1535 Päijänne

1535 Päijänne (pæi(j)ænːe), provisional designation 1939 RC, is an asteroid from the outer region of the asteroid belt, approximately 25 kilometers in diameter. It was discovered on 9 September 1939, by Finnish astronomer Yrjö Väisälä at the Turku Observatory in Southwest Finland.^[10] It was later named for Lake Päijänne.^[2]

1535 Päijänne

Discovery[1]
Discovered by	Y. Väisälä
Discovery site	Turku Obs.
Discovery date	9 September 1939
Designations
MPC designation	(1535) Päijänne
Pronunciation	pæi(j)ænːe
Named after	Lake Päijänne (Finland)[2]
Alternative designations	1939 RC · 1933 QE1 1944 OA · 1956 XB 1985 XE2 · A916 OB
Minor planet category	main-belt · (outer)[3]
Orbital characteristics[1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc	83.77 yr (30,598 days)
Aphelion	3.7718 AU
Perihelion	2.5586 AU
Semi-major axis	3.1652 AU
Eccentricity	0.1916
Orbital period (sidereal)	5.63 yr (2,057 days)
Mean anomaly	23.100°
Mean motion	0° 10m 30s / day
Inclination	6.0561°
Longitude of ascending node	264.79°
Argument of perihelion	39.922°
Physical characteristics
Dimensions	23.836±0.206 km[4] 25.518±0.187 km[5] 26.12±0.42 km[6] 26.36 km (derived)[3] 26.72±1.0 km[7]
Synodic rotation period	8.8448±0.0007 h[8]
Geometric albedo	0.0638 (derived)[3] 0.1299±0.011[7] 0.140±0.005[6] 0.1430±0.0230[5] 0.164±0.031[4]
Spectral type	CX[9] · S[3]
Absolute magnitude (H)	10.7[5][6][7] · 11.44±0.09[9] · 11.5[1][3]

Orbit

Päijänne orbits the Sun in the outer main-belt at a distance of 2.6–3.8 AU once every 5 years and 8 months (2,057 days). Its orbit has an eccentricity of 0.19 and an inclination of 6° with respect to the ecliptic.^[1] It was first identified as A916 OB at Simeiz Observatory in 1916. The body's observation arc begins 6 years prior to its official discovery with its identification as 1933 QE₁ at Heidelberg Observatory.^[10]

Physical characteristics

Päijänne is classified as both S-type and transitional CX-type asteroid.^[3][9]

Lightcurves

In September 2006, a rotational lightcurve of Päijänne was obtained from photometric observations taken by French amateur astronomer Laurent Bernasconi. The lightcurve analysis gave a well-defined rotation period of 8.8448 hours with a change in brightness of 0.50 magnitude (U=3).^[8]

Diameter and albedo

According to the surveys carried out by the Infrared Astronomical Satellite IRAS, the Japanese Akari satellite, and NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, Päijänne measures between 23.836 and 26.72 kilometers in diameter, and its surface has an albedo between 0.1299 and 0.164.^[4][5][6][7] The Collaborative Asteroid Lightcurve Link derives an albedo of 0.0638 and a diameter of 26.36 kilometers with an absolute magnitude of 11.5.^[3]

Naming

This minor planet was named for Finland's second largest lake, Päijänne, located in south-central Finland, and more than a thousand square kilometers in size.^[2] The official naming citation was published by the Minor Planet Center on 20 February 1976 (M.P.C. 3929).^[11]