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IAUC 8997: P/2008 U1; V1309 Sco

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                                                  Circular No. 8997
Central Bureau for Astronomical Telegrams
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
URL http://www.cfa.harvard.edu/iau/cbat.html  ISSN 0081-0304
Phone 617-495-7440/7244/7444 (for emergency use only)

     Robert S. McMillan, Lunar and Planetary Laboratory, University
of Arizona, reports his discovery of a comet with a 15" tail
(spanning 20 deg) toward the west-southwest and a coma of diameter
about 5" on CCD images taken with the Spacewatch 1.8-m f/2.7
reflector at Kitt Peak (discovery observation tabulated below).
Four co-added 25-s unfiltered CCD images taken by A. R. Gibbs at
the Mt. Lemmon 1.5-m reflector on Oct. 20.4 UT show a condensed
coma of size 6" x 8", elongated in p.a. 250 deg, with an additional
"fuzziness" of diameter 10".

     2008 UT             R.A. (2000) Decl.       Mag.
     Oct. 19.19689    2 03 22.46   +11 44 54.6   18.9

The available astrometry (including prediscovery observations with
the Spacewatch 0.9-m f/3 reflector back to Sept. 20), the following
elliptical orbital elements, and an ephemeris appear on MPEC

     T = 2008 May  12.8317 TT         Peri. = 310.3471
     e = 0.375714                     Node  =  36.4170  2000.0
     q = 2.523942 AU                  Incl. =   4.4150
       a =  4.042929 AU    n = 0.1212439    P =   8.13 years

     R. J. Rudy, D. K. Lynch, and R. W. Russell, Aerospace
Corporation; M. Sitko, Space Science Institute; C. E. Woodward,
University of Minnesota; and C. Aspin, University of Hawaii, report
that 0.8-5.5-micron spectroscopy and K-band imagery of the nova
V1309 Sco (cf. IAUC 8972, 8976) on Oct. 4 and 16 UT using the
Infrared Telescope Facility (+ Spex) shows very narrow emission
lines of H I, He I, and Ca II sitting atop a strong continuum that
closely matches that of a late M giant star.  The spectrum includes
strong molecular absorptions of CO, H_2O, and weaker features of
TiO and VO, while the overall continuum shape is that of a cool
star.  Magnitudes derived from the spectroscopic observations are
J = 6.7, H = 5.7, and K = 5.2.  All of the observations would be
consistent with V1309 Sco being a symbiotic nova (a nova consisting
of a white dwarf and a late giant) except that the 2MASS images
show no object close to the location of V1309 Sco with K < 11.
If V1309 Sco has shed a massive envelope, such as V838 Mon or V4332
Sgr, its appearance at this epoch is very different.  Additional
observations of this interesting object are strongly encouraged.

                      (C) Copyright 2008 CBAT
2008 October 21                (8997)            Daniel W. E. Green

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