9991 Anežka

"Anezka" redirects here. For the given name Anezka, the Czech variant of Agnes, see Agnes (name).

9991 Anežka, provisional designation 1997 TY₇, is a carbonaceous Themistian asteroid from the outer region of the asteroid belt, approximately 10 kilometers in diameter.

9991 Anežka

Orbit comparison of 9991 Anežka (blue), inner planets (red) and Jupiter (outermost)
Discovery[1]
Discovered by	Z. Moravec
Discovery site	Kleť Obs.
Discovery date	5 October 1997
Designations
MPC designation	(9991) Anezka
Named after	Anežka Moravcová (discoverer's grandmother)[2]
Alternative designations	1997 TY7 · 1977 DX9 1983 GV1 · 1994 BZ
Minor planet category	main-belt · Themis[3]
Orbital characteristics[1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc	40.19 yr (14,681 days)
Aphelion	3.7082 AU
Perihelion	2.6975 AU
Semi-major axis	3.2028 AU
Eccentricity	0.1578
Orbital period (sidereal)	5.73 yr (2,094 days)
Mean anomaly	356.19°
Mean motion	0° 10m 19.2s / day
Inclination	2.1773°
Longitude of ascending node	80.608°
Argument of perihelion	115.62°
Physical characteristics
Dimensions	7.92 km (calculated)[3] 12.293±0.294 km[4][5]
Synodic rotation period	4.4692±0.0019 h[6]
Geometric albedo	0.08 (assumed)[3] 0.097±0.013[4][5]
Spectral type	C[3]
Absolute magnitude (H)	12.7[4] · 13.3[1] · 13.415±0.003 (R)[6] · 13.86[3] · 13.89±0.32[7]

The asteroid was discovered on 5 October 1997, by Czech astronomer Zdeněk Moravec at the South Bohemian Kleť Observatory in the Czech Republic.^[8] It was named after the discoverer's grandmother, Anežka Moravcová.^[2]

Orbit and classification

Anežka is a carbonaceous asteroid and member of the Themis family, a dynamical family of outer main-belt asteroids with nearly coplanar ecliptical orbits. It orbits the Sun at a distance of 2.7–3.7 AU once every 5 years and 9 months (2,094 days). Its orbit has an eccentricity of 0.16 and an inclination of 2° with respect to the ecliptic.^[1] It was first identified as 1977 DX₉ at the Japanese Kiso Observatory in 1977, extending the body's observation arc by 20 years prior to its discovery.^[8]

Physical characteristics

Rotation period

A rotational lightcurve for this asteroid was obtained from photometric observations at the Palomar Transient Factory in December 2012. It gave it a rotation period of 4.4692±0.0019 hours with a brightness variation of 0.24 in magnitude (U=2).^[6]

Diameter and albedo

According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, the asteroid measures 12.3 kilometers in diameter and its surface has an albedo of 0.097,^[4] while the Collaborative Asteroid Lightcurve Link assumes an albedo of 0.08 and calculates a diameter of 7.9 kilometers.^[3]

Naming

This minor planet was named after the discoverer's grandmother, Anežka Moravcová (born 1924), on her 75th birthday.^[2] The official naming citation was published by the Minor Planet Center on 4 May 1999 (M.P.C. 34632).^[9]