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IAUC 9255: C/2012 F6; 168P

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                                                  Circular No. 9255
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
New postal address:  Hoffman Lab 209; Harvard University;
 20 Oxford St.; Cambridge, MA  02138; U.S.A.
CBATIAU@EPS.HARVARD.EDU           ISSN 0081-0304
URL http://www.cbat.eps.harvard.edu/index.html
Prepared using the Tamkin Foundation Computer Network


COMET C/2012 F6 (LEMMON)
     L. Paganini, M. J. Mumma, and G. L. Villanueva, Goddard Space
Flight Center; M. Lippi and H. Boehnhardt, Max Planck Institute for
Solar System Research; and Hans U. Kaeufl, European Southern
Observatory (ESO), report the detection of parent volatiles in
comet C/2012 F6 (cf. CBET 3070) on 2013 Feb. 2-4 (when r = 1.20 AU,
Delta = 0.99 AU, geocentric velocity = -4 km/s) using high-
resolution infrared spectra acquired with CRIRES at the ESO's Very
Large Telescope.  The slit was oriented along the sun-comet line.
Nine volatile species were targeted:  H_2O, OH (prompt emission),
C_2H_6, C_2H_2, CH_3OH, HCN, NH_2, NH_3, and HDO.  Preliminary
results for the number of lines detected, mean production rates
(in units of 10**27 molecules/s), rotational temperatures, and
abundance ratios (in percent, relative to water), respectively,
are as follows:  H_2O, 8 lines, 189.1 +/- 11.0, 69 K, 100 percent;
C_2H_6, 6 lines, 0.5 +/- 0.1, 69 K, 0.26; CH_3OH, 10 lines, 3.6
+/- 0.5, 66 K, 1.91; HCN, 3 lines, 0.2 +/- 0.1, 70 K (assumed),
0.11; NH_2, 4 lines, 0.6 +/- 0.1, 70 K (assumed), 0.31; NH_3, 1
line, < 1.2, 70 K (assumed), 0.63.  Additional trace species are
under evaluation.  (The authors thank the ESO for allocation of
Director's Discretionary Time to program 290.C-5016.)
     Additional naked-eye visual total-magnitude estimates by
David A. J. Seargent, Cowra, NSW, Australia (cf. CBET 3433):
Mar. 10.42 UT, 4.4; 12.41, 4.3; 14.41, 4.3.  With 15x80
binoculars on Mar. 12.41, Seargent measured a 5' coma and a
3.5-deg tail.


COMET 168P/HERGENROTHER
     As first published on CBET 3257, Schleicher also reports that
he obtained five sets of narrowband photometry of comet 168P on
2012 Oct. 9 (when r = 1.42 AU and Delta = 0.45 AU) using the Hall
1.1-m telescope, resulting in the following averaged production
rates:  log Q(OH) = 27.85; equivalent log Q(water; vectorial) =
27.91; log Q(NH) = 25.01; log Q(CN) = 25.33; log Q(C_2) = 24.52;
log Q(C_3) = 23.77; log [Af(rho)] at 526.0 nm = 2.5 (cf. IAUC
7342).  These measurements reveal that the comet is strongly
carbon-chain depleted (cf. A'Hearn et al. 1995, Icarus 118, 223),
by even more than that of comet 21P/Giacobini-Zinner, the proto-
type of this class.

                      (C) Copyright 2013 CBAT
2013 March 23                  (9255)            Daniel W. E. Green

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