[vsnet-alert 1709] Re: LY Hya

[Tonny Vanmunster <tvanmuns@innet.be>]

At 22:56 22/04/98 +1000, Rod Stubbings wrote:
>LY Hya appears to be in outburst.    Confirmation is requested.
>
>Visual observations
>
>April 20   11:42UT   <14.8
>April 22   10:56UT    14.4 seq: vsnet
>           12:40UT    14.4

Tried to confirm the outburst using a 0.25-m f/6.3 SCT & ST-7 CCD (unfiltered)
at April 22, 1998 - 23h15m UT (object being extremely low above Belgian
horizon). On the CCD image, I can see stars down to mag 15, but I could
not detect a trace of LY Hya. 
Can someone -located at a more favourable (= southern) location take a deeper
image to get a definite answer ? Remember LY Hya is a very interesting object
(see CVC 79 and also attached note of Taichi Kato).

Regards,
Tonny

   Tonny Vanmunster relays in his CVC 79 (also vsnet-obs 2047) that LY Hya
is being observed in outburst at V~14.4 by Steve Howell, who is performing
infrared spectroscopy of CVs at Mauna Kea.  Although this object has been
suspected to be a dwarf nova, this is probably the first-ever recorded
outburst.  Further observations are emegerntly needed.

   LY Hya, also called 1329-294, was originally discovered as a faint
blue object near the famous spiral galaxy M83.  This object soon turned
to be a cataclysmic variable.  Echevarria et al. 1983 (MNEAS 205, 559)
obtained spectra which showed doubly peaked emission lines of Balmer and
HeI, suggesting a high-inclination system.

   Haefner et al. 1993 (Astrophys. and Space Sci. 204, 199) performed
a radial velocity study, reporting the most probable orbital period of
0.13688 day.  Their spectra showed very strong Balmer and HeI emission
lines, whose equivalent widths suggest a dwarf nova with a low mass-
transfer rate, rather than a nova-like system as initially thought.

   More recent observations by Still et al. 1994 (NNRSA 267, 957) favored
a solution of the system below the period gap.  All these observations
suggest that the object has been observed in quiescence, and that we
may expect dwarf nova outbursts.  Altough it is not still clear whether
the present reported outburst is a normal or a super- outburst, the obser-
vations by Howell seem to verify its suggested classification.

    133153.93  -294059.9    2000 LY Hya     UGSU:         (?)-17.4-18.4V

   For observers' convenience, we have put VSNET charts with calibrated
V-magnitude accesible via VSNET anonymous ftp or VSNET WWW Home Page.

   They may be found:
   ftp.kusastro.kyoto-u.ac.jp, under pub/vsnet/DNe/LY_Hya : GIF files
   and ftp.kusastro.kyoto-u.ac.jp/pub/vsnet/charts/LY_Hya.ps (PostScript)

   WWW Home Page can be reached at http://vsnet.kusastro.kyoto-u.ac.jp/vsnet
   (select "Topics & Alerts")

Regards,
Taichi Kato

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