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\IBVShead{4531}{31 October 1997}

\IBVStitle{NEW ELEMENTS FOR BW CASSIOPEIAE}

\IBVSauth{R. DIETHELM}
\IBVSinsto{BBSAG, Rennweg 1, CH-4118 Rodersdorf, Switzerland, e-mail: diethelm@astro.unibas.ch}

\SIMBADobj{BW Cas}
\IBVStyp{ EA }
\IBVSkey{CCD-photometry}

\begintext

Beljawsky (1933) reported the variability of the star BW Cassiopeiae =
SVS\,281 = AN\,372.1931 = GSC\,4035.00408 ($\alpha_{J2000}:01\hr
39\mm 29\sec; \delta_{J2000}:+63\deg 26\arcm 10\arcs$) and gave the
uncertain elements:
$$
{\rm JD}(min,hel) = 2425999.26 + 1\fday895~\times~E \eqno(1)
$$
cited in the GCVS (Kholopov et al., 1985). No other source of information on
the variability of BW Cas is known to the author.

\IBVSfig{8cm}{4531-f1.eps}{Unfiltered CCD light curve of BW
Cassiopeiae folded with the elements (2)}

We started to observe this neglected eclipsing binary this observational
season with the 35cm SC-reflector of R. Szafraniec Observatory,
Metzerlen, Switzerland, equipped with a SBIG ST-6 CCD camera at its
prime focus. The unfiltered CCD photometry soon showed that the GCVS
elements are spurious. The 109 observations on 17 nights from
JD\,2450692 to JD\,2450727 (comparison star: GSC\,4035.00401; check
star: GSC\,4035.00212), folded with the newly deduced elements of
variation
$$
{\rm JD}(min,hel) = 2450710.2973(2) + 1\fday263~\times~E \eqno(2)
$$
are shown in Figure 1.

The primary minimum is about 1.3 magnitudes deep (unfiltered CCD) and
probably shows no sign of totality. The eclipse lasts for $0.\!\!^{\rm p}14$
(0\fday18). A very shallow secondary minimum at phase $0.\!\!^{\rm p}5$ with
an amplitude of about 0\fmm02 can be discerned in our light
curve. We will continue to observe minima of BW Cas in order to refine
the elements (2) given above. Results of this work will be published
in the BBSAG Bulletins.

This research has made use of the SIMBAD database operated by the CDS,
Strasbourg, France. The author wishes to thank the ``Emilia
Guggenheim-Schnurr Foundation'' for financial support.

\references

Beljawsky, S., 1933, {\it Poulkovo Obs.\ Circ.\ No.\ 6}, 22

Kholopov, P. N. et al., 1985, {\it General Catalogue of Variable Stars}, Moscow

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