\documentstyle[twoside,epsf]{article}

\input ibvs2.sty

\begin{document}

\IBVShead{5225}{23 January 2002}

\IBVStitle{H\lowercase{ad}V67 = V648 O\lowercase{ph}, a Remarkably Regular Mira}

\IBVSauth{Kazarovets, E. V.; Pastukhova, E. N.}

\IBVSinsto{Institute of Astronomy, Russian Academy of Sciences,
48, Pyatnitskaya Str., Moscow 109017, Russia}

\IBVSabs{A photographic study of the Mira variable HadV67 shows it to be}
\IBVSabs{identical to V648 Oph, as follows from the coincidence of the}
\IBVSabs{periods.}

\IBVStyp{ M }
\IBVSkey{photometry; identifications}
\SIMBADobj{V648 Oph}

\begintext


In 1925, F. Ross suspected variability of the star located at
18\hr32\mm06\sec, +08\deg06\fmm9 (1875), later designated Ross~51 (Ross,
1926). No finding chart was published.
Ten years later, Hoffmeister (1936) discovered a Mira variable in the field
of Ross~51 and decided it was a rediscovery of Ross~51. As usual for his
rediscoveries, Hoffmeister did not present a finding chart either. Ahnert
(1942) studied Hoffmeister's star, gave improved variability range
(12\fmm5--$<$17\mm) and the star's light elements (${\rm Max} = 2425665
+ 168\fday7\cdot E$). His paper also does not give a finding chart.
Until recently, we were not aware of any other studies of this star,
known as V648~Oph in the system of GCVS names, and the star's accurate
position remained unknown.

In 2000, K. Haseda (Aichi, Japan) discovered the variable HadV67. This
discovery was announced by Kato (2000) who remarked that the star's
position was close to that of V648 Oph. The star can be identified with
IRAS 18358+0810. Its coordinates in the USNO A2.0
catalog (Monet {\it et al.}, 1998) are 18\hr38\mm17\fsec59,
+08\deg13\arcm22\farcs7 (2000.0), and
its brightness and color
are $b=16\fmm0$, $b-r=2\fmm5$. From a limited number of observations of
1997--2000, with four brightenings, the star
was considered a possible Mira with variations within $11\fmm2-<13\fmm9\ V$.
Greaves (2000) noted that bright estimates of HadV67 during the above time
interval agreed with the GCVS period value for V648 Oph (169\day).

We attempted to prove or reject the identification of HadV67 with V648~Oph
on the base of our estimates of HadV67 on 114 plates of the 40 cm astrograph
of the Sternberg Institute's Crimean Laboratory
(JD 2445198--2447749). The estimates were made by E.N.P. The magnitude scale
of the comparison stars relies on blue magnitudes of the USNO A2.0
catalog.

Figure 1 presents a $5'\times5'$ finding chart for HadV67 based upon the
blue image of the second POSS. The cross is the nominal position of Ross~51.
HadV67 is obviously strongly variable and red, judging from POSS~I and POSS~II
images available at the Digitized Sky Survey and at the USNO Image and
Catalogue Archive. Along with HadV67, we also estimated the star GSC~1024.3127,
situated in 0\farcm5 to the north-west of the nominal position of Ross~51
and having, in the USNO A2.0 catalog, $b=14\fmm2$, $b-r=2\fmm2$. This star
(``GSC'' in Fig. 1)
was found constant for the whole time interval of our observations.

Our estimates confirm Mira-type variability of HadV67 within $13\fmm3-17\fmm1
\ B_{pg}$.
The star's light elements are ${\rm Max} = 2447059 + 168\fday76\cdot E$.
The light curve with these elements is presented in Fig. 2. It is remarkably
regular for a Mira. The four brightenings from Kato (2000) are in a good
agreement with our light elements, whereas the old epoch of maximum from
Ahnert (1942) gives $O-C=+39\day$.

The period we find is very close to the value from
Ahnert (1942), thus we conclude that HadV67 is identical with V648 Oph.


Thanks are due to S.V. Antipin and N.N. Samus for their
attention and assistance. Our variable star studies are supported, in
part, by grants from the Russian Foundation for Basic Research and from
the Council of the Program of Support for Leading Scientific Schools of
Russia. We used the Digitized Sky Survey images provided
by the Hubble Space Telescope Science Institute under support from grant
NAG-W2166 of the USA Government and images provided by the US Naval
Observatory Image and Catalogue Archive.

\IBVSfig{7cm}{5225-f1.eps}{The finding chart of HadV67 = V648 Oph ($5'\times
5'$). The cross is the nominal position of Ross~51. ``GSC'' is
GSC~1024.3127.}

\IBVSfig{7cm}{5225-f2.eps}{The light curve of HadV67 = V648 Oph.}

\newpage

\references

Ahnert, P. 1942, Mitt. ver\"and. Sterne, Nr. 3

Greaves, J. 2000, vsnet-newvar No. 558 (http://www.kusastro.kyoto-u.ac.jp/vsnet/Mail/vsnet-newvar/msg00558.html)

Hoffmeister, C. 1936, Astron. Nachr., {\bf 259}, 37

Kato, T. 2000, vsnet-newvar No. 557 (http://www.kusastro.kyoto-u.ac.jp/vsnet/Mail/vsnet-newvar/msg00557.html)

Monet, D., Bird, A., Canzian, B. {\it et al.} 1998, USNO-A V2.0. A Catalog
of Astrometric Standards, US Naval Observatory, Washington, DC (11 CD-ROMs)

Ross, F. 1926, Astron. J., {\bf 36}, 122

\end{document}
