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Hello Again to Hermes?
Hello Again to Hermes?
15 Oct 2002
(Source: Sky & Telescope)

HAS HERMES RETURNED?
Roger W. Sinnott
Senior Editor
Sky & Telescope

Earlier this month, the Minor Planet Center's electronic circular 2002-T14 contained this intriguing comment by Timothy B. Spahr: "The orbital elements above for 2002 SY50 bear a striking resemblance to those of 1937 UB." With those words, Spahr was suggesting that a newfound object might be none other than Hermes, the famous asteroid that whizzed by Earth just before World War II but has eluded astronomers for 65 years.

Shortly after the Hermes flyby of October 1937, the American Museum of Natural History created a spine-tingling exhibit for public display. Poised above a model of New York City was Hermes, represented by a ball the size of Central Park. Pictures of the scene appeared in many astronomy books of the day.

For now, the new object is simply being called 2002 SY50. It was picked up by the LINEAR survey telescope in New Mexico on September 30th of this year. At about 17th magnitude, it was moving slowly southwestward through the constellation Cetus just a few degrees from the variable star Mira. The Minor Planet Center alerted observers via the Near-Earth Object Confirmation Page of its Web site, and within a few days more than 100 astrometric measurements were sent in by amateur and professional observatories around the world. The center also identified the object with four positions of a moving object obtained at Lowell Observatory two weeks earlier as part of the LONEOS survey.

According to Spahr's calculations, 2002 SY50 is traveling in an Earth-crossing orbit inclined 9 degrees to the ecliptic plane. Its revolution period is very nearly 2 years and 3 months. When closest to the Sun, at perihelion, 2002 SY50 is roughly midway between the orbits of Venus and Mercury. When farthest, at aphelion, it is well out in the main asteroid belt between the orbits of Mars and Jupiter.

But is this the long-lost Hermes? Spahr commented that attempts by him and others had failed, so far, to establish that 2002 SY50 and Hermes were one and the same. Further astrometric measurements will be needed to be sure, and this may take weeks or months. "Both the 1937 and the 2002 observations yield orbits that allow very close approaches to the earth, Venus and Mars," he added, a situation that greatly complicates the problem of linking the two objects.

On October 14th, Gianluca Masi told members of the Minor Planet Mailing List (http://www.bitnik.com/mp) that he, Franco Mallia, and Ugo Tagliaferri have obtained a detailed light curve of 2002 SY50 at Campo Catino Astronomical Observatory in Italy. The fluctuations in brightness suggest that the object is rotating once every 4.67 hours. To view the light curve, visit http://www.bellatrixobservatory.org/2002sy50.gif.

Later this month, Jean-Luc Margot and his colleagues at Caltech plan to make highly accurate radar measurements of the object's range and radial velocity using the large Goldstone radio dish.

During the next two weeks 2002 SY50 is expected to become as bright as 14th magnitude, putting it within easy reach of CCD-equipped amateur telescopes. (See the daily ephemeris below.) As it continues on an inbound trajectory toward the Sun, 2002 SY50 will pass 13 million kilometers (less than one-tenth the Sun's distance) from our planet in the first few days of November.


The following ephemeris, adapted from the Minor Planet Ephemeris Service at http://cfa-www.harvard.edu/iau/mpc.html, gives the right ascension and declination of 2002 SY50 at 0h Universal Time on successive dates. Also listed are its distance from the Earth (Delta) and Sun (r) in astronomical units, 1 a.u. being 149,600,000 kilometers. The last two columns give its predicted visual magnitude and angular motion on the sky (in arcseconds per minute). To display the ephemeris properly, your e-mail program should be set to use a fixed-space font such as Courier.

The Minor Planet Center notes that accurate astrometric measurements are especially desirable between October 15th and 27th.

Ephemeris of 2002 SY50

Date R.A. (2000) Dec. Delta r V Motion
(0h UT) h m o ' (au) (au) "/min
Oct 15 01 29.1 -02 37 0.227 1.221 15.3 2.74
Oct 16 01 24.8 -03 00 0.216 1.209 15.2 3.03
Oct 17 01 19.9 -03 24 0.205 1.198 15.1 3.36
Oct 18 01 14.5 -03 50 0.194 1.186 15.0 3.73
Oct 19 01 08.5 -04 19 0.184 1.174 14.9 4.15
Oct 20 01 01.8 -04 51 0.173 1.162 14.9 4.64
Oct 21 00 54.2 -05 25 0.163 1.151 14.8 5.20
Oct 22 00 45.7 -06 03 0.154 1.139 14.7 5.86
Oct 23 00 36.1 -06 45 0.144 1.127 14.6 6.62
Oct 24 00 25.2 -07 31 0.135 1.115 14.6 7.50
Oct 25 00 12.7 -08 21 0.126 1.103 14.5 8.52
Oct 26 23 58.5 -09 16 0.118 1.091 14.5 9.69
Oct 27 23 42.2 -10 16 0.111 1.078 14.4 11.02
Oct 28 23 23.5 -11 19 0.104 1.066 14.4 12.49
Oct 29 23 02.3 -12 25 0.097 1.054 14.4 14.05
Oct 30 22 38.4 -13 31 0.092 1.042 14.4 15.62
Oct 31 22 11.7 -14 33 0.088 1.030 14.5 17.05
Nov 01 21 42.7 -15 27 0.085 1.017 14.7 18.17
Nov 02 21 12.0 -16 09 0.084 1.005 14.9 18.80
Nov 03 20 40.6 -16 34 0.084 0.993 15.2 18.83
Nov 04 20 09.6 -16 41 0.085 0.980 15.5 18.25
Nov 05 19 40.0 -16 32 0.088 0.968 15.9 17.17
Nov 06 19 12.5 -16 10 0.092 0.955 16.4 15.77


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Last Updated: 15 Oct 2002