- ID:
- ivo://CDS.VizieR/J/AJ/137/4186
- Title:
- UBVRI standards around celestial equator
- Short Name:
- J/AJ/137/4186
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- New broadband UBVRI photoelectric observations on the Johnson-Kron-Cousins photometric system have been made of 202 stars around the sky, and centered at the celestial equator. These stars constitute both an update of and additions to a previously published list of equatorial photometric standard stars. The list is capable of providing, for both celestial hemispheres, an internally consistent homogeneous broadband standard photometric system around the sky. When these new measurements are included with those previously published by Landolt (1992, Cat. II/183), the entire list of standard stars in this paper encompasses the magnitude range 8.90<V<16.30, and the color index range -0.35<(B-V)<+2.30.
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2532. UBVRI Standard Stars
- ID:
- ivo://CDS.VizieR/J/AJ/133/2502
- Title:
- UBVRI Standard Stars
- Short Name:
- J/AJ/133/2502
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- UBVRI photoelectric observations have been made of 109 stars around the sky, centered more or less at -50{deg} declination. The majority of the stars fall in the magnitude range 10.4<V<15.5 and in the color index range -0.33<(B-V)<+1.66. These new broadband photometric standard stars average 16.4 measurements each from data taken on 116 different nights over a period of 4yr. Similar data are tabulated for 19 stars of interest that were not observed often enough to make them well-defined standard stars.
- ID:
- ivo://CDS.VizieR/J/AJ/146/88
- Title:
- UBVRI standard stars around the celestial equator
- Short Name:
- J/AJ/146/88
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- High-quality CCD-based UBVRI photometry is presented for ~45000 stars distributed among 60 different fields centered on the celestial equator and at {delta}{approx}-50{deg}. This photometry has been calibrated to the standard Johnson UBV and Kron-Cousins RI systems via observations of the UBVRI standard stars presented in the works of Landolt. The majority of the stars in our photometric catalog fall in the magnitude range 12<~V<~22 and in the color range -0.3<~(B-V)<~1.8. Each star averages 67 measures in each UBVRI filter from data taken on 250 different photometric nights over a period of ~6.5yr from two different telescopes. Our final photometric database effectively extends the UBVRI standard star network defined by Landolt to much fainter magnitudes and increases the number density of stars within pre-existing standard fields. Hence, these new, fainter standards serve as suitable calibrators for investigators who employ either small or large-aperture telescopes for their observational projects.
- ID:
- ivo://CDS.VizieR/J/AJ/146/131
- Title:
- UBVRI standard stars at +50{deg} declination
- Short Name:
- J/AJ/146/131
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- UBVRI photoelectric observations have been made of 335 stars around the sky, and centered approximately at +50{deg} declination. The majority of the stars fall in the magnitude range 9<V<16, and in the color range -0.3<(B-V)<+1.8. Those 243 stars best suited as new broadband photometric standard stars average 12.5 measures each from data taken on 98 different nights over a period of 17 years at the Kitt Peak National and Lowell Observatories.
- ID:
- ivo://CDS.VizieR/J/PASP/94/244
- Title:
- UBVRI standard stars in the E-regions
- Short Name:
- J/PASP/94/244
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Photometry on the UBVRI Kron-Cousins system is presented for 102 stars covering the magnitude range 7 to 16 in the nine Harvard E-regions. These stars, at declination close to -45{deg}, are suitable for use as Southern Hemisphere standards in the photometry of faint stars and galaxies. The large magnitude range in most fields makes the sequences useful for the calibration of the Pickering-Racine wedge, a device widely used to extend photometric sequences to fainter limits on photographic plates. Positions accurate to a few arcseconds as well as identification charts are given for each star.
- ID:
- ivo://CDS.VizieR/J/A+A/415/63
- Title:
- UBVRI surface brightness of 26 bright galaxies
- Short Name:
- J/A+A/415/63
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The UBVRI images of 26 bright spiral galaxies were decomposed in disks and bulges. Correlations of the resulting structural parameters are investigated, giving clues to the formation history of the bulges. We confirm that the large and bright bulges of early-type spirals are similar to elliptical galaxies. They were probably formed prior to the disks in a monolithic collapse or via early mergers. Late-type spirals have tiny and faint bulges with disk-like profiles. These bulges were probably formed after the disk in secular evolution processes, e.g. from a disk instability. The comparison of the color indices of corresponding spirals and bulges with population synthesis computations support above formation scenarios.
- ID:
- ivo://CDS.VizieR/J/AJ/126/632
- Title:
- UBVRIz'HK' photometry of 2Ms CDFN X-ray sources
- Short Name:
- J/AJ/126/632
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an optical and near-infrared catalog for the X-ray sources in the 2Ms Chandra observation of the Hubble Deep Field North region. We have high-quality multicolor imaging data for all 503 X-ray point sources in the X-ray-selected catalog and reliable spectroscopic redshifts for 284. We spectroscopically identify six high-redshift (z>1) type II quasars (L_2-8keV_>10^44^ergs/s) in our sample. Our spectroscopic completeness for the R<=24 sources is 87%. The spectroscopic redshift distribution shows two broad redshift spikes that have clearly grown over those originally seen in the 1Ms exposure. The spectroscopically identified extragalactic sources already comprise 75% of the measured 2-8keV light. Redshift slices versus 2-8keV flux show that an impressive 54% of the measured 2-8keV light arises from sources at z<1 and 68% from sources at z<2.
- ID:
- ivo://CDS.VizieR/J/AJ/151/33
- Title:
- UBVRIz light curves of 51 Type II supernovae
- Short Name:
- J/AJ/151/33
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a compilation of UBVRIz light curves of 51 type II supernovae discovered during the course of four different surveys during 1986-2003: the Cerro Tololo Supernova Survey, the Calan/Tololo Supernova Program (C&T), the Supernova Optical and Infrared Survey (SOIRS), and the Carnegie Type II Supernova Survey (CATS). The photometry is based on template-subtracted images to eliminate any potential host galaxy light contamination, and calibrated from foreground stars. This work presents these photometric data, studies the color evolution using different bands, and explores the relation between the magnitude at maximum brightness and the brightness decline parameter (s) from maximum light through the end of the recombination phase. This parameter is found to be shallower for redder bands and appears to have the best correlation in the B band. In addition, it also correlates with the plateau duration, being shorter (longer) for larger (smaller) s values.
- ID:
- ivo://CDS.VizieR/J/A+A/479/827
- Title:
- UBVR light curves of weak-line T Tauri stars
- Short Name:
- J/A+A/479/827
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- T Tauri stars exhibit variability on all timescales, whose origin is still debated. On WTTS the variability is fairly simple and attributed to long-lived, ubiquitous cool spots. We investigate the long term variability of WTTS, extending up to 20 years in some cases, characterize it statistically and discuss its implications for our understanding of these stars. We have obtained a unique, homogeneous database of photometric measurements for WTTS extending up to 20-years. It contains more than 9000 UBVR observations of 48 WTTS. All the data were collected at Mount Maidanak Observatory (Uzbekistan) and they constitute the longest homogeneous record of accurate WTTS photometry ever assembled. Definitive rotation periods for 35 of the 48 stars are obtained. Phased light curves over 5 to 20 seasons are now available for analysis. Light curve shapes, amplitudes and colour variations are obtained for this sample and various behaviors exhibited, discussed and interpreted. Our main conclusion is that most WTTS have very stable long term variability with relatively small changes of amplitude or mean light level. The long term variability seen reflects modulation in the cold spot distributions. Photometric periods are stable over many years, and the phase of minimum light can be stable as well for several years. On the long term, spot properties do change in subtle ways, leading to secular variations in the shape and amplitudes of the light curves.
- ID:
- ivo://CDS.VizieR/J/ApJ/630/784
- Title:
- UBVR observations of nearby galaxies
- Short Name:
- J/ApJ/630/784
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We introduce a data set of 142 mostly late-type spiral, irregular, and peculiar (interacting or merging) nearby galaxies observed in UBVR at the Vatican Advanced Technology Telescope (VATT), and we present an analysis of their radial color gradients.
