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51. Astrometric observations of radio stars
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.
52. Astrometric obs. of Phobos and Deimos in 1971
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.
53. Astrometric orbit of DENIS-P J082303.1-49120
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.
54. Astrometric orbit of HR 6046
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.
55. Astrometric positions for (84922) 2003 VS2
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.
56. 2292 astrometric positions of asteroids
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.
57. Astrometric positions of radio sources
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.
58. Astrometric study of ADS 48
ID:
ivo://CDS.VizieR/J/PAZh/27/456
Title:
Astrometric study of ADS 48
Short Name:
J/PAZh/27/456
Date:
21 Oct 2021
Publisher:
CDS
Description:
The series of relative positions of the hierarchical triple system ADS 48 ABF (AB=6",AF=327") obtained with the 26-inch Pulkovo refractor during 1961-1995 and measured with the Fantazia automated measuring system are analyzed.
59. 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.
60. 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.

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