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IAUC 7578: 2001 C1; C/1999 T1

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                                                  Circular No. 7578
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
CBAT@CFA.HARVARD.EDU (science)
URL http://cfa-www.harvard.edu/iau/cbat.html  ISSN 0081-0304
Phone 617-495-7440/7244/7444 (for emergency use only)


COMET 2001 C1
     L. Manguso, Lincoln Laboratory, reports the discovery of an
apparent comet by LINEAR.  Confirming CCD observations by G. Hug
(Eskridge, KS) reveal a condensed coma and a suggestion of a faint,
broad tail in p.a. about 325 deg.  Available astrometry:

     2001 UT             R.A. (2000) Decl.        m1    Observer
     Feb.  1.48039   14 41 46.55   -10 15 14.8   18.9   LINEAR
           1.49581   14 41 46.66   -10 15 21.8   19.5     "
           1.52622   14 41 46.75   -10 15 32.2   18.6     "
           2.49528   14 41 49.06   -10 19 51.8   18.3   Hug
           2.50030   14 41 49.08   -10 19 52.8   17.9     "
           2.51013   14 41 49.11   -10 19 55.0   18.3     "


COMET C/1999 T1 (McNAUGHT-HARTLEY)
     M. J. Mumma, N. Dello Russo, and M. A. DiSanti, Goddard Space
Flight Center, NASA; K. Magee-Sauer, Rowan University; R. Novak,
Iona College; and A. Conrad and F. Chaffee, W. M. Keck Observatory,
report:  "Water and CO were detected simultaneously near 4.67
microns on Jan. 13.7 UT in observations made at the NASA Infrared
Telescope Facility (+ CSHELL).  Three lines in the 1-0 band of CO
(R0, R1, and P2) and two lines in the nu_3-nu_2 band of H_2O
yielded production rates (x 10**27 molecules s**-1) of 14 for CO
and 82 for H_2O.  On Jan. 14.7, C_2H_6 (nu_7, nine Q-branches),
CH_3OH (nu_3 Q-branch and other lines), and OH 'prompt' emission
were detected using NIRSPEC at the W. M. Keck Observatory.  The
water-production rate derived from OH 'prompt' emission (P12.5 1-
and 1+, near 3042 cm**-1) was 160 (calculated using g-factors from
comet C/1999 H1), and other production rates were 2.7 for CH_3OH
and 1.1 for C_2H_6.  A residual 2-sigma signal was seen at the
expected position of CH_4 R0 (nu_3 band), and this is formally
consistent with a 3-sigma upper limit of 2.5 for CH_4.  The mixing
ratios are then H_2O:CO = 100:17 on Jan. 13.7, and H_2O:CH_3OH:
C_2H_6:CH_4 = 100:1.7:0.65:(<1.6) on Jan. 14.7.  A rotational
temperature of 70 K was adopted for all species on both dates.
Multiple lines of HCN and C_2H_2 were detected on Jan. 14, and
quantitative analysis is in progress.  The CO mixing ratio in this
comet is similar to that found for native CO in comets C/1996 B2
and C/1995 O1, but it is much higher than those found for comets
C/1999 H1 and C/1999 S4.  Abundances of C_2H_6 and CH_3OH are
similar to those in comets C/1996 B2, C/1995 O1, and C/1999 H1."

                      (C) Copyright 2001 CBAT
2001 February 2                (7578)            Daniel W. E. Green

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