1757 Porvoo

Main-belt asteroid October 2019 yes 1757 Porvoo #D6D6D6 17 March 1939 Y. Väisälä Turku Obs. (1757) Porvoo 1939 FC1964 BB1968 FK Porvoo (Finnish city) main-belt(inner) 4 September 2017 (JD 2458000.5) 0 77.87 yr (28,442 days) 2.6478 AU 2.0551 AU 2.3514 AU 0.1260 3.61 yr (1,317 days) 263.06° 0.2733 ms / day 3.9765° 39.423° 149.40° 1 unconfirmed 6.32 km (calculated)10.03 2.85 km12.81 0.45 km 4.89 h 0.049 0.0040.072 0.0970.073 0.0820.20 (assumed) S 13.3613.4713.49 0.26 1757 Porvoo, provisional designation 1939 FC, is a presumably stony, and possible binary asteroid from the inner regions of the asteroid belt, approximately 10 kilometers in diameter. It was discovered on 17 March 1939, by Finnish astronomer Yrjö Väisälä at Turku Observatory on the coast of southwestern Finland. The asteroid was named for the Finnish city of Porvoo. Naming This minor planet was named for Porvoo, a Finnish city and municipality located on the southern coast of Finland, and east of the capital Helsinki. Porvoo is one of the six medieval towns in Finland, and is its second oldest city after Turku, location of the discovering observatory. In 1809, at the Diet of Porvoo, the Russian czar confirmed that Finland was annexed to the Russian empire as an autonomous nation. The official naming citation was published by the Minor Planet Center on 1 August 1980 (M.P.C. 5449). Orbit and classification Porvoo orbits the Sun in the inner main-belt at a distance of 2.1–2.6 AU once every 3 years and 7 months (1,317 days). Its orbit has an eccentricity of 0.13 and an inclination of 4° with respect to the ecliptic. As no precoveries were taken, and no prior identifications were made, Porvoo's observation arc begins with its official discovery observation. Physical characteristics Rotation period In the early 1980s, a rotational lightcurve of Porvoo was obtained from photometric observations taken by American astronomer Richard P. Binzel using the 0.91- and 2.1-m telescopes at the University of Texas McDonald Observatory. It gave it a well-defined rotation period of 4.89 hours with a brightness variation of 0.30 magnitude (U=3). Diameter and albedo According to the surveys carried out by NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, Porvoo measures 10.03 and 12.81 kilometers in diameter, and its surface has an albedo of 0.049 and 0.073, respectively. The Collaborative Asteroid Lightcurve Link assumes a standard albedo for stony asteroids of 0.20 – contrary to the rather carbonaceous albedo given by the space-based surveys – and calculates a diameter of 6.32 kilometers with an absolute magnitude of 13.36. Suspected satellite During an occultation event on 7 July 2026, viewed by Blair Lade, Andrew Wendelborn, and Paul Martinaitis of the Astronomical Society of South Australia, Porvoo passed in front of the star UCAC4 312-094580. Data from the event was recorded by the three viewers from differing locations across Adelaide, and while Porvoo's shape was clearly visible to all three observations, Lade was the only one who managed to record another unexpected drop in the star's light.Comets, Occultations, Meteors and Asteroids (COMA) https://www.assa.org.au/comets--occultations--meteors-and-asteroids--coma-#porvoo-discovery 2026-09-26 www.assa.org.au Results from this event were officially reported on 26 September 2026, and further observations of Porvoo are said to help determine the existence of its natural satellite.(1757) Porvoo https://www.johnstonsarchive.net/astro/astmoons/am-01757.html 2026-09-26 www.johnstonsarchive.net References 30em 2017-01-28 last obs. JPL Small-Body Database Browser: 1757 Porvoo (1939 FC) https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2001757 https://web.archive.org/web/20200820184117/https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2001757 dead 20 August 2020 Jet Propulsion Laboratory 8 June 2017 Dictionary of Minor Planet Names – (1757) Porvoo Schmadel Lutz D. Springer Berlin Heidelberg 140 2007 978-3-540-00238-3 10.1007/978-3-540-29925-7_1758 (1757) Porvoo 1757 Porvoo (1939 FC) Minor Planet Center https://www.minorplanetcenter.net/db_search/show_object?object_id=1757 20 December 2016 MPC/MPO/MPS Archive Minor Planet Center https://www.minorplanetcenter.net/iau/ECS/MPCArchive/MPCArchive_TBL.html 20 December 2016 1757 20 December 2016 6 Fumihiko Usui Daisuke Kuroda Thomas G. Müller Sunao Hasegawa Masateru Ishiguro Takafumi Ootsubo Daisuke Ishihara Hirokazu Kataza Satoshi Takita Shinki Oyabu Munetaka Ueno Hideo Matsuhara Takashi Onaka October 2011 Asteroid Catalog Using Akari: AKARI/IRC Mid-Infrared Asteroid Survey Publications of the Astronomical Society of Japan 63 5 1117–1138 2011PASJ...63.1117U 10.1093/pasj/63.5.1117 (online, AcuA catalog p. 153) 6 Joseph R. Masiero A. K. Mainzer T. Grav J. M. Bauer R. M. Cutri C. Nugent M. S. Cabrera November 2012 Preliminary Analysis of WISE/NEOWISE 3-Band Cryogenic and Post-cryogenic Observations of Main Belt Asteroids https://adsabs.harvard.edu/cgi-bin/bib_query?bibcode=2012ApJ...759L...8M The Astrophysical Journal Letters 759 1 5 2012ApJ...759L...8M 10.1088/2041-8205/759/1/L8 1209.5794 20 December 2016 R. P. Binzel J. D. Mulholland December 1983 A photoelectric lightcurve survey of small main belt asteroids https://adsabs.harvard.edu/cgi-bin/bib_query?bibcode=1983Icar...56..519B Icarus 56 3 519–533 0019-1035 1983Icar...56..519B 10.1016/0019-1035(83)90170-7 20 December 2016 6 Peter Veres Robert Jedicke Alan Fitzsimmons Larry Denneau Mikael Granvik Bryce Bolin Serge Chastel Richard J. Wainscoat William S. Burgett Kenneth C. Chambers Heather Flewelling Nick Kaiser Eugen A. Magnier Jeff S. Morgan Paul A. Price John L. Tonry Christopher Waters November 2015 Absolute magnitudes and slope parameters for 250,000 asteroids observed by Pan-STARRS PS1 - Preliminary results https://adsabs.harvard.edu/cgi-bin/bib_query?bibcode=2015Icar..261...34V Icarus 261 34–47 2015Icar..261...34V 10.1016/j.icarus.2015.08.007 1506.00762 20 December 2016 External links Asteroid Lightcurve Database (LCDB), query form (info https://web.archive.org/web/20171216050541/http://www.minorplanet.info/lightcurvedatabase.html 16 December 2017 ) Dictionary of Minor Planet Names, Google books Asteroids and comets rotation curves, CdR https://web.archive.org/web/20241208174218/http://obswww.unige.ch/~behrend/page_cou.html 8 December 2024 – Observatoire de Genève, Raoul Behrend Discovery Circumstances: Numbered Minor Planets (1)-(5000) – Minor Planet Center 1757 1756 Giacobini 1757 1758 Naantali 001757 Category:Discoveries by Yrjö Väisälä Category:Named minor planets 19390317