Web Publications

                THE AMERICAN ASSOCIATION OF VARIABLE STAR OBSERVERS
                      25 Birch Street, Cambridge, MA 02138 USA
                             INTERNET:  aavso@aavso.org
                     Tel. 617-354-0484       FAX 617-354-0665

                    AAVSO ALERT NOTICE 255 (February 25, 1999)

OUTBURST OF THE RECURRENT NOVA 1616-17 U SCORPII

We have been informed by Patrick Schmeer, Bischmisheim, Germany, that the
recurrent nova U Scorpii has gone into outburst at visual magnitude 9.5 on
February 25.194 UT.  Visual confirmation was obtained by Lance Shaw, Pinole,
Calfornia, at magnitude 7.6 on Feb 25.5625, and by Michael Mattiazzo, Wallaroo,
South Australia, at magnitude 8.0 on Feb 25.625.  This outburst has also been
reported by the Central Bureau for Astronomical Telegrams in IAU Circular 7113.

Other outbursts of U Sco have occurred in 1863, 1906, 1936, 1979 (see AAVSO
Alert Notice 31), and 1987 (see AAVSO Alert Notice 93).  In the 1979 outburst,
U Sco, which is V magnitude 17.9 at minimum, was reported in outburst on June
24 at visual magnitude 9.4 and faded to <13.6 by July 4.  In 1987, U Sco was
reported in outburst on May 15 at visual magnitude 10.8 and faded to <15.0 by
May 29; it is believed that the beginning of this outburst may not have been
observed.

U Sco is also an eclipsing binary.  The ephemeris for eclipses given by B.
Schaefer and F. Ringwald in Astrophys. Journ. 447, L45 (1995) is:

                  Min HJD = 2447717.6061 + 1.2305631 E
                                 ñ0.0032  ñ0.0000030

Accompanying are revised AAVSO "d" and "e" scale preliminary charts.  These
charts may also be retrieved from our ftp site and web site (see below).
Please monitor U Sco throughout this outburst using these charts, and report
your observations to AAVSO Headquarters.

Congratulations to Patrick on his discovery of this outburst!

CHARTS AVAILABLE ON AAVSO WEB AND FTP SITES

Electronic copies of the AAVSO charts of U Sco  mentioned in this Alert Notice
are available through our web site at the following address:

http://www.aavso.org

All of these charts may also be obtained directly from our FTP site:

ftp.aavso.org (198.116.78.5), in /alerts/alert255)

The answering machine at AAVSO Headquarters is on nights and weekends for your
convenience. Please call our charge-free number (888-802-STAR = 888-802-7827)
to report your observations. We also encourage observers to send observations
by fax to 617-354-0665 or by e-mail through the Internet to
observations@aavso.org.

Many thanks for your valuable astronomical contributions and your efforts.

Good observing!

Elizabeth O. Waagen, Senior Technical Assistant
on behalf of
Janet A. Mattei, Director