Central Bureau for Astronomical Telegrams

IAUC 7489: Z And; V4642 Sgr

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                                                  Circular No. 7489
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)


Z ANDROMEDAE
     J. A. Mattei, AAVSO, reports that this star has gone into
outburst for the first time since 1997 (cf. IAUC 6679), when the
star peaked at m_v about 9.7 on June 4 and began a slow fade later
that month towards minimum at m_v about 10.9 in 1998 March.  A.
Baransky, Kiev, Ukraine, has also reported the current outburst
independently to the Bureau.  Selected visual magnitude estimates
(mostly from the AAVSO):  Aug. 28.85 UT, 10.8 (Baransky); Sept.
1.10, 10.4 (M. Komorous, London, ON); 1.93, 10.8 (J. Ripero Osorio,
Madrid, Spain); 2.81, 10.5 (Baransky); 3.24, 10.3 (E. Van
Ballegoij, Oranjestad, Aruba); 4.09, 10.4 (B. Granslo, Oslo,
Norway); 4.86, 10.1 (E. Muyllaert, Oostende, Belgium); 5.06, 10.1
(P. Dombrowski, Glastonbury, CT); 5.80, 10.0 (Baransky); 6.08, 10.1
(P. McDonald, Toronto, ON); 6.23, 9.8 (M. Simonsen, Macomb, MI);
7.07, 9.8 (J. Bortle, Stormville, NY); 7.92, 10.1 (Ripero Osorio);
8.10, 9.6 (Dombrowski).


V4642 SAGITTARII
     D. K. Lynch, R. J. Rudy, S. Mazuk, and C. Venturini, The
Aerospace Corporation; R. C. Puetter, Center for Astrophysics and
Space Science, University of California at San Diego; and T.
Armstrong, Thomas K. Armstrong Development Corporation,
McKinleyville, CA, report 0.8-2.5-micron spectrophotometry of V4642
Sgr (= N Sgr 2000) using the Lick Observatory 3-m telescope and the
Aerospace Near Infrared Imaging Spectrograph (NIRIS) on July 20.31
UT, about 161 days after peak brightness:  "Although the
fluorescently excited lines of O I persist, He II lines are now
strong and coronal lines are now present.  The latter include [S
VIII] at 0.9913 micron, [Si VI] at 1.9629 microns, [Ca VIII] at
2.3214 microns, [Si VII] at 2.4827 microns, and possibly [Al IX] at
2.0469 microns.  As is frequently the case, the He I line at 1.0830
microns is the strongest feature.  There was no evidence of thermal
emission from dust in the region 1-2.5 microns, although a
significant, relatively flat continuum was present.  J, H, and K
magnitudes determined from the spectrum are 12.5, 12.7, and 11.6,
respectively.  The spectrum generally resembled that of V4633 Sgr
(N Sgr 1998), as reported by Rudy et al. in 1999 (IAUC 7259)."
     Additional visual magnitude estimates by A. Pearce, Nedlands,
W. Australia (cf. IAUC 7381):  Mar. 23.841 UT, 12.6; 27.844, 13.6;
Apr. 1.836, 13.2; 9.831, 13.7; May 22.858, 14.7; June 1.842, 15.1;
11.837, 15.1.

                      (C) Copyright 2000 CBAT
2000 September 8               (7489)            Daniel W. E. Green

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