CBET 3675)              Daniel W. E. Green