[vsnet-newvar 1458] CGCS 1749 = GSC 0190 0120 is a long period variable

[jg <jg@jgws.freeisp.co.uk>]

Carbon Star CGCS 1749 = GSC1.2 0190 0120 = IRAS 07294+0556

TASS (www.tass-survey.org) Johnson V and Cousins I photometry for
individual nights (courtesy of Tom Droege's data CD 23) :-

GJD                     VJ      V       I       I       num. obs.
nightly time range      mean    stdev   mean    stdev

2452263.800 to .893     12.48   0.05     9.91   0.02    44
2452299.695 to .791     12.43   0.07     9.91   0.02    38
2452310.665 to .741     12.53   0.09     9.88   0.01    15
2452344.580 to .672     12.69   0.06     9.95   0.02    10
2452350.558 to .611     12.78   0.08    10.08   0.02    10

mean TASS VJ-Ic = +2.57


Confirmation of variability comes from archive survey plates sourced via
the USNO NOFS image server (http://ftp.nofs.navy.mil/data/FchPix/) ,
best shown by the two "blue" IIIaJ plates, both using GG385-3 filters,
dated 1997.2635 and 1997.8467 (temporarily available at the following
links:-

http://vsnet.nofs.navy.mil/tmp/fchaafEda_sj0774.000.jpg
http://vsnet.nofs.navy.mil/tmp/fchaafEda_sj0773.000.jpg )


Interestingly the three available E and F "red" plates show little
evidence of variation suggesting either coincidental times at the same
point in the lightcurve or less variation in the redder wavelengths. 
Only one of the red plates is anywhere near in epoch to one of the blue
plates.

Two "far-red" N plates are near contemporaneous with the two above noted
blue plates and show the star to be at very similar brightness despite
the variation in the blue.  Variation is fairly small in V over roughly
90 days in the TASS data, and even less in I.  The two J plates are
roughly 210 days apart.


Cheers

John

John Greaves
UK

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