COMMISSION 27 OF THE I. A. U.
        	  INFORMATION BULLETIN ON VARIABLE STARS
	                       NUMBER 811

        		                      Konkoly Observatory
                        		      Budapest
                              		      1973 July 16


     ANOMALOUS BRIGHTENING OF TX Cam NEAR MINIMUM LIGHT



    The long-period (P = 557.4 days) M-type Mira variable, TX Cam
has been included in a photographic program to monitor the light
and spectral variations of several infrared objects. On March 23,
1973 a photograph was obtained which indicated that TX Cam was 
unusually bright. The observations summarized below were determined
from one hour exposures on Kodak 103a-D plates behind a Wratten 12
filter.

   U.T. Date     J.D.         TX Cam   Nearby Star
     1973      2.440.000+       V          V
14 February      1728.3       15.3       14.8
23 March         1765.2       14.5       14.9
24 March         1766.2       15.5       14.9

The magnitudes were derived from an extrapolation of the UBV 
sequence determined by Wing et al.^1. As a consistency check on the
extrapolation, the magnitude of a companion star only eight 
seconds of arc distance was also determined on each plate.The images
of TX Cam and the companion on the plates were well-separated and
easily measurable. We estimate the errors of the extrapolated 
magnitudes to be +/- 0.2m.
    Evidently TX Cam brightened by one magnitude sometime between
February 14 and March 23. That it was a short-term phenomenon is
suggested by the fact that TX Cam returned to V = 15.5 in only 
twenty-four hours. Such a large and rapid change in the V magnitude, if
real, is difficult to explain for a long-period variable. Both the
observed magnitudes and the light elements of Kukarkin et al.^2 
indicate that TX Cam was very close to minimum light in March 1973.
    An image-tube spectrogram (495 A/mm) obtained on April 3, 1973
reveals the spectrum of a normal late-type long-period variable with
very strong VO band features indicating a spectral type of M10. A
spectrogram at the same dispersion in the 4000 to 5000 A region 
reveals no evidence of unusual features in the blue and rules out the
presence of a close, unresolved companion with a B magnitude
brighter than 17.
    Additional observations are needed to confirm this anomalous, 
short-term brightening of TX Cam near minimum light.
    We acknowledge the support of Smithsonian Research Foundation 
Grant SFC-0-3005.




SUSAN WYCKOFF and PETER WEHINGER
Wise Observatory, Tel-Aviv University
Tel-Aviv, Israel


References:
1. Wing, R.F., Spinrad, H. and Kuhi, L.V., Astrophys.J. 147,
          117 (1967). [BIBCODE 1967ApJ...147..117W ]
2. Kukarkin, B.V., Kholopov, P.N., Efremov, Yu.N., Kukarkina,N.P.,
          Kurochkin, N.E., Medvedeva, G.I., Perova, N.B.,
          Fedorovich, V.P. and Frolov, M.S., General Cata-
          logue of Variable Stars, (3d. ed.; Publishing House
          of the Academy of Sciences of the U.S.S.R., Moscow,
          1970).