(cba:news) March stars, take one (Joe Patterson) [2008-03-06T10:42:19Z]

Dear CBAers,

This new optical transient in Hya (I think), from the Catalina Sky 
Survey, has a good chance of being quite a gem!  Below is ATEL 1411, the 
discovery announcement, and Kato's comment.  Since it is 17th mag now, 
near the peak of outburst, it won't torment us for very long... but with 
about a week of data we should be able to squeeze out a decent period.
Top - if transient! - priority for northern and southern observers.

Time to usher a few stars off the stage. V485 Cen, UMa 6, V436 Car, T 
Pyx, DW Cnc... these stars are sufficiently well recorded for the year, 
and can rest up for the off-season.  I still have some hope for MU Cam, 
but so far it doesn't seem to be too popular.  HV Vir came down from its 
superoutburst, and may now have some echoes; these are certainly 
interesting but usually don't hump much (and they're hard to study 
because the nightly light curves often have large slopes).  So I'm 
inclined, with reservation, to demote HV Vir also.

For northerners, it's a great time to get long runs on AM CVn.  I'm just 
wrapping a long-term period study.  Such a study is maximally 
constrained by the earliest (1978) and latest (now) data, so long time 
series of this star are now - just for a few more weeks - would be great.

Has anyone been following OT1112-35?  Since Greg Bolt's superb data of 
December, I've been awfully curious about this star.  Unfortunately we 
can't reach this dec from Arizona, so I rely on australite CBAers to 
tell me anything about it.  It had a very long outburst, and I assume 
has faded now.  Has it?  How bright is it?  I'd really like to pursue 
this guy any way possible!

I also recommend RX1039-05 = Sex.  Finishing a long-term study on this 
star also, and hence need 2008 timings.  It's very faint (18) but has a 
HUGE photometric modulation - try it, you'll be impressed with how faint 
you can go when the wave amplitude really cooperates.

I'll write again later today.  I'd love to hear any news about the new 
Hydra (I think) transient.

joe


******
   CSS080304:090240+052500 is indeed a dwarf nova in outburst.
The presence of He II emission lines, as well as the large
outburst amplitude, suggest another WZ Sge-type outburst!
The splitting in the line profile would suggest a high inclination.

===

ATEL #1411 
ATEL #1411

Title:          Discovery of a Bright Optical Transient from the Catalina
                Sky Survey
Author: S.G. Djorgovski, A.J. Drake, R. Williams, A. Mahabal, M. Graham,
                E. Glikman, C. Donalek (Caltech); J. Hennawi (UCB/LBL); 
E.C. Beshore,
                S.M. Larson (UAz/LPL); E. Christensen (Gemini Obs.)
Queries:        george@xxxxxxxxxxxxxxxxx
Posted: 4 Mar 2008;  23:58  UT
Subjects:       Optical, Request for Observations, Cataclysmic Variables,
                Novae, Transients

We have detected a bright (V ~ 16 mag) optical transient in Catalina Sky
Survey   (CSS) images obtained at the Mt. Bigelow 0.7m Catalina Schmidt
Telescope on 04 March 2008 UT.

<table border=1>   <tr align=center><td><a 
href='http://voeventnet.caltech.edu/feeds/ATEL/CSS/8030410
40494145217.atel.html'>
CSS080304:090240+052500</a></td><td>    2008-03-04 UT 05:34:11 </td><td>
RA 09:02:39.70  </td><td> Dec 05:25:01.0 </td><td> Mag 16.3</td></tr>
</table>

The transient is coincident within the astrometric uncertainties with
a   marginally detected SDSS source (ID = 587732578836087360), which has
listed   magnitudes:
u = 23.76 +- 0.60
g = 23.17 +- 0.18
r = 23.10 +- 0.22
i = 23.00 +- 0.30
z = 22.19 +- 0.37
Thus, the source has brightened by about 7 magnitudes relative to the
SDSS detection.

The discovery data and the finding charts are posted at this webpage:
http://voeventnet.caltech.edu/feeds/ATEL/CSS   The source was posted
in the real time at VOEvent pages, 
http://voeventnet.caltech.edu/feeds/Catalina.shtml

A spectrum of the transient has been obtained with the ESI spectrograph
at the   WMKO Keck-II 10m telescope on the same night, 04 March 2008 UT,
approximately 5   hours after the initial detection.  It shows a blue 
continuum,
with emission   lines of H-alpha 6563, H-beta 4861, He I 5015, He I 7065,
He II 4687, and He II   6683, with an approximate observed redshift of
150 km/s.  The lines are   bimodal, with a velocity splitting of about
500 km/s.

We tentatively interpret this as a nova-like phenomenon.  Further analysis
of   the spectra is in progress.