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AAVSO Alert Notice 399: Nightly monitoring of AG Dra in support of HST calibration observations AAVSO HOME > publications > alert notice

AAVSO Alert Notice 399

Nightly monitoring of AG Dra in support of HST calibration observations
July 27, 2009

Edward Smith (STScI) has requested nightly photometric monitoring of
the symbiotic star AG Draconis during the period 2009 August 2, and
tentatively scheduled to continue through mid-September 2009.  They are
specifically requesting nightly B and V-band monitoring, with B-band
observations strongly encouraged; the onset of activity will result in
larger changes in the B-band than in V and will provide the clearest and
earliest evidence of activity in AG Dra.  However, all observers, both
visual and instrumental, are encouraged to observe during this time. 
Intensive time-series are not required.

Smith and STScI staff will be observing this bright symbiotic using
the Cosmic Origins Spectrograph on the Hubble Space Telescope during
this time period.  Their observations are intended to test and calibrate
this newly-installed instrument.  Observations of the system in
quiescence rather than outburst are needed, and so observers are asked
to report quickly any observations significantly above quiescence to the
AAVSO via WebObs.  According to Smith, they want to observe narrow
ultraviolet spectral lines typical of quiescence, rather than the broad
lines observed in outburst.  He also notes that bright outbursts may
overwhelm and damage the instrument, and so your observations will also
serve to safeguard the spacecraft.

The estimated time of first observation is August 17, 2009, with further
observations tentatively scheduled two and four weeks later.  They
request that monitoring begin by August 2 to provide a 1-2 week baseline
of photometry with which to estimate the current state of the system. 
The AAVSO light curve will then be continually monitored through the end
of observations.  Monitoring is requested to continue through at least
mid-September 2009; exact dates may be announced in a subsequent AAVSO
Special Notice.

For more information on this HST observing program, please visit the 
proposal information pages at the following URL:

where the relevant proposal IDs for these observations are 11480 
and 11490.

AG Draconis is located at the following (J2000) coordinates:

RA: 16 01 41.00 , Dec: +66 48 10.0

Customized charts for AG Dra may be created with AAVSO VSP:

Please submit all data promptly to the AAVSO via WebObs, using the name

This AAVSO Alert Notice was prepared by M. Templeton.


Information on submitting observations to the AAVSO may be found at:


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