- ID:
- ivo://CDS.VizieR/J/A+AS/115/41
- Title:
- UBV(RI) photometry of cool stars
- Short Name:
- J/A+AS/115/41
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present high-precision UBV(RI)_c_ photometry for a sample of active stars detected serendipitously by the EXOSAT satellite. Fourteen objects, out of 47 likely optical counterparts, turned out to be clearly variable, with periods in the range 1-8 days, including a newly discovered eclipsing binary. For most of them the optical variability is consistent with the presence of photospheric cool spots. We have used our multicolour photometry to estimate spectral classifications and distances. The derived distances indicate that some of the observed stars are previously unidentified nearby (d<=25pc) M dwarfs. When combined with the results of high resolution spectroscopy, our photometric observations allow us to investigate the stellar content of the selected X-ray sample. Young stars and RS CVn-type binaries appear to constitute a large fraction of the selected sample. For a description of the UBV and (RI)c photometric systems, see e.g. <http://obswww.unige.ch/gcpd/ph01.html> and <http://obswww.unige.ch/gcpd/ph54.html>.
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- ID:
- ivo://CDS.VizieR/J/A+AS/120/127
- Title:
- UBVRI photometry of 7 dwarfs in Alpha Per
- Short Name:
- J/A+AS/120/127
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The UBVRI light curves of 7 late-type dwarfs amongst the fastest rotators of the Alpha Per cluster (vsini>=140km/s) are presented. The shape of the light curves suggests that the photometric variations are most often dominated by a single group of cool spots located at intermediate or high latitude on the stellar surface. Assuming that starspots are good tracers of the stellar magnetic field, the smooth light curves indicate the existence of a large scale, slowly varying magnetic structure at the surface of these ultrafast rotators. For a description of the UBVRI photometric system, see e.g. <GCPD/08>
- ID:
- ivo://CDS.VizieR/J/A+AS/138/87
- Title:
- UBVRI photometry of EUV stellar sources
- Short Name:
- J/A+AS/138/87
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of high-precision UBV(RI)_c_ photometric observations and of spectroscopic radial velocity measurements obtained at the European Southern Observatory for a sample of 51 cool stars detected in the EUV by the ROSAT Wide Field Camera (WFC). Using also recent results from HIPPARCOS, we infer spectral types and investigate the single or binary nature of the sample stars. Optical variability, with periods in the 0.4-13 day range, has been detected for the first time in 15 of these stars.
- ID:
- ivo://CDS.VizieR/II/277
- Title:
- UBVRI photometry of faint field stars
- Short Name:
- II/277
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This file, originally prepared for the needs of the Lowell Observatory Near-Earth Object Search (LONEOS), contains a rough working collection of Johnson-Cousins UBVRI photometry assembled mainly from the published literature or from publicly available datasets. The V-R and V-I colors are all on the Cousins system. Most of the stars are fainter than V=10.0; the median magnitude is V=13.9, and significant numbers of stars are listed below 20mag. Besides several large surveys, several hundred small sequences in the regions of variable stars, star clusters, galaxies hosting supernovae, quasars, etc were built by determining coordinates for the sequence stars using the published finder charts. At minimum the data include V magnitudes and at least one ordinary photometric color, most commonly B-V. The data were collected for use in determining approximate photometric zero-points in wide-field imaging, with external accuracy of 0.05 mag or better. Though each dataset was vetted for consistency in magnitude and colors, neither high accuracy nor high precision is guaranteed. Obvious variable stars were omitted, but some unknown variables are inevitably included. In any given field, it is advisable use all the available stars for calibration rather than a single comparison. Several large datasets are included. The Guide Star Photometric Catalogue (GSPC, Lasker et al 1988, Cat. II/143) provides BV sequences near the centers of all the Schmidt sky survey plates. At high latitudes in the southern sky, additional data on the 5-degree Schmidt grid were obtained by Platais et al (1998, Cat. I/277) that extend the GSPC sequences to V=~16. More southern fields were observed by Demers et al (1993A&AS...99..437D and 1993A&AS...99..461D); coordinates for these stars have been determined for the first time. Nearly a thousand high-quality sequences in the northern sky have been observed by Henden, partly published in relation to work on cataclysmic variables (e.g. Cat. J/PASP/107/324) and symbiotic stars (e.g. Cat. J/A+A/143/343). Additional Henden sequences have been adopted from the files cited below at the AAVSO ftp site. These large sequences were trimmed to include only a few stars per magnitude interval, and also to omit crowded stars (no significant companions closer than 15" radius). The star coordinates are mainly from early versions of the GSC or USNO series. As such they are given to 1" precision, and in some cases small systematic errors and (now) proper motion mean their accuracy is in the 1" to 5" range. Thus for automated linkage to CCD frames, some modest search radius should be adopted to match with the catalogue. Because the file was originally intended for private use, bibliographic references were not included except in a very few instances. Usually it is straightforward to recover the source paper by inspection of the SIMBAD bibliography for specific objects. Problematic cases can be directed to the compiler (Brian Skiff).
- ID:
- ivo://CDS.VizieR/J/A+AS/126/311
- Title:
- UBVRI photometry of FK5 Ext. stars
- Short Name:
- J/A+AS/126/311
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Table 1 includes: the star number in the E-regions; the HD or CPD number; the V magnitude; the B-V, U-V, V-R and R-I color indices; e, the mean square error of the averages published (unit: 0.001 magnitude); n, the number of observations for each star; and Sp, the spectral types (Graham, 1982PASP...94..244G). Table 2 gives similar information for the program stars. An asterisk after the star number means that the observations were made with a diaphragm, and a v means a variable star. The results of the observations of the FK5 Extension stars Nx 4173, 4409, 5355, 5400, 5410, 5593, 5671, 5886 and 6056 shows that they are variable stars; the published results correspond to the mean values obtained from the observations.
- ID:
- ivo://CDS.VizieR/J/A+AS/100/489
- Title:
- UBVRI photometry of FKSZ stars
- Short Name:
- J/A+AS/100/489
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- UBVRI photometry in the Kron-Cousins system was observed for 117 stars of the Catalogue of Fundamental Faint Stars (FKSZ stars) in the declination zone 0 to +18{deg}. The observations were made in 24 nights from July 1988 to March 1989 with the European Southern Observatory (ESO) 0.50m telescope at La Silla, Chile.
- ID:
- ivo://CDS.VizieR/J/other/SAAOC/14.11
- Title:
- UBVRI photometry of GSPC stars
- Short Name:
- J/other/SAAOC/14
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Photoelectric UBVRI observations are given for 336 stars brighter than 11.5mag from the Hubble Space Telescope Guide Star Photometric Catalogue (GSPC). Apart from a Declination-dependent effect in the V magnitudes there are no systematic differences between GSPC (Cat. <II/143>) and SAAO (Menzies et al., 1989SAAOC..13....1M) data which are significantly greater than differences between the Landolt and E-region standard systems. The Declination effect might be due to the occurrence of unusually high atmospheric extinction coefficients at CTIO following the eruption of the Mexican volcano, El Chichon.
- ID:
- ivo://CDS.VizieR/J/AJ/119/2571
- Title:
- UBVRI photometry of HDF QSOs and galaxies
- Short Name:
- J/AJ/119/2571
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have imaged a 45'x45' area centered on the Hubble Deep Field (HDF) in UBVRI passbands, down to the limiting magnitudes of approximately 21.5, 22.5, 22.2, 22.2, and 21.2, respectively. The principal goals of the survey are to identify quasi-stellar objects (QSOs) and to map structure traced by luminous galaxies and QSO absorption line systems in a wide volume containing the HDF. The area surveyed is 400 times as large as that of the HDF, and 40 times as large as that of the HDF Flanking Fields. We have selected QSO candidates from color space and identified four QSOs and two narrow emission line galaxies not yet discovered, bringing the total number of known QSOs in the area to 19.
- ID:
- ivo://CDS.VizieR/J/AJ/126/2971
- Title:
- UBVRI photometry of 131 Herbig Ae/Be
- Short Name:
- J/AJ/126/2971
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new catalog of 108 Herbig Ae/Be candidate stars identified in the Pico dos Dias Survey (Gregorio-Hete et al., 1992AJ....103..549G; Torres et al., 1995AJ....109.2146T and 1999, Special Publ. 10, Rio de Janeiro: Obs. Nac.), together with 19 previously known candidates and four objects selected from the IRAS Faint Source Catalog (<II/156>). These 131 stars were observed with low- and/or medium-resolution spectroscopy, and we complement these data with high-resolution spectra of 39 stars.
- ID:
- ivo://CDS.VizieR/J/AJ/144/41
- Title:
- UBVRI photometry of M33 star clusters. I.
- Short Name:
- J/AJ/144/41
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present UBVRI photometry for 392 star clusters and candidates in the field of M33, which are selected from the most recent star cluster catalog. In this catalog, the authors listed star clusters' parameters such as cluster positions, magnitudes, colors in the UBVRIJHK_s_filters, and so on. However, a large fraction of objects in this catalog do not have previously published photometry. Photometry is performed using archival images from the Local Group Galaxies Survey, which covers 0.8deg^2^ along the major axis of M33. Detailed comparisons show that, in general, our photometry is consistent with previous measurements. Positions (right ascension and declination) for some clusters are corrected here. Combined with previous literature, ours constitute a large sample of M33 star clusters. Based on this cluster sample, we present some statistical results: none of the youngest M33 clusters (~10^7^yr) have masses approaching 10^5^M_{sun}_; roughly half the star clusters are consistent with the 10^4^-10^5^M_{sun}_ mass models; the continuous distribution of star clusters along the model line indicates that M33 star clusters have been formed continuously from the epoch of the first star cluster formation until recent times; and there are ~50 star clusters which are overlapped with the Galactic globular clusters on the color-color diagram, and these clusters are old globular cluster candidates in M33.
