The solar-age open cluster M 67 (C0847+ 120, NGC 2682) is a touchstone in studies of the old Galactic disk. Despite its outstanding role, the census of cluster membership for M 67 at fainter magnitudes and their properties are not well-established. Using proprietary and archival ESO data, we have obtained astrometric, photometric, and radial velocities of stars in a 34x33arcmin^2^ field centered on the old open cluster M 67. The two-epoch archival observations separated by 4-years and acquired with the Wide-Field Imager at the 2.2m MPG/ ESO telescope were reduced with our new astrometric techniques, as described in the first paper in this series (Anderson et al., 2006A&A...454.1029A). The same observations served to derive calibrated BVI photometry in M 67. Radial velocities were measured using the archival and new spectroscopic data obtained at the VLT.
CCD BVI photometry of the faint open clusters Berkeley 73, Berkeley 75 and Berkeley 25 are presented. The two latter are previously unstudied clusters to our knowledge. While Berkeley 73 is found to be of intermediate-age (about 1.5Gyr old), Berkeley 75 and Berkeley 25 are old clusters, with ages greater than 3.0Gyr. We provide also estimates of the clusters size. All these clusters lie far away from the Galactic Center, at R_GC_>=16kpc, and quite high on the Galactic plane, at |Z_{sun}_|>=1.5kpc. They are therefore important targets to probe the properties of the structure of the Galaxy in this direction, where the Canis Major over-density has been discovered to be located.
We present BVI photometry of 190 galaxies in the central 4x3deg^2^ region of the Fornax cluster observed with the Michigan Curtis Schmidt Telescope. Results from the Fornax Cluster Spectroscopic Survey (FCSS) and the Flair-II Fornax Surveys have been used to confirm the membership status of galaxies in the Fornax Cluster Catalogue (FCC, Cat. <VII/180>). In our catalogue of 213 member galaxies, 92 (43 per cent) have confirmed radial velocities.
We have compiled the asymptotic giant, horizontal, and upper red giant branch (AGB, HB, and RGB) stars in the globular cluster M55 (NGC 6809). Using the star counts and the R-parameter we compute the initial helium abundance Y=0.274+/-0.016.
The observation of young stars with circumstellar disks suggests that the disks are dissipated, starting from the inner region, by the radiation of the central star and eventually by the formation of rocky planetesimals, over a time scale of several million years. It was also shown that strong UV radiation emitted by nearby massive stars can heat a circumstellar disk up to some thousand degrees, inducing the photoevaporation of the gas. This process strongly reduces the dissipation time scale. We study whether there exists a correlation between the spatial distribution of stars with circumstellar disks and the position of massive stars with spectral class earlier than B5, in the open cluster NGC 6611. We created a multiband catalog of the cluster, down to V~23mag, using optical data from a WFI observation at 2.2m of ESO in the BVI bands, the 2MASS public point source catalog and an archival X-ray observation made with CHANDRA/ACIS. We selected the stars with infrared excess (due to the emission of a circumstellar disk) using suitable color indices independent of extinction, and studied their spatial distribution.
Based on 13 nights of observations of four fields in NGC 300, we have set up an extensive sequence of stars with accurate BVI photometry covering a relatively large (25'x25') region centered on this galaxy. This sequence of standard stars is very useful for calibrating the photometry of variable stars and other objects in NGC 300 and other galaxies obtained from wide-field mosaic images. Our standard-star list contains B, V, and I measurements for 390 stars. The accuracy of the zero points in the V filter and B-V color is better than 0.02mag, and about 0.03mag for the V-I color. We found very good agreement between our measurements and those previously obtained by Walker for 26 stars near NGC 300.
We present broadband BVI photometry for the open cluster NGC 6791, based upon analysis of 1764 individual CCD images. Data tables listing measured magnitudes and standard errors, image-quality indices, a variability index, and equinox J2000.0 equatorial coordinates for 14,342 stars to V~24 have been made available to the public through the services of the Canadian Astronomy Data Centre. Equatorial coordinates only have been provided for a further 1916 stars, the photometry for which we were unable to calibrate because of lack of color information.
The aim of this paper is to present the results of photometric investigations of the central cluster of the W5 E HII region as well as a follow-up study of the triggered star formation in and around bright-rimmed clouds (BRCs). We have carried out wide-field UBVIc and deep VIc photometry of the W5 E HII region. A distance of ~2.1kpc and a mean age of ~1.3Myr have been obtained for the central cluster. The young stellar objects (YSOs) associated with the region are identified on the basis of near-infrared and mid-infrared observations.
In this paper, we present the investigation of the evolutionary status of three open clusters: Berkeley 27, Berkeley 34 and Berkeley 36, all located in the Galactic anticentre direction. All of them were observed with SUperb Seeing Imager 2 at the New Technology Telescope using the Bessel B, V and I filters.
The DIRECT project aims to determine direct distances to two important galaxies in the cosmological distance ladder - M31 and M33 - using detached eclipsing binaries (DEBs) and Cepheids. The search for these variables requires time-series photometry of large areas of the target galaxies and yields magnitudes and positions for tens of thousands of stellar objects, which may be of use to the astronomical community at large. During the first phase of the project, between 1996 September and 1997 October, we were awarded 95 nights on the F. L. Whipple Observatory 1.2 m telescope and 36 nights on the Michigan-Dartmouth-MIT 1.3 m telescope to search for DEBs and Cepheids in the M31 and M33 galaxies. This paper, the first in our series of stellar catalogs, lists the positions, three-color photometry, and variability indices of 57,581 stars with 14.4<V<23.6 in the central part of M33. The catalog is available from our FTP site.
