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IAUC 8559: N Sgr 2005 No. 2; C/2005 A1

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                                                  Circular No. 8559
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://cfa-www.harvard.edu/iau/cbat.html  ISSN 0081-0304
Phone 617-495-7440/7244/7444 (for emergency use only)

     W. Liller, Vina del Mar, Chile, reports his discovery of an
apparent nova (mag approximately 8.0) on two red photographs taken
on July 4.049 UT (85-mm camera lens + Technical Pan film + deep
orange filter), the new object appearing at R.A. = 18h17m.9, Decl.
= -30o27' (equinox 2000.0); nothing was visible at this location on
films taken by Liller on June 12 (limiting mag about 11.0).  Liller
adds that an unfiltered CCD image taken on July 5.085 shows the
nova at mag 7.2, and that a spectrum taken at July 5.099 shows
H_alpha peaking at about 2.1 times the brightness of the nearby
continuum; its FWHM is approximately 970 km/s, while the expansion
velocity derived from the sharp P-Cyg line is approximately 1300
     A. C. Gilmore and P. M. Kilmartin report the following precise
position for the nova from an unfiltered 0.4-s CCD exposure taken
on July 5.380 UT with the 1-m f/3.8 reflector at the University of
Canterbury's Mt. John Observatory (measured by Gilmore using
'Astrometrica' with UCAC2 stars):  R.A. = 18h17m50s.77, Decl. =
-30o26'31".2 (equinox 2000.0).  Photoelectric photometry by
Kilmartin and Gilmore with the 0.6-m f/16 reflector in marginal
conditions (occasional fog and low cloud crossing) yields:  July
5.408, V = 8.15, U-B = -0.04, B-V = +0.48, V-R = +0.38, V-I = +0.75,
air mass 1.167; 5.456, 8.17, +0.03, +0.46, +0.33, +0.67, 1.064
(comparison star Cousins' E749).  Attempts to identify a precursor
star on the Digitized Sky Survey were unsuccessful; a 15th-mag star
that is near the nova position, but too far off to be a likely
precursor, hides fainter stars.
     C. Jacques, Belo Horizonte, Brazil, reports the following
position end figures for the nova (whose unfiltered magnitude was
7.9) from CCD astrometry obtained on July 5.1 UT with a 0.30-m
reflector:  50s.79, 32".4.
     Visual magnitude estimates, in part via E. Waagen, AAVSO:
July 5.014 UT, 7.6 (R. Shida, Sao Paulo, Brazil); 5.271, 8.0 (M.
Linnolt, Woodside, CA); 5.359, 8.0 (J. Bedient, Hololulu, HI);
5.438, 8.1 (A. Pearce, Nedlands, W. Australia).

     M. Kidger, Instituto de Astrofisica de Canarias, reports that
CCD frames taken by S. Pastor and A. Reyes since June 25 show an
apparent splitting of this comet's nucleus, the companion being 0.7
mag fainter than the primary in a 10" aperture; the absolute
astrometry appear on MPEC 2005-N21.  The offsets of the secondary
(B) from the primary (A) are:  June 25.1 UT, 4" west, 7" south;
July 3.1, 4", 10"; July 4.1, 4", 12".

                      (C) Copyright 2005 CBAT
2005 July 5                    (8559)            Daniel W. E. Green

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