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\begin{document}
\IBVShead{4920}{13 July 2000}
\IBVStitletl{New Variables on the Edge of the Northern}{ Milky Way -- Paper 1: B\lowercase{e}V1--30 }

\IBVSauth{Bernhard, K.$^{1,2}$; Lloyd, C.$^3$}
\IBVSinst{Kafkaweg 5, A-4030 Linz, Austria,  e-mail: {\tt kl.bernhard@aon.at}}
\IBVSinst{Bundesdeutsche Arbeitsgemeinschaft f\"{u}r Veraenderliche Sterne e.V.
(BAV), Munsterdamm 90,\\ \indent D-12169 Berlin, Germany}
\IBVSinst{Space Science \& Technology Department, Rutherford Appleton
Laboratory, Chilton, Didcot,\\ \indent Oxon.\ OX11 0QX, UK, e-mail: {\tt cl@astro1.bnsc.rl.ac.uk}}


\IBVStyp{ RR Lyrae, W UMa, beta Cephei, delta Scuti, SR, EA }
\IBVSkey{variable stars, eclipsing binary, periods, RR Lyrae, SR variables}
\IBVSabs{These new variable stars were discovered as part of a search}
\IBVSabs{programme to find short-period variables in fields on the edge of the}
\IBVSabs{northern milky way. Only half of the new variable stars discovered}
\IBVSabs{are short-period variables, eclipsing binaries, RR Lyrae stars etc}
\IBVSabs{while the other half are apparently late-type variables.}

\begintext

The new variable stars reported here have been found as part of a
programme to discover and classify new variables using CCD observations
of selected fields on the edge of the northern milky way (eg.\ Bernhard et
al.\ 1997, Bernhard 1999). In this paper the details of the first group of
stars resulting from this programme are given.

The observations were made using a 20-cm Schmidt-Cassegrain telescope and
an unfiltered Starlight Xpress SX CCD camera. The CCD camera uses a Sony
ICX027B chip which has a very broad response, peaking near 5500 \AA,
giving approximate $V$-band magnitudes, depending on the colour of the
star. The frames are processed and analysed automatically. A mean dark
frame is subtracted and the images are flat fielded. The reduction method
has evolved from simple aperture photometry, used initially, to a
variable aperture based on the signal in each pixel, and this
has led to some improvement in the photometry. Further observations of
some of the stars have been made by a number of collaborators using a
variety of equipment, and these are detailed in the references to
individual stars given later.

The observing programme is specifically designed for the detection and
classification of short-period variables, and passes through distinct
survey and follow-up phases. During the survey part of the programme
several series of overlapping exposures are made systematically across
sections of the sky. The same areas are re-observed between 5 and 10
times over one or two months. Ideally the observations are made in short
runs of two or three consecutive days, at irregular intervals, but the
usual observing constraints often disrupt this pattern. The survey
exposures are 20 seconds long and typically provide useful photometry
down to magnitude 13.5.

Survey images are analysed automatically and software is used to compare
the magnitudes and identify likely variables. Stars with a variation of
0.2 mag on at least two images are considered as variable, plus those
which show an obvious drop in brightness, $\sim$ 0.5 mag on one image. A
preliminary selection of the most likely short-period variables is made
from the survey observations, on the basis of range and time scale of the
variation, and colour. A period analysis on even this small number of
observations may point towards a likely classification or period.
Follow-up observations are made of all the likely short-period variables
with the apparently most tractable stars being given the highest
priority. Further observations of the other variables are taken when
possible. The apparently slowest variables with USNO-A2.0 (Monet et al.\
1998) $b-r$ $\sim$ 2 or more are assumed to be red variables of some
persuasion, and are not actively pursued.

During the follow-up phase each star is observed as continuously as
possible. In general the exposure times are increased to 30 seconds to
improve signal to noise, or tailored more specifically to the magnitudes
of the variable and comparison stars. As these observations accumulate
the likely nature of the variation becomes more clear and period analysis
is performed. Once the period, or likely periods have been identified,
further observations are timed to fill in the light curve or remove any
ambiguities in the period.

The details of the positions and cross identifications of the Be
variables are given in Table 1. The columns contain, 1; running Be
number, 2; RA \& Dec (2000) taken from the USNO-A2.0 catalogue, 3; the
GSC number, 4; likely IRAS identification and 5; any other
identification. The photometric data are given in Table 2. The columns
are 1; running Be number, 2; the unfiltered CCD magnitude range based on
the GSC comparison star magnitudes, 3; USNO-A2.0 $r$ \& $b-r$ magnitudes,
4; $V$ and $B-V$ derived from Tycho-2, 5; the type of variation, 6;
period, 7; reference. Additional comments, indicated by $\dagger$, are
given in notes to the table. All the red variables are identified as
``SR'', although it is recognised that they could be almost any type
late-type variable, with the magnitude range possibly grossly under
estimated.

\bigskip

\begin{center}
\normalsize
Table 1: Positions and Identifications for BeV1--30
\vskip 2pt
\begin{tabular}{lccccll} \hline
No. & RA (2000) Dec & GSC & IRAS & Other \\ \hline
BeV1  & 19 53 40.2  +09 23 50 & 1062-0033 & & V1490 Aql  \\
BeV2  & 20 11 44.6  +08 55 17 & & & V1492 Aql/A2.0 0975.18231027 \\
BeV3  & 14 51 17.1 $-$11 09 43 & 5582-0545 & &  \\
BeV4  & 05 52 27.9  +06 20 53 & 0128-1121 & 05497+0620\phantom{F} & CSS 170\\
BeV5  & 06 20 40.0  +06 16 08 & 0144-1300 & 06179+0617\phantom{F} & \\
BeV6  & 18 04 57.5  +08 57 38 & 1008-0332 & F18025+0857 & V2501 Oph\\
BeV7  & 18 09 57.3  +08 50 25 & 1009-0766 & & \\
BeV8  & 19 46 25.0  +08 45 12 & 1057-1309 & & \\
BeV9  & 07 11 52.6  +04 04 05 & 0171-2059 & & \\
BeV10 & 18 32 06.9  +08 07 13 & 1024-2911 & 18297+0804\phantom{F} & \\
BeV11 & 18 35 06.1  +08 14 28 & & & A2.0 0975.12232581 & \\
BeV12 & 18 19 46.8  +08 00 24 & 1010-0732 & & \\
BeV13 & 06 18 56.2  +04 09 20 & 0140-1831 & & \\
BeV14 & 16 24 49.7  +08 04 15 & 0959-1397 & & \\
BeV15 & 16 51 29.9  +06 22 27 & 0396-1710 & & \\
BeV16 & 18 07 29.2  +06 22 36 & & 18050+0622\phantom{F} & A2.0 0900.11650430 & & \\
BeV17 & 19 24 36.4  +06 31 28 & 0477-3880 & & \\
BeV18 & 19 37 11.8  +06 28 10 & 0490-4680 & & \\
BeV19 & 19 43 40.3  +10 39 07 & & & A2.0 0975.16187403 & \\
BeV20 & 19 39 30.6  +10 43 14 & 1060-2412 & & \\
BeV21 & 19 54 12.7  +10 39 29 & 1062-2668 & & \\
BeV22 & 19 49 15.2  +10 35 42 & 1062-1819 & & \\
BeV23 & 20 09 36.2  +10 39 09 & 1076-1805 & & \\
BeV24 & 20 18 13.7  +10 37 55 & 1078-0852 & F20158+1028 & \\   
BeV25 & 21 10 21.1  +10 36 01 & 1108-0961 & 21079+1023\phantom{F} & \\   
BeV26 & 21 04 22.4  +10 28 29 & 1108-2511 & F21019+1016 & \\
BeV27 & 20 03 00.6  +10 34 56 & 1076-1332 & & \\
BeV28 & 21 28 30.2  +10 45 23 & 1123-1704 & & \\
BeV29 & 22 01 40.7  +10 37 19 & 1139-0011 & & \\
BeV30 & 23 32 32.6  +10 33 21 & 1172-1452 & & \\
\hline
\end{tabular}
\end{center}

\newpage

\begin{center}
\normalsize
Table 2: Photometric data for BeV1--30
\vskip 2pt
\begin{tabular}{lccccll} \hline
No.&       Range &  ~~~$r$~~~~$b-r$ & ~~~~$V$~~~~$B-V$ & Type & Period (d) & Reference \\ \hline
BeV1  & 10.5--11.0 & 10.9 ~~~0.4 & 11.00 ~\phantom{+}0.45 & EA & 1.6160 & IBVS No. 4540 \\
BeV2  & 12.6--13.6 & 13.3 ~~~2.3 & & SR & $\sim$ 60 & vsnet-obs 17668 \\
BeV3  & 11.6--11.9 & 11.8 ~~~0.7 & 11.18 ~\phantom{+}0.62 & EA? & 1.0672 ? & vsnet-obs 15317 \\
BeV4  & 11.7--12.2 & 11.6 ~~~2.5 & & SR & 189$\dagger$ & vsnet-obs 15402 \\
BeV5  & 11.6--12.1 & 11.8 ~~~1.8 & & SR & & vsnet-obs 15840 \\
BeV6  & 11.7--12.0 & 11.5 ~~~2.5 & & SR & $\sim$ 41 & vsnet-obs 17997 \\
BeV7  & 11.6--12.1 & 11.1 ~~~1.6 & 11.59 ~\phantom{+}0.51 & EA & 2.16347$\dagger$ & IBVS No. 4685 \\
BeV8  & 11.7--12.2 & 11.6 ~~~1.4 & 11.82 ~\phantom{+}0.38 & $\dagger$ & $\dagger$ & IBVS No. 4685 \\
BeV9  & 11.4--11.9 & 11.4 ~~~0.6 & 12.19 ~$-$0.15 & EA? &  & vsnet-obs 20089 \\
BeV10 & 12.1--12.5 & 11.8 ~~~3.0 & & SR & $>$ 40 & vsnet-obs 21154 \\
BeV11 & 12.2--12.4 & 11.7 ~~~3.1 & & SR & & vsnet-obs 21220 \\
BeV12 & 11.5--11.8 & 11.7 ~~~0.7 & 11.75 ~\phantom{+}0.62 & ? & & vsnet-obs 21457 \\
BeV13 & 12.1--12.8 & 12.0 ~~~0.7 & & EA & 1.1496 & IBVS No. 4797 \\
BeV14 & 12.6--13.6 & 12.3 ~~~0.7 & & RRa & 0.6446 & IBVS No. 4797 \\
BeV15 & 12.7--13.4 & 12.6 ~~~0.6 & & RRa & 0.7789 & IBVS No. 4797 \\
BeV16 & 12.8--13.1 & 12.0 ~~~3.2 & & SR & & vsnet-obs 23743 \\
BeV17 & 12.3--12.7 & 12.1 ~~~1.5 & & EW? & 0.73254 ? & vsnet-obs 23759 \\
BeV18 & 12.8--13.1 & 12.4 ~~~1.1 & & ? & & vsnet-obs 23790 \\
BeV19 & 12.4--12.7 & 12.4 ~~~2.6 & & SR & & vsnet-obs 23834 \\
BeV20 & 12.7--13.0 & 12.7 ~~~1.8 & & SR & & vsnet-obs 23842 \\
BeV21 & 12.2--12.5 & 12.4 ~~~2.8 & & SR & & vsnet-obs 23861 \\
BeV22 & 12.1--12.4 & 12.4 ~~~3.0 & & SR & & vsnet-obs 23893 \\
BeV23 & 12.6--13.0 & 12.8 ~~~2.5 & & SR & & vsnet-obs 23916 \\
BeV24 & 11.6--11.9 & 11.8 ~~~3.0 & & SR & & vsnet-obs 23936 \\
BeV25 & 12.3--12.8 & 12.4 ~~~3.1 & & SR & & vsnet-obs 23949 \\
BeV26 & 12.1--12.6 & 11.7 ~~~2.7 & & SR & & vsnet-obs 24086 \\
BeV27 & 11.5--11.9 & 11.4 ~~~1.3 & & EA? & 0.7789 ? & vsnet-obs 24169 \\
BeV28 & 12.7--13.2 & 12.7 ~~~0.3 & & EW? & 0.5579 ? & vsnet-obs 24187 \\
BeV29 & 12.5--13.5 & 12.5 ~~~0.5 & & EA? & & vsnet-obs 24334 \\
BeV30 & 12.1--12.4 & 12.3 ~~~0.9 & & ? & & vsnet-obs 24340 \\
\hline
\end{tabular}

\begin{tabular}{@{}l@{}}
{\bf Notes:}\\
BeV4: $P$ = 189 days Lloyd (2000) and Takamizawa (2000), S star\\
BeV7: Revised ephemeris 2451243.46 + 2.16347$\times E$\\
BeV8: Colour suggests a $\delta$ Scuti with $P$ = 0.1726 or 0.2087 days, 
with 0.3453 and 0.4175 days less\\ 
likely\\
\end{tabular}
\end{center}

\bigskip
The magnitude ranges of the variables are given with respect to the
approximate $V$-band GSC magnitudes of the comparison stars. For stars of
intermediate colour these values are probably close to the V magnitude,
but for the red variables there is an increasingly large colour equation,
and the values are probably more representative of the r magnitude.

Discrimination between the short-period and the SR variables is
made principally on the time scale of the variation but with some guidance
from the $b-r$ colour. The distribution of $b-r$ for this sample is shown
in Figure 1, and while the two groups are easily identified there is
little clear air between them. It is possible that some of the
short-period variables contain late-type stars, but photometric errors and
time differences between the b and r plates will conspire to reduce the
separation.

\IBVSfig{8cm}{4920-f1.eps}{The distribution of $b-r$ for the stars in Table 2
with the assumed SR variables shaded.}

\vskip -11pt
The initial announcements about these stars, which contain the survey
data and some preliminary analysis, were made electronically (Bernhard
1998--1999) and are available on the VSnet at {\tt
http://www.kusastro.kyoto-u.ac.jp/vsnet/Mail/} as given in Table 2. More
detailed observations and analysis are available for BeV1 (Bernhard et
al.\ 1997), BeV7 \& 8 (Lloyd \& Bernhard 1999) and BeV13, 14 \& 15 (Lloyd
et al.\ 1999).

Although the programme is aimed at the detection of short-period
variables it is clear from Table 2 that many of the variables are late-type
stars. Exactly half (15) of the stars in this sample are designated
SR, and of the remaining stars three are confirmed eclipsing binaries with
a further six possibilities, two are confirmed RR Lyrae variables, and
the remaining four stars are unclassified short-period variables.

{\it Acknowledgements:} It is a pleasure to acknowledge the collaboration of U. Bastian, P.
Frank, K. Haseda, S. Kiyota, W. Moschner, W. Quester and K. Takamizawa in
the confirmation of these new variable stars. It is also a pleasure to
thank the providers and managers of the VSnet for providing this service for
the variable star community, and to B. Skiff for helpful comments.

\references

Bernhard, K., 1998--1999, vsnet-obs (see Table 2) \\
{\tt http://www.kusastro.kyoto-u.ac.jp/vsnet/Mail/}

Bernhard, K., 1999, {\it Der Sternenbote}, {\bf 2/1999}, Astronomisches Buero, 
A-1238 Wien p.\ 34

Bernhard, K., Quester, W., Bastian, U., 1997, {\it IBVS}, No.\ 4540      

Lloyd, C., Bernhard, K., 1999, {\it IBVS}, No.\ 4685

Lloyd, C., Bernhard, K., Frank, P., Moschner, W., 1999, {\it IBVS}, No.\ 4797

Lloyd, C., 2000, vsnet-obs No.\ 27077 \\
{\tt http://www.kusastro.kyoto-u.ac.jp/vsnet/Mail/obs27000/msg00077.html}

Monet, D., Bird, A., Canzian, B., Harris, H., Reid, N., Rhodes, A., Sell,
S., Ables, H., Dahn, C., Guetter, H., Henden, A., Leggett, S., Levison,
H., Luginbuhl, C., Martini, J., Monet, A., Pier, J., Riepe, B., Stone,
R., Vrba, F., Walker, R., 1998, {\it The USNO--A2.0 Catalogue}, U.S.
Naval Observatory, Washington DC

Takamizawa K., 2000, vsnet-obs No.\ 26946 \\
{\tt http://www.kusastro.kyoto-u.ac.jp/vsnet/Mail/obs26000/msg00946.html}

\end{document}
