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1101. Astrometry and photometry of UCAC4 double stars
ID:
ivo://CDS.VizieR/J/AJ/146/76
Title:
Astrometry and photometry of UCAC4 double stars
Short Name:
J/AJ/146/76
Date:
21 Oct 2021
Publisher:
CDS
Description:
The newly completed Fourth USNO CCD Astrographic Catalog (UCAC4) has proven to be a rich source of double star astrometry and photometry. Following initial comparisons of UCAC4 results against those obtained by speckle interferometry, the UCAC4 catalog was matched against known double stars in the Washington Double Star Catalog in order to provide additional differential astrometry and photometry for these pairs. Matches to 58131 pairs yielded 61895 astrometric and 68935 photometric measurements. Finally, a search for possible new common proper motion (CPM) pairs was made using new UCAC4 proper motion data; this resulted in 4755 new potential CPM doubles (and an additional 27718 astrometric and photometric measures from UCAC and other sources).
1102. Astrometry around RX J0720.4-3125
ID:
ivo://CDS.VizieR/J/ApJ/660/1428
Title:
Astrometry around RX J0720.4-3125
Short Name:
J/ApJ/660/1428
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have used a set of dedicated astrometric data from the Hubble Space Telescope to measure the parallax and proper motion of the nearby neutron star RX J0720.4-3125. At each of eight epochs over 2 years, we used the High Resolution Camera of the Advanced Camera for Surveys to measure the position of the B=26.6 target to a precision of ~2mas (~0.07pix) relative to 22 other stars. From these data we measure a parallax of plx=2.8+/-0.9mas (for a distance of 360^+170^_-90_pc) and a proper motion of mu=107.8+/-1.2mas/yr. Exhaustive testing of every stage of our analysis suggests that it is robust, with a maximum systematic uncertainty on the parallax of 0.4mas. The distance is compatible with earlier estimates made from scaling the optical emission of RX J0720.4-3125 relative to the even closer neutron star RX J1856.5-3754. The distance and proper motion imply a transverse velocity of 180^+90^_-40_km/s, comparable to velocities observed for radio pulsars. The speed and direction suggest an origin for RX J0720.4-3125 in the Trumpler 10 OB association ~0.7Myr ago, with a possible range of 0.5-1.0Myr given by the uncertainty in the distance.
1103. Astrometry for 14 debris disk stars with SPHERE
ID:
ivo://CDS.VizieR/J/AJ/161/78
Title:
Astrometry for 14 debris disk stars with SPHERE
Short Name:
J/AJ/161/78
Date:
21 Oct 2021
Publisher:
CDS
Description:
Debris disk stars are good targets for high-contrast imaging searches for planetary systems, since debris disks have been shown to have a tentative correlation with giant planets. We selected 20 stars identified as debris disk hosts by the WISE mission, with particularly high levels of warm dust. We observed these with the VLT/SPHERE high-contrast imaging instrument with the goal of finding planets and imaging the disks in scattered light. Our survey reaches a median 5{sigma} sensitivity of 10.4MJ at 25au and 5.9MJ at 100au. We identified three new stellar companions (HD18378B, HD19257B, and HD133778B): two are mid-M-type stars and one is a late-K or early-M star. Three additional stars have very widely separated stellar companions (all at >2000au) identified in the Gaia catalog. The stars hosting the three SPHERE-identified companions are all older (>~700Myr), with one having recently left the main sequence and one a giant star. We infer that the high volumes of dust observed around these stars has been caused by a recent collision between the planets and planetesimal belts in the system, although for the most evolved star, mass loss could also be responsible for the infrared excess. Future mid-infrared spectroscopy or polarimetric imaging may allow the positions and spatial extent of these dust belts to be constrained, thereby providing evidence as to the true cause of the elevated levels of dust around these old systems. None of the disks in this survey is resolved in scattered light.
1104. Astrometry in the Galactic Center
ID:
ivo://CDS.VizieR/J/ApJ/725/331
Title:
Astrometry in the Galactic Center
Short Name:
J/ApJ/725/331
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present significantly improved proper motion measurements of the Milky Way's central stellar cluster. These improvements are made possible by refining our astrometric reference frame with a new geometric optical distortion model for the W. M. Keck II 10m telescope's adaptive optics camera (NIRC2) in its narrow field mode. For the first time, this distortion model is constructed from on-sky measurements and is made available to the public in the form of FITS files. When applied to widely dithered images, it produces residuals in the separations of stars that are a factor of ~3 smaller compared with the outcome using previous models. By applying this new model, along with corrections for differential atmospheric refraction, to widely dithered images of SiO masers at the Galactic center (GC), we improve our ability to tie into the precisely measured radio Sgr A*-rest frame. The resulting infrared reference frame is ~2-3 times more accurate and stable than earlier published efforts. In this reference frame, Sgr A* is localized to within a position of 0.6mas and a velocity of 0.09mas/yr, or ~3.4km/s at 8kpc (1{sigma}). Also, proper motions for members of the central stellar cluster are more accurate, although less precise, due to the limited number of these wide field measurements. We define a reference frame with SiO masers and this reference frame's stability should improve steadily with future measurements of the SiO masers in this region ({propto}t^-3/2^). This is essential for achieving the necessary reference frame stability required to detect the effects of general relativity and extended mass on short-period stars at the GC.
1105. Astrometry of globular clusters (47 Tuc)
ID:
ivo://CDS.VizieR/J/A+AS/93/293
Title:
Astrometry of globular clusters (47 Tuc)
Short Name:
J/A+AS/93/293
Date:
21 Oct 2021
Publisher:
CDS
Description:
The study determines relative proper motions for stars brighter than 17.0mag in a 1.5x1.5{deg} field centered on the globular cluster 47 Tuc (NGC 104). Proper motion and membership probabilities are tabulated for 3076 stars within 32 arcmin of the cluster center. A proper motion of 47 Tuc relative to the SMC is derived, which relies on the assumption that the mean proper motion of field stars is the same as that in the nearby field of NGC 362, and on the detection of SMC stars in that field. The resulting space motion confirms the membership of 47 Tuc in the rapidly rotating, flattened, metal-rich disk subgroup of the galactic cluster system. Relative proper motions for stars centered on the globular cluster NGC 362 are determined. NGC 362 is found to exhibit a highly eccentric orbit, typical for a member of the halo subgroup of the galactic globular cluster system. The perigalactic distance of NGC 362 is very small (less than about 1kpc).
1106. Astrometry of minor planets in 2003
ID:
ivo://CDS.VizieR/J/other/CoSka/35.45
Title:
Astrometry of minor planets in 2003
Short Name:
J/other/CoSka/35
Date:
21 Oct 2021
Publisher:
CDS
Description:
The paper presents the results of position determination of minor planets carried out at the Skalmate Pleso Observatory in the year 2003. 108 CCD observations of 16 minor planets are given together with the list of reference stars.
1107. Astrometry of (486958) 2014 MU_69_ with HST
ID:
ivo://CDS.VizieR/J/AJ/156/20
Title:
Astrometry of (486958) 2014 MU_69_ with HST
Short Name:
J/AJ/156/20
Date:
21 Oct 2021
Publisher:
CDS
Description:
NASA's New Horizons spacecraft will conduct a close flyby of the cold-classical Kuiper Belt Object (KBO) designated (486958) 2014 MU69 on 2019 January 1. At a heliocentric distance of 44 au, "MU69" will be the most distant object ever visited by a spacecraft. To enable this flyby, we have developed an extremely high-precision orbit fitting and uncertainty processing pipeline, making maximal use of the Hubble Space Telescope's Wide Field Camera 3 (WFC3) and pre-release versions of the ESA Gaia Data Release 2 (DR2) catalog. This pipeline also enabled successful predictions of a stellar occultation by MU69 in 2017 July. We describe how we process the WFC3 images to match the Gaia DR2 catalog, extract positional uncertainties for this extremely faint target (typically 140 photons per WFC3 exposure), and translate those uncertainties into probability distribution functions for MU69 at any given time. We also describe how we use these uncertainties to guide New Horizons, plan stellar occultions of MU69, and derive MU69's orbital evolution and long-term stability.
1108. Astrometry of outer Jovian satellites
ID:
ivo://CDS.VizieR/J/A+AS/115/295
Title:
Astrometry of outer Jovian satellites
Short Name:
J/A+AS/115/295
Date:
21 Oct 2021
Publisher:
CDS
Description:
In the course of The Uppsala-ESO Survey of Asteroids and Comets astrometric positions of the faint outer Jovian satellites J VI-XIII were obtained from photographic plates and films taken at the European Southern Observatory, La Silla, Chile and at the Anglo-Australian Observatory, Siding Spring, Australia
1109. Astrometry of Pluto and Saturn in 1995-2001
ID:
ivo://CDS.VizieR/J/A+A/383/1054
Title:
Astrometry of Pluto and Saturn in 1995-2001
Short Name:
J/A+A/383/1054
Date:
21 Oct 2021
Publisher:
CDS
Description:
In this work, we publish astrometric positions of Pluto and satellites of Saturn obtained with the Bordeaux and Valinhos CCD meridian circles. These observations are used to test the DE403 and DE405 ephemerides.
1110. Astrometry of Pluto and trans-Neptunian objects
ID:
ivo://CDS.VizieR/J/AJ/152/80
Title:
Astrometry of Pluto and trans-Neptunian objects
Short Name:
J/AJ/152/80
Date:
21 Oct 2021
Publisher:
CDS
Description:
We use astrometry of Pluto and other trans-neptunian objects to constrain the sky location, distance, and mass of the possible additional planet (Planet Nine) hypothesized by Batygin & Brown. We find that over broad regions of the sky, the inclusion of a massive, distant planet degrades the fits to the observations. However, in other regions, the fits are significantly improved by the addition of such a planet. Our best fits suggest a planet that is either more massive or closer than argued for by Batygin & Brown based on the orbital distribution of distant trans-neptunian objects (or by Fienga et al. based on range measured to the Cassini spacecraft). The trend to favor larger and closer perturbing planets is driven by the residuals to the astrometry of Pluto, remeasured from photographic plates using modern stellar catalogs, which show a clear trend in decl. over the course of two decades, that drive a preference for large perturbations. Although this trend may be the result of systematic errors of unknown origin in the observations, a possible resolution is that the decl. trend may be due to perturbations from a body, in addition to Planet Nine, that is closer to Pluto but less massive than Planet Nine.

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