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AAVSO Special Notice #46: GW Lib fading AAVSO HOME > publications > special notice

AAVSO Special Notice #46

GW Lib fading
May 8, 2007

Reports from VSNET, as well as AAVSO observers
MTH, PYG and CLW01, indicate that GW Lib is
undergoing a rapid fade from its outburst.
Sonoita observations show fading at 1.5mag/day, with
a Vmag of about 13.1 at JD2454228.9.  At the
current rate, GW Lib will be back to quiescent
level within a day or two.  Since this is the
prime time for monitoring the return of the
white dwarf pulsations, we request observers
to carefully monitor GW Lib during this fade.
In addition, WZ Sge stars are known for echo
outbursts, where the star will increase in
brightness again after the fade.  In other words,
we are in a period where GW Lib will show lots
of activity on all time scales.

You should continue to obtain S/N=50 observations,
primarily with a V filter, but if you cannot do
so within a minute or two exposure, then switch
to unfiltered observations during this faint
period.  Visual observers should continue monitoring,
as rebrightenings can happen on fast timescales and
you may be the only observer watching when such an
event starts.

The F-scale chart is ok for visual and V-band CCD observers;
if you are observing at Rc or Ic, you can obtain
the Rc,Ic magnitudes for stars from 9th to 14th
magnitude from the SRO calibration file at
ftp://ftp.aavso.org/public/calib/gwlibsro.dat
Be sure to indicate the magnitudes used in the
comment field when uploading your data.

Good luck and clear skies!

Arne


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