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\IBVShead{4584}{17 April 1998}

\IBVStitletl{ON IDENTIFICATIONS OF SEVERAL VARIABLE STARS IN CYGNUS}

\IBVSauth{E. V.~Kazarovets, N. N.~Samus}

\IBVSinsto{Institute of Astronomy (Russian Acad. Sci.), 48, Pyatnitskaya Str.,
          Moscow 109017, Russia}
\vskip -1.5mm
\IBVSinsto{e-mail: samus@sai.msu.su}

\SIMBADobj{OX Cyg}
\SIMBADobj{OY Cyg}
\SIMBADobj{PR Cyg}
\IBVSkey{identification}

\IBVSabs{A confused case of identifications of several variable stars}
\IBVSabs{in Cygnus discovered by Baade in 1928 or erroneously identified}
\IBVSabs{with them later is discussed. We present the version of identification}
\IBVSabs{currently accepted by the GCVS team and recommended to}
\IBVSabs{variable star researchers.}

\begintext

In the earlier practice of variable-star research, lack of sufficient
attention to accurate coordinates created a number of problem cases
even when discoverers presented quite accurate coordinates in their
original announcements. In this paper, we present a solution of a problem
case for several variable stars in Cygnus as it is accepted now by the GCVS
team, based upon detailed discussions with T. Kato (Kyoto University,
Japan), J. Manek (Stefanik Observatory, Czech Republic), and R. Webbink
(University of Illinois, USA).

Baade (1928) announced his discovery of a number of new variable stars. He
did not publish finding charts but presented rather accurate coordinates
for the equinox 1925.0. Among stars designated in the Namelist (NL) No. 31
(Guthnick and Prager, 1933), there were Baade's variables OX Cyg (108.1928), OY Cyg
(76.1928), and PR Cyg (70.1928).

{\bf OX Cyg.} Baade's coordinates (19\hr 52\mm 0\fsec 6, +39\deg 3\arcm 9\arcs, 1925.0)
clearly correspond, in the USNO A1.0 catalog, to a star at
19\hr 54\mm 39\fsec 46, +39\deg 14\arcm 59\farcs 2, 2000.0 (USNO A1.0 blue
magnitude: 16\fmm 1; red magnitude: 14\fmm 7). The discoverer attributed the star
to eclipsing variables (NL No.31 calls it a short-period variable); the
variability of the A1.0 star has been confirmed
by J. Manek (private communication) on Sonneberg plates, with probable
Algol-like changes. As it will be shown below, all other information
published for `OX Cyg' actually refers to OY Cyg.

{\bf OY Cyg.} Baade's coordinates (19\hr 52\mm 5\fsec 2, +39\deg 6\arcm 6\arcs, 1925.0)
correspond to GSC 3137.1152 (12\fmm 9; 19\hr 54\mm 43\fsec 86,
+39\deg 17\arcm 58\farcs 2, 2000.0). For unclear reasons, NL No. 31 gives
declination different by approximately 25\arcm; the GCVS accepted the NL
coordinates, having in mind that the NL contains a reference to a letter
from Baade concerning his new variables. Baade considered his star a Mira
(in the NL, an irregular variable).

Nassau and van Albada (1949) identified OY Cyg with the red giant 23--30;
their paper contains good photographic charts for program stars. The
star 23--30 is actually in approximately 1\farcm 5 from the NL position.
The photometry presented by Nassau and van Albada shows only marginal
evidence for variability.

Hoffleit (1975) published a detailed study of a large-amplitude variable,
probably a symbiotic one, called OX Cyg in her paper. She presented a
finding chart. The star, later included into catalogs of symbiotics
and into programs of amateur groups, is definitely GSC 3137.1152.
Note that, for OX Cyg, both references in the GCVS (4th edition) are
to Hoffleit (1975).

{\bf PR Cyg.} Baade's star, classified as an irregular variable, has
coordinates 19\hr 52\mm 59\fsec 9, +38\deg4\arcm 5\arcs , 1925.0. It is
identical with GSC 3137.1721 (13\fmm 3; 19\hr 55\mm 41\fsec 23,
+38\deg 16\arcm 3\farcs 9, 2000.0). Nassau and van Albada (1949) identified it
with their red giant 24--40 and presented several photographic and
infrared measurements, again with only marginal evidence for variability.
They stated, however, that their photographic data show PR Cyg as much
as 1\fmm 7 fainter than the catalog value. The USNO A1.0 coordinates of 24--40
are: 19\hr 56\mm 11\fsec 20, +38\deg 15\arcm 52\farcs 7 (2000.0), about 0\fmm 5 in right ascension and 0\farcm 2 in declination from Baade's position.
The star's magnitudes in the A1.0 catalog are: 18\fmm 3 (blue) and
15\fmm 3 (red).
Baade's coordinates correspond, however, to Nassau and van Albada's
star 24--39.

{\bf Decision taken by the GCVS team.} We accept the following
identifications to be used in future:

OX Cyg = Baade's original 108.1928. (Type EA:).

OY Cyg = Baade's original 76.1928 = Hoffleit's `OX Cyg' = IRAS 19529+3910 =
GSC 3137.1152. Not identical with Nassau and van Albada's 23--30. (Type ZAND:).

PR Cyg = Baade's original 70.1928 = Nassau and van Albada's 24--39 =
GSC 3137.1721. (Type LB).

Nassau and van Albada's stars 23--30 and 24--40 are to be considered
suspected variables; they will enter one of the future catalogs of suspects
(supplementing the NSV catalog).

Versions of the GCSV with corrections regularly introduced can be retrieved
from the GCVS home page (http://zeus.sai.msu.su/groups/cluster/gcvs/gcvs/).

The authors are grateful to T. Kato, J. Manek, and R. Webbink for attracting
our attention to the case and many useful suggestions and discussions.
Our work on the catalogs of variable stars is partially supported
by the Russian Foundation for Basic Research (grant 97-02-16739) and
by the State Program ``Astronomy'' of Russian Federation.

\references

Baade, W., 1928, {\it Astron. Nachr.}, {\bf 232}, 65

Guthnick, P., Prager, R., 1933, {\it Astron. Nachr.}, {\bf 249}, 253

Hoffleit, D. 1975, {\it IBVS}, No.\,1063

Nassau, J.J., van Albada, G.B., 1949, {\it Astrophys. J.}, {\bf 109}, 391

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