File table1 contains various identifications the master list of 977 stars that were included in the photometric variability survey, and which were cross-identified with stars in the study of Fan et al. (1996, Cat. <J/AJ/112/628>). Another 13 stars included in the study, but not cross-identified with the study of Fan et al. can be found in Table 2, which is published in the paper. These 977 stars are those that were included in a roughly square region, 23 arcminutes on each side, centered approximately 5 arcminutes north of the cluster center. The stars have magnitudes in the approximate range 12.5<B<18.5, 12.5<V<18.5, and 12<I<18. File table3 contains BVI photometry for all 990 stars (from Tables 1 and 2) included in the photometric variability study.
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.
We used HST-WFPC2 and the 1.54 Danish ESO-telescope at La Silla (Chile) to obtain photometry for stars located within 200 arcsec from the center of the cluster NGC 6101. HST-WFPC2 data for 1 field centered on the cluster, have been collected during HST-cycle 6. The resulting V, V-I photometry reach a limiting magnitude of V~25.5. Ground observations have been collected on July 1995. The resulting photometry containing the stars simultaneously detected in the V, B and I filters, is characterized by a limiting magnitude of V~22.5.
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.
A photometric sequence consisting of 53 stars measured in the V, B, and I bands has been set up in the vicinity of the rich, young Large Magellanic Cloud cluster, NGC 1866. Many of these stars are relatively isolated and are thus suitable for use as local standard stars for photometric studies of the cluster. Color magnitude diagrams to a limit of V=20.5 for various parts of the 13x13arcmin field, centered on the cluster, show that NGC 1866 is embedded in a mix of populations which includes stars younger than the cluster itself, the dominant 0.5-3Gyr population, plus some very old stars represented by four RR Lyrae variables.
We report on a multiwavelength study of the relationship between young star clusters in the Antennae galaxies (NGC 4038/9) and their interstellar environment, with the goal of understanding the formation and feedback effects of star clusters in merging galaxies.
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.
