- ID:
- ivo://CDS.VizieR/J/A+A/580/A28
- Title:
- Astrometric observations of Phobos
- Short Name:
- J/A+A/580/A28
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Mars Express (MEX) carried out 74 Phobos flybys at distances between 669 and 5579km from April 2008 to August 2011. Images taken with the Super Resolution Channel (SRC) were used to determine the Martian moon's spacecraft-centered right ascension and declination. Image positions of Phobos were measured using the control point and limb fit measurement techniques. Camera pointing and pointing drift were controlled by means of background star observations that were compared to the corresponding positions from the Tycho-2 catalog. Blurred and noisy images were restored by applying an image-based point spread function in a Richardson-Lucy deconvolution. Altogether, we provide 158 astrometric observations of Phobos with estimated uncertainties between 0.224 and 3.405km circular about the direction to the satellite. Control point measurements yield more accurate results than limb fit observations.
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- ID:
- ivo://CDS.VizieR/J/other/PBeiO/32.87
- Title:
- Astrometric observations of radio stars
- Short Name:
- J/other/PBeiO/32
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using the data observed in San Juan with the photoelectric Astrolabe Mark II of the Beijing Astronomical Observatory from February, 1992 through March, 1997, the radio stars catalogue in San Juan (RSSJ95) has been compiled. There are 69 radio stars in this catalogue. The Positions of the radio stars are for the epoch of observation and the equinox J2000.0 and a system close that of the system FK5. The mean precisions are +/-2.2ms and +/-0.035" in right ascensions and declinations, respectively. The magnitudes of stars are from 0.9 to 10.7. The declinations are from -2.5{deg} to -60{deg}. The mean epoch is 1995.1. Finally, the comparison results with Hipparcos catalogue and CAMC are given.
- ID:
- ivo://CDS.VizieR/J/A+A/572/A104
- Title:
- Astrometric obs. of Phobos and Deimos in 1971
- Short Name:
- J/A+A/572/A104
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Accurate positional measurements of planets and satellites are used to improve our knowledge of their dynamics and to infer the accuracy of planet and satellite ephemerides. In the framework of the FP7 ESPaCE project, we provide positions of Mars, Phobos and Deimos taken with the U.S. Naval Observatory 26-inch refractor during the 1971 opposition of the planet. These plates were measured with the digitizer of the Royal Observatory of Belgium and reduced through an optimal process that includes image, instrumental and spherical corrections to provide the most accurate data.
- ID:
- ivo://CDS.VizieR/J/A+A/556/A133
- Title:
- Astrometric orbit of DENIS-P J082303.1-49120
- Short Name:
- J/A+A/556/A133
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Little is known about the existence of extrasolar planets around ultracool dwarfs. Furthermore, binary stars with Sun-like primaries and very low-mass binaries composed of ultracool dwarfs show differences in the distributions of mass ratio and orbital separation that can be indicative of distinct formation mechanisms. Using FORS2/VLT optical imaging for high precision astrometry we are searching for planets and substellar objects around ultracool dwarfs to investigate their multiplicity properties for very low companion masses. Here we report astrometric measurements with an accuracy of one tenth of a milli-arcsecond over two years that reveal orbital motion of the L1.5 dwarf DENIS-P J082303.1-491201 (having 7.5+/-1% of the Sun's mass) caused by a companion with a mass of 28+/-2 Jupiter masses that revolves about its host on an eccentric orbit in 246.4+/-1.4days. This new system is nearby at 20.77+/-0.08pc and has the smallest mass ratio (0.36+/-0.02) of known very low-mass binaries with a characterised orbit. With this discovery we demonstrate 100 micro-arcsecond astrometry over an arc-minute field and over several years that is sufficient to discover sub-Jupiter mass planets around ultracool dwarfs. We also show that the achieved parallax accuracy of <0.4% makes it possible to remove distance as a dominant source of uncertainty in the modelling of ultracool dwarfs.
- ID:
- ivo://CDS.VizieR/J/AJ/134/1916
- Title:
- Astrometric orbit of HR 6046
- Short Name:
- J/AJ/134/1916
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The previously known, 6yr single-lined spectroscopic binary HR 6046 has been speculated in the past to contain a compact object as the secondary. A recent study has redetermined the orbit with great accuracy and shown that the companion is an evolved but otherwise normal star of nearly identical mass to the primary, which is also a giant. The binary motion was detected by the Hipparcos mission but was not properly accounted for in the published astrometric solution. Here we use the Hipparcos intermediate data in combination with the spectroscopic results to revise that solution and establish the orbital inclination angle for the first time, and with it the absolute masses M_A_=1.38^+0.09^_-0.03_M_{sun}_ and M_B_=1.36^+0.07^_-0.02_M_{sun}_. Aided by other constraints, we investigate the evolutionary status and confirm that the primary star is approaching the tip of the red giant branch, while the secondary is beginning its first ascent.
- ID:
- ivo://CDS.VizieR/J/A+A/442/365
- Title:
- Astrometric orbits of SB9 stars
- Short Name:
- J/A+A/442/365
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Hipparcos Intermediate Astrometric Data (IAD) have been used to derive astrometric orbital elements for spectroscopic binaries from the newly released Ninth Catalogue of Spectroscopic Binary Orbits (S_B^9^_). This endeavour is justified by the fact that (i) the astrometric orbital motion is often difficult to detect without the prior knowledge of the spectroscopic orbital elements, and (ii) such knowledge was not available at the time of the construction of the Hipparcos Catalogue for the spectroscopic binaries which were recently added to the S_B^9^_ catalogue. Among the 1374 binaries from S_B^9^_ which have an HIP entry (excluding binaries with visual companions, or DMSA/C in the Double and Multiple Stars Annex), 282 have detectable orbital astrometric motion (at the 5% significance level). Among those, only 70 have astrometric orbital elements that are reliably determined (according to specific statistical tests), and for the first time for 20 systems. This represents a 8.5% increase of the number of astrometric systems with known orbital elements (The Double and Multiple Systems Annex contains 235 of those DMSA/O systems).
- ID:
- ivo://CDS.VizieR/J/A+A/642/A21
- Title:
- Astrometric parameters for 135 OB stars
- Short Name:
- J/A+A/642/A21
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Our goal is to better understand the origin and the star-formation history of regions NGC 6334 and NGC 6357. We focus our study on the young stars (young stellar objects and OB stars) kinematics in both regions using mainly Gaia-DR2 data. For both regions we compiled OB stars and young stellar objects catalogues from literature and we complemented them using VPHAS+ DR2 and Spitzer IRAC/GLIMPSE photometry catalogues. A cross-match is performed with the Gaia-DR2 catalogue in order to obtain the parallax and transverse motion information. We confirm that NGC 6334 and NGC 6357 are in the far side of the Saggitarius-Carina arm at a distance of 1.76kpc. For NGC 6357, OB stars show strong clustering and ordered star motion with Vlon~-10.7km/s and Vlat ~3.7km/s while for NGC 6334, no significant systemic motion is observed. The OB stars motions and distribution in NGC 6334 suggest to classify it as an association. Ten and two runaway candidates can be related to NGC 6357 and NGC 6334, respectively. The spatial distributions of the runaway candidates in and around NGC 6357 favor a dynamical (and early) ejection during the cluster(s) formation. Because such stars are likely to be ejected during cluster's formation the fact of not observing as many of such stars towards NGC 6334 suggest different formation conditions than for NGC 6357.
- ID:
- ivo://CDS.VizieR/J/AJ/158/159
- Title:
- Astrometric positions for (84922) 2003 VS2
- Short Name:
- J/AJ/158/159
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results from three world-wide campaigns that resulted in the detections of two single-chord and one multi-chord stellar occultations by the plutino object (84922) 2003 VS_2_. From the single-chord occultations in 2013 and 2014 we obtained accurate astrometric positions for the object, while from the multi-chord occultation on 2014 November 7, we obtained the parameters of the best-fitting ellipse to the limb of the body at the time of occultation. We also obtained short-term photometry data for the body in order to derive its rotational phase during the occultation. The rotational light curve present a peak-to-peak amplitude of 0.141+/-0.009 mag. This allows us to reconstruct the 3D shape of the body, with principal semi-axes of a=313.8+/-7.1 km, b=265.5_-9.8_^+8.8^ km, and c=247.3_-43.6_^+26.6^ km, which is not consistent with a Jacobi triaxial equilibrium figure. The derived spherical volume equivalent diameter of 548.3_-44.6_^+29.5^ km is about 5% larger than the radiometric diameter of 2003 VS_2_ derived from Herschel data of 523+/-35 km, but still compatible with it within error bars. From those results we can also derive the geometric albedo (0.123_-0.014_^+0.015^) and, under the assumption that the object is a Maclaurin spheroid, the density {rho}=1400_-300_^+1000^ for the plutino. The disappearances and reappearances of the star during the occultations do not show any compelling evidence for a global atmosphere considering a pressure upper limit of about 1 microbar for a pure nitrogen atmosphere, nor secondary features (e.g., rings or satellite) around the main body.
- ID:
- ivo://CDS.VizieR/J/other/KFNT/34.270
- Title:
- 2292 astrometric positions of asteroids
- Short Name:
- J/other/KFNT/34.
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- A catalogue of equatorial coordinates and magnitudes for 2162 asteroids and 11 comets was compiled based on the results of processing of digitized photographic observations of the northern sky performed in 1981-1985. The positions were compared with the JPL DE431 ephemeris. The mean (O-C)_RA,DE_ values for all positions obtained in this comparison are -0.08" and 0.04", and their root-mean-square errors are 0.70" and 0.64" in {alpha} and {delta}, respectively. It was found that the observations of 54 asteroids predate their discoveries, and the observations of four of them are the earliest known for these asteroids.
- ID:
- ivo://CDS.VizieR/J/A+A/510/A10
- Title:
- Astrometric positions of radio sources
- Short Name:
- J/A+A/510/A10
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We discuss the results of an investigation of astrometric positions of extragalactic radio sources from a list for the International Celestial Reference Frame.
