THE AMERICAN ASSOCIATION OF VARIABLE STAR OBSERVERS
25 Birch Street, Cambridge, MA 02138 USA
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Tel. 617-354-0484 FAX 617-354-0665
AAVSO ALERT NOTICE 169 (March 30,1993)
SUPERNOVA IN NGC 3031 (M81)
We have been informed by J. Ripero and F. Pujol, Madrid, Spain, of the visual discovery of a possible supernova in NGC 3031 (M81) by Francisco Garcia Diaz, Lugo, Spain, who is a member of the Supernova Search Group "M 1" of the Madrid Astronomical Association (IVIAA) and the AAVSO. The object was discovered at visual magnitude 11.8 (revised from 12.0) on March 28.86 UT using a 25-cm f/3.9 telescope. The discovery was confirmed at magnitude 11.6 (revised from 11.8) on March 28.89 UT (revised from March 29.1) by D. Rodriguez, Madrid, Spain, using an ST-4 unfiltered CCD with a 20-cm f/5 telescope.
The object is about 25 arcseconds northeast of a 14.0 magnitude star. No object was seen at the reported position down to magnitude 14.0 on March 26 during a regular check of this galaxy by Pujol and Ripero. On March 29.82 UT (revised from March 29.875) Pujol and Rodriguez reported the object to be at magnitudes 11.2 (revised from 11.3) visual and 11.0 unfiltered CCD, respectively. Further visual observations include: March 29.01 UT, 11.3, Garcia; 29.82, 11.0, Ripero; and 29.95, 11.1, Garcia.
IAU Circular 5731 notes that A. V. Filippenko of University of California, Berkeley (UCB), reports that "a CCD image of M81 obtained on March 30.1 UT by R. R. Treffers and Y. Paik of UCB with the 0.8-m reflector at Leuschner Observatory confirms the presence of a new stellar object roughly 45" W and 160" S of the nucleus. The visual magnitude is approximately 11. Inspection of CCD spectra obtained on March 30.3 UT by M. Davis and D. Schlegel of UCB with the Lick 3-m Shane reflector reveals that the object is indeed a supernova. The continuum is very blue and remarkably featureless. 1t is probable but not yet certain that the object is a Type-II supernova observed only a few days after the explosion. Depending on the spectral type, distance, and extinction, this supernova may reach 8th magnitude during the next two weeks. Aside from Supernova 1987A in the Large Magellanic Cloud, it is therefore the brightest supernova since the supernova in NGC 5253."
F. D. A. Hartwick, D. D. Balam, D. Zurek, and R. M. Robb, Climenhaga Observatory at University of Victoria, provide the following precise position for the supernova:
R.A. = 09h 51m 19.27s Decl. = +69deg 15' 25.7" (1950.0)
P. Garnavich and B. A. Hong, Dominion Astrophysical Observatory, communicate that the spectrum shows a strong, flat continuum with weak H-alpha and HeI features consistent with that of a Type-II supernova.
We congratulate F. Garcia on his discovery!
Please use the accompanying finder chart from G. D. Thompson and J. T. Bryan's Supernova Chart Series to monitor this supernova visually and photoelectrically and report your observations of this supernova as 0947+69 SN 3031 to AAVSO Headquarters so we may transmit them to the astronomical community.
OUTBURST OF 0749+22 U GEMINORUM
The cataclysmic variable U Geminorum is undergoing an outburst, as indicated by observations reported by telephone. The outburst started on March 18 and by March 19 had reached maximum, with mean magnitude 9.0. Since then it has been at maximum and been oscillating between magnitudes 8.8 and 9.9. We thank the following observers for telephoning in their observations:
W. Albrecht, R. Blake, J. Bortle, E. Broens, W. Clarke, P. Collins, G. Comello, A. Diepvens, W. Dillon, P. Dombrowski, G. Dyck, R. Fidrich, O. Gabzo, G. Glenn, B. Granslo, J. Griese, L. Kiss, S. Knight, M. Kohl, K. Krisciunas, J. Lovett, J. McKenna, K. Medway, M. Novak, S. O'Connor, M. Poxon, G. Poyner, R. Raphael, J. Ripero, P. Robbins, R. Royer, P. Schmeer, C. Scovil, S. Sharpe, O. Shemmer, R. Stewart, R. Szabo, L. Szentasko, D. Taylor, I. Tepliczky, P. Van Cauteren, F. Van Loo, T. Vanmunster, D. Williams, D. Wilson, M. Yamada, and D. York.
The last outburst of U Gem was in August 1992, when it reached magnitude 9.3 on August 30 and was brighter than magnitude 11 for 12 days. U Gem has been monitored extremely closely since then and no outburst activity has been reported. This outburst interval of 202 days is one of the longest recorded for this star. We thank our observers very sincerely for monitoring U Gem closely before and during this outburst.
A group of astronomers are very interested in monitoring U Gem with the IUE as soon as it reaches minimum, so please continue to report your observations to Headquarters so that the observations with IUE can be scheduled.
FADING OF 0543+19 SU TAURI
The R Coronae Borealis star SU Tauri appears to be fading, as indicated by observations phoned in to Headquarters. It has been fading slowly since the beginning of March, from its maximum mean magnitude of 9.5, to 11.5 on March 29. The last major minimum of SU Tau occurred between November 1986 and September 1987, reaching minimum magnitude 15.9. Since then it has been at maximum, with observations reported in August 1992 when it emerged from the seasonal gap showing slightly fainter (approximately 10.9). Since September 1992 it has been at maximum. We thank the following observers for telephoning in their observations:
W. Albrecht, J. Bortle, P. Collins, B. Granslo, K. Medway, A. Pereira, M. Poxon, G. Poyner, P. Schmeer, D. Williams, and D. York.
Please monitor SU Tau closely and telephone your observations in to AAVSO Headquarters so we may inform the astronomical community.
REQUEST TO MONITOR 1834-23 V348 SAGITTARII
A group of astronomers has requested our assistance in monitoring V348 Sagittarii, as they plan to observe it with the IUE. Please monitor this star, which has been in its down state, closely and report your observations to AAVSO Headquarters so we may inform the astronomers.
The answering machine (617-354-0484) is on nights and weekends for your convenience.
Many thanks for your efforts and valuable observations.
Clear skies and good observing!
files: NGC 3031 chart,
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