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- ID:
- ivo://CDS.VizieR/J/A+A/647/A167
- Title:
- Using H-bump to identify RSGs in NGC6822
- Short Name:
- J/A+A/647/A167
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a case study in which we used a novel method to identify red supergiant (RSG) candidates in NGC 6822 based on their 1.6um H-bump. We collected 32 bands of photometric data for NGC 6822 ranging from the optical to the mid-infrared (MIR), derived from Gaia, PS1, LGGS, VHS, UKIRT, IRSF, HAWK-I, Spitzer, and WISE. Using the theoretical spectra from MARCS, we demonstrate that there is a prominent difference around 1.6um (H-bump) between targets with high and low surface gravity (HSG and LSG). Taking advantage of this feature, we identify efficient color-color diagrams of rzH (r-z versus z-H) and rzK (r-z versus z-K) to separate HSG (mostly foreground dwarfs) and LSG targets (mainly background red giant stars, asymptotic giant branch stars, and RSGs) from crossmatching of optical and near-infrared (NIR) data. Moreover, synthetic photometry from ATLAS9 gives similar results. We further separated RSG candidates from the remaining LSG candidates as determined by the H-bump method by using semi-empirical criteria on NIR color-magnitude diagrams, where both the theoretic cuts and morphology of the RSG population are considered. This separation produced 323 RSG candidates. The simulation of foreground stars with Besancon models also indicates that our selection criteria are largely free from the contamination of Galactic giants. In addition to the H-bump method, we used the traditional BVR method (B-V versus V-R) as a comparison and/or supplement by applying a slightly aggressive cut to select as many RSG candidates as possible (358 targets). Furthermore, the Gaia astrometric solution was used to constrain the sample, where 181 and 193 targets were selected with the H-bump and BVR method, respectively. The percentages of selected targets in the two methods are similar at ~60%, indicating a comparable accuracy of the two methods. In total, there are 234 RSG candidates after combining targets from the two methods, and 140 (~60%) of them are in common. The final RSG candidates are in the expected locations on the mid-infrared color-magnitude diagram with [3.6]-[4.5]<~0 and J-[8.0]~1.0. The spatial distribution is also coincident with the far-ultraviolet-selected star formation regions, suggesting that the selection is reasonable and reliable. We indicate that our method can also be used to identify other LSG targets, such as red giants and asymptotic giant branch stars, and it can also be applied to most of the nearby galaxies by using recent large-scale ground-based surveys. Future ground- and space-based facilities may promote its application beyond the Local Group.
- ID:
- ivo://org.gavo.dc/tutreg/gavo_vocourse/rec
- Title:
- Using the Virtual Observatory
- Short Name:
- GAVO vo course
- Date:
- 03 Apr 2025 09:49:31
- Publisher:
- The GAVO DC team
- Description:
- This is a course on using the Virtual Observatory (VO), an international research data infrastructure in Astronomy and Astrophysics. Starting with a brief discussion of some general concepts, it introduces some of the major client programs like TOPCAT and Aladin, together with some simple discovery protocols. A first focus topic is the query language ADQL, which is treated within the equivalent of three lectures. The second major focus of the course is the premier Python interface to the VO, pyVO, which is used to also more deeply investigate the topics treated before. The course is complemented by a number of side tracks, brief discussions of more fundamental or more specialised VO topics. The course comes with many exercises, most of which also have solutions. We hope it is suitable for both self-study and as lecture notes in teacher-led situations. In the latter case, it is designed to work as a semester-long course with two hours of lectures and lab work each per week.
22614. US Naval Observatory B
- ID:
- ivo://sdss.jhu/openskynode/usnob
- Title:
- US Naval Observatory B
- Short Name:
- USNOB
- Date:
- 05 Dec 2018 20:07:20
- Publisher:
- US Naval Observatory
- Description:
- The USNO-B1.0 Catalogue presents positions, proper motions, magnitudes in various optical passbands, and star/galaxy estimators for 1,045,175,762 objects derived from 3,648,832,040 separate observations. The data were taken from scans of 7,435 Schmidt plates taken from various sky surveys during the last 50 years. The catalogue is expected to be complete down to V=21; the estimated accuracies are 0.2arcsec for the positions at J2000, 0.3mag in up to 5 colors, and 85% accuracy for distinguishing stars from non-stellar objects
- ID:
- ivo://CDS.VizieR/I/163
- Title:
- US Naval Observatory Pleiades Catalog
- Short Name:
- I/163
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This catalog is a special subset of the Eichhorn et al. (1970) Pleiades catalog (see <I/90>) updated to B1950.0 positions and with proper motions added. It was prepared for the purpose of predicting occultations of Pleiades stars by the Moon, but is useful for general applications because it contains many faint stars not present in the current series of large astrometric catalogs.
- ID:
- ivo://CDS.VizieR/I/157
- Title:
- U.S. Naval Observatory Zodiacal Zone Catalog
- Short Name:
- I/157
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The catalog provides positions and proper motions at equinox and epoch J2000.0, on the FK5 system, for stars in the magnitude range 4-10, lying within 16 degrees of the ecliptic and north of declination -30 degrees. In order that references to earlier catalogs can be made, the B1950.0 positions and proper motions are given in both the FK5 and the FK4 systems. Other useful information, such as visual magnitudes and spectral types, is also provided. Stellar identification is strictly by Durchmusterung number, and the catalog is ordered by J2000.0 right ascension. It is important to understand that the present catalog does not cover the entire zodiacal zone, since stars south of zone -29 degrees could not be observed from the Washington site. These will be observed from the USNO Black Birch station in New Zealand commencing in 1991.
22617. USNO-A2 Catalogue
- ID:
- ivo://fs.usno/cat/usnoa2
- Title:
- USNO-A2 Catalogue
- Short Name:
- USNO-A2
- Date:
- 03 Feb 2020 22:20:44
- Publisher:
- United States Naval Observatory, Flagstaff Station
- 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, see Cat. <I/220>) as its reference frame whereas A2.0 uses the ICRF as realized by the USNO ACT catalog (Urban et al. 1997, see Cat. II/246>). A2.0 presents right ascension and declination (J2000, epoch of the mean of the blue and red plate) and the blue and red magnitude for each star. Usage of the ACT catalog as well as usage of new astrometric and photometric reduction algorithms should provide improved astrometry (mostly in the reduction of systematic errors) and improved photometry (because the brightest stars on each plate had B and V magnitudes measured by the Tycho experiment on the Hipparcos satellite). The basic format of the catalog and its compilation is the same as for A1.0, and most users should be able to migrate to this newer version with minimal effort. (1 data file).
22618. 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.
22619. 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.
22620. 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.
