Electronic Telegram No. 3530
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


COMETS C/2012 F6 (LEMMON), C/2013 E2 (IWAMOTO), and 63P/WILD
     C. Opitom, E. Jehin, J. Manfroid, and M. Gillon, Liege University, report
that they obtained one set of narrowband photometry of the long-period comet
C/2012 F6 on May 15 (when r = 1.21 AU) using the robotic TRAPPIST 0.6-m
telescope at the European Southern Observatory, resulting in the following
production rates (Haser model with V_p = V_d = 1 km/s):  log Q(OH) = 29.0;
log Q(NH) = 27.2; log Q(CN) = 26.6; log Q(C_3) = 26.1; log Q(C_2) = 26.8.
Also, Af(rho) at 526.0 nm = 3200 cm at 10000 km.  They followed the comet
since May 6 several times a week, and its activity is now slowing down
regularly since perihelion (T = 2013 Mar. 24.5 TT).
     A complete set of narrowband photometry was also collected on comet
C/2013 E2 from Apr. 15 to 17 (when r = 1.51 AU, a month past perihelion),
resulting in the following averaged production rates:  log Q(OH) = 27.7; log
Q(NH) = 25.6; log Q(CN) = 25.2; log Q(C_3) = 24.7; log Q(C_2) = 25.2.  Also,
Af(rho) at 526.0 nm = 165 cm.
     On May 16.0 UT, they noticed that comet 63P was 2.1 magnitudes brighter
in the R band (with R = 13.5 in an aperture of size 8") than five and ten
days earlier (with R = 15.6 and 15.7, respectively, in the same-sized
aperture).  The onset of the outburst must have been very close in time, as
the inner coma was sharp (diameter 4") in all the filters.  But the day after,
on May 17.0, the CN coma was much more extended, and they derived log Q(CN)
= 25.2, and Af(rho) at 526.0 nm = 350 cm, with a large dependence on the
distance from the nuclear condensation.


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      superseded by text appearing later in the printed IAU Circulars.

                         (C) Copyright 2013 CBAT
2013 May 18                      (CBET 3530)              Daniel W. E. Green