(31345) 1998 PG

(31345) 1998 PG

Discovery
Discovered by	LONEOS
Discovery date	3 August 1998
Orbital characteristics[1]
Epoch 13 January 2016 (JD 2457400.5)
Uncertainty parameter 0
Observation arc	13601 days (37.24 yr)
Aphelion	2.8041 AU (419.49 Gm)
Perihelion	1.2264 AU (183.47 Gm)
Semi-major axis	2.0153 AU (301.48 Gm)
Eccentricity	0.39143
Orbital period	2.86 yr (1045.0 d)
Mean anomaly	8.9514°
Mean motion	0° 20^m 40.236^s / day
Inclination	6.4937°
Longitude of ascending node	222.79°
Argument of perihelion	155.93°
Known satellites	1
Earth MOID	0.232976 AU (34.8527 Gm)
Jupiter MOID	2.66484 AU (398.654 Gm)
Proper orbital elements
Proper mean motion	125.7425 deg / yr
Proper orbital period	2.86299 yr (1045.708 d)
Physical characteristics
Dimensions	900 m (3,000 ft)[2]
Rotation period	2.51620 h (0.104842 d)[1][3]
Geometric albedo	0.16[2]
Temperature	188 K (-85°C)
Spectral type	Q
Absolute magnitude (H)	17.3[1][2]

(31345) 1998 PG is an Amor near-Earth asteroid discovered by the LONEOS program on August 3, 1998. It is known to have a moon, S/2001 (31345) 1.^[4]

Status as a Near-Earth Object

1998 PG is classified as an Amor asteroid. It has made multiple close approaches to Earth, with the closest being 35,648,680 kilometres (22,151,060 mi) on 15 October 1978.^[1]

Moon

Table Mountain Observatory, where S/2001 (31345) 1 was discovered.

The 1998 PG system compared to other binary asteroids.

1998 PG has a single moon, S/2001 (31345) 1. The moon was discovered at the Table Mountain Observatory by analyzing observations from 29 August to 25 October 1998. S/2001 (31345) 1 has a size of 300 metres (980 ft), one-third the size of the asteroid itself, and orbits every 14 hours with a semi-major axis of 1.5 kilometres (0.93 mi).^[2] From the surface of 1998 PG, the moon would have an angular diameter of about 16.3°.^{[lower-alpha 1]} For comparison, the Sun appears to be 0.5° from Earth.

Notes

1. Calculated by solving $\scriptstyle{\mathrm{tan}\left(\frac{\theta}{2}\right) = \frac{\mathrm{radius~of~moon}}{\mathrm{distance~from~surface~of~asteroid~to~center~of~moon}}}$.

References

1. "(31345) 1998 PG orbit diagram". JPL Small-Body Database. Jet Propulsion Laboratory. SPK-ID: 2031345. Retrieved 5 April 2016.
2. Johnston, W. R. (1 September 2005). "(31345) 1998 PG". Johnston's Archive. Retrieved 2013-09-20.
3. Pravec, P.; et al. (2000). "Two-Period Lightcurves of 1996 FG₃, 1998 PG, and (5407) 1992 AX: One Probable and Two Possible Binary Asteroids". Icarus 146 (1): 190–200. Bibcode:2000Icar..146..190P. doi:10.1006/icar.2000.6375.
4. Lance, B. (6 August 2013). "Binary and Ternary Near-Earth Asteroids Detected by Radar". JPL/NASA. Retrieved 2013-09-20.

Further reading

• Kiss, L. L.; Szabó, Gy.; Sárneczky, K. (1999). "CCD photometry and new models of 5 minor planets". Astronomy and Astrophysics Supplement Series 140: 21–28. arXiv:astro-ph/9909159. Bibcode:1999A&AS..140...21K. doi:10.1051/aas:1999115.

External links

• (31345) 1998 PG at the JPL Small-Body Database

• Discovery · Orbit diagram · Orbital elements · Physical parameters