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16471. USNO-A V2.0, A Catalog of Astrometric Standards
ID:
ivo://astronet.ru/cas/usnoa2
Title:
USNO-A V2.0, A Catalog of Astrometric Standards
Short Name:
usnoa2
Date:
17 Jun 2006 18:44:05
Publisher:
Sternberg Astronomical Institute Virtual Observatory Project
Description:
USNO-A2.0 is a catalog of 526,280,881 stars, and is based on a re-reduction of the Precision Measuring Machine (PMM) scans that were the basis for the USNO-A1.0 catalog. The major difference between A2.0 and A1.0 is that A1.0 used the Guide Star Catalog (Lasker et al. 1986, as its reference frame whereas A2.0 uses the ICRF as realized by the USNO ACT catalog (Urban et al. 1997).
16472. USNO-B Catalog ConeSearch
ID:
ivo://archive.stsci.edu/catalogs/USNOB
Title:
USNO-B Catalog ConeSearch
Short Name:
USNOB CS
Date:
13 Feb 2020 17:42:39
Publisher:
Space Telescope Science Institute Archive
Description:
USNO-B is an all-sky catalog that presents positions, proper motions, magnitudes in various optical passbands, and star/galaxy estimators for 1,042,618,261 objects derived from 3,643,201,733 separate observations. The data were obtained from scans of 7435 Schmidt plates taken for the various sky surveys during the last 50 years. USNO-B1.0 is believed to provide all-sky coverage, completeness down to V = 21, 0>2 astrometric accuracy at J2000, 0.3 mag photometric accuracy in up to five colors, and 85% accuracy for distinguishing stars from nonstellar objects. A more detailed description of the construction and contents of the USNO-B1 catalog can be found in Monet et al. (2003, "The USNO-B Catalog", AJ, 125, 984), http://www.usno.navy.mil/USNO/astrometry/optical-IR-prod/usno-b1.0/resolveuid/41be0c1a4d1a8372289bad3baf27cde5. A mirror of USNOB exists in the MAST holdings and is thus available as a cone search. All available catalogs are listed at http://archive.stsci.edu/vo/mast_services.html.
16473. USNO-B1 Catalogue
ID:
ivo://fs.usno/cat/usnob
Title:
USNO-B1 Catalogue
Short Name:
USNO-B1
Date:
03 Feb 2020 22:21:11
Publisher:
United States Naval Observatory, Flagstaff Station
Description:
USNO-B is an all-sky catalog that presents positions, proper motions, magnitudes in various optical passbands, and star/galaxy estimators for 1,042,618,261 objects derived from 3,643,201,733 separate observations. The data were obtained from scans of 7435 Schmidt plates taken for the various sky surveys during the last 50 years. USNO-B1.0 is believed to provide all-sky coverage, completeness down to V=21, 0.2" astrometric accuracy at J2000, 0.3 mag photometric accuracy in up to five colors, and 85% accuracy for distinguishing stars from nonstellar objects. A brief discussion of various issues is given here, but the actual data are available from the US Naval Observatory Web site and others.
16474. USNO Martian observations
ID:
ivo://CDS.VizieR/J/A+A/582/A36
Title:
USNO Martian observations
Short Name:
J/A+A/582/A36
Date:
21 Oct 2021
Publisher:
CDS
Description:
Accurate positional measurements of planets and satellites are used to improve their orbits, our knowledge of their dynamics and to infer the accuracy of the planet and satellite ephemerides. In the framework of the European FP7 ESPaCE program, we provide the positions of Mars, Phobos, and Deimos taken with the U.S. Naval Observatory 61-inch astrometric reflector and 26-inch refractor from 1967 to 1997. 425 astrophotographic plates were measured with the digitizer of the Royal Observatory of Belgium and reduced through an optimal process which includes image, instrumental, and spherical corrections using the UCAC4 catalog to provide the most accurate equatorial (RA, DEC) positions.
16475. USNO Photographic Parallaxes. I.
ID:
ivo://CDS.VizieR/J/AJ/103/638
Title:
USNO Photographic Parallaxes. I.
Short Name:
J/AJ/103/638
Date:
21 Oct 2021
Publisher:
CDS
Description:
The U.S. Naval Observatory CCD trigonometric parallax program is described in detail, including the instrumentation employed, observing procedures followed, and reduction procedures applied. Astrometric results are presented for 72 stars ranging in apparent brightness from V=15.16 to 19.58. Photometry (V and V-I on the Kron-Cousins system) is presented for the parallax stars and for all 426 individual reference stars employed in the astrometric solutions. Corrections for differential color refraction, calibrated to the observed V-I colors, have been applied to all astrometric measures. The mean errors in the relative parallaxes range from +/-0.0005" to +/-0.0027" with a median value of +/-0.0010". Seventeen of the 23 stars with V_tan_>200km/s form a well-delineated sequence of extreme subdwarfs covering 11.5<M_V_<14.5 in the M_V_ vs V-I diagram. The transformation to the M_bol_ vs log T_eff_ plane is presented and the results are compared with various model interior computations. Within the limitations due to the uncertain T_eff_ scale for cool dwarfs and subdwarfs, the coolest members of the extreme subdwarf sequence appear to be near the hydrogen-burning minimum mass limit for stars with metallicities of [M/H]~-2.
16476. USNO Photographic Parallaxes IX
ID:
ivo://CDS.VizieR/J/AJ/105/1571
Title:
USNO Photographic Parallaxes IX
Short Name:
J/AJ/105/1571
Date:
21 Oct 2021
Publisher:
CDS
Description:
Trigonometric parallaxes, relative proper motions, and photometry are presented for 122 stars in 111 systems. Of these stars, 70 are brighter than V = 10.0.
16477. USNO Saturnian observations 1974-1998
ID:
ivo://CDS.VizieR/J/A+A/596/A37
Title:
USNO Saturnian observations 1974-1998
Short Name:
J/A+A/596/A37
Date:
21 Oct 2021
Publisher:
CDS
Description:
Accurate positional measurements of planets and satellites are used to improve our knowledge of both their orbits and their dynamics and to infer the accuracy of the planet and satellite ephemerides. In the framework of the European FP7 ESPaCE program, we provide the positions of Saturn and its major satellites taken with the U.S. Naval Observatory 26-inch refractor from 1974 to 1998. 526 astrophotographic plates were measured with the digitizer of the Royal Observatory of Belgium and reduced through an optimal process that includes image, instrumental, and spherical corrections using the UCAC4 catalog to provide the most accurate equatorial (RA, DEC) positions.
16478. UTMOST pulsar timing programme. I.
ID:
ivo://CDS.VizieR/J/MNRAS/484/3691
Title:
UTMOST pulsar timing programme. I.
Short Name:
J/MNRAS/484/3691
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present an overview and the first results from a large-scale pulsar timing programme that is part of the UTMOST project at the refurbished Molonglo Observatory Synthesis Radio Telescope (MOST) near Canberra, Australia. We currently observe more than 400 mainly bright southern radio pulsars with up to daily cadences. For 205 (8 in binaries, 4 millisecond pulsars), we publish updated timing models, together with their flux densities, flux density variability, and pulse widths at 843 MHz, derived from observations spanning between 1.4 and 3 yr. In comparison with the ATNF pulsar catalogue, we improve the precision of the rotational and astrometric parameters for 123 pulsars, for 47 by at least an order of magnitude. The time spans between our measurements and those in the literature are up to 48 yr, which allow us to investigate their long-term spin-down history and to estimate proper motions for 60 pulsars, of which 24 are newly determined and most are major improvements. The results are consistent with interferometric measurements from the literature. A model with two Gaussian components centred at 139 and 463km/s fits the transverse velocity distribution best. The pulse duty cycle distributions at 50 and 10 per cent maximum are best described by lognormal distributions with medians of 2.3 and 4.4 per cent, respectively. We discuss two pulsars that exhibit spin-down rate changes and drifting subpulses. Finally, we describe the autonomous observing system and the dynamic scheduler that has increased the observing efficiency by a factor of 2-3 in comparison with static scheduling.
16479. UV absorption sight lines of LMC and SMC
ID:
ivo://CDS.VizieR/J/ApJ/745/173
Title:
UV absorption sight lines of LMC and SMC
Short Name:
J/ApJ/745/173
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have determined column densities of H I and/or H_2_ for sight lines in the Magellanic Clouds from archival Hubble Space Telescope and Far-Ultraviolet Spectroscopic Explorer spectra of H I Ly{alpha} and H_2_Lyman-band absorption. Together with some similar data from the literature, we now have absorption-based N(H I) and/or N(H_2_) for 285 Large Magellanic Cloud (LMC) and Small Magellanic Cloud (SMC) sight lines (114 with a detection or limit for both species) - enabling more extensive, direct, and accurate determinations of molecular fractions, gas-to-dust ratios, and elemental depletions in these two nearby, low-metallicity galaxies. For sight lines where the N(H I) estimated from 21 cm emission is significantly higher than the value derived from Ly{alpha} absorption (presumably due to emission from gas beyond the target stars), integration of the 21 cm profile only over the velocity range seen in Na I or H_2_absorption generally yields much better agreement. Conversely, N(21 cm) can be lower than N(Ly{alpha}) by factors of 2-3 in some LMC sight lines - suggestive of small-scale structure within the 21 cm beam(s) and/or some saturation in the emission. The mean gas-to-dust ratios obtained from N(H_tot_)/E(B-V) are larger than in our Galaxy, by factors of 2.8-2.9 in the LMC and 4.1-5.2 in the SMC - i.e., factors similar to the differences in metallicity. The N(H_2_)/E(B-V) ratios are more similar in the three galaxies, but with considerable scatter within each galaxy. These data may be used to test models of the atomic-to-molecular transition at low metallicities and predictions of N(H_2_) based on comparisons of 21 cm emission and the IR emission from dust.
16480. UV and FIR properties of nearby galaxies
ID:
ivo://CDS.VizieR/J/ApJS/164/38
Title:
UV and FIR properties of nearby galaxies
Short Name:
J/ApJS/164/38
Date:
21 Oct 2021
Publisher:
CDS
Description:
This work presents the main ultraviolet (UV) and far-infrared (FIR) properties of two samples of nearby galaxies selected from the GALEX ({lambda}=2315{AA}, hereafter NUV) and IRAS ({lambda}=60{mu}m) surveys, respectively. They are built in order to obtain detection at both wavelengths for most of the galaxies. Star formation rate (SFR) estimators based on the UV and FIR emissions are compared. Systematic differences are found between the SFR estimators for individual galaxies based on the NUV fluxes corrected for dust attenuation and on the total IR luminosity.

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