[vsnet-flare 31] Re: [vsnet-chat 5812] Re: Flare stars and other rapid brightenings

["Stan Walker" <astroman@xtra.co.nz>]

Hello,

Some overlooked points about flares is that they are essentially random
'explosions' with a quick rise time and a slower fall (usually). As well,
they are best seen at the blue/ultra-violet end of the visible spectrum.
Thus conventional CCDs suffer from low time resolution and see only the
long-wavelength tail of the energy distribution. Extended response CCDs are
better but still suffer from low time resolution - we used 5 and 10 seconds
with pep (which is normally most sensitive in the B/UV region) but even this
seemed a bit slow at times.

As far as amplitude goes with eyeballing a flare you're not looking in the
UV where it's brightest and it takes time to make an estimate. So any
estimate probably underestimates the amplitude. The method
recommended in the 1960s was to make an estimate every 30 seconds but the
results were so confusing that they led us to build a photometer to get
accuracy. But if you're lucky enough to see a flare they can be quite
exciting. Real 'astronomy for entertainment!' However, I don't think that
eyeball measures can provide much
information about amplitude - nor even frequency as most flares are only a
few tenths of a magnitude.

Regards,
Stan


----- Original Message -----
From: "Thorsten Lange" <tl@thola.de>
To: "Thom Gandet" <tgandet@mindspring.com>
Cc: <vsnet-flare@ooruri.kusastro.kyoto-u.ac.jp>;
<vsnet-chat@ooruri.kusastro.kyoto-u.ac.jp>
Sent: Tuesday, December 31, 2002 11:12 PM
Subject: [vsnet-chat 5812] Re: Flare stars and other rapid brightenings


> Hello,
>
> You can find a catalogue of flare stars at
> http://cdsweb.u-strasbg.fr/viz-bin/VizieR?-source=J/A+AS/139/555
>
> Some information about the duration in UV Cet is given in IBVS 3338 and
IBVS
> 5250.
>
> Other question, has somebody successfully visual observed some flares? Or
do
> we need an automatically complete night observation with CCD cameras?
>
> Best regards,
> Thorsten Lange
>
> --
> Thorsten Lange
> EMail tl@thola.de
> http://thola.de/

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