2608 Seneca

2608 Seneca, provisional designation 1978 DA, is a stony asteroid and sub-kilometer near-Earth object of the Amor group, approximately 0.9 kilometers in diameter. It was discovered on 17 February 1978, by German astronomer Hans-Emil Schuster at ESO's La Silla Observatory in northern Chile, and named after Roman philosopher Seneca.^[3][4]

2608 Seneca

Discovery[1]
Discovered by	H.-E. Schuster
Discovery site	La Silla Obs.
Discovery date	17 February 1978
Designations
MPC designation	(2608) Seneca
Pronunciation	/ˈsɛnɪkə/ SEN-ik-ə[2]
Named after	Seneca the Younger (Roman philosopher)[3]
Alternative designations	1978 DA
Minor planet category	NEO · Amor[1][4]
Orbital characteristics[1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 1
Observation arc	38.92 yr (14,217 days)
Aphelion	3.9532 AU
Perihelion	1.0777 AU
Semi-major axis	2.5154 AU
Eccentricity	0.5716
Orbital period (sidereal)	3.99 yr (1,457 days)
Mean anomaly	353.12°
Mean motion	0° 14m 49.56s / day
Inclination	14.682°
Longitude of ascending node	167.37°
Argument of perihelion	37.350°
Earth MOID	0.1321 AU · 51.5 LD
Physical characteristics
Dimensions	0.9 km[1][5][6] 1.0±0.3[6]
Synodic rotation period	8 h[6]
Geometric albedo	0.15±0.03[6] 0.20 (derived)[5] 0.21[1]
Spectral type	Tholen = S[1] · S[5] B–V = 0.826[1] U–B = 0.454[1]
Absolute magnitude (H)	17.52[1] · 17.59[5][7] · 17.73[6]

Orbit

Seneca orbits the Sun at a distance of 1.1–4.0 AU once every 3 years and 12 months (1,457 days). Its orbit has an eccentricity of 0.57 and an inclination of 15° with respect to the ecliptic.^[1]

The body's observation arc begins with its official discovery observation in 1978, as no precoveries were taken, and no prior identifications were made.^[4]

Close approaches

Seneca has an Earth minimum orbital intersection distance of 0.1321 AU (19,800,000 km), which corresponds to 51.5 lunar distances.^[1] On 22 March 2062, it will pass 0.254 AU (38,000,000 km) from the Earth.^[8]

Physical characteristics

In the Tholen taxonomy, Seneca is a stony S-type asteroid.^[1]

Photometry

In March 1978, a photometric observations taken by Degewij and Lebofsky at the Lunar and Planetary Laboratory, Arizona, using a 154-cm reflector, gave a rotational lightcurve with a rotation period of 8 hours and a brightness amplitude of 0.4 (0.5) magnitude (U=2).^[6]

Radiometry

In addition, radiometric observations by L. and M. Lebofsky with the 71-cm reflector gave a mean-diameter of 1.0±0.3 kilometers and albedo of 0.15±0.03.^[6]

Diameter and albedo

The Minor Planet Center classifies Seneca as an object larger than 1 kilometer ("1+ KM Near-Earth Object"),^[4] while Collaborative Asteroid Lightcurve Link derives an albedo of 0.20 and a diameter of 0.9 kilometers based on an absolute magnitude of 17.59.^[5] In 1994, astronomer Tom Gehrels published a diameter of 0.9 kilometers with an albedo of 0.21 in his Hazards Due to Comets and Asteroids.^[1]

Naming

This minor planet was named after Roman philosopher and statesman Lucius Annaeus Seneca (c. 4 BC – AD 65), also known as "Seneca the Younger" or simply "Seneca".^[3] The approved naming citation was published by the Minor Planet Center on 8 April 1982 (M.P.C. 6835).^[9] The lunar crater Seneca was also named in his honor.^[3]