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461. Spitzer follow up of 95 brown dwarfs
ID:
ivo://CDS.VizieR/J/ApJ/899/123
Title:
Spitzer follow up of 95 brown dwarfs
Short Name:
J/ApJ/899/123
Date:
14 Mar 2022 07:05:10
Publisher:
CDS
Description:
We present Spitzer follow-up imaging of 95 candidate extremely cold brown dwarfs discovered by the Backyard Worlds: Planet 9 citizen science project, which uses visually perceived motion in multiepoch Wide-field Infrared Survey Explorer (WISE) images to identify previously unrecognized substellar neighbors to the Sun. We measure Spitzer [3.6]-[4.5] color to phototype our brown dwarf candidates, with an emphasis on pinpointing the coldest and closest Y dwarfs within our sample. The combination of WISE and Spitzer astrometry provides quantitative confirmation of the transverse motion of 75 of our discoveries. Nine of our motion-confirmed objects have best-fit linear motions larger than 1"/yr; our fastest-moving discovery is WISEAJ155349.96+693355.2 ({mu}~2.15/yr), a possible T-type subdwarf. We also report a newly discovered wide-separation (~400au) T8 comoving companion to the white dwarf LSPMJ0055+5948 (the fourth such system to be found), plus a candidate late T companion to the white dwarf LSRJ0002+6357 at 5.5 projected separation (~8700au if associated). Among our motion-confirmed targets, five have Spitzer colors most consistent with spectral type Y. Four of these five have exceptionally red Spitzer colors suggesting types of Y1 or later, adding considerably to the small sample of known objects in this especially valuable low-temperature regime. Our Y dwarf candidates begin bridging the gap between the bulk of the Y dwarf population and the coldest known brown dwarf.
462. SPM Catalog 2.0
ID:
ivo://CDS.VizieR/I/277
Title:
SPM Catalog 2.0
Short Name:
I/277
Date:
21 Oct 2021
Publisher:
CDS
Description:
The SPM Catalog 2.0 provides positions, absolute proper motions and photographic BV photometry for over 320,000 stars and galaxies. The Catalog covers an area of ~3700 square degrees in an irregularly bounded band between declinations of -43 and -22 degrees, with a slight extension near the South Galactic Pole, but excluding fields in the plane of the Milky Way. Stars cover the magnitude range 5<V<18.5. The standard errors for the best measured stars are as follows: 20 mas for positions in each coordinate; 2mas/yr for absolute proper motions and 0.05mag for B and V magnitudes. Standard error estimates of positions, absolute proper motions and magnitudes are given for each individual object. In addition to the Catalog, a list of CCD calibrating sequences is provided. Note that all fields (and objects) contained in the 1.0 version of the Catalog are also included in this version. The values of the astrometric parameters for these objects, however, may be different due to refinements in the reduction procedure, (i.e. the SGP fields were re-reduced for inclusion in the SPM catalog 2.0).
463. SPM 4.0 Catalog
ID:
ivo://CDS.VizieR/I/320
Title:
SPM 4.0 Catalog
Short Name:
I/320
Date:
21 Oct 2021
Publisher:
CDS
Description:
The SPM4 Catalog contains absolute proper motions, celestial coordinates, and B,V photometry for 103,319,647 stars and galaxies between the south celestial pole and -20 degrees declination. The catalog is roughly complete to V=17.5. It is based on photographic and CCD observations taken with the Yale Southern Observatory's double-astrograph at Cesco Observatory in El Leoncito, Argentina. The first-epoch survey, taken from 1965 to 1979, was entirely photographic. The second-epoch survey is approximately 1/3 photographic (taken from 1988 to 1998) and 2/3 CCD-based (taken from 2004 through 2008). Full details about the creation of the SPM4.0 catalog can be found in the paper, and also in the document "spm4_doc.txt" file which describes the original files, accessible from http://www.astro.yale.edu/astrom/spm4cat/
464. Stability of VLBI reference frame
ID:
ivo://CDS.VizieR/J/A+A/375/661
Title:
Stability of VLBI reference frame
Short Name:
J/A+A/375/661
Date:
21 Oct 2021
Publisher:
CDS
Description:
The file table 2 gives the results of various tests and noise measurements performed on time serie of extragalactic radio source coordinates. Systematic and random behaviours in time serie of individual determinations of cooordinates for 283 sources over 1987-1999 are investigated. The random variability of the source coordinates is characterized by the {chi}^2^ test (Bevington, 1969, p.187) and the "goodness of fit (gof)" (Bevington, 1969, p.188). The Allan variance method (Allan, 1966, Proc. IEEE, vol. 54, 221) is used to investigate spectral characteristics of the time series. The source structure index (Fey & Charlot, 1997ApJS..111...95F, 2000, Cat. <J/ApJS/128/17>) qualifies the level of position disturbance expected at the date of the map (1 for the less disturbed, 4 for the most disturbed). The estimation of "linear rates" in the coordinates is a qualifier of the systematic parts of the source instability. This table contains the 283 best observed sources and is divided in three parts, with the left hand side giving general information and counts, the middle part giving statistics in the source local frame, and the right hand side giving statistics in the equatorial frame.
465. Standard errors for PPM and Tycho stars
ID:
ivo://CDS.VizieR/J/other/RoAJ/10.51
Title:
Standard errors for PPM and Tycho stars
Short Name:
J/other/RoAJ/10.
Date:
21 Oct 2021
Publisher:
CDS
Description:
The connection between the optical reference frame and the radio one constitutes one of the main purposes of the astrometry. The paper is pointing out the contribution of the Bucharest Observatory in this direction. The statistic analysis of the standard errors for the astrometric PPM and TYCHO stars is presented.
466. Star catalogue of Hevelius (1690)
ID:
ivo://CDS.VizieR/J/A+A/516/A29
Title:
Star catalogue of Hevelius (1690)
Short Name:
J/A+A/516/A29
Date:
21 Oct 2021
Publisher:
CDS
Description:
The catalogue by Johannes Hevelius with the positions and magnitudes of 1564 entries was published by his wife Elisabeth Koopman in 1690. We provide a machine-readable version of the catalogue, and briefly discuss its accuracy on the basis of comparison with data from the modern Hipparcos Catalogue. We compare our results with an earlier analysis by Rybka (1984), finding good overall agreement. The magnitudes given by Hevelius correlate well with modern values. The accuracy of his position measurements is similar to that of Brahe, with error distributions with widths of about 2 arcmin for longitudes and latitudes, but with more errors larger than 5 arcmin than expected for a Gaussian distribution. The position accuracy decreases slowly with magnitude. The fraction of stars with position errors larger than a degree is 1.5 per cent, rather smaller than the fraction of 5 per cent in the star catalogue of Brahe.
467. Star catalogue of Tycho Brahe (1627)
ID:
ivo://CDS.VizieR/J/A+A/516/A28
Title:
Star catalogue of Tycho Brahe (1627)
Short Name:
J/A+A/516/A28
Date:
21 Oct 2021
Publisher:
CDS
Description:
Tycho Brahe completed his catalogue with the positions and magnitudes of 1004 fixed stars in 1598. This catalogue circulated in manuscript form. Brahe edited a shorter version with 777 stars, printed in 1602, and Kepler edited the full catalogue of 1004 stars, printed in 1627. We provide machine-readable versions of the three versions of the catalogue, describe the differences between them and briefly discuss their accuracy on the basis of comparison with modern data from the Hipparcos Catalogue. We also compare our results with earlier analyses by Dreyer (1916Obs....39..127D, On Tycho Brahe's manual of trigonometry) and Rawlins (1993BAAS...25.1335R, Atmospheric Clarity and Tycho's Fake Stars), finding good overall agreement. The magnitudes given by Brahe correlate well with modern values, his longitudes and latitudes have error distributions with widths of 2-arcmin, with excess numbers of stars with larger errors (as compared to Gaussian distributions), in particular for the faintest stars. Errors in positions larger than about 10-arcmin, which comprise about 15 per cent of the entries, are likely due to computing or copying errors.
468. Star catalogues of Ptolemaios, Ulugh Beg
ID:
ivo://CDS.VizieR/J/A+A/544/A31
Title:
Star catalogues of Ptolemaios, Ulugh Beg
Short Name:
J/A+A/544/A31
Date:
21 Oct 2021
Publisher:
CDS
Description:
In late antiquity and throughout the middle ages, the positions of stars on the celestial sphere were obtained from the star catalogue of Ptolemaios. A catalogue based on new measurements appeared in 1437, with positions by Ulugh Beg, and magnitudes from the 10th-century astronomer al-Sufi. We provide machine-readable versions of these two star catalogues, based on the editions by Toomer (1998) and Knobel (1917), and determine their accuracies by comparison with the modern Hipparcos Catalogue. The magnitudes in the catalogues correlate well with modern visual magnitudes; the indication `faint' by Ptolemaios is found to correspond to his magnitudes 5 and 6. Gaussian fits to the error distributions in longitude/latitude give widths sigma ~27-arcmin/23-arcmin in the range |{Delta}{lambda},{Delta}{beta}|<50-arcmin for Ptolemaios and {sigma}~22-arcmin/18-arcmin\ in Ulugh Beg. Fits to the range |{Delta}{lambda},{Delta}{beta}<100-arcmin gives 10-15 per cent larger widths, showing that the error distributions are broader than gaussians. The fraction of stars with positions wrong by more than 150-arcmin is about 2 per cent for Ptolemaios and 0.1 percent in Ulugh Beg; the numbers of unidentified stars are 1 in Ptolemaios and 3 in Ulugh Beg. These numbers testify to the excellent quality of both star catalogues (as edited by Toomer and Knobel).
469. Star kinematics catalog in 19 Kapteyn's areas
ID:
ivo://CDS.VizieR/J/PAZh/23/931
Title:
Star kinematics catalog in 19 Kapteyn's areas
Short Name:
J/PAZh/23/931
Date:
21 Oct 2021
Publisher:
CDS
Description:
1214 individual measurements of radial velocities made with CORAVEL-type spectrometer (Tokovinin, 1987AZh....64..196T) are presented for 1134 stars in 19 northern Kapteyn's areas. Precise coordinates are given for all these stars. Proper motions of stars are taken from NLTT (Luyten, 1979, Cat. <I/98>), PPM (Roser, Bastian, 1991, Cat. <I/146> and <I/193>), NPM1 (Klemola, Hanson, Jones, 1987, Cat. <I/200>) and Four-million catalog (Kuimov, 1992, In: On the four-million catalog of stars, eds. Izd. MGU, Moscow, P.27.; Glushkova et al., 1996PAZh...22..850G). A list of suspected binary stars and stars with variable radial velocities is also given. Two-dimensional spectral classification for these area is available (Bartaya, 1979AbaOB..51....1B).
470. Star positions in 14 southern galactic clusters
ID:
ivo://CDS.VizieR/J/A+AS/53/181
Title:
Star positions in 14 southern galactic clusters
Short Name:
J/A+AS/53/181
Date:
21 Oct 2021
Publisher:
CDS
Description:
Positions for a total of 3487 stars, scattered over 14 regions, have been determined using the Danish 1.5-m telescope at La Silla. The 14 regions are centred on one of the southern galactic clusters NGC 1981, 2287, 2437, 2451, 2516, 2546, 2547, 2548, 3114, 3532, IC 2391, 2395, 2602 and Trumpler 10. Combining the Ritchey-Chretien reflector optics with a single element Schmidt-type corrector, gives a considerably enlarged flat field (radius about 25 minutes of arc, or 95mm) with stellar images of excellent definition. With the exception of distortion, which can be allowed for, the effect of the primary aberrations is negligible. A frame of reference has been established for each region using ESO Schmidt plates centred on the clusters, each plate containing from 20 to 35 measurable Perth 70 stars. These objects have served for determining positions of some 200 to 400 fainter stars within a central field of 25 minutes of arc radius, covering the corresponding 1.5-m plates. The fainter stars serve as a secondary standard. Based on three 1.5-m plates for each region, taken on different nights, an internal mean error in one plate position in the range 0.030 to 0.048 seconds of arc has been derived.

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