Earth and Space News: July 2011

Wednesday, July 27, 2011

Uranian Moons Prospero, Setebos and Stephano Were Discovered July 1999

Summary: Uranian moons Prospero, Setebos and Stephano were discovered July 1999 as third, fourth and fifth Uranian irregular satellite discoveries.

Uranian irregular moons Prospero, Setebos and Stephano were discovered July 18, 1999, via the Canada–France–Hawaii Telescope at Mauna Kea Observatories (MKO) on the Big Island of Hawai'i: Litlok, IIVeaa (1Veertje), CC BY SA 3.0 Unported, via Wikimedia Commons

Uranian moons Prospero, Setebos and Stephano were discovered July 1999 as the third, fourth and fifth irregular satellite discoveries in the Uranian system.

Brian G. (Geoffrey) Marsden, director of the Central Bureau for Astronomical Telegrams (CBAT), announced “the discovery of two probable new satellites of Uranus” in IAUC (International Astronomical Union Circular) no. 7230, dated July 27, 1999. Marsden assigned provisional designations of S/1999 U 1 and S/1999 U 2 to the two new Uranian irregular satellite discoveries.

Credit for the discoveries went to J.J. (John J. “JJ”) Kavelaars of McMaster University; B. (Brett) Gladman of Observatoire de la Cote d’Azur (OCA); M. (Matthew) Holman of Harvard-Smithsonian Center for Astrophysics (CfA); and J.-M. (Jean-Marc) Petit and H. (Hans) Scholl of OCA. The discoveries were made from CCD (charged-couple detector) images obtained July 18, 1999, with the 3.5-meter Canada-France-Hawaii Telescope at Mauna Kea Observatories (MKO) on the Big Island of Hawai’i.

The discovery announcement provided six pairs of celestial coordinates over three dates for S/1999 U 1. The two pairs for July 18 found the irregular satellite July 18.51250 at right ascension 21 hours 14 minutes 55.58 seconds, declination minus 16 degrees 39 arcminutes 31.9 arcseconds and July 18.59355 at right ascension 21 hours 14 minutes 54.87 seconds, declination minus 16 degrees 39 arcminutes 35.1 arcseconds. Two pairs for July 19 placed S/1999 U 1 July 19.50227 at right ascension 21 hours 14 minutes 47.10 seconds, declination minus 16 degrees 40 arcminutes 12.5 arcseconds and July 19.57032 at right ascension 21 hours 14 minutes 46.47 seconds, declination minus 16 degrees 40 arcminutes 15.3 arcseconds. Two pairs for July 21 sited S/1999 U 1 July 21.46464 at right ascension 21 hours 14 minutes 29.75 seconds, declination minus 16 degrees 41 arcminutes 35.2 arcseconds and July 21.51919 at right ascension 21 hours 14 minutes 29.26 seconds, declination minus 16 degrees 41 arcminutes 47.5 arcseconds.

Six pairs of celestial coordinates for the same dates and times were also provided for S/1999 U 2. S/1999 U 2 was found July 18.51250 at right ascension 21 hours 13 minutes 38.33 seconds, declination minus 16 degrees 49 arcminutes 57.1 arcseconds and July 18.59355 at right ascension 21 hours 13 minutes 37.61 seconds, declination minus 16 degrees 50 arcminutes 00.6 arcseconds. For July 19, S/1999 U 2 was found July 19.50227 at right ascension 21 hours 13 minutes 29.54 seconds, declination minus 16 degrees 50 arcminutes 39.5 arcseconds and July 19.57032 at right ascension 21 hours 13 minutes 28.89 seconds, declination minus 16 degrees 50 arcminutes 42.2 arcseconds. For July 21, S/1999 U 2’s coordinates were July 21.46464 at right ascension 21 hours 13 minutes 11.76 seconds, declination minus 16 degrees 52 arcminutes 06.7 arcseconds and July 21.51919 at right ascension 21 hours 13 minutes 11.26 seconds, declination minus 16 degrees 52 arcminutes 09.3 arcseconds.

IAUC 7248, dated Sept. 4, 1999, added S/1999 U 3 as a third Uranian irregular satellite discovered via the July 18, 1999, CCD images. The discovery date’s two pairs of coordinates placed S/1999 U 3 July 18.52608 at right ascension 21 hours 12 minutes 55.18 seconds, declination minus 16 degrees 47 arcminutes 38.0 arcseconds and July 18.58036 at right ascension 21 hours 12 minutes 54.68 seconds, declination minus 16 degrees 47 arcminutes 40.2 arcseconds.

The takeaways from the July 1999 discoveries of Uranian moons Prospero, Setebos and Stephano are that four co-discoverers detected the three Uranian irregular satellites on frames obtained July 18 by the Canada-France-Hawaii Telescope at the Big Island of Hawai’I’s Mauna Kea Observatories (MKO) and that the three satellite discoveries numbered as the third, fourth and fifth irregular satellite discoveries in the Uranian system.

The Canada-France-Hawaii Telescope (CFHT) captured images of three Uranian irregular satellites on July 18, 1999; northwest-looking view, toward Maui, of CFHT atop Mauna Kea, Big Island of Hawai'i; Wednesday, May 25, 2011, 20:04: Gordon W Myers, CC BY SA 4.0 International, via Wikimedia Commons

Acknowledgment

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

Image credits:

Uranian irregular moons Prospero, Setebos and Stephano were discovered July 18, 1999, via the Canada–France–Hawaii Telescope at Mauna Kea Observatories (MKO) on the Big Island of Hawai'i: Litlok, IIVeaa , IIVeaa (1Veertje), CC BY SA 3.0 Unported, via Wikimedia Commons @ https://commons.wikimedia.org/wiki/File:CFHT-03.jpg

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Marriner, Derdriu. “Caliban and Sycorax Orbit With Respectively Low and High Eccentricity.” Earth and Space News. Wednesday, July 20, 2011.
Available @ https://earth-and-space-news.blogspot.com/2011/07/caliban-and-sycorax-orbit-with.html

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Available @ https://earth-and-space-news.blogspot.com/2011/07/nine-irregular-uranian-moons-were.html

Marriner, Derdriu. “Uranian Irregular Moons Caliban and Sycorax Were Discovered Sept. 6, 1997.” Earth and Space News. Wednesday, July 13, 2011.
Available @ https://earth-and-space-news.blogspot.com/2011/07/uranian-irregular-moons-caliban-and.html

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Marsden, Brian G. "Probable New Satellites of Uranus." Central Bureau for Astronomical Telegrams > IAU Circular No. 7248. Sept. 4, 1999.
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Wednesday, July 20, 2011

Caliban and Sycorax Orbit With Respectively Low and High Eccentricity

Summary: Uranian irregular moons Caliban and Sycorax orbit with respectively low and high eccentricity.

Animation shows orbits of five Uranian irregular moons around their primary body, Uranus; Sycorax=magenta, Caliban=yellow, Francisco=aqua, Stephano=orange/red, Trinculo=green; data source NASA JPL HORIZONS System (https://ssd.jpl.nasa.gov/horizons/): Phoenix7777, CC BY SA 4.0 International, via Wikimedia Commons

Caliban and Sycorax orbit with respectively low and high eccentricity in their distant placement as irregular satellites in the Uranian system.

Brian G. (Geoffrey) Marsden, director of the Central Bureau for Astronomical Telegrams (CBAT), announced the discoveries in IAUC (International Astronomical Union Circular) no. 6764, dated Oct. 31, 1997. The two newly discovered satellites were assigned temporary designations of S/1997 U 1 and S/1997 U 2.

Marsden noted that the discoveries of S/1997 U 1 (Caliban) and S/1997 U 2 (Sycorax) on Sept. 6, 1997, eliminated a significant difference between Uranus and the solar system’s three other giant planets of Jupiter, Saturn and Neptune. Prior to their detection, Uranus was the only solar system giant apparently lacking irregular satellites. Occurrence in the outer reaches of its primary body’s gravitational sphere of influence and an inclined, often eccentric orbit characterize an irregular satellite.

In IAUC 6765, dated Oct. 31, 1997, Marsden indicated that computations made by him in collaboration with Gareth Vaughan Williams of the International Astronomical Union’s (IAU) Minor Planet Center (MPC) suggested S/1997 U 2 as orbiting in retrograde, that is, directionally opposite from the spin of its primary body. An arbitrary assignment of a retrograde orbit to S/1997 U 1 ensued from the “poorer distribution” of its observations.

IAUC 6780, dated Nov. 29, 1997, confirmed the status of both objects as Uranian irregular satellites. Marsden also affirmed both orbits as “indeed retrograde.”

IAUC 6833, dated March 7, 1998, noted that, per discoverer P.D. (Philip David) Nicholson’s report, co-discoverers B.J. (Brett James) Gladman and J.A. (Joseph Arthur) Burns had located images of S/1997 U 2, the brighter irregular Uranian satellite, on plates obtained in 1984 by the Canada-France-Hawaii Telescope (CFHT). The CFHT is located near the summit of Mauna Kea, in north-central Hawaii Island.

Gladman, as measurer, with D.P. (Dale Paul) Cruikshank as observer, provided semiaccurate measurements for the 1984 images of S/1997 U 2. The measurements, calculated for epoch 2000, had an uncertainty of plus / minus 3 arcseconds. For June 1.5556, S/1997 U 2 was found at right ascension 16 hours 40 minuts 44.2 seconds and declination minus 22 degrees 07 arcminutes 02 arcseconds. For June 2.5410, the irregular satellite was positioned at right ascension 16 hours 40 minutes 34.0 seconds and declination minus 22 degrees 06 arcminutes 40 arcseconds.

In IAUC 6870, dated April 7, 1998, Marsden shared 1984 precovery data, also with an uncertainty of plus / minus 3 arcseconds, for S/1997 U 1, the dimmer of the two Uranian irregular moons. Gladman as measurer and Cruikshank as observer placed the dim satellite’s right ascension at 16 hours 40 minutes 58.4 seconds and declination at minus 22 degrees 03 arcminutes 56 arcseconds on June 1.5556. For June 2.5410, it was located at right ascension 16 hours 40 minutes 48.5 seconds and declination minus 22 degrees 03 arcminutes 36 arcseconds.

Marsden noted that recovery observations of S/1997 U 1 were conducted March 27, 1998, with the 4-meter reflector and charged-couple detector (CCD) camera at the Anglo-Australian Observatory in New South Wales, southeastern Australia, by R.M. Smith, J.B. Jones and D. (David) Windridge, with discoverer Gladman as measurer. On March 31, 1998, with co-discoverer J.J. (John J. “JJ”) Kavelaars as measurer, P. Hall and D. Graham made successful recovery observations with the 4-meter reflector and CCD camera at Cerro Tololo Interamerican Observatory. The 1998 recovery observations and orbital data computed by Marsden in collaboration with G.V. (Gareth Vaughan) Williams of the International Astronomical Union’s (IAU) Minor Planet Center (MPC) and K. (Kaare) Aksnes of the IAU Working Group for Planetary System Nomenclature (WGPSN) validated the satellite’s 1984 candidacy.

The 1998 recovery observations and orbital computations for S/1997 U 1 by Marsden et alia also confirmed the satellite’s low-e (low eccentricity; more circular than elliptical). Marsden had described previously, in IAUC no. 6780, dated Nov. 29, 1997, the fainter satellite’s orbit as “significantly less eccentric than that of the brighter.”

Marsden reported the 1998 recovery of S/1997 U 2 via IAUC no. 6869, dated April 7, 1998. The team of Smith, Jones and Windridge, with discoverer Gladman as measurer, successfully recovered the brighter of the two irregular satellites March 27 with the 4-meter reflector and CCD camera at the Anglo-Australian Observatory. Hall and Graham, with discoverer “JJ” Kavelaars as measurer, succeeded in recovering S/1997 U 2 with the 4-meter reflector and CCD camera at Cerro Tololo Interamerican Observatory.

The recovery positions varied by “fully 30”” from the prediction discussed March 7, 1998, via IAUC no. 6834. Marsden explained that computations by William, Aksnes and himself presented “another orbital solution from the 1984-1997 observations.” Their computations revealed the brighter irregular satellite’s orbit as “much more strongly perturbed by the sun.” The 1998 recovery observations clearly demonstrated the correctness of “this high-e solution” (high eccentricity) for S/1997 U 2’s orbit.

The takeaways from the determination that Caliban and Sycorax orbit with respectively low and high eccentricity are that the first irregular satellite discoveries in the Uranian system trace orbits in retrograde, i.e., in the opposite direction of Uranus’ spin, and that perturbations by the sun account for the highly eccentric orbit of the brighter satellite, S/1997 U 2 (Sycorax).

discovery images, taken one hour apart, for S/1997 U 2 (Uranus XVII; Sycorax); NASA- and Cornell University-funded study; Brett Gladman, postdoctoral associate, Canadian Institute for Theoretical Astrophysics; Sunday, Sep. 7, 1997: Public Domain, via Wikimedia Commons

Acknowledgment

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

Image credits:

Burns, Joseph A.; and Mildred Shapley Matthews, eds. Satellites. Space Science Series. Tucson AZ: University of Arizona Press, Nov. 1, 1986.

Cornell Chronicle. “’Irregular’ Satellites S/1997 U1 and S/1997 U2 Discovered With Palomar Mountain’s 5-Meter Hale Telescope.” Cornell University > Stories. Oct. 31, 1997.
Available @ http://news.cornell.edu/stories/1997/10/planet-uranus-has-two-more-moons-cornell-and-canadian-astronomers-find

Gladman, Brett J.; Philip D. Nicholson; Joseph A. Burns; JJ Kavelaars; Brian J. Marsden; Gareth V. Williams; and Warren B. Offutt. “Discovery of Two Distant Irregular Moons of Uranus.” Nature, vol. 392 (April 30, 1998): 897-899.
Available via Nature @ https://www.nature.com/articles/31890

Grav, Tommy; and Matthew J. Holman. “Photometry of Irregular Satellites of Uranus and Neptune.” The Astrophysical Journal, vol. 613 (Sept. 20, 2004): L77-L80. Available @ https://iopscience.iop.org/article/10.1086/424997/pdf

Johnston, William Robert. “List of IAU Preliminary Designations of Natural Satellites.” Johnston’s Archive > Astronomy and Space.
Available @ http://www.johnstonsarchive.net/astro/moonlist.html

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

Maris, Michele; Giovanni Carraro; Gabriele Cremonese; and Marco Fulle. “Multicolor Photometry of the Uranus Irregular Satellites Sycorax and Caliban.” The Astronomical Journal, vol. 121, no. 5 (May 2001): 2800-2803.
Available via IOPscience @ https://iopscience.iop.org/article/10.1086/320378

Marsden, Brian G. “S/1997 U 1.” Central Bureau for Astronomical Telegrams > IAU Circular No. 6833. March 7, 1998.
Available @ http://www.cbat.eps.harvard.edu/iauc/06800/06833.html

Marsden, Brian G. “S/1997 U 1.” Central Bureau for Astronomical Telegrams > IAU Circular No. 6870. April 7, 1998.
Available @ http://www.cbat.eps.harvard.edu/iauc/06800/06870.html

Marsden, Brian G. “S/1997 U 2.” Central Bureau for Astronomical Telegrams > IAU Circular No. 6833. March 7, 1998.
Available @ http://www.cbat.eps.harvard.edu/iauc/06800/06833.html

Marsden, Brian G. “S/1997 U 2.” Central Bureau for Astronomical Telegrams > IAU Circular No. 6834. March 7, 1998.
Available @ http://www.cbat.eps.harvard.edu/iauc/06800/06834.html

Marsden, Brian G. “S/1997 U 2.” Central Bureau for Astronomical Telegrams > IAU Circular No. 6869. April 7, 1998.
Available @ http://www.cbat.eps.harvard.edu/iauc/06800/06869.html

Marsden, Brian G. “Satellites of Uranus.” Central Bureau for Astronomical Telegrams > IAU Circular No. 6764. Oct. 31, 1997.
Available @ http://www.cbat.eps.harvard.edu/iauc/06700/06764.html

Marsden, Brian G. “Satellites of Uranus.” Central Bureau for Astronomical Telegrams > IAU Circular No. 6765. Oct. 31, 1997.
Available @ http://www.cbat.eps.harvard.edu/iauc/06700/06765.html

Marsden, Brian G. “Satellites of Uranus.” Central Bureau for Astronomical Telegrams > IAU Circular No. 6780. Nov. 29, 1997.
Available @ http://www.cbat.eps.harvard.edu/iauc/06700/06780.html

Marsden, Brian G. “Satellites of Uranus.” Central Bureau for Astronomical Telegrams > IAU Circular No. 7132. March 27, 1999.
Available @ http://www.cbat.eps.harvard.edu/iauc/07100/07132.html

Minor Planet Center. “Uranus XVI (Caliban).” Minor Planet Circular 40991. July 26, 2000.
Available @ https://www.minorplanetcenter.net/iau/ECS/MPCArchive/2000/MPC_20000726.pdf

Minor Planet Center. “Uranus XVII (Sycorax).” Minor Planet Circular 40991. July 26, 2000.
Available @ https://www.minorplanetcenter.net/iau/ECS/MPCArchive/2000/MPC_20000726.pdf

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Nemiroff, Robert; and Jerry Bonnell. “Irregular Moons Discovered Around Uranus.” NASA Astronomy Picture of the Day (APOD). Nov. 3, 1997.
Available @ https://apod.nasa.gov/apod/ap971103.html

Segelken, Roger. “Planet Uranus Has Two More Moons.” Cornell University News Service. Oct. 31, 1997.
Available via NASA GSFC (Goddard Space Flight Center) NSSDC (NASA Space Science Data Coordinated Archive) > Solar System Exploration > Planetary Science > Uranus.
Available @ https://nssdc.gsfc.nasa.gov/planetary/text/uran_pr_971031.txt

Wednesday, July 13, 2011

Uranian Irregular Moons Caliban and Sycorax Were Discovered Sept. 6, 1997

Summary: Uranian irregular moons Caliban and Sycorax were discovered Sept. 6, 1997, via Palomar Observatory’s 200-inch (5.1-meter) Hale Telescope.

artist’s concept of Sycorax, created with Celestia software Sunday, May 8, 2011: Lanthanum-138, Public Domain, via Wikimedia Commons

Uranian irregular moons Caliban and Sycorax were discovered Sept. 6, 1997, via the 200-inch (5.1-meter) Hale Telescope, which is housed southeast of Los Angeles at the California Institute of Technology’s (Caltech) Palomar Observatory.

The discoveries of “two probable distant satellites of Uranus” were announced by Brian G. (Geoffrey) Marsden, director of the Central Bureau for Astronomical Telegrams (CBAT) in IAUC (International Astronomical Union Circular) no. 6764, dated Oct. 31, 1997. Marsden assigned provisional designations of S/1997 U 1 and S/1997 U 2 to the Uranian satellite discoveries.

Marsden identified the discoverers as B.J. (Brett James) Gladman of the Canadian Institute for Theoretical Astrophysics (CITA) in Toronto, Ontario, Central Canada; P.D. (Philip David) Nicholson and J.A. (Joseph Arthur) Burns of Cornell University in Ithaca, Finger Lakes region, Central New York; and J.J. (John “JJ”) Kavelaars of McMaster University in Hamilton, Ontario, Central Canada. In early October Gladman had detected the satellites on a set of 12 CCD (charged-couple detector) frames obtained Sept. 6 and 7 with the COSMIC camera on the 5.1-meter (200-inch) Hale Telescope.

The fainter satellite, S/1997 U 1, was positioned about 6 arcminutes east of Uranus. The brighter satellite, S/1997 U 2, was located about 7 arcminutes west-northwest of Uranus.

Gladman’s team posted coordinates, epoch 2000, for S/1997 U 1, for Sept. 6 and 7. For Sept. 6.21723, the faint satellite registered right ascension (abbreviated RA; symbol α) of 20 hours 31 minutes 52.90 arcseconds and declination (abbreviated dec; symbol δ) of minus 19 degrees 33 arcminutes 24.4 arcseconds. Its right ascension and declination for Sept. 7.20042 measured 20 hours 31 minutes 45.88 seconds and minus 19 degrees 33 arcminutes 52.2 arcseconds, respectively.

Nicholson’s team posted coordinates, epoch 2000, for S/1997 U2, for Sept. 6 and 7. For Sept. 6.22938, the bright satellite was at right ascension 20 hours 30 minutes 59.93 seconds and declination minus 19 degrees 30 arcminutes 51.9 arcseconds. For Sept. 7.20902, S/1997 U 2 was found at right ascension 20 hours 30 minutes 53.31 seconds and declination minus 19 degrees 31 arcminutes 13.3 arcseconds.

Marsden noted that the discoverers reobserved their finds with the Hale Telescope in late October. Two reobservations were achieved for S/1997 U 2, but “bad seeing” allowed for only one night’s detection of S/1997 U 1.

Gladman’s team reobserved S/1997 U 1 Oct. 27.14067 at right ascension 20 hours 29 minutes 34.32 seconds, declination minus 19 degrees 42 minutes 44.7 seconds. Marsden commented that the satellite’s position differed by "some 30"" from Nicholson’s prediction, which had been based upon “a circular uranicentric orbit.”

Nicholson’s team reobserved S/1997 U 2 on Oct. 28 and 29. For Oct. 27.16834, S/1997 U 2 appeared at right ascension 20 hours 29 minutes 06.15 seconds, declination minus 19 degrees 35 arcminutes 56.5 arcseconds. For Oct. 28.14304, it was detected at right ascension 20 hours 29 minutes 09.11 seconds, declination minus 19 degrees 35 arcminutes 44.6 arcseconds.

In IAUC no. 7132, dated March 27, 1999, Marsden referenced the first two Uranian irregular satellite discoveries by their official and proposed names. Uranus XVI, the IAU’s official sequential designation for the fainter satellite, S/1997 U 1, reflects the fainter satellite’s status as the 16th satellite discovery in the Uranian system. Uranus XVII indicates that S/1997 U 2 numbers as the Uranian system’s 17th satellite discovery.

The discoverers suggested Caliban as the name for Uranus XVI (S/1997 U 1) and Sycorax as the name for Uranus XVII (S/1997 U 2). Caliban is the misshapen son of the exiled Algerian witch Sycorax in “The Tempest” by Elizabethan playwright William Shakespeare (bapt. April 26, 1564-April 23, 1616).

The IAU’s Gazetteer of Planetary Nomenclature website, maintained by the U.S. Geological Survey’s Astrogeology Science Center, states that characters in “The Rape of the Lock” by 18th-century English poet Alexander Pope (May 21, 1688-May 30, 1744) and in Shakespearean plays inspire the names of the Uranian system’s satellites. Official approval of Caliban and Sycorax occurred during the IAU’s XXIVth (24th) General Assembly, held Monday, Aug. 7, to Friday, Aug. 18, 2000, in Manchester, United Kingdom.

The takeaways from the Sept. 6, 1997, discoveries of Uranian irregular moons Caliban and Sycorax are that the first two irregular satellites in the Uranian system were discovered on frames obtained by the Hale Telescope’s COSMIC camera at California’s Palomar Observatory; that their official designations of Uranus XVI and Uranus XVII denote their rank as the 16th and 17th satellite discoveries in the Uranian system; and that the satellites’ names observe the convention of namesaking characters in 18th-century English poet Alexander Pope’s “The Rape of the Lock” and in Elizabeth playwright William Shakespeare’s plays.

artist’s concept of Caliban, created with Celestia software; Aug. 6, 2011: Lanthanum-138, CC 1.0 Universal (CC0 1.0) Public Domain dedication, via Wikimedia Commons

Acknowledgment

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

Image credits:

artist’s concept of Sycorax, created with Celestia software Sunday, May 8, 2011: Lanthanum-138, Public Domain, via Wikimedia Commons @ https://commons.wikimedia.org/wiki/File:Sycorax.png

artist’s concept of Caliban, created with Celestia software; Aug. 6, 2011: Lanthanum-138, CC 1.0 Universal (CC0 1.0) Public Domain dedication, via Wikimedia Commons @ https://en.wikipedia.org/wiki/File:Caliban_artistic.png

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