Earth and Space News: Helin discovery 6489 Golevka 1991 JX

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Wednesday, May 13, 2020

Asteroid 6489 Golevka Has Two Close Earth Approaches in 21st Century

Summary: Apollo asteroid 6489 Golevka has two close Earth approaches in the 21st century, but neither approach is considered potentially hazardous.

Apollo asteroid 6489 Golevka made its first close Earth approach of the 20th century on Tuesday, May 20, 2003: Courtesy NASA/JPL-Caltech, May be used for any purpose without prior permission, via NASA JPL Solar System Dynamics

Apollo asteroid 6489 Golevka has two close Earth approaches in the 21st century, but, at distances of greater than 0.05 astronomical units (7,479,893.53 kilometers), neither approach poses potential hazards to Earth.

American astronomer Eleanor Francis “Glo” Helin (Nov. 19, 1932-Jan. 25, 2009) discovered 6489 Golevka on Friday, May 10, 1991, at southwestern California’s Palomar Observatory about one month before the asteroid’s first potentially hazardous close Earth approach of the 20th century. The International Astronomical Union (IAU), which authorizes astronomy’s designations and names, recognizes Helin’s discovery under the official citation of 6489 Golevka and under its temporary designation of 1991 JX.

The NASA (National Aeronautics and Space Administration) Jet Propulsion Laboratory (JPL) Solar System Dynamics (SSD) website classifies 6489 Golevka as an Apollo asteroid. The NASA JPL’s Center for Near Earth Object Studies (CNEOS) website defines Apollos as near-Earth asteroids with perihelion (Ancient Greek: περί, perí, “near” + ἥλιος, hḗlios, “sun”) distances of less than 1.017 astronomical units (152,141,034.50 kilometers) and major semi-axes at greater than 1.0 astronomical unit (149,597,870.7 kilometers). (Also known as the semi-major axis, the major semi-axis equates to half of an elliptical orbit’s longest diameter.)

Golevka also classifies as a potentially hazardous asteroid (PHA). The NASA JPL CNEOS website defines PHAs as near-Earth asteroids with an Earth Minimum Orbit Intersection Distance (MOID) of 0.05 astronomical units (au) or less and with an absolute magnitude (H) of 22.0 or less. CNEOS explains the absolute magnitude of asteroids and planets, commonly designated as H, as the object’s apparent, or visual, magnitude under an ideal solar opposition of zero, or full, phase angle and at a distance of one astronomical unit from both the observer and the sun. The CNEOS website registers Golevka’s absolute magnitude (H) at 19.2 for the asteroid’s two potentially hazardous approaches in the 20 century and its single potentially hazardous approach in the 22nd century.

A report by Washington State University professor of electrical engineering and computer science Raymond Scott Hudson (born 1959) and 26 co-researchers on NASA-funded radar observations in June 1995 during Golevka’s second 20th century close Earth approach includes a table of Golevka’s close approaches “to within 0.1 AU of inner Solar System bodies” (page 41). Between the 17th and 29th centuries, the asteroid tallies 36 close approaches. Earth experiences 25 close approaches, of which 11 pose potential hazards. The asteroid nears Mars in 11 approaches, of which five calculate at less than 0.05 astronomical units.

The close planetary approach table provided by Hudson et al. details the century’s first of two close Earth approaches as having occurred on Julian date 2452780.17251. The date equates to Tuesday, May 20, 2003, at 16:08:24.9 UT1 (Universal Time 1, UT’s principal form), according to the U.S. Naval Observatory Astronomical Applications Department’s Julian Date Converter.

The May 2003, close Earth approach was distanced at 0.092265 au (13,802,647.54 kilometers). Astronomy’s measure of solar system distances in terms of astronomical units is based on the distance between the sun and Earth. The IAU precisely values one astronomical unit at 149,597,870,700 meters (149,597,870.7 kilometers).

The asteroid’s second close Earth approach in the 21st century takes place on Julian date 2468479.72649. Converted to UT1, the event is expected on Monday, May 14, 2046, at 05:26:08.7. The asteroid’s center-to-center distance with Earth is calculated at 0.050800 au (7,599,571.83 kilometers).

The 21st century’s absence of potentially hazardous approaches succeeds the 20th century’s threats of two possibly threatening approaches. The first potentially hazardous approach happened approximately one month after the asteroid’s discovery. Golevka’s reach of 0.033185 au (4,964,405.33 kilometers) occurred on Julian date 2448419.30338 (Tuesday, June 11, 1991, at 19:16:52.0 UT1). The century’s second potentially hazardous approach, during which NASA-funded research grants made radar observations of Golevka, took place on Julian date 2449877.59441 (Friday, June 9, 1995, at 02:15:57.0 UT1). The asteroid logged a distance of 0.034106 au (5,102,184.97 kilometers).

The takeaways for Apollo asteroid 6489 Golevka’s two close Earth approaches in the 21st century is that, with distances of more than 0.05 astronomical units in May 2003 and in May 2046, Golevka poses no potential threat to Earth.

Golevka was released April 7, 2005, by Swiss post-rock band The Evpatoria Report; the band's name honors Western Crimea’s Evpatoria RT-70 radio telescope, which joined the Goldstone antenna in California and the Kashima antenna in Japan in conducting the first intercontinental radar astronomy experiments during asteroid 6489 Golevka’s potentially hazardous close Earth approach in June 1995; album cover designed by Swiss designer Fabian Sbarro, eldest son of Italian-born Swiss concept car designer Francesco “Franco” Zefferino Sbarro (born Feb. 27, 1939): Post-Rock Egypt @postrockX, via Twitter April 7, 2019

Acknowledgment

My special thanks to talented artists and photographers/concerned organizations who make their fine images available on the internet.

Image credits:

Golevka was released April 7, 2005, by Swiss post-rock band The Evpatoria Report; Laurent Quint, Simon Robert, David Di Lorenzo, Fabrice Berney and Daniel Bacsinszky named their band after Western Crimea’s Evpatoria RT-70 radio telescope, which joined the Goldstone antenna in California and the Kashima antenna in Japan in conducting the first intercontinental radar astronomy experiments during asteroid 6489 Golevka’s potentially hazardous close Earth approach in June 1995; album cover designed by Swiss designer Fabian Sbarro, eldest son of Italian-born Swiss concept car designer Francesco “Franco” Zefferino Sbarro (born Feb. 27, 1939): Post-Rock Egypt @postrockX, via Twitter April 7, 2019, @ https://twitter.com/postrockX/status/1114906745250439168

For further information:

A.X.Z ‏@CHISTESRA. “Impacto en Júpiter por (6489)Golevka en 2024-02-17-08:26 PM GTM-06:00.” Twitter. Jan. 26, 2017.
Available @ https://twitter.com/CHISTESRA/status/824658900146216960

Chesley, Steven R.; Steven J. Ostro; David Vokrouhlický; David Čapek; Jon D. Giorgini; Michael C. Nolan; Jean-Luc Margot; Alice A. Hine; Lance A. M. Benner; and Alan B. Chamberlin. “Direct Detection of the Yarkovsky Effect by Radar Ranging to Asteroid 6489 Golevka.” Science, vol. 302, issue 5651 (Dec. 5, 2003): 1739-1742.
Available @ https://echo.jpl.nasa.gov/asteroids/chesley+golevka.pdf

Chodas, Paul. “6489 Golevka (1991 JX).” NASA Jet Propulsion Laboratory Center for Near Earth Object Studies > Close Approaches > NEOs.
Available @ https://cneos.jpl.nasa.gov/ca/

Chodas, Paul. “NASA Scientists Use Radar to Detect Asteroid Force.” NASA Jet Propulsion Laboratory Center for Near Earth Object Studies > Extras > News Archive > News Story. Dec. 5, 2003.
Available @ https://cneos.jpl.nasa.gov/news/news141.html

Chodas, Paul. “NEO Basics.” NASA Jet Propulsion Laboratory Center for Near Earth Object Studies > About.
Available @ https://cneos.jpl.nasa.gov/about/neo_groups.html

Crockett, Christopher. “The Yarkovsky Effect: Pushing Asteroids Around With Sunlight.” EarthSky > Astronomy Essentials. July 20, 2012.
Available @ https://earthsky.org/astronomy-essentials/the-yarkovsky-effect-pushing-asteroids-around-with-sunlight

Green, Daniel W.E. “1991 JX.” Central Bureau for Astronomical Telegrams > IAU Circular No. 5268. May 15, 1991.
Available @ http://www.cbat.eps.harvard.edu/iauc/05200/05268.html

Green, Daniel W.E. “1991 JX.” Central Bureau for Astronomical Telegrams > IAU Circular No. 5289. June 13, 1991.
Available @ http://www.cbat.eps.harvard.edu/iauc/05200/05289.html

Hudson, R.S.; S.J. Ostro; R.F. Jurgens; K.D. Rosema; J.D. Giorgini; R. Winkler; R. Rose; D. Choate; R.A. Cormier; C.R. Franck; R. Frye; D. Howard; D. Kelley; R. Littlefair; M.A. Slade; L.A.M. Benner; M.L. Thomas; D.L. Mitchell; P.W. Chodas; D.K. Yeomans; D.J. Scheeres; P. Palmer; A. Zaitsev; Y. Koyama; A. Nakamura; A.W. Harris; and M.N. Meshkov. “Radar Observations and Physical Model of Asteroid 6489 Golevka.” Icarus, vol. 148, no. 1 (November 2000): 37-51.
Available via JPL TRS (Technical Report Server) @ https://trs.jpl.nasa.gov/handle/2014/14189
Available via NASA NTRS (NASA Technical Reports Server) @ https://trs.jpl.nasa.gov/bitstream/handle/2014/14189/00-0596.pdf

Lakdawalla, Emily. “Very Close Approach by Asteroid 4179 Toutatis: It’s Not a Crisis, It’s an Opportunity.” The Planetary Society > Blogs. Sept. 27, 2004.
Available @ http://www.planetary.org/blogs/emily-lakdawalla/2004/0927_Very_Close_Approach_by_Asteroid_4179.html

Levy, David H. Skywatching. Revised and updated. San Francisco CA: Fog City Press, 1994.

Malik, Tariq. “NASA Maps Dangerous Asteroids That May Threaten Earth (Photos).” Space.com > Science & Astronomy. Aug. 14, 2013.
Available @ https://www.space.com/22369-nasa-asteroid-threat-map.html

Marriner, Derdriu. “Asteroid 4660 Nereus Makes Four Close Earth Approaches in 21st Century.” Earth and Space News. Wednesday, March 11, 2020.
Available @ https://earth-and-space-news.blogspot.com/2020/03/asteroid-4660-nereus-makes-four-close.html

Marriner, Derdriu. “Eleanor Helin Discovered Apollo Asteroid 6489 Golevka in May 1991.” Earth and Space News. Wednesday, May 6, 2020.
Available @ https://earth-and-space-news.blogspot.com/2020/05/eleanor-helin-discovered-apollo.html

Marriner, Derdriu. “Eleanor Helin Discovered Asteroid 4660 Nereus in February 1982.” Earth and Space News. Wednesday, Feb. 26, 2020.
Available @ https://earth-and-space-news.blogspot.com/2020/02/eleanor-helin-discovered-asteroid-4660.html

Marriner, Derdriu. “Robert Cutler Named Helin 1982 Asteroid Discovery 4660 Nereus in 1991.” Earth and Space News. Wednesday, March 4, 2020.
Available @ https://earth-and-space-news.blogspot.com/2020/03/robert-cutler-named-helin-1982-asteroid.html

Marsden, Brian G. “1991 JX.” Central Bureau for Astronomical Telegrams > IAU Circular No. 5277. May 26, 1991.
Available @ http://www.cbat.eps.harvard.edu/iauc/05200/05277.html

Marsden, Brian G. “1991 JX.” Central Bureau for Astronomical Telegrams > IAU Circular No. 5308.
Available @ http://www.cbat.eps.harvard.edu/iauc/05300/05308.html

Minor Planet Center. “1991 JX.” Minor Planet Circular 18443. June 27, 1991.
Available @ https://www.minorplanetcenter.net/iau/ECS/MPCArchive/1991/MPC_19910627.pdf

Minor Planet Center. “(6489)* 1991 JX.” Minor Planet Circular 25418. July 12, 1995.
Available @ https://www.minorplanetcenter.net/iau/ECS/MPCArchive/1995/MPC_19950712.pdf

Minor Planet Center. “(6489) Golevka = 1991 JX.” Minor Planet Circular 26425. Jan. 5, 1996.
Available @ https://www.minorplanetcenter.net/iau/ECS/MPCArchive/1996/MPC_19960105.pdf

Minor Planet Center. “Errata: MPC 26425 Line 48.” Minor Planet Circular 26439. Feb. 4, 1996.
Available @ https://www.minorplanetcenter.net/iau/ECS/MPCArchive/1996/MPC_19960204.pdf

NASA JPL Solar Systems Dynamics. "6489 Golevka (1991 JX) Orbital Elements." NASA Jet Propulsion Laboratory (JPL) Solar System Dynamics (SSD) > JPL Small-Body Database Browser.
Available @ https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=Golevka;old=0;orb=0;cov=0;log=0;cad=0#elem

NASA JPL Solar Systems Dynamics. "6489 Golevka (1991 JX) Mission Design." NASA Jet Propulsion Laboratory (JPL) Solar System Dynamics (SSD) > JPL Small-Body Database Browser > JPL Small-Body Mission-Design Tool.
Available @ https://ssd.jpl.nasa.gov/?mdesign_server&sstr=golevka

NEODyS. “(6489) Golevka: Close Approaches.” NEODyS-2 > Objects.
Available @ https://newton.spacedys.com/neodys/index.php?pc=1.1.8&n=Golevka

Post-Rock Egypt @postrockX. “Happy anniversary to one of the greatest post-rock albums of all time. The Evpatoria Report’s ‘Golevka’ turns 14 today.” Twitter. April 7, 2019.
Available @ https://twitter.com/postrockX/status/1114906745250439168

Schmadel, Lutz D. “(6489) Golevka.” Dictionary of Minor Planet Names: 514. Sixth revised and enlarged edition. Prepared on behalf of Commission 20 under the auspices of the International Astronomical Union. Berlin, Heidelberg, Germany: Springer-Verlag Berlin Heidelberg, 2012.
Available via Google Books @ https://books.google.com/books?id=aeAg1X7afOoC&pg=PA514

Zaitsev, Alexander L.; Steven J. Ostro; Sergei P. Ignatov; Donald K. Yeomans; Alexei G. Petrenko; Dennis Choate; Oleg K. Margorin; Reginald A. Cormier; Viatcheslav V. Mardyshkin; Ron Winkler; Oleg N. Rghiga; Raymond F. Jurgens; Vladimir A. Shubin; Jon D. Giorgini; Alexander P. Krivtsov; Keith D. Rosema; Yurii F. Koluka; Martin A. Slade; Anatolii L. Gavrik; Victor B. Andreev; Dmitrii V. Ivanov; Philip S. Peshin; Yasuhiro Koyama; Makoto Yoshikava; and Akiko Nakamura. “Intercontinental Bistatic Radar Observations of 6489 Golevka (1991 JX).” Planetary Space Science, vol. 45, no. 7 (July 1997): 771-778.
Available @ https://echo.jpl.nasa.gov/asteroids/zaitsev+1997.pdf

Wednesday, May 6, 2020

Eleanor Helin Discovered Apollo Asteroid 6489 Golevka in May 1991

Summary: American astronomer Eleanor Helin discovered Apollo asteroid 6489 Golevka at northern San Diego County’s Palomar Observatory on Friday, May 10, 1991.

American astronomer Eleanor Helin discovered Apollo asteroid 6489 Golevka on Friday, May 10, 1991, at the California Institute of Technology’s (Caltech) Palomar Observatory in northern San Diego County’s Palomar Mountain Range.

The International Astronomical Union’s (IAU) Central Bureau for Astronomical Telegrams (CBAT) issued an official notification of the asteroid’s discovery. American astronomer Daniel W.E. Green, CBAT director since 2000, announced the discovery via IAU Circular No. 5268, dated May 15, 1991.

Green assigned the temporary designation of 1991 JX to the newly discovered asteroid. The designation’s catalog number, 1991, represents the year of discovery. The two-letter code, JX, indicates the first half of the month, May 1 to 15, as the discovery’s half-month and the asteroid’s placement as number 23 in the order of discovery for the first half of May. The IAU’s naming convention for minor planets sequentially assigns letters A to Z for each half-month’s first 25 discoveries. The letter I, the ninth letter of the English alphabet, is not used in order to avoid potential confusion with the digit 1 (one).

Eleanor Francis “Glo” Helin (Nov. 19, 1932-Jan. 25, 2009) discovered the “fast-moving asteroidal object” on films exposed by Helin and American astronomers and minor planet discoverers Kenneth J. Lawrence (born 1964) and Perry J. Rose (born 1966). They used Palomar Observatory’s first instrument, the historic 18-inch (0.46-meter) Schmidt Telescope, for their film exposures. The telescope’s exposed films were then scanned with custom-built microscopes.

The discovery happened approximately one month before the asteroid’s orbit made its first of two close Earth approaches in the 20th century. Its 1991 close approach took place Tuesday, June 11, at approximately 19:17 TDB (Barycentric Dynamical Time; Temps Dynamique Barycentrique), according to NASA Jet Propulsion Laboratory’s (JPL) Center for Near Earth Object Studies (CNEOS). TDB is a relativistic spacetime coordinate time standard that takes into account the theory of relativity’s time dilation in astronomical calculations.

The 1991 close approach measured a nominal, or most likely, center-to-center distance of 0.03318 astronomical units (au) (4,963,657.34 kilometers) with Earth. The IAU definition equates an astronomical unit to exactly 149,597,870,700 meters (149,597,870.7 kilometers). The CNEOS table placed its close-approach velocity, relative to Earth, at 8.71 kilometers per second (5.41 miles per second).

The asteroid’s last close Earth approach of the 20th century occurred Friday, June 9, 1995, at approximately 02:16 TDB. Its nominal close approach distance was calculated at 0.03411 astronomical units (5,102,783.36 kilometers). Its relative velocity reached 8.96 kilometers per second (5.56 miles per second).

The 1995 close approach occasioned radar observations of the Earth-crossing asteroid (ECA) between Saturday, June 3, and Thursday, June 15. Bistatic observations, conducted from Tuesday, June 13, to Thursday, June 15, signaled both the first intercontinental radar astronomy experiments and Japan’s initiation into planetary radar astronomy. Goldstone Solar System Radar’s (GSSR) 70-meter (230-foot) Cassegrain antenna, located in the Mojave Desert in southeastern California, operated as the transmitter. The 70-meter antenna at the Western Crimean city of Evpatoria (then in the Ukraine but part of Russia since 2014) and the 34-meter antenna at the Kashima Space Research Center in east central Honshu, Japan, acted as receivers.

The next step in the official naming process happened with the assignment of a permanent designation, a sequentially issued number by the IAU’s Minor Planet Center (MPC). The assignment of 6489 as the permanent numerical designation for 1991 JX was announced in M.P.C. (Minor Planet Circular) 25418, issued Wednesday, July 12, 1995.

On Friday, Jan. 5, 1996, the Minor Planet Center published the asteroid’s official naming citation as 6489 Golevka in M.P.C. 26425. American planetary scientist Steven Jeffrey Ostro (March, 9, 1946-Dec. 15, 2008) wrote the official naming citation. The acronym of Golevka was constructed from the leading letters of the names of three sites that participated in radar observations of the 1995 close approach: Gol for Goldstone, ev for Evpatoria and ka for Kashima.

The Errata section in M.P.C. 26439, issued Sunday, Feb. 4, 1996, credited Russian and Soviet radio engineer and astronomer Alexsander Leonidovich Zaitsev (born May 19, 1945) with the name of Golevka. The Errata for line 48 of M.P.C. 26425 specified that Eleanor Helin’s proposal of the name of Golevka followed Zaitsev’s suggestion.

NASA JPL’s Solar System Dynamics (SSD) website classifies 6489 Golevka as an Apollo asteroid. The website describes Apollos as near-Earth asteroids with crossings of Earth’s orbit that are similar to that of the classification’s stony namesake, 1862 Apollo. Apollo asteroids present orbital parameters of perihelion distance at less than 1.017 astronomical units and major semi-axis at greater than 1.0 astronomical unit. (The major semi-axis, also known as semi-major axis, represents half of an ellipse’s longest diameter.)

The takeaways for Eleanor Helin’s discovery of Apollo asteroid 6489 Golevka are that the asteroid’s discovery preceded its first of two close Earth approaches in the 20th century by approximately one month; that its second approach, in 1995, occasioned the first intercontinental radar astronomy experiments that also initiated planetary radar astronomy in Japan; and that the acronym honors the three sites (North America’s Goldstone, Europe’s Evpatoria, Asia’s Kashima) that participated in the asteroid’s radar observations in 1995.

3D model of asteroid 6489 Golevka, a near-Earth asteroid with a diameter of one-half kilometer (0.33 mile) and a weight of about 210 billion kilograms (460 billion pounds): NASA Ames SpaceShop, Public Domain, via NASA 3D Resources

Acknowledgment

My special thanks to talented artists and photographers/concerned organizations who make their fine images available on the internet.

Image credits:

Computer-generated model of 6489 Golevka presents sequence of 45-degree rotations of the asteroid's short-axis, with the asteroid’s north pole pointing up; model created from data obtained by Puerto Rico’s Aracibo Observatory: NASA JPL, Public Domain, via Wikimedia Commons @ https://commons.wikimedia.org/wiki/File:Asteroid-golevka.jpeg and via NASA JPL @ https://www.jpl.nasa.gov/releases/2003/163.cfm

Anderson, Charlene. “Steven J. Ostro, 1946-2008.” The Planetary Society > Explore > Planetary News: Space People (2008). Dec. 16, 2008.
Available via Internet Archive Wayback Machine @ https://web.archive.org/web/20081220151130/http://www.planetary.org/news/2008/1216_Steven_J_Ostro_1946__2008.html

Chodas, Paul. “6489 Golevka (1991 JX).” NASA Jet Propulsion Laboratory Center for Near Earth Object Studies > Close Approaches > NEOs.
Available @ https://cneos.jpl.nasa.gov/ca/

Chodas, Paul. “NEO Basics.” NASA Jet Propulsion Laboratory Center for Near Earth Object Studies > About.
Available @ https://cneos.jpl.nasa.gov/about/neo_groups.html

Green, Daniel W.E. “1991 JX.” Central Bureau for Astronomical Telegrams > IAU Circular No. 5268. May 15, 1991.
Available @ http://www.cbat.eps.harvard.edu/iauc/05200/05268.html

Green, Daniel W.E. “1991 JX.” Central Bureau for Astronomical Telegrams > IAU Circular No. 5289. June 13, 1991.
Available @ http://www.cbat.eps.harvard.edu/iauc/05200/05289.html

Hudson, R.S. (Raymond Scott); S.J. Ostro; R.F. Jurgens; K.D. Rosema; J.D. Giorgini; R. Winkler; R. Rose; D. Choate; R.A. Cormier; C.R. Franck; R. Frye; D. Howard; D. Kelley; R. Littlefair; M.A. Slade; L.A.M. Benner; M.L. Thomas; D.L. Mitchell; P.W. Chodas; D.K. Yeomans; D.J. Scheeres; P. Palmer; A. Zaitsev; Y. Koyama; A. Nakamura; A.W. Harris; and M.N. Meshkov. “Radar Observations and Physical Model of Asteroid 6489 Golevka.” Icarus, vol. 148, no. 1 (November 2000): 37-51.
Available via JPL TRS (Technical Report Server) @ https://trs.jpl.nasa.gov/handle/2014/14189
Available via NASA NTRS (NASA Technical Reports Server) @ https://trs.jpl.nasa.gov/bitstream/handle/2014/14189/00-0596.pdf