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THE ASTRONOMER Electronic Circular No 2830      2012 Jun 21 15.47UT
Ed:Guy M Hurst, 16,Westminster Close, Kempshott Rise,  Basingstoke,
Hants, RG22 4PP,England.Telephone/FAX(01256)471074Int:+441256471074
INTERNET: GUY@TAHQ.DEMON.CO.UK      Backup: gmh@wdcc1.bnsc.rl.ac.uk
WORLD WIDE WEB                         http://www.theastronomer.org
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NOVA SCORPII 2012
R. M. Wagner, Ohio State University (OSU) and Large Binocular Telescope 
Observatory et. al., report the discovery and initial photometry and 
spectroscopy of a bright transient in the direction of the Galactic 
bulge.  The MOA collaboration detected a candidate microlensing event, 
designated MOA 2012 BLG-320, on 2012 May 22.80 UT at magnitude I = 18.5, 
located at:
RA 17h 50m 53.90s DEC -32 37' 20.5" (2000).  No significant source 
appears at this position on either the R or N survey plates of the 
Digitised Sky Survey.

MOA photometry of the source before the outburst shows that the 
progenitor was at I magnitude about 19.0-19.5, but with substantial 
variability on nightly time scales.  Between May 14 and 16 UT, the 
source began a slow monotonic increase in brightness, and after May 24 
UT, the rate increased significantly.  The light curve obtained May 
28-31 exhibits periodic modulations with an amplitude of about 0.1 mag 
and a period of about 1.6 hr superposed on the brightening source. 
Between June 1.77 and 2.55 UT, the transient brightened dramatically 
from I magnitude about 17, reaching I magnitude about 11 on June 3.33 UT 
-- prompting more detailed follow-up by both MOA and the microFun 
collaborations.

On June 4.08 UT, a high-resolution optical spectrum was obtained with 
the Very Large Telescope (+ UVES).  The spectrum exhibits strong 
emission lines with striking P-Cyg profiles of the Balmer series of 
hydrogen and many multiplets of Fe II, as well as O I 777.4- and 
844.6-nm.  The equivalent widths of both H-beta emission and absorption 
are 1.7 and 0.3 nm, respectively.  The interstellar Na D lines are 
resolved and exhibit considerable structure at this spectral resolution. 
The total equivalent widths of the D1 and D2 lines are 0.16 and 0.19 nm, 
respectively.  The spectrum is reminiscent of either a slow "Fe II-type" 
classical nova or an intermediate-luminosity red transient like V838 
Mon.  However, the measured H-beta and H-alpha FWHM of about 800 km/s 
(average expansion velocity of about 400 km/s) are more consistent with 
slow classical novae that have t_2 around 50-200 days and are 
thermonuclear events on accreting white dwarfs.  Other historical slow 
novae include V450 Cyg and HR Del, which were observed to have 
comparable expansion velocities and t_2 of 90 and 150 days, 
respectively.

The most recent photometry of June 7.29, from images obtained with the 
Cerro Tololo 1.3-m telescope (+ ANDICAM) are magnitudes V = 11.6 and I = 
9.4.  The transient continues to brighten at a rate of about 0.4 mag/day 
in the I band over the past three nights.

SUPERNOVA 2012bo IN NGC 4726 (KOICHI ITAGAKI)
2012bo  Mar 27.71   12 50 45.23  -14 16 08.5  16.4  12.4"W,   1.5"S
E. Cappellaro: spectrum March 28 type-Ia similar to SN 2003du, one week 
before B-band maximum

SUPERNOVA 2012bp (MASTER)
2012bp  Mar 24.85   16 18 12.44  +36 28 52.8  15.5
Andrea Pastorello: spectrum Mar 27 type-Ia similar to SN 2003du close to 
B-band maximum light.

Guy M Hurst