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231. WISE/NEOWISE NEOs preliminary thermal fits
ID:
ivo://CDS.VizieR/J/ApJ/760/L12
Title:
WISE/NEOWISE NEOs preliminary thermal fits
Short Name:
J/ApJ/760/L12
Date:
21 Oct 2021
Publisher:
CDS
Description:
Enhancements to the science data processing pipeline of NASA's Wide-field Infrared Survey Explorer (WISE) mission, collectively known as NEOWISE, resulted in the detection of >158000 minor planets in four infrared wavelengths during the fully cryogenic portion of the mission. Following the depletion of its cryogen, NASA's Planetary Science Directorate funded a four-month extension to complete the survey of the inner edge of the Main Asteroid Belt and to detect and discover near-Earth objects (NEOs). This extended survey phase, known as the NEOWISE Post-Cryogenic Survey, resulted in the detection of ~6500 large Main Belt asteroids and 86 NEOs in its 3.4 and 4.6{mu}m channels. During the Post-Cryogenic Survey, NEOWISE discovered and detected a number of asteroids co-orbital with the Earth and Mars, including the first known Earth Trojan. We present preliminary thermal fits for these and other NEOs detected during the 3-Band Cryogenic and Post-Cryogenic Surveys.
232. WISE/NEOWISE observations of Hilda asteroids
ID:
ivo://CDS.VizieR/J/ApJ/744/197
Title:
WISE/NEOWISE observations of Hilda asteroids
Short Name:
J/ApJ/744/197
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the preliminary analysis of 1023 known asteroids in the Hilda region of the solar system observed by the NEOWISE component of the Wide-field Infrared Survey Explorer (WISE). The sizes of the Hildas observed range from ~3 to 200km. We find no size-albedo dependency as reported by other projects. The albedos of our sample are low, with a weighted mean value of p_V_=0.055+/-0.018, for all sizes sampled by the NEOWISE survey. We observed a significant fraction of the objects in the two known collisional families in the Hilda population. It is found that the Hilda collisional family is brighter, with a weighted mean albedo of p_V_=0.061+/-0.011, than the general population and dominated by D-type asteroids, while the Schubart collisional family is darker, with a weighted mean albedo of p_V_=0.039+/-0.013. Using the reflected sunlight in the two shortest WISE bandpasses, we are able to derive a method for taxonomic classification of ~10% of the Hildas detected in the NEOWISE survey. For the Hildas with diameter larger than 30km, there are 67^+7^_-15_% D-type asteroids and 26^+17^_-5_% C-/P-type asteroids (with the majority of these being P-types).
233. WISE/NEOWISE observations of main belt asteroids
ID:
ivo://CDS.VizieR/J/ApJ/759/L8
Title:
WISE/NEOWISE observations of main belt asteroids
Short Name:
J/ApJ/759/L8
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present preliminary diameters and albedos for 13511 Main Belt asteroids (MBAs) that were observed during the 3-Band Cryo phase of the Wide-field Infrared Survey Explorer (WISE; after the outer cryogen tank was exhausted) and as part of the NEOWISE Post-Cryo Survey (after the inner cryogen tank was exhausted). With a reduced or complete loss of sensitivity in the two long wavelength channels of WISE, the uncertainty in our fitted diameters and albedos is increased to ~20% for diameter and ~40% for albedo. Diameter fits using only the 3.4 and 4.6 {mu}m channels are shown to be dependent on the literature optical H absolute magnitudes. These data allow us to increase the number of size estimates for large MBAs which have been identified as members of dynamical families. We present thermal fits for 14 asteroids previously identified as the parents of a dynamical family that were not observed during the fully cryogenic mission.
234. W1J00 and W2J00 Transit Circle Catalogs
ID:
ivo://CDS.VizieR/I/334
Title:
W1J00 and W2J00 Transit Circle Catalogs
Short Name:
I/334
Date:
21 Oct 2021
Publisher:
CDS
Description:
W1J00. We present the result of observations made with the Six-inch Transit Circle in Washington, D.C., between September 1977 and July 1982. The catalog, called W1J00, contains mean positions of 7267 stars, all but five are north of -30 degrees declination, and 4383 observations of solar system objects. Positions of stars are for mean epoch of observation, on equator and equinox J2000.0. Positions of solar system objects are apparent places. Error estimates are about 100mas per coordinate for the majority of stars. W2J00. We present the result of observations made with the Six-inch Transit Circle in Washington, D.C. and the Seven-inch Transit Circle at the Black Birch station near Blenheim, New Zealand between April 1985 and February 1996. The catalog, called W2J00, contains mean positions of 44,395 globally distributed stars, 5048 observations of the planets, and 6518 observations of the brighter minor planets. Positions of stars are for mean epoch of observation, on equator and equinox J2000.0. Positions of solar system objects are apparent places. Error estimates are about 75mas per coordinate for the majority of stars.
235. Yarkovsky drift measurements for NEAs
ID:
ivo://CDS.VizieR/J/AJ/159/92
Title:
Yarkovsky drift measurements for NEAs
Short Name:
J/AJ/159/92
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Yarkovsky effect is a thermal process acting upon the orbits of small celestial bodies, which can cause these orbits to slowly expand or contract with time. The effect is subtle (<da/dt>~10^-4^au/My for a 1km diameter object) and is thus generally difficult to measure. We analyzed both optical and radar astrometry for 600 Near-Earth Asteroids (NEAs) for the purpose of detecting and quantifying the Yarkovsky effect. We present 247 NEAs with measured drift rates, which is the largest published set of Yarkovsky detections. This large sample size provides an opportunity to examine the Yarkovsky effect in a statistical manner. In particular, we describe two independent population-based tests that verify the measurement of Yarkovsky orbital drift. First, we provide observational confirmation for the Yarkovsky effect's theoretical size dependence of 1/D, where D is diameter. Second, we find that the observed ratio of negative to positive drift rates in our sample is 2.34, which, accounting for bias and sampling uncertainty, implies an actual ratio of 2.7_-0.7_^+0.3^. This ratio has a vanishingly small probability of occurring due to chance or statistical noise. The observed ratio of retrograde to prograde rotators is two times lower than the ratio expected from numerical predictions from NEA population studies and traditional assumptions about the sense of rotation of NEAs originating from various main belt escape routes. We also examine the efficiency with which solar energy is converted into orbital energy and find a median efficiency in our sample of 12%. We interpret this efficiency in terms of NEA spin and thermal properties.