(31345) 1998 PG

Eccentric, stony asteroid and binary system yes (31345) 1998 PG #FFC2E0 3 August 1998 LONEOS Anderson Mesa Stn. (31345) 1998 PG NEOAmor 4 September 2017 (JD 2458000.5) 0 38.54 yr (14,075 days) 2.8048 AU 1.2277 AU 2.0162 AU 0.3911 2.86 yr (1,046 days) 215.36° 0.3443 ms / day 6.5013° 222.74° 156.11° 0.2354 AU91.7 LD 1Pravec-2006-figures 0.880 km (derived)0.9 0.2 kmPravec-2006-figures0.940 0.21 (derived) 2.5 h2.51620 0.00003 h 0.18Pravec-2006-figures0.20 (assumed) SMASS = SqSB–V = 0.810 0.020V–R = 0.440 0.010V–I = 0.760 0.020 17.317.64 0.14 (31345) 1998 PG is an eccentric, stony asteroid and binary system, classified as near-Earth object of the Amor group of asteroids, approximately 900 meters in diameter. It minor-planet moon has an estimated diameter of 270 meters. This asteroid was discovered on 3 August 1998, by the Lowell Observatory Near-Earth-Object Search (LONEOS) at Anderson Mesa Station, near Flagstaff, Arizona, United States. Orbit 1998 PG orbits the Sun at a distance of 1.2–2.8 AU once every 2 years and 10 months (1,046 days). Its orbit has an eccentricity of 0.39 and an inclination of 7° with respect to the ecliptic. A first precovery was taken at Palomar Observatory in 1978, extending the body's observation arc by 20 years prior to its official discovery observation at Anderson Mesa. Close approaches The asteroid has an Earth minimum orbital intersection distance of 0.2354 AU km on off 3, which translates into approximately 92 lunar distances. It has made multiple close approaches to Earth, with the closest being 35,648,680 kilometers on 15 October 1978. With an aphelion of more than 2.8 AU, 1998 PG is also a Mars-crosser. Physical characteristics Spectral type In the SMASS taxonomy, 1998 PG is classified as a transitional Sq-type, which is an intermediary between the common stony S-type and the less frequent Q-type asteroids. Diameter and albedo According to the 2006-published Photometric survey of binary near-Earth asteroids by Petr Pravec and derived data from the Collaborative Asteroid Lightcurve Link and the "Johnston's archive", 1998 PG measures between 880 and 940 meters in diameter and its surface has an albedo of 0.18 and 0.20, respectively.Pravec-2006-figures Rotation In the late 1990s, a rotational lightcurve of 1998 PG was obtained from photometric observations by Hungarian astronomers László Kiss, Gyula Szabó and Krisztián Sárneczky. Lightcurve analysis gave a rotation period of 2.5 hours with a brightness variation of 0.1 magnitude (U=n.a.). A second lightcurve obtained and published in 2000, by an international collaboration of astronomers gave a rotation period of 2.51620 0.00003 hours with a brightness amplitude of 0.11 magnitude (U=2). Moon During the second photometric observation, it was discovered that 1998 PG is a probable/possible asynchronous binary system with a minor-planet moon orbiting it every 7.0035 hours, or twice this period solution. The moon remains undesignated. The system has an estimated secondary-to-primary mean-diameter ratio of more than 0.3,Pravec-2006-figures which translates into a diameter of 270 meter for the satellite. The "Johnston's archive" also estimates that the moon's orbit has a semi-major axis of 1.4 kilometers. From the surface of 1998 PG, the moon would have an angular diameter of about 16.3°.calculated For comparison, the Sun appears to be 0.5° from Earth. Numbering and naming This minor planet was numbered by the Minor Planet Center on 30 November 2001. As of 2018, it has not been named. Gallery Notes calculated Calculated by solving . Pravec-2006-figures Pravec (2006) Photometric survey of binary near-Earth asteroids, Icarus, 181:63-93. Summary figures: albedo of 0.18; diameter of primary 0.9 0.2 km; ratio: Ds/Dp of 0.3;. Figures are listed at johnstonsarchive.net References 30em 2017-04-20 last obs. JPL Small-Body Database Browser: 31345 (1998 PG) https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2031345 Jet Propulsion Laboratory 26 May 2017 (31345) 1998 PG Minor Planet Center https://www.minorplanetcenter.net/db_search/show_object?object_id=31345 31 March 2017 MPC/MPO/MPS Archive Minor Planet Center https://www.minorplanetcenter.net/iau/ECS/MPCArchive/MPCArchive_TBL.html 24 February 2018 Johnston Robert (31345) 1998 PG johnstonsarchive.net 21 September 2014 http://www.johnstonsarchive.net/astro/astmoons/am-31345.html 31 March 2017 31345 31 March 2017 L. L. Kiss Gy. Szabó K. Sárneczky November 1999 CCD photometry and new models of 5 minor planets Astronomy and Astrophysics Supplement 140 21–28 1999A&AS..140...21K 10.1051/aas:1999115 astro-ph/9909159 16733071 6 Petr Pravec Lenka Sarounová David L. Rabinowitz Michael D. Hicks Marek Wolf Yurij N. Krugly Fiodor P. Velichko Vasilij G. Shevchenko Vasilij G. Chiorny Ninel M. Gaftonyuk Guy Genevier July 2000 Two-Period Lightcurves of 1996 FG 3, 1998 PG, and (5407) 1992 AX: One Probable and Two Possible Binary Asteroids Icarus 146 1 190–203 2000Icar..146..190P 10.1006/icar.2000.6375 6 P. Pravec P. Scheirich P. Kusnirák L. Sarounová S. Mottola G. Hahn P. Brown G. Esquerdo N. Kaiser Z. Krzeminski D. P. Pray B. D. Warner A. W. Harris M. C. Nolan E. S. Howell L. A. M. Benner J.-L. Margot A. Galád W. Holliday M. D. Hicks Yu. N. Krugly D. Tholen R. Whiteley F. Marchis D. R. DeGraff A. Grauer S. Larson F. P. Velichko W. R. Cooney R. Stephens J. Zhu K. Kirsch R. Dyvig L. Snyder V. Reddy S. Moore S. Gajdos J. Világi G. Masi D. Higgins G. Funkhouser B. Knight S. Slivan R. Behrend M. Grenon G. Burki R. Roy C. Demeautis D. Matter N. Waelchli Y. Revaz A. Klotz M. Rieugné P. Thierry V. Cotrez L. Brunetto G. Kober March 2006 Photometric survey of binary near-Earth asteroids Icarus 181 1 63–93 2006Icar..181...63P 10.1016/j.icarus.2005.10.014 Petr Pravec Alan W. Harris Peter Kusnirák Adrián Galád Kamil Hornoch September 2012 Absolute magnitudes of asteroids and a revision of asteroid albedo estimates from WISE thermal observations Icarus 221 1 365–387 2012Icar..221..365P 10.1016/j.icarus.2012.07.026 External links MPEC 1998-P13 : 1998 PG, Minor Planet Electronic Circular 6 August 1998 (31345) 1998 PG at E.A.R.N. – European Asteroid Research Node Asteroids with Satellites, Robert Johnston, johnstonsarchive.net Binary and Ternary Near-Earth Asteroids Detected by Radar, Lance Benner, JPL Asteroid Lightcurve Database (LCDB), query form (info https://web.archive.org/web/20171216050541/http://www.minorplanet.info/lightcurvedatabase.html 2017-12-16 ) Dictionary of Minor Planet Names, Google books Asteroids and comets rotation curves, CdR https://web.archive.org/web/20160729213840/http://obswww.unige.ch/~behrend/page_cou.html 2016-07-29 – Observatoire de Genève, Raoul Behrend 31345 31345 1998PG 31345 31345 031345 031345 031345 031345 19980803