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AAVSO Alert Notice 418: Request for monitoring of V842 Cen in support of HST Observations AAVSO HOME > publications > alert notice

AAVSO Alert Notice 418

Request for monitoring of V842 Cen in support of HST Observations
March 12, 2010

Further to Alert Notice 417, the AAVSO requests intensive monitoring
observations of the cataclysmic variable V842 Cen beginning immediately
(2010 March 12.5 UT; JD 2455268.0) and continuing through 2010 March 19
(2455274.5).  These observations are in support of the Hubble Space
Telescope Cosmic Origins Spectrograph observations of V842 Cen planned
for 2010 March 18 UT.  Space Telescope ground controllers will need to
know that V842 Cen is fainter than V=15 on March 17, based upon data
from the night of March 16, in order to proceed with the planned
observations.  Observers are asked to observe V842 Cen during the next
week and report their observations promptly to the AAVSO using WebObs.
Please contact Dr. Matthew Templeton at to report
your observations if it is not possible for you to use WebObs, or if you
have not been assigned an AAVSO observer code.  We request that
intensive observations continue until at least 2010 March 19 UT before
returning to a normal schedule of observations of this star.

Note that the comparison stars currently in VSP do not cover the star in
its current quiescent state. All observers -- but particularly visual
observers -- should note that there is a red star with V band magnitude
of approximately 14.9 about 7 arcseconds south-southwest of V842 Cen,
and another red star of comparable brightness about 20 arcseconds
south-southwest of the variable.  These objects are currently being
evaluated for suitability as formal comparison stars, but for now they
may be used as references for "fainter-than" estimates.  Please be
certain that you do not confuse the star 7 arcseconds away with the
variable, and if the two are severely blended, please be sure to note
this in your observation.

The NOMAD1 ID, position, and magnitudes for the two potential
comparison objects are:

7":  0323-0709135 , RA 14 35 52.170 , Dec -57 37 43.82 , V=14.88

20": 0323-0709110 , RA 14 35 51.839 , Dec -57 37 57.54 , V=14.76

If using either of these objects as "fainter-than" reference stars,
please give the NOMAD ID in the Comparison star name field. Note that we
may update the comparison star sequence, and will be sending out a
follow-up Special Notice on or before March 16.

V842 Cen is located at the following (J2000) coordinates:

        RA: 14 35 52.58 , Dec: -57 37 35.1

Charts for V842 Cen may be plotted using AAVSO VSP:

For more information on this campaign, please see AAVSO Alert Notice 417:

Please report all observations of V842 Cen to the AAVSO using the name
"V842 CEN".

This AAVSO Alert Notice was prepared by Matthew Templeton.


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


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