984 Gretia

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984 Gretia Template:IPAc-en is a stony background asteroid from the central regions of the asteroid belt, approximately Script error: No such module "convert". in diameter. It was discovered by German astronomer Karl Reinmuth at the Heidelberg-Königstuhl State Observatory on 27 August 1922 and given the provisional designation Template:Mp.[1] The asteroid was named after Greta, sister-in-law of ARI-astronomer Albrecht Kahrstedt.[1]

Orbit and classification

Gretia is a background asteroid that has not been associated with any known asteroid family. It orbits the Sun in the central main belt at a distance of 2.2–3.4 AU once every 4 years and 8 months (1,714 days). Its orbit has an eccentricity of 0.20 and an inclination of 9° with respect to the ecliptic.[2]

It was first observed as Template:Mp at the discovering observatory in 1910, and five years later as Template:Mp at the United States Naval Observatory. The body's observation arc begins at Vienna Observatory in September 1922, two weeks after its official discovery observation.[1]

Naming

This minor planet was named after Greta, sister-in-law of Albrecht Kahrstedt (1897–1971), a German astronomer at ARI and director of the institute's Potsdam division, who requested the naming of this asteroid and 1026 Ingrid (daughter of Greta) in a personal letter to the discoverer in February 1926.[3][4] Kahrstedt himself was honored with the naming of Template:MoMP.

The official naming citation was mentioned in The Names of the Minor Planets by Paul Herget in 1955 (H 94Script error: No such module "Check for unknown parameters".).[3] Lutz Schmadel quoted an excerpt of Kahrstedt's letter in his Dictionary of Minor Planet Names (LDS).[4]

Physical characteristics

In the SMASS classification, Gretia is a Sr-subtype that transitions between the common S-type and rare R-type asteroids.[2]

Lightcurves

Since 1997, a large number of rotational lightcurves of Gretia have been obtained from photometric observations. Analysis of the best-rated lightcurves gave a rotation period of 5.778 hours with a maximal brightness amplitude from 0.26 to 0.75 magnitude (U=2–3Script error: No such module "Check for unknown parameters".).[5][6][7][8][9][10][11][12]

The asteroid's spin axis of (92.0°, 67.0°) and (247.0°, 48.0°) in ecliptic coordinates (λ, β) have also been derived from modeled lightcurves (Q=3Script error: No such module "Check for unknown parameters".).[8]

Diameter and albedo

According to the surveys carried out by the Infrared Astronomical Satellite IRAS, the Japanese Akari satellite and the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Gretia measures between 31.91 and 36.60 kilometers in diameter and its surface has a high albedo between 0.3566 and 0.4239.[13][14][15][16]

The Collaborative Asteroid Lightcurve Link adopts the results obtained by IRAS, that is, an exceptionally high albedo of 0.4239 and a diameter of 31.91 kilometers with an absolute magnitude of 9.03.[13][17]

References

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External links

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