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THE ASTRONOMER Electronic Circular No 2434      2008 Mar 27 15.48UT
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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V2468 CYGNI = NOVA CYGNI 2008
N. N. Samus, Institute of Astronomy, Russian Academy of Sciences,
advises that this nova (cf. TA E-Circular 2429) has been assigned the 
variable-star designation V2468 Cyg.

On IAUC 8928, M. M. Beaky, Truman State University, reports that a CCD 
spectrum (range 450-850 nm, resolution 0.4 nm/pixel) acquired with the 
0.36-m telescope at the Truman Observatory on 2008 Mar. 11.46 UT, shows 
H_alpha (FWHM = 790 km/s) and H_beta lines to be prominent in emission, 
and numerous Fe II emission lines are also visible.  Thus, the nova 
belongs to the 'Fe II' class of Williams (1992, A.J. 104, 725).

TAHQ has received a large number of observations although very few from 
the UK, and these indicate that by March 27 the nova has faded to about 
magnitude 10.3 (visual). A light curve graph is in the progress of being 
updated for our website.

A chart and sequence appeared on Early Warning Circular 187 and also in 
the March issue of 'The Astronomer' magazine on page 287.

POSSIBLE NOVA IN M81
K. Hornoch, Ondrejov Observatory, reports on CBET 1281 his discovery of 
an apparent nova in the galaxy Messier 81 from co-added unfiltered CCD 
frames taken with the 0.65-m telescope on Mar. 2.775 UT. The new object 
is located at:
RA 09h 55m 58.31s DEC +69 06' 07.9" (2000) which is 135"E and 133"N of 
the centre of the host galaxy.

Available magnitudes for the apparent nova from his images (unfiltered 
unless otherwise noted):  Feb. 11.788, [21.8; Mar. 2.775,20.3; 4.083, 
20.1; 4.123, 19.9 (R band).

SUPERNOVA 2008ax IN NGC 4490: PROGENITOR
W. Li, University of California, Berkeley (UCB) and others, report on 
CBET 1290 that they have isolated a possible progenitor for the young 
type-II supernova 2008ax in Hubble Space Telescope images of NGC 4490 
taken with the Wide Field Planetary Camera 2 (WFPC2).

Within the uncertainty of the supernova position, an object is clearly 
detected in the F450W image, with a position of:
RA 12h 30m 40.82s DEC +41 38' 15.2" (2000), and a magnitude of B = 23.6. 
The object is also present in the F606W image (with V = 23.5) and F814W 
image (with I = 22.6, but it might be contaminated by another source). 
The nature of this object depends on the host-galaxy reddening 
estimates.

Various investigations suggest the object has an absolute V magnitude of 
-6.9 and colours of B-V = -0.2 and V-I = 0.4, consistent with 
blue/yellow supergiant stars. Another possibility is that the object is 
a compact star cluster, although the point-spread function of the source 
appears stellar. Note that the progenitor of SN 1987A in the Large 
Magellanic Cloud was a blue supergiant star with a zero-age 
main-sequence mass of about 20
solar masses, and there is spectroscopic similarity between SN 2008ax 
and SN 1987A.

Guy M Hurst