quai at eps.harvard.edu quai at eps.harvard.edu
Thu Dec 9 17:39:57 EST 2021

                                                  Electronic Telegram No. 5080
Central Bureau for Astronomical Telegrams
Mailing address:  Hoffman Lab 209; Harvard University;
 20 Oxford St.; Cambridge, MA  02138; U.S.A.
e-mail:  cbatiau at eps.harvard.edu (alternate cbat at iau.org)
URL http://www.cbat.eps.harvard.edu/index.html
Prepared using the Tamkin Foundation Computer Network

     G. Rhemann, Vienna, writes that he has observed a long dust trail both
preceeding and following the comet (extending basically east-west) in CMOS
camera images (field-of-view 75' x 113') obtained remotely this past month
with a 30-cm f/3.6 reflector (+ Luminance filter) located in Namibia.  On
Nov. 1.77 and 2.76 UT, the tail extended beyond the 113' field size in both
directions with the comet centered and the tail extending in p.a. 267 and 87
degrees; the tail was about 85" thick.  The two position angles on other
nights were measured to be as follows:  Nov. 5.88, 261 and 81 degrees; Nov.
8.84, 256 and 76 deg; Nov. 22.77, 248 and 68 deg.  In early November, the
brightness of the two dust trails appeared similar, but by Nov. 22, the
eastward tail was notably fainter than the westward tail; on Nov. 27.78,
the brighter dust tail was at least 2 deg long in p.a. 240 deg.
     Follow-up observations obtained remotely by T. Lehmann, Weimar, Germany,
on Nov. 1.78, 6.89, and 13.03 UT with a 20-cm f/3 reflector (+ green filter)
located at Hakos, Namibia, show the dust trail in p.a. 89, 87, and 83.5 deg,
respectively (observations consist of four 3-min, six 2-min, and five 2-min
exposures, respectively, with the last night having some high clouds and with
the comet at low altitude).  Lehmann also notes that the dust feature is
stronger and narrower on the western side of the comet.
     Selected recent CCD total-magnitude measurements:  Aug. 9.64 UT, 16.7
(Hidetaka Sato, Tokyo, Japan, remotely with 0.51-m astrograph at Siding
Spring, NSW; coma diameter 12"); Nov. 24.39, 11.1 (K. Kadota, Ageo, Japan,
0.25-m reflector); Dec. 2.37, 11.0 (Kadota); 9.38, 11.1 (T. Ikemura and
Hirohisa Sato, Shinshiro, Japan, 0.35-m reflector).  Recent selected visual
total-magnitude and coma-diameter estimates:  Oct. 21.99, 12.0, 2' (J. G. de
S. Aguiar, Campinas, Brazil, 0.27-m reflector); Nov. 1.99, 11.7, 2' (Aguiar);
5.99, 11.4, 2.5' (Aguiar); Dec. 2.82, 9.8, 6' (J. J. Gonzalez, Leon, Spain,
0.20-m reflector).

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

                         (C) Copyright 2021 CBAT
2021 December 9                  (CBET 5080)              Daniel W. E. Green

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