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AAVSO Special Notice #25

Variable Star in Leo - 1016+24 VAR LEO 06
(November 20, 2006)

Daniel W. E. Green, Central Bureau for Astronomical Telegrams, reports
(Central Bureau Electronic Telegram 746) that "E. J. Christensen, Lunar and
Planetary Laboratory, University of Arizona, reports his discovery of an
apparent high-amplitude variable star on unfiltered CCD images obtained in
the course of the Catalina Sky Survey, the position of the variable given as

R.A. = 10h 21m 46.42s, Decl. = +23o 49' 26.2" (equinox 2000.0)

"Approximate V magnitudes derived from the Catalina images:  Oct. 28.503-28.523
UT (four images), 13.9; Nov. 17.533-17.537, 14.4.  There is an object at V
around 21 at this position in an archival CSS image, and there is a star
catalogued in the Sloan Digital Sky Survey DR5 database with the following
magnitudes:  u = 20.83, g = 20.74, r = 20.63, i = 20.84, z = 20.45."

The blue color and large magnitude amplitude indicate that the object could
be a cataclysmic variable of SU UMa or WZ Sge type. Nothing variable is found
at this position in ASAS3, NSVS, or via SIMBAD and the online GCVS; Arne Henden
reports there are no 2MASS observations.

CCD and visual observations are encouraged. CCD observers are asked to carry
out CCD time series runs (V filter), with a cadence such that each observation
has at least S/N=50. If observations with more than one filter are possible,
all should be made within the same S/N=50 constraint. Visual observers should
observe a few times during the night. If it becomes evident the star is a
SU UMa- or WZ Sge-type CV, the CCD runs should be as long as possible, and the
visual observations should be made several times during the night at regular,
frequent intervals (~10 minutes).

Please report observations to the AAVSO as: 1016+24 VAR LEO 06. Also, be
sure to indicate what chart/comparison star(s) you used.


This special notice was compiled by: Elizabeth O. Waagen
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