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\IBVShead{4223}{10 August 1995}     % Use it with dummy or empty arguments

% Call for macro \title {Title of the paper}
\title {\ft NEW VARIABLE IN OPHIUCHUS}

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    During the analysis of results from photometric monitoring 
of members of the open cluster IC 4665, a new variable star 
has been found near the center of the cluster.    The variable's position is
approximately; RA = 17\fh 43\fmm 42\fss 7, DEC = +5\degr 42' 04'' (1950).
The variable's mean magnitude is approximately V $\simeq$ 14.9.
The accompanying finding chart  (north at top, east at left) in Figure 1
is approximately 4 arcminutes on a side and identifies the variable 
and the nearby solar-type cluster member P100 (Prosser 1993).    
The bright member K64, normally defined as the center of the cluster, is also
indicated.   A check of the GCVS and NSV catalogs did not reveal a previously 
known variable at the above position. 

   V-band CCD photometry of the region was obtained during May 1995 
with the 0.9m telescope at CTIO.     36 observations over a 14 night 
period (JD: 2449845-2449859) provided relative photometry between the new variable 
and several stars of comparable brightness.    
Periodogram analysis was performed on the relative photometry using a
program which incorporates the method outlined by Horne \& Baliunas (1986)
and Scargle (1982) for unevenly sampled data.
A period of approximately 12.7 days was found, with an amplitude $\Delta$V$\simeq$0.2 mag
and a maximum occuring near JD $= 2449856.5$. 
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\centerline{Figure 1}
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\centerline{Figure 2}
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Figure 2 illustrates the resulting light curve for the new variable relative 
to an anonymous comparison star found to be constant.  
Further monitoring over longer time
intervals should be able to refine this period estimate.   It should be noted
that the nearby cluster member P100 has been observed to undergo
brightness variations due to rotational modulation by starspots with a 
period of 2.27 days and amplitude of 0.1 mag (Allain et al. 1995),  
making it unsuitable for use as a comparison star to the new variable.
Although centrally located in the IC 4665 cluster,  the variable is not
a cluster member.
The period is indicative of a Pop I or Pop II Cepheid at a large distance beyond the
cluster; further observations are needed to conclusively determine the class,  though the faint apparent
magnitude together with the relatively high galactic latitude (+17\degr)
at which it is observed would appear to suggest that it is Pop II Cepheid
or W Vir type variable.        

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% Call for macros \authors - \authorsrightcol - \endauthors
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Charles F. PROSSER
Center for Astrophysics
60 Garden St. MS-66
Cambridge, MA 02138 USA
email: prosser@cfa0.harvard.edu

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Allain, S., Bouvier, J., Prosser, C., Marschall, L.A., and Laaksonen, B.D., 1995, {\it A\&A}, in press

General Catalog of Variable Stars (GCVS), 4th edition, Kholopov, P.N. editor, 
Kholopov,P.N. {\it et al.}, ``Nauka'', 1985

Horne, J.H. and Baliunas, S.L., 1986, {\it ApJ}, {\bf 302}, 757

New Catalogue of Suspected Variable Stars (NSV), Kholopov, P.N. editor, Kukarkin, 
B.V. {\it et al.}, ``Nauka'', 1982

Prosser, C.F., 1993, {\it AJ}, {\bf 105}, 1441

Scargle, J.D., 1982, {\it ApJ}, {\bf 263}, 835

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