Electronic Telegram No. 5280
Central Bureau for Astronomical Telegrams
Mailing address:  Hoffman Lab 209; Harvard University;
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Prepared using the Tamkin Foundation Computer Network


COMET 12P/PONS-BROOKS
     This comet (cf. CBETs 4727, 4805) has undergone an outburst of perhaps
five magnitudes in the last few days, from total mag 16-17 to total mag 11-12.
T. Prystavski (Lyiv, Ukraine) reported total magnitude 16.3 from CCD images
obtained on July 1.42 UT with a 0.51-m f/4.5 corrected Dall-Kirkham telescope
located at the Utah Desert Remote Observatory (near Beryl Junction, UT, USA).
On July 4.6, K. Kadota (Ageo, Japan) reported total mag 16.3 from CCD images
obtained with a 0.25-m f/5 reflector.  P. Carson (Leigh, Essex, UK) posted a
stacked image of comet 12P on the "ICQ Comet Observations" Facebook forum
(ICOFF) that was taken on July 16.0 with a 0.32-m Dall-Kirkham f/8 telescope
located at the Paramount Remote Observatory at Fregenal de la Seirra, Spain,
with a measured magnitude of 16.9-17.1.  M. Tsumura (Wakayama, Japan)
measured total mag 15.9 (and coma diameter 0'.2) on July 16.65 from a CCD
image taken with a 0.30-m reflector (image posted on the ICOFF).  MPEC
2023-O39 tabulates astrometry of 12P through July 19.1 with average magnitude
around 16.5.
     All of the images pertaining to the following information are posted at
the ICOFF.  F. Kugel (Dauban, France) posted his photo of comet 12P taken on
July 20.90 UT and showing the outburst with indicated magnitude 11.5, noting
that he learned of the outburst from E. Tamas (Nyiregyhaza, Hungary).  Carson
posted a follow-up photo of the outburst taken on July 20.92 and indicating
mag 11.6.  M. Mattiazzo (Swan Hill, Victoria, Australia) measured magnitudes
V = 11.8 and G = 11.6 from CCD images taken with a 0.32-m f/5.3 astrograph at
Nerpio, Spain, on July 21.08.  T. Scarmato (San Costantino di Briatico,
Calabria, Italy) reports magnitudes R = 11.2, G = 11.4, B = 11.7 from CCD
images obtained with a 0.25-m f/4.8 reflector on July 20.95.  E. Guido
(Castellammare di Stabia, Italy) writes that a single unfiltered 120-s CCD
exposure obtained by M. Rocchetto, A. Valvasori, and himself on July 21.17
with a "Telescope Live" 0.10-m f/3.6 reflector located at Oria, Spain, shows a
starlike object of mag 11.6.
     Total visual magnitude estimates (observers reporting the comet to have
a stellar appearance):  July 20.94 UT, 11.3 (S. Gabor, God, Hungary, 0.12-m
refractor); July 20.98, 11.5 (R. J. Bouma, Groningen, The Netherlands, 0.25-m
reflector); July 21.16, 11.5 (A. Hale, Cloudcroft, NM, 0.41-m reflector).


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

                         (C) Copyright 2023 CBAT
2023 July 21                     (CBET 5280)              Daniel W. E. Green