THE AMERICAN ASSOCIATION OF VARIABLE STAR OBSERVERS
25 Birch Street, Cambridge, MA 02138 USA
BITNET: aavso@cfa8 SPAN: nssdca::cfa8::aavso
Tel. 617-354-0484 FAX 617-354-0665
AAVSO ALERT NOTICE 171 (May 5,1993)
2252-36 SN 1993L in IC 5270
We have been informed by the Central Bureau for Astronomical Telegrams of the visual discovery by Robert O. Evans, Hazelbrook, Australia, Chair of the AAVSO Supernova Search Committee, of a supernova in IC 5270 on April 30.8 UT at approximate visual magnitude 14. R. H. McNaught, Anglo-Australian Observatory, confirmed the presence of the supernova and reported the following precise position from a short-exposure plate taken on April 30.83 UT with the Uppsala Schmidt telescope:
RA = 22h 55m 05.81s Decl. = -36deg 07' 31.0" (1950) (IAU Circular 5780)
N. Suntzeff, Cerro Tololo Interamerican Observatory (CTIO), reported that the CCD image taken with the CTIO 0.9-m telescope by G. Williger on May 1.43 UT showed SN 1993L to be 25" West and 1.4" North of the galaxy center and with a V magnitude of 13.60 reduced by R. Aviles. Suntzeff communicated that IC 5270 is a particularly interesting galaxy because of its membership in the Grus Cluster and because it has been used in Tully-Fisher distance scale work AU Cvcular5781). Suntzeff and M. Della Valle and E. Cappellaro, European Southern Observatory (ESO), report that the spectra obtained of this supernova show it to be Type Ia about two weeks after maximum (IAU Circular 5782).
Enclosed are a section from the AAVSO Variable Star Atlas showing the galaxy and the position of the supernova and a chart for ST PsA, which is close to the galaxy, from the Royal Astronomical Society of New Zealand, Variable Star Section.
Congratulations to Bob on this, his 26th visual supernova discovery and his first discovery of 1993!
REQUEST TO MONITOR 2138+43 SS CYGNI AND 1014+20 AD LEO FOR ASCA MISSION
We have been informed, through MultiWaveLink, that the recently-launched Japanese x-ray satellite ASCA, formerly Astro-D, will be observing the dwarf nova-type cataclysmic variable SS Cyg and the flare star AD Leo in May. The astronomers involved with this observing program are requesting both visual and photoelectric observations of these stars during the following times: SS Cyg, the week of May 31; AD Leo, the week of May 24.
Please monitor these stars closely in the coming weeks and inform Headquarters by telephone of their behavior, particularly if you observe SS Cyg brightening and/or you observe a flare of AD Leo.
2106-09 VY AQUARII OUTBURST
The interesting dwarf nova-type cataclysmic variable VY Aqr is undergoing a superoutburst, as indicated by the following observations: Apr 24.59 UT, <13.5 (W. Albrecht, Pahala, HI); 24.70, <13.0 (A. Jones, Nelson, New Zealand) (IAU Circular 5758); 25.57, 10.0 (Albrecht); 26.541, 10.2 (Albrecht); 28.73, 10.3 (Jones) (IAU Circular 5758); 29.579, 10.8 (Albrecht); 29.68, 10.3 (Jones) (IAU Circular 5758); May 1.548, 11.1 (Albrecht); 3.574,11.5 (Albrecht); 4.620,11.2 (Albrecht); 5.113,11.6 (Schmeer).
The last recorded outburst of VY Aqr was in June-July 1990, when it reached magnitude 10.5 and was brighter than 12.5 for 13 days.
0846+58 BZ URSAE MAJORIS OUTBURST
The dwarf nova-type cataclysmic variable BZ UMa has been undergoing an outburst, as indicated by the following observations: Apr 23.972, 15.8 (G. Poyner, Birmingham, England); 26.89, <15.4 (T. Vanmunster, Landen, Belgium); 28.895, <13.7 (Poyner); 29.890,11.4 (P. Schmeer, Bischmisheim, Germany); 29.914, 11.4 (Schmeer); 29.92, 10.9 (H. Dahle, Oslo, Norway); 29.972,10.6 (Vanmunster); 30.033, 11.2 (Schmeer); 30.1611,10.5 D. York, Abiquiu, NM); 30.1792, 11.5 (R. Stewart, Rochelle Park, NJ); May 1.0486, 11.8 Stewart); 1.1361, 12.2 (J. Griese, Rocky Hill, CT); 1.1444, 11.8 (Griese); 2.1389, 14.0 York); 2.881, <13.7 (Poyner).
The last recorded outburst of BZ UMa was in October 1992.
0947+69 SUPERNOVA 1993J in NGC 3031
This bright supernova, officially designated 1993J (the first supernova discovered in a year is designated by the year and A), has been fading since reaching 10.9 ± 0.3 magnitude in mid-April, and is presently at approximately magnitude 12.
Accompanying is the second AAVSO preliminary revised chart for SN 1993J, which includes photoelectric measurements of comparison stars 'A' and 'E' in AAVSO Alert Notice 170, plus an additional comparison star of magnitude 10.8 northeast of the galaxy. Please note that comparison star D has been reported to be variable, and so should not be used for making estimates. Please continue your close monitoring of this supernova as it slowly fades and indicate which comparison stars you have used and from which AAVSO Alert Notice they have come when reporting your observations. Your doing so will help us immensely in standardizing the observations we have been receiving from observers around the world.
1719-23 NOVA OPHIUCHI 1993 [V2295 Oph]
This nova, discovered by P. Camilleri at magnitude 9.5 (see AAVSO Alert Notice 170), has been fading rapidly, and as of the beginning of May, was reported at about magnitude 11.9.
Accompanying is an AAVSO finder chart for N Oph 93, with additional photoelectric (V) magnitudes by A. Gilmore, Mt. John Observatory, New Zealand, together with extrapolated photovisual magnitudes by C. Scovil for those comparison stars indicated with letters in AAVSO Alert Notice 170. Observers are requested to use this sequence to reduce the observations they have already made and to report which comparison stars they have used in making estimates of this nova.
1809-00 FG SERPENTIS (AS 296) (Please note revised designation)
Since distribution of AAVSO Alert Notice 170, which contained a finder chart for FG Ser with photoelectric (V) and CCD (V) photometric comparison star magnitudes, several observers have reported that these photoelectric and CCD magnitudes do not fit together. We welcome comments from observers concerning the individual comparison star magnitudes. Please report which comparison star(s) were used in making estimates of FG Ser and whether they were photoelectric or CCD magnitudes.
Please continue to monitor the objects mentioned above along with your regular variable stars, and tele hone your observations to AAVSO Headquarters. The answering machine (617-354-0484) in on nights and weekends for your convenience.
Many thanks for your valuable observations and your efforts.
Clear skies and good observing!
files:IC 5270 on RASNZ ST PsA chart with AAVSO VSA insert; NGC 3031 'e' chart; N Oph 1993 'd' preliminary chart
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