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Alert Notice 167: The symbiotic star 1810-00 FG Serpentis (AS 296) AND Forthcoming outburst of 0749+22 U Geminorum

THE AMERICAN ASSOCIATION OF VARIABLE STAR OBSERVERS
25 Birch Street, Cambridge, MA 02138 USA
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AAVSO ALERT NOTICE 167 (February 1, 1993)

THE SYMBIOTIC STAR 1810-00 FG SERPENTIS (AS 296)

FG Serpentis = AS 296 is a symbiotic system consisting of a hot compact primary and a late type giant secondary. It varies between magnitudes 12 and 9.8 (V). Since its recent outburst in 1988, it has been monitored closely both by professional and amateur astronomers. Munari et. al. (Astr. Journ., 104, 262; 1992) give a very good description of its multiwavelength behavior and its two post-outburst suggested eclipses, separated by 650 days. Its next possible eclipse is predicted to occur in June 1993.

We have been requested to monitor this interesting system closely in the coming months both for the forthcoming predicted eclipse and also a possible pre-eclipse dip in the light curve, which had been observed before.

Please use the accompanying RASNZ chart with letter sequence added at AAVSO Headquarters. Please report your observations monthly in your regular monthly report, using this letter sequence and assuming 10 steps between lettered stars.

FORTHCOMING OUTBURST OF 0749+22 U GEMINORUM

Several astronomers scheduled to observe this dwarf nova with various space satellites, including EUVE, have requested to be informed when U Gem has its next outburst, predicted for the coming weeks. Its last outburst was in late August and early September 1992, when the star reached magnitude 9.3 at maximum, and stayed brighter than magnitude 11 for 12 days.

Please monitor this dwarf nova and call in your observations to Headquarters if you observe it at 13.5 magnitude or brighter. Please call in your observations throughout the outburst so we may monitor its shape and duration for astronomers interested in its decline from outburst.

The Headquarters answering machine is on weekends and nights. Observers in the USA can call in using the 800-number (toll-free) added to AAVSO Headquarters for the EUVE mission. The AAVSO's 800 number is:

800-642-EUVE (617-642-3883)

For our observers outside the USA, please use our regular telephone number (617-354-0484). We will reimburse telephone charges for reporting your observations on U Gem or other stars in the EUVE observing program.

Thank you very much for your observing efforts and contributions.

Clear skies! Good Observing!


Director

files: AS296 Ser (FG Ser) RASNZ chart (#945) with annotated letter sequence

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