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.

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

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

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 @ https://nasa3d.arc.nasa.gov/detail/golevka

For further information:

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

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

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

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 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

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

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