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51. 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.
52. 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.
53. 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).
54. 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.
55. 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.
56. 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.
57. 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.
58. Astrometry of Pluto from 1930-1951 observations
ID:
ivo://CDS.VizieR/J/AJ/149/22
Title:
Astrometry of Pluto from 1930-1951 observations
Short Name:
J/AJ/149/22
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a new analysis of 843 photographic plates of Pluto taken by Carl Lampland at Lowell Observatory from 1930-1951. This large collection of plates contains useful astrometric information that improves our knowledge of Pluto's orbit. This improvement provides critical support to the impending flyby of Pluto by New Horizons. New Horizons can do inbound navigation of the system to improve its targeting. This navigation is capable of nearly eliminating the sky-plane errors but can do little to constrain the time of closest approach. Thus the focus on this work was to better determine Pluto's heliocentric distance and to determine the uncertainty on that distance with a particular eye to eliminating systematic errors that might have been previously unrecognized. This work adds 596 new astrometric measurements based on the USNO CCD Astrograph Catalog 4. With the addition of these data the uncertainty of the estimated heliocentric position of Pluto in Developmental Ephemerides 432 (DE432) is at the level of 1000km. This new analysis gives us more confidence that these estimations are accurate and are sufficient to support a successful flyby of Pluto by New Horizons.
59. Astrometry of the 5 largest Uranian sat.
ID:
ivo://CDS.VizieR/J/other/PSS/210.1
Title:
Astrometry of the 5 largest Uranian sat.
Short Name:
J/other/PSS/210.
Date:
14 Dec 2021 08:12:44
Publisher:
CDS
Description:
We present the astrometry of the five largest satellites of Uranus from observations spread over almost three decades with photographic plates and CCDs (mainly), taken at the Pico dos Dias Observatory - Brazil. All positions presented here are obtained from the reanalysis of measurements and images used in previous publications. Reference stars are those from the Gaia Early Data Release 3 (Gaia EDR3) allowing, in addition to a higher accuracy, a larger number of positions of the largest satellites as compared to our previous works. From 1982 to 1987, positions were obtained from photographic plates. From 1989 to 2011, CCDs were used. On average, we obtained {Delta}{alpha}cos{delta}=-11(+/-52) milli-arcseconds and {delta}{delta}=-14 (+/-43) milli-arcseconds for the differences in the sense observation minus ephemerides (DE435+ura111). Comparisons with different ephemerides (DE440, INPOP21a, INPOP19a and NOE-7-2013-MAIN) and results from stellar occultations indicate a possible offset in the (Solar System) barycentric position of the Uranian system barycenter. Overall, our results are useful to improve dynamical models of the Uranian largest satellites as well as the orbit of Uranus.
60. Astrometry of the main satellites of Uranus
ID:
ivo://CDS.VizieR/J/A+A/582/A8
Title:
Astrometry of the main satellites of Uranus
Short Name:
J/A+A/582/A8
Date:
21 Oct 2021
Publisher:
CDS
Description:
We determine accurate positions of the main satellites of Uranus: Miranda, Ariel, Umbriel, Titania, and Oberon. Positions of Uranus, as derived from those of these satellites, are also determined. The observational period spans from 1992 to 2011. All runs were made at the Pico dos Dias Observatory, Brazil. We used the software called Platform for Reduction of Astronomical Images Automatically (PRAIA) to perform a digital coronography to minimise the influence of the scattered light of Uranus on the astrometric measurements and to determine accurate positions of the main satellites. The positions of Uranus were then indirectly determined by computing the mean differences between the observed and ephemeris positions of these satellites. A series of numerical filters was applied to filter out spurious data. These filters are mostly based on (a) the comparison between the positions of Oberon with those of the other satellites and on (b) the offsets as given by the differences between the observed and ephemeris positions of all satellites. We have, for the overall offsets of the five satellites, -29mas (+/-63mas) in right ascension and -27mas (+/-46mas) in declination. For the overall difference between the offsets of Oberon and those of the other satellites, we have +3mas (+/-30mas) in right ascension and -2mas (+/-28mas) in declination. Ephemeris positions for the satellites were determined from DE432+ura111.

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