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3728 IRAS
Discovery
Discovered by	IRAS
Discovery date	23 August 1983
Designations
MPC designation	(3728) IRAS
Named after	IRAS (space observatory)
Alternative designations	1983 QF · 1948 RN; 1963 FA · 1972 FH; 1976 GL · 1985 GT
Minor planet category	main-belt · (middle)
Orbital characteristics
	Epoch 4 September 2017 (JD 2458000.5)
	Uncertainty parameter 0
Observation arc	68.74 yr (25,108 days)
Aphelion	3.2138 AU
Perihelion	2.0862 AU
Semi-major axis	2.6500 AU
Eccentricity	0.2128
Orbital period (sidereal)	4.31 yr (1,576 days)
Mean anomaly	276.44°
Mean motion	0° 13m 42.6s / day
Inclination	22.595°
Longitude of ascending node	167.37°
Argument of perihelion	281.02°
Physical characteristics
Dimensions	19.41 km (derived); 19.55±1.7 km (IRAS:12); 19.83±0.38 km; 21.40±0.38 km; 23.450±0.115; 27.480±0.177 km
Synodic rotation period	8.323±0.002 h
Geometric albedo	0.0352±0.0015; 0.0815 (derived); 0.086±0.015; 0.101±0.004; 0.1161±0.023 (IRAS:12)
Spectral type	CX · S
Absolute magnitude (H)	11.50 · 11.80 · 11.9 · 12.20±0.23

3728 IRAS, provisional designation 1983 QF, is a stony asteroid from the middle region of the asteroid belt, approximately 20 kilometers in diameter. On 23 August 1983, it was discovered by and later named after IRAS, a spaceborne all-sky infrared survey satellite.^[10]

Classification and orbit

The S-type asteroid is also classified as a CX-type by Pan-STARRS' large-scale survey.^[9] It orbits the Sun in the central main-belt at a distance of 2.1–3.2 AU once every 4 years and 4 months (1,576 days). Its orbit has an eccentricity of 0.21 and an inclination of 23° with respect to the ecliptic.^[1] The first used precovery was taken at Palomar Observatory in 1950, extending the asteroid's observation arc by 33 years prior to its discovery.^[10]

Rotation period

In August 2008, a photometric lightcurve analysis by U.S. astronomer Brian Warner at his Palmer Divide Observatory (716), Colorado, gave a well-defined rotation period of 8.323±0.002 hours with a brightness amplitude of 0.21 in magnitude (U=3).^[8]

Diameter estimates

According to 12 observations by the discovering Infrared Astronomical Satellite, IRAS, the asteroid has an albedo of 0.12 and a diameter of 19.6 kilometers. The Collaborative Asteroid Lightcurve Link derives similar figures, as do the space-based surveys carried out by the Japanese Akari satellite, and NASA's Wide-field Infrared Survey Explorer.^[3]^[5]^[4] Two publications from the post-cryogenic NEOWISE mission find a larger diameter of 23.4 and 27.5 kilometers, respectively.^[6]^[7]

Naming

This minor planet was named for the discovering Infrared Astronomical Satellite (IRAS), a collaboration between the United States (NASA), the Netherlands (NIVR), and the United Kingdom (SERC), which observed more than 250,000 celestial bodies in the infrared at wavelengths between 12 and 100 μm during 10 months in 1983. IRAS has also discovered two other minor planets, the 11-kilometer sized main-belt asteroid (10714) 1983 QG^[11] and 3200 Phaethon, a near-Earth and potentially hazardous object, parent body of the Geminid meteor shower, as well as six comets, such as 126P/IRAS, a short-period Jupiter family comet, which was also named after the discovering space observatory.^[2]^[12] The approved naming citation was published by the Minor Planet Center on 4 May 1999 (M.P.C. 34619).^[13]