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\IBVShead{5275}{16 May 2002}

\IBVStitletl{OP A\lowercase{ql} and V926 A\lowercase{ql}}

\IBVSauth{Hazen, M.L.$^1$; Hoffleit, D.$^2$; Kazarovets, E.$^3$; Kroll, P.$^4$; Samus, N.$^{3,5}$; Webbink, R.F.$^6$}

\IBVSinst{Harvard College Observatory, 60 Garden St., Cambridge,
MA 02138, USA, e-mail: mhazen@cfa.harvard.edu}

\IBVSinst{Department of Astronomy, Yale University, PO Box 208101, New
Haven, CT 06520, USA}

\IBVSinst{Institute of Astronomy, Russian Academy of Sciences, 48,
Pyatnitskaya St., Moscow 119017, Russia, e-mail: elena\_k@sai.msu.ru, samus@sai.msu.ru}

\IBVSinst{Sonneberg Observatory, Sternwartestr. 32, D-96515 Sonneberg,
Germany, e-mail: pk@stw.tu-ilmenau.de}

\IBVSinst{Sternberg Astronomical Institute, 13, University Ave.,
Moscow 119992, Russia}

\IBVSinst{Department of Astronomy, University of Illinois,
1002 W. Green St., Urbana, IL 61801, USA, e-mail: webbink@astro.uiuc.edu}


\IBVSabs{OP Aql and V926 Aql were wrongly identified in the literature.}
\IBVSabs{We describe the decisions taken by the GCVS group and by Sonneberg}
\IBVSabs{Observatory to minimize further confusion.}

\SIMBADobj{OP Aql}
\SIMBADobj{V926 Aql}


\begintext

Presenting accurate coordinates for all catalogued variable
stars, especially for those originally announced with only
approximate positional information and no finding charts, is an
urgent task in our era of extensive automatic variable star
surveys, and considerable effort is being dedicated to it (cf.
Samus et al., 2002).
In the course of a large-scale project aimed at improving
positions for many variable stars discovered at Harvard
Observatory (Webbink et al., 2002), a case of confusion concerning
OP~Aql and V926~Aql was revealed. This paper describes the circumstances
and announces decisions taken by the Sonneberg Observatory and by
the team of the General Catalogue of Variable Stars (GCVS) to
minimize confusion.

The discovery of Harvard variable star HV~5469, of unknown type or
period, was announced by Hoffleit (1932). This star was soon named OP~Aql
(Guthnick \& Prager 1932),
though it remained unstudied. The discoverer did not publish a
finding chart.

Several decades later in Sonneberg, Gessner (1959) found that
OP~Aql was an eclipsing star with 3\fday227797 period, and published
a finding chart. The chart shows two variable stars,
one of them labeled OP~Aql, and the other
one S~5341. Gessner announced the latter star as a new discovery,
also an Algol, with a period of 2\fday97303. Kukarkin, Efremov, \&
Kholopov (1960) assigned S~5341
the GCVS designation V926~Aql. Several minima have since been
published for each of these two stars by amateur astronomers.

A search in the plate stacks of the Harvard Observatory, using
Hoffleit's original notebooks, shows beyond doubt
that the original HV~5469 is actually the star labeled S~5341 in
Gessner (1959), whereas OP~Aql in the same chart is a new variable
discovered by Gessner.

In order to minimize further confusion, we take the
following decisions.

We announce that V926 Aql = HV 5469 = S 5341, and thus OP Aql is a
new eclipsing variable discovered by Gessner (1959). This is
scarcely the first case of a variable star having both HV and
Sonneberg Ver\"anderlicher Stern numbers. With the designation HV~5469
transferred to V926~Aql, the finding chart
in Gessner (1959) remains quite correct, and the
ephemeris of each variable remains correct as published.
The finding chart for OP~Aql in Tsesevich \& Kazanasmas (1971)
also shows the right star. We give
OP~Aql the new Sonneberg number, S~10948. We hope that
astronomers will not be taken aback by the paradox that the
name ``OP~Aql'' had been first introduced decades before the
variable now called OP~Aql was actually discovered. Figure~1
presents a Digitized Sky Survey finding chart of OP~Aql and
V926~Aql, with the relevant identifications given in the caption.

The GCVS work is supported, in part, by grants from the Russian
Foundation for Basic Research (02-02-16069) and from the program
of support for leading scientific schools of Russia (00-15-96627).
Participation by RFW is supported in part by U.S. National Science
Foundation grant AST-9618462.
The Digitized Sky Survey images are provided by the Hubble Space
Telescope Science Institute under support from grant NAG W-2166 of
the USA Government.


\IBVSfig{7.5cm}{5275-f1.eps}{The photographic $10\arcm\times10\arcm$ finding 
chart for OP~Aql and V926~Aql (from the blue-light image of the Second 
Digitized Sky  Survey). 1: OP~Aql = S~10948 = GSC~1058.0287 
(19\hr48\mm08\fsec3, +9\deg20\arcm45\arcs, 2000.0). 2: V926~Aql = HV~5469 = 
S~5341 = GSC~1062.0024 (19\hr48\mm13\fsec4, +9\deg23\arcm43\arcs, 2000.0).}

\vspace*{-1.5cm}

\references

Gessner, H. 1959, {\it Mitt. Ver\"and. Sterne}, {\bf 1}, Nr. 390, 391

Guthnick, P., Prager, R. 1932, {\it Astr. Nachr.}, {\bf 247}, 121

Hoffleit, D. 1932, {\it Harvard Obs. Bull.}, {\bf No. 887}

Kukarkin, B.V., Efremov, Yu.I., Kholopov, P.N.  1960, {\it First Supplement
to the Second Edition of the General Catalogue of Variable Stars}
(Moscow: Astr. Council Acad. Sci. U.S.S.R. and Sternberg State Astr.
Inst., Univ. Moscow)

Samus, N.N., Goranskii, V.P., Durlevich, O.V., Zharova, A.V.,
Kazarovets, E.V., Pastukhova, E.N., Hazen, M.L., Tsvetkova, T.M.
2002, {\it Astronomy Letters}, {\bf 28}, 174

Tsesevich, V.P., Kazanasmas, M.S. 1971, {\it Atlas of Finding Charts
for Variable Stars}, Moscow: Nauka

Webbink, R.F., Hazen, M.L., Hoffleit, D.  2002, IBVS (submitted)

\endreferences


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