[vsnet-chat 1141] On EX Hya eclipses (Walker)

[Taichi Kato <tkato>]

Message-ID: <vsnet-chat1141@hoge.baba.hajime.jp>
Reply-To: <astroman@voyager.co.nz>
From: "William S G Walker" <astroman@voyager.co.nz>
To: "Taichi Kato" <tkato@kusastro.kyoto-u.ac.jp>,
        <vsnet-chat@kusastro.kyoto-u.ac.jp>,
        <vsnet-obs@kusastro.kyoto-u.ac.jp>
Date: Tue, 11 Aug 1998 08:23:00 -0700
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Subject: [vsnet-obs 0] Re: [vsnet-chat 1131] On EX Hya eclipses
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Greetings,

Bill Allen and I have been CCD monitoring EX Hydrae along with other DN
during
the last few months. The eclipse events measured (20 to 30) are close to
the predicted times. However the 67 minute cycle which is visible as a
sinusoidal wave with an amplitude of ~0.5 to 0.7 magnitudes is rather
different to the GCVS ephemeris - which dates back to 1979 - and we'd be
interested in any more recent information on this. 

Incidentally, the last outbust we measured at Auckland was in the
mid-eighties and may well have been in 1987. From memory this event was
double
with a week or so between outbursts. Unfortunately the records are not
immediately
accessible to me in Kaitaia but it would be worthwhile keeping a watch out
for a similar occurrence. And the storm which hit New South Wales last
week has now made it to northern New Zealand. Beautiful lightning display
at the moment but very non-astronomical!

Regards,
Stan



----------
> From: Taichi Kato <tkato@kusastro.kyoto-u.ac.jp>
> To: vsnet-chat@kusastro.kyoto-u.ac.jp; vsnet-obs@kusastro.kyoto-u.ac.jp
> Subject: [vsnet-chat 1131] On EX Hya eclipses
> Date: Monday, August 10, 1998 1:02 AM
> 
> On EX Hya eclipses
> 
>   Rod Stubbing's observations (vsnet-obs 13673):
> 
> >  Star          Date      UT      mag.
> > EX HYA        980808     9:14    13.5
> >               980809     9:03     9.6
> >               980809     9:20     9.5  (*)
> >               980809     9:31     9.5
> >               980809     9:42     9.4
> >               980809     9:56     9.5
> >               980809    10:52     9.4  (*)
> 
>   The epochs of observations (*) are close to predicted eclipses.
> 
>   YYMMDD hh:mm:ss
>   980809 09:13:36 
>   980809 10:51:52 
> 
>   The latter observation done at expected mid-eclipse.  This observation
very
> likely suggests that eclipses become shallower during outbursts.
> 
>   We observed during the 1987 outburst (during the fading branch) several
> eclipses, which were seen as broad, shallow features (published in VSOLJ
> Variable Star Bulletin).  The full data are available from
> 
>  
http://ftp.kusastro.kyoto-u.ac.jp/pub/vsnet/VSOLJ/database/stars/HYAEX.jd
> 
>   Hope this information helps.
> 
> Regards,
> Taichi Kato
>

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