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The June
2003 superoutburst of GO Com
Analysis of data from the CBA network
Joe Patterson (Columbia University, NY) and myself
have been working on a first analysis of the GO Com
CCD observations, collected so far by the CBA
network. Here's an overview of selected intermediate
results.
Observations have been contributed by Tom Krajci
(CBA New Mexico), David Messier, Bob Fried (CBA
Flagstaff), Lew Cook (CBA Concord), Jerry Foote (CBA
Utah), Donn Starkey (CBA Indiana) and Tonny
Vanmunster (CBA Belgium). In total, 1859
observations were included, obtained between JD
+2793.5 and JD +2797.8.
The data were split in two sets : a first set
covers the period JD +2793.5 to JD +2794.8 and the
second set JD +2795.1 to JD +2797.8. This
corresponds to the precursor outburst stage (first
set) and the superoutburst stage (second set).
Combined
('zeroed') light curve of CCD observations of GO
Com, collected by the CBA network
The precursor data reveal no coherent signal (using
the PDM technique), as the GO Com modulation is
rather weak with an amplitude of 0.1 mag at most. I
made several attempts to detect a stable period, but
could not conclude. For the second set of data
(superoutburst stage), I derived a dominant
superhump period value of 0.06288 +/- 0.00009 d
(using the PDM technique) and a very stable phase
diagram. The average amplitude now was about 0.30
mag. This superhump period value is somewhat
different from the one recently reported by the
VSNET team (0.06268 d) in vsnet-campaign-dn 3751. I
did not (yet) attempt to detect changes in the
superhump period, as the time line is still too
short. Such an analysis will become more meaningful
in the next week, provided that sufficient
observations are available.
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GO Com
periodogram showing the dominant superhump
period at 0.06288 d |
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GO Com phase
diagram |
The combined CBA light curve shows exceptionally
well the transit between the 2 stages of GO Com's
present outburst (see above).
The above analysis tends to confirm most of the
findings also reported by the VSNET collaboration
team, which is not surprising given the fact that
quite a number of CBA observers share their
observations also with their VSNET colleagues from
Kyoto University.
With the moon now on its way to hamper our GO Com
observations, it remains crucial to maintain the
intensive coverage, and to continue and study the
overall outburst characteristics of this rare
cataclysmic variable (cfr the July/August 1995
outburst, which showed a rather complex pattern of
outbursts / rebrightenings).
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Copyright © 2003 - Tonny Vanmunster.
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