[vsnet-alert 137] (No subject in original)

[aavso@cfa0.harvard.edu (Janet Mattei)]

TO:vsnet-alert@kusastro.kyoto-u.ac.jp
FROM:aavso@cfa.harvard.edu     Janet A. Mattei      
Date:05 May, 1995


AL COMAE BERENICES 

In view of the recent interesting behavior of AL Com, I would
like to share with the readers of vsnet, information received at 
AAVSO, which was published in AAVSO Alert Notice 207 (03 May,1995).  
I would also like to report positive observations received since then.
_________________________________________________________________
From: AAVSO Alert Notice 207 (03 May, 1995); J. A. Mattei

ENDING OF THE SUPEROUTBURST OF 1227+14 AL COMAE BERENICES

The superoutburst of this interesting cataclysmic variable has been very well
monitored by observers worldwide. It appears that this rare superoutburst has
now ended, as shown by the observation of D. York, Abiquiu, NM, on May 3.1792 
UT at fainter than 16.0.   

Analyzing the data, received at the AAVSO, we find that from the start of the 
outburst on 5 April 1995, AL Com declined to 13.5 in 9 days, at a rate of 0.15 
magnitude per day. It was then at standstill for 5 days at magnitude 13.5.  
Subsequently, it continued to decline, from April 19 at 13.5 to April 30 at 
15.0, at a rate of 0.13 magnitude per day.

AAVSO observers R. Zissell (South Hadley, MA) and G. Walker (Dover, MA) 
monitored the superhumps of this cataclysmic variable with CCDs.  We analyzed 
the CCD(V) observations obtained by Zissell on the nights of April 6, 11, 23, 
and 25, using the CLEANEST Fourier Spectrum analysis method developed by 
G. Foster at AAVSO Headquarters (see G. Foster, Astron. Journ. 109, p. 1889, 
April 1995).  We find periods ranging from 80.4 to 84.7 minutes with a 
suggestion of the beating of two close frequencies on April 6 and 11.  
Particularly from R. Zissell's CCD(V) observations, we find that the data on 
April 6 show superhumps with double-peak maxima; on April 11 the amplitude of 
the superhumps has decreased and the light curve has shifted to double peak 
minima; on April 23 and 25 the shape of the superhumps is sinusoidal.
_____________________________________________________________________________

Below are observations received since AAVSO Alert Notice 207 on 03 May, 1995:

COMAL     950503.2070 UT    16.0  R. Royer, CCD visual inspection
          950503.8298       16.1: L. Szentasko
          950503.91         16.5: J. Pietz,  CCD(V) visual inspection -- via VSNET
          950504.1201       15.2  J. Bortle, transmitted earlier to vsnet 
          950504.1590       15.2  D. York
          950504.1729       15.3  Bortle, transmitted earlier to vsnet
          950504.1757       15.2  York
          950504.1979       15.2  York 
          950504.2993       15.6  Royer, CCD  visual inspection
          950504.3069       15.6  Royer, CCD  visual inspection
          950504.3153       15.6  Royer, CCD  visual inspection
          950504.86         16.0: Pietz, CCD(V) visual inspection - via VSNET
 
Now that AL Com is faint,  the correct identification of this variable 
is crucial. The AAVSO finder charts both for visual and CCD observers may 
still be retrieved by anonymous FTP from cfa0.harvard.edu (131.142.10.30) 
in /outgoing/aavso.  Postscript files, TIFF and GIF images are available.

Regards,
Janet A. Mattei
AAVSO, Director

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