1644 Rafita

1644 Rafita, provisional designation 1935 YA, is a stony asteroid from the middle region of the asteroid belt, approximately 15 kilometers in diameter. It is the namesake of the Rafita family, a family of stony asteroids in the intermediate main-belt. However, Rafita is a suspected interloper in its own family.^[4]: 23 It was discovered on 16 December 1935, by Spanish astronomer Rafael Carrasco Garrorena at the Royal Observatorio Astronómico de Madrid in Spain, and named in memory of the discoverer's son.^[2][12]

1644 Rafita

Discovery[1]
Discovered by	R. Carrasco
Discovery site	Madrid Obs.
Discovery date	16 December 1935
Designations
MPC designation	(1644) Rafita
Named after	Rafael Carrasco (discoverer's son)[2]
Alternative designations	1935 YA · 1939 XA 1941 JB · 1949 JC 1951 VF · 1955 TS 1957 GD · 1959 UD A906 RB · A916 BA
Minor planet category	main-belt · (middle)[3] Rafita-interloper[4]: 23
Orbital characteristics[1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc	110.53 yr (40,371 days)
Aphelion	2.9426 AU
Perihelion	2.1539 AU
Semi-major axis	2.5483 AU
Eccentricity	0.1548
Orbital period (sidereal)	4.07 yr (1,486 days)
Mean anomaly	13.784°
Mean motion	0° 14m 32.28s / day
Inclination	7.0193°
Longitude of ascending node	270.90°
Argument of perihelion	197.05°
Physical characteristics
Dimensions	13.958±0.157 km[5] 15.405±0.072 km[6] 15.48 km (taken)[3] 15.482 km[7] 17.69±1.08 km[8]
Synodic rotation period	5.100±0.002 h[9] 6.800±0.004 h[10]
Geometric albedo	0.106±0.014[8] 0.1329[7] 0.1403±0.0148[6] 0.164±0.028[5]
Spectral type	Tholen = S[1][3] B–V = 0.867[1] U–B = 0.404[1]
Absolute magnitude (H)	11.82[1][6][8] · 11.82±0.21[11] · 11.86±0.02[3][7][9]

Orbit and classification

Rafita asteroid orbits the Sun in the central main-belt at a distance of 2.2–2.9 AU once every 4 years and 1 month (1,486 days). Its orbit has an eccentricity of 0.15 and an inclination of 7° with respect to the ecliptic.^[1] Rafita was first observed as A906 RB at Heidelberg Observatory in 1906, extending the body's observation arc by 29 years prior to its official discovery observation.^[12]

Lightcurves

Rafita's first rotational lightcurve was obtained by American astronomer Alan Harris of JPL in January 1981. It gave a rotation period of 5.100 hours with a brightness variation of 0.31 magnitude (U=2).^[9] Photometric observations by French amateur astronomer Laurent Bernasconi in December 2004, gave a period of 6.800 hours and an amplitude of 0.13 magnitude (U=2).^[10]

Diameter and albedo

According to the surveys carried out by the Japanese Akari satellite and NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, Rafita measures between 13.96 and 17.69 kilometers in diameter, and its surface has an albedo between 0.106 and 0.164.^[5][6][8] The Collaborative Asteroid Lightcurve Link agrees with Petr Pravec's revised WISE-results, that is an albedo of 0.1329 and a diameter of 15.482 kilometers, based on an absolute magnitude of 11.86.^[3][7]

Naming

This minor planet was named by the discoverer in honor of his late son, Rafael Carrasco.^[2] The official naming citation was published by the Minor Planet Center on 30 January 1964 (M.P.C. 2277).^[13]