- 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.
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/475/1725
- Title:
- Astrometry of double stars measured in 2011
- Short Name:
- J/MNRAS/475/1725
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present speckle interferometric measurements of binary stars performed during 2011 February and April with the 1.5-m telescope and during 2011 July and November with the 2.1-m telescope of the Observatorio Astronomico Nacional, San Pedro Martir, Mexico, focusing on objects from the Washington Double Star Catalog with separations less than 1 arcsec. Among these objects, we have been interested in performing a follow-up observation of new double stars discovered by Hipparcos. For these observations, we developed a new detector, which is a combination of CCD Watec 120N with a third generation image intensifier. This image intensifier allows us to perform near-infrared speckle interferometric observations for the first time. In this paper, we report 761 astrometric measurements of 478 pairs, with angular separations ranging from 0.09 to 2.61-arcsec. We found that 722 of our measured separations are smaller than 1-arcsec. We estimated a mean error in separation of 16mas and 1.29{deg} in position angle. In order to overcome the usual 180{deg} ambiguity inherent to speckle measurements, we created a shift-and-add reconstructed image of each source, to establish the true quadrant of the secondary star. We confirmed 40 double stars discovered by Hipparcos and found 4 field stars resolved as interferometric pairs for the first time, with separations smaller than 0.60-arcsec.
- 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).
- 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.
- 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.
- 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
- 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.
- 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.
- 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.
- ID:
- ivo://CDS.VizieR/J/A+AS/130/77
- Title:
- Astrometry of Satellites of Uranus
- Short Name:
- J/A+AS/130/77
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Table7 contains standard Co-ordinates (J2000.0) in arcseconds relative to the reference satellite. The numbers of the satellites 1-5 correspond to the conventional designation of the satellites I-V.
