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Robert D. Stephens

Robert D. Stephens
MoreData!, Inc. · .

Master of Business Administration (MBA)

About

263
Publications
10,255
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1,370
Citations
Introduction
I currently focus on three areas of study; Jovian Trojan asteroids, Hilda asteroids, and Near Earth asteroids.
Additional affiliations
June 2011 - present
Center for Solar System Studies
Position
  • CEO
Description
  • An nonprofit observatory complex established in 2011. Currently has 15 telescopes in nine observatories primarily observing asteroids.
May 2010 - present
MoreData!, Inc.
Position
  • Research Scientist, CEO
Description
  • A grant management company receiving grants from NASA/NSF to study Near-Earth asteroids.
Education
September 1989 - June 1991
September 1975 - June 1978
California State Polytechnic University, Pomona
Field of study
  • Business Administration

Publications

Publications (263)
Article
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CCD photometric observations of 25 main-belt asteroids were obtained at the Center for Solar System Studies (CS3) from 2019 July to September.
Article
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Lightcurves for 11 L 4 Jovian Trojan asteroids were obtained at the Center for Solar System Studies (CS3) from 2019 July to September. CCD Photometric observations of 11 Trojan asteroids from the L 4 (Trojan) Lagrange point were obtained at the Center for Solar System Studies (CS3, MPC U81).
Article
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CCD photometric observations of four main-belt and one near-Earth asteroid were made in 2019. Of these, the Vestoid 2602 Moore and Hungaria (27568) 2000 PT6 were confirmed to be binary asteroids. The Hungaria 3880 Kaiserman is a suspected binary. Near-Earth asteroid (142040) 2002 QE15 was found to have a long period (46.4 h). Re-evaluation of data...
Article
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CCD photometric observations of seven Hilda asteroids were made at the Center for Solar System Studies (CS3) from 2019 April and June. Analysis of data for 1269 Rollandia and 3843 OISCA based on 2019 data led to review of our earlier results. For both objects, this resulted not in solving but deepening the mystery of the their true rotation periods...
Article
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Lightcurves for 38 near-Earth asteroids (NEAs) obtained at the Center for Solar System Studies (CS3) from 2019 March-July were analyzed for rotation period, peak-to-peak amplitude, and signs of satellites or tumbling.
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Lightcurves for five L 5 Jovian Trojan asteroids were obtained at the Center for Solar System Studies (CS3) from 2019 April to June.
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CCD photometric observations of 19 main-belt asteroids were obtained at the Center for Solar System Studies (CS3) from 2019 April to June.
Article
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Lightcurves for four L5 Jovian Trojan asteroids were obtained at the Center for Solar System Studies (CS3) from 2019 January to March. The suspected binary Trojan, 2207 Antenor was observed again and a single attenuation event was detected.
Article
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CCD photometric observations of three Hilda asteroids were made at the Center for Solar System Studies (CS3) from 2019 January-March. For 1038 Tuckia, the period solution was ambiguous at either P = 18.020 h, amplitude 0.22 mag or P = 14.401 h, amplitude 0.20 mag. For 2246 Bowell, the analysis found P = 4.997 and amplitude 0.46 mag. For 4317 Gariba...
Article
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CCD photometric observations of 10 main-belt asteroids were obtained from the Center for Solar System Studies from 2019 January to March. In light of recent period analysis, images of 2120 Tyumenia obtained in 2004 were reexamined. The resulting analysis found a period of 17.515 h, which is consistent with the recent results.
Article
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CCD photometric observations of the near-Earth asteroid (152931) 2000 EA107 were made in 2019 March and April at the Center for Solar System Studies (CS3). Analysis of the data found that the asteroid is likely a binary. The primary period is P 1 = 4.1367 ± 0.0002 h with a lightcurve amplitude of A 1 = 0.29 ± 0.02 mag. The secondary period is P 2 =...
Article
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Lightcurves for 24 near-Earth asteroids (NEAs) obtained at the Center for Solar System Studies (CS3) from 2019 January-April were analyzed for rotation period, peak-to-peak amplitude, and signs of satellites or tumbling. Two asteroids, (381677) 2009 BJ81 and (454177) 2013 GJ35, were found to have two periods that make them additional candidates for...
Article
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Lightcurves for 28 near-Earth asteroids (NEAs) obtained at the Center for Solar System Studies (CS3) from 2019 July to September were analyzed for rotation period, peak-to-peak amplitude, and signs of satellites or tumbling. 2059 Baboquivari, (90403) 2003 YE45, and 2016 AU130 are candidates for membership within the very wide binary asteroids class...
Article
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CCD photometric observations of 18 main-belt asteroids were obtained from the Center for Solar System Studies from 2018 October to December. A pole solution was found for 4910 Kawasato of (, , P SID) = (355°, 35°, 4.66271 h). (31320) 1998 HX2 is a binary asteroid with a P 1 of 2.8149 ± 0.0001 h and P 2 of 47.06 ± 0.05 h.
Article
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Lightcurve analysis of the near-Earth asteroids (442742) 2012 WP3, (523604) 2004 QB17, and 2018 RL indicate that they are potential members of a relatively rare class of “very wide binary asteroids.” These objects feature a primary rotational period of tens to hundreds of hours and a secondary rotational period less than 24 hours, usually less than...
Article
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CCD photometric observations of three Hilda asteroids were made at the Center for Solar System Studies (CS3) in 2019 September. Analysis of the 2019 data for 4495 Dassanowsky, a reported binary (Warner and Stephens, 2019), found three periods, one being very long (431 h). The long period and a secondary one made it a potential member of the very wi...
Article
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Lightcurves for four Hilda asteroids were obtained at the Center for Solar System Studies (CS3) from 2018 September-November: 3514 Hooke, 3557 Sokolsky, 4495 Dassanowksy, and 10331 Peterbluhm. 4495 Dassanowksy appears to be a binary asteroid with a primary period of either 2.6314 hr or 5.263 hr and an orbital period of 18.516 hr. The secondary-to-p...
Article
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Lightcurves for 32 near-Earth asteroids (NEAs) obtained at the Center for Solar System Studies (CS3) from 2018 September-December were analyzed for rotation period and signs of satellites or tumbling.
Article
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Lightcurves for five Jovian Trojan asteroids were obtained at the Center for Solar System Studies (CS3) from 2018 July to September. CCD Photometric observations of five Trojan asteroids from the L 4 (Greek) Lagrange point were obtained at the Center for Solar System Studies (CS3, MPC U81).
Article
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CCD photometric observations of 10 main-belt asteroids were obtained from the Center for Solar System Studies from 2018 July to September.
Article
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CCD photometric observations of the Mars-crosser asteroid 7002 Bronshten show it to be a binary system. The primary period is P1 = 2.67025 ± 0.00007 h. The orbital period of the satellite, which is also its rotation period, is PORB = 13.323 ± 0.003 h. The mutual event attenuations in the satellite lightcurve are 0.06-0.11 mag. This establishes a lo...
Article
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Lightcurves for 45 Near-Earth asteroids (NEAs) obtained at the Center for Solar System Studies (CS3) from 2018 July-September were analyzed for rotation period and signs of satellites or tumbling. NEA 13553 Massakikoyama appears to be in non-principal axis rotation, i.e., tumbling. 2011 UA (D = 0.6 km) is a super-fast rotator with a period of 0.316...
Article
Context. The recent close approach of the near-Earth asteroid (3200) Phaethon offered a rare opportunity to obtain high-quality observational data of various types. Aims. We used the newly obtained optical light curves to improve the spin and shape model of Phaethon and to determine its surface physical properties derived by thermophysical modeling...
Preprint
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The recent close approach of the NEA (3200) Phaethon offered a rare opportunity to obtain high-quality observational data. We used the newly obtained optical light curves to improve the spin and shape model of Phaethon and to determine its surface physical properties derived by thermophysical modeling. We also used the available astrometric observa...
Article
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We report that asteroid 2207 Antenor is a very likely binary asteroid candidate. If confirmed, it would be the fifth known binary Jovian Trojan asteroid. The primary lightcurve has a period of 7.96436 ± 0.00006 h and an amplitude 0.22 to 0.23 mag. A secondary orbital period could not be determined.
Article
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Lightcurves of four Jovian Trojan asteroids were obtained at the Center for Solar System Studies (CS3) from 2018 April to May. One of the Trojans observed was 617 Patroclus to time the start of mutual events in support of NASA’s Lucy mission.
Article
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CCD photometric observations of 8 main-belt asteroids were obtained from the Center for Solar System Studies from 2018 April to June.
Article
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Analysis of CCD photometric observations of the near-Earth asteroid (139345) 2001 KA67 show that it may be a very wide asynchronous binary, which features a long primary and short secondary period. The two periods that were found for 2001 KA67, P 1 = 44.25 ± 0.05 h and P 2 = 6.011 ± 0.003 h, are in-line with other potential members of this class. T...
Article
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We report that asteroid 4435 Holt is a singly-asynchronous binary asteroid. The primary lightcurve has a primary period of 2.8670 ± 0.0002 h and an amplitude 0.15 to 0.30 mag. with a secondary orbital period of 42.65 ± 0.05 h.
Article
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CCD Photometric observations of six Trojan asteroids from the L 5 (Trojan) Lagrange point were obtained at the Center for Solar System Studies (CS3, MPC U81).
Article
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CCD photometric observations of 6 main-belt asteroids were obtained from the Center for Solar System Studies from 2018 January to March.
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A combination of dense lightcurves obtained by the authors over several apparitions and sparse data was used to model the outer main-belt asteroid 607 Jenny. A reasonably reliable spin axis with ecliptic coordinates of (220°, –40°, 8.52234 h) was found, although one of (35°, –17°, 8.52234 h) cannot be formally excluded.
Article
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Lightcurves for four Hilda asteroids were obtained at the Center for Solar System Studies (CS3) from 2016 December thru 2017 April.
Article
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Lightcurves for four Jovian Trojan asteroids were obtained at the Center for Solar System Studies (CS3) from 2017 September to December. From observations in 2016 June, 2759 Idomeneus was found to be another candidate for the special case of very wide binaries. This would be the fifth confirmed Jovian Trojan binary asteroid CCD Photometric observat...
Article
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CCD photometric observations of 7 Main Belt asteroids were obtained from the Center for Solar System Studies from 2017 October to December.
Article
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Lightcurves for eight Jovian Trojan asteroids were obtained at the Center for Solar System Studies (CS3) from 2017 April to June.
Article
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We report that asteroid (24495) 2001 AV1 is a binary asteroid. It is another candidate for the special case of very wide binaries. The primary lightcurve has a period of 24.083 ± 0.005 h and an amplitude 0.58 ± 0.05 mag. and the secondary lightcurve has a period of 2.7375 ± 0.0001 h. The Mars crosser (24495) 2001 AV1 was initially observed by Steph...
Article
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CCD photometric observations of 11 main-belt asteroids were obtained from the Center for Solar System Studies from 2017 April to June.
Poster
Jovian Trojan asteroids are of interest both as objects in their own right and as possible relics of Solar System formation. Several lines of evidence support a common origin for, and possible hereditary link between, Jovian Trojan asteroids and cometary nuclei. Asteroid lightcurves give information about processes that have affected a group of ast...
Article
Lightcurves for ten Hilda asteroids were obtained at the Center for Solar System Studies (CS3) from 2017 April thru July.
Article
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Lightcurves for four Hilda asteroids were obtained at the Center for Solar System Studies (CS3) from 2016 December thru 2017 April.
Article
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Lightcurves for 18 Jovian Trojan asteroids were obtained at the Center for Solar System Studies (CS3) from 2017 January to March.
Article
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CCD photometric observations of two Hungaria asteroids were obtained from the Center for Solar System Studies from 2017 January to March.
Article
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CCD photometric observations of eight asteroids were obtained from the Center for Solar System Studies from 2016 October to December.
Article
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CCD photometry observations made in 2016 October and November of the Hungaria asteroid (24465) 2000 SX155 showed it to be binary. The primary lightcurve has a period of 2.66087 ± 0.00005 h and an amplitude 0.08 ± 0.02 mag. The orbital period of the satellite is 9.252 ± 0.001 h, the shortest detected so far.
Article
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Lightcurves for six Jovian Trojan asteroids were obtained at the Center for Solar System Studies (CS3) from 2016 October to December.
Article
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Lightcurves for 19 Hilda asteroids were obtained at the Center for Solar System Studies (CS3) from 2016 August through December.
Article
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CCD photometry observations made in 2016 October and November of the Hungaria asteroid (24465) 2000 SX155 showed it to be binary. The primary lightcurve has a period of 2.66087 ± 0.00005 h and an amplitude 0.08 ± 0.02 mag. The orbital period of the satellite is 9.252 ± 0.001 h, the shortest detected so far.
Article
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Lightcurves for six Jovian Trojan asteroids were obtained at the Center for Solar System Studies (CS3) from 2016 October to December.
Article
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Lightcurves for 16 Hilda asteroids were obtained at the Center for Solar System Studies (CS3) from 2016 June to September.
Article
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Thirty main-belt asteroids were observed from CTIO (Cerro Tololo Inter-American Observatory MPC 807) in April 2016. Rotational periods were determined for 25 of them. Four are reported as having an indeterminate long-period.
Article
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CCD photometric observations of twelve asteroids were obtained at the Center for Solar System Studies from 2016 July to September.
Article
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Lightcurves of four Jovian Trojan asteroids were obtained at the Center for Solar System Studies (CS3) from 2017 July to September.
Article
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Jovian Trojan asteroids larger than ~ 30 km were studied from the Center for Solar System Studies (CS3, MPC U81). Lightcurves for 30 Trojan asteroids in the L4 (Greek) cloud were between May and June 2016. These were mostly from the L4 " Greek " cloud, but several were L5 " Trojan " cloud lightcurves not previously published. For three years, CS3 h...
Article
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CCD photometric observations of seven asteroids were obtained from the Center for Solar System Studies from 2016 April to June. The Center for Solar System Studies " Trojan Station " (CS3, MPC U81) has two telescopes which are normally used in program asteroid family studies. During bright moon times, those targets are usually too dim to continue o...
Article
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CCD photometric observations of 9 asteroids were obtained from the Center for Solar System Studies from 2016 January to March.
Article
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Jovian Trojan asteroids larger than 30 km were studied from the Center for Solar System Studies (CS3, MPC U81). Lightcurves for 22 Trojan asteroids were between November 2015 and February 2016.
Article
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CCD photometric observations in 2016 February and March and a reevaluation of observations made in 2013 June of 19204 Joshuatree show it to be a possible binary. It is another candidate for the special case of very wide binaries. The primary lightcurve has a period of 480 ± 5 h and an amplitude 0.25 ± 0.02 mag and the secondary lightcurve has a per...
Article
CCD photometric observations in 2016 February and March and a reevaluation of observations made in 2013 June of 19204 Joshuatree show it to be a possible binary. It is another candidate for the special case of very wide binaries. The primary lightcurve has a period of 480 ± 5 h and an amplitude 0.25 ± 0.02 mag. and the secondary lightcurve has a pe...
Conference Paper
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The Center for Solar Systems Studies (CS3) is located in the California high desert in Landers, north of Joshua Tree National Park. Currently, ten telescopes are exclusively used to observe asteroids and two more are under construction. The facility is fully robotic with local computers running the telescope/camera software as well opening and clos...
Article
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CCD photometric observations of four main-belt and one Near-earth asteroids observed at Center for Solar System Studies (CS3, MPC U81). During this quarter, this observatory was observing Jovan Trojans asteroids. When a bright moon swamped the Trojan cloud with moonlight, other targets were selected because of their known short rotational periods a...
Article
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The Hungaria asteroid 7958 Leakey is a known binary (Warner et al., 2012). It was observed in 2015 to confirm and refine the original periods for the primary rotation and satellite orbit. The analysis of the 2015 data found a noticeably different orbital period. We report on the analysis of the new data and a second look at the data from 2012.
Article
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Correction to "Lightcurve Observations of (348400) 2005 JF21: an NEA Binary."
Article
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CCD photometry observations made in 2015 October and November of the Vestoid asteroid 5425 Vojtech showed it to be binary. The primary lightcurve has a period of 2.64759 ± 0.000004 h and an amplitude 0.27 ± 0.02 mag. The orbital period of the satellite is 25.43 ± 0.02 h. Based on mutual events ranging from 0.05 to 0.09 mag, the estimated effective...
Article
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Jovian Trojan asteroids larger than 35 km were studied from the Center for Solar System Studies (CS3, MPC U81). Lightcurves for 24 Trojan asteroids were obtained between January and June 2015. For three years, CS3 has been conducting a study of Jovian Trojan asteroids. Parts of this study include accumulating data for family rotational studies and...
Article
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Lightcurves for 20 asteroids were obtained from the Center for Solar System Studies from 2015 July to September
Article
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CCD photometric observations were made of the near- Earth asteroid (348400) 2005 JF21 in 2015 June and August. Initial analysis in June did not find any signs of a satellite. Follow-up analysis in August using both data sets found indications that the asteroid was binary with a primary period of 2.41 h and an orbital period for the satellite of abo...
Article
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25 main-belt asteroids were observed from CTIO (Cerro Tololo Inter-American Observatory MPC 807) in May and June 2015. Rotational periods were determined for 22 of them. Three are reported as having a long-period. Observations of 25 main-belt asteroids were a byproduct of an observing run of Jovian Trojans. Observing time was scheduled for five nig...
Article
CCD photometric observations were made of the near-Earth asteroid (348400) 2005 JF21 in 2015 June and August. Initial analysis in June did not find any signs of a satellite. Follow-up analysis in August using both data sets found indications that the asteroid was binary with a primary period of 2.41 h and an orbital period for the satellite of abou...
Article
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We collected data on rotations and elongations of 46 secondaries of binary and triple systems among near-Earth, Mars-crossing and small main belt asteroids. 24 were found or are strongly suspected to be synchronous (in 1:1 spin–orbit resonance), and the other 22, generally on more distant and/or eccentric orbits, were found or are suggested to have...
Article
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Asteroid modeling efforts in the last decade resulted in a comprehensive dataset of almost 400 convex shape models and their rotation states. This amount already provided a deep insight into physical properties of main-belt asteroids or large collisional families. We aim to increase the number of asteroid shape models and rotation states. Such resu...
Article
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Two near-Earth asteroids (NEAs) were observed from Cerro Tololo Inter-American Observatory in May and June 2015. 2014 YB35 was found to have a synodic rotation period of 3.277 h with an amplitude of 0.16 mag. (68216) 2001 CV26 has a well-established rotational period of 2.429 h and displayed some weak evidence of mutual events.
Article
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CCD photometric observations of 1754 Cunningham, and 7023 Heiankyo were obtained from the Center for Solar System Studies from 2015 June to July. For 1754, the period of 7.7416 ± 0.0005 hours appears to be about twice the previously reported value. For 7023, our solution of 10.807 ± 0.002 hours matches one previously noted possible solution.
Article
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CCD photometric observations of 9 Hungaria asteroids and one NEA were obtained from the Center for Solar System Studies from 2015 January to March.
Article
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Rotational periods were determined for 35 members of the Jovian L5 Trojan group. Data were obtained by the Center for Solar System Studies from 2014 October to 2015 January.
Article
CCD photometry observations of the Hungaria asteroid 4868 Knushevia were made in 2013 April-June at the Center for Solar System Studies. Analysis of the data indicates that the asteroid may be a binary with a primary period P1 = 3.4122 ± 0.0001 h, A1 = 0.05 ± 0.01 mag and a secondary period of P2 = 11.922 ± 0.003 h with possible mutual events, i.e....
Article
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CCD photometric observations of 8 asteroids were obtained from the Center for Solar System Studies from 2014 October to December.
Article
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A combination of dense lightcurves obtained by the authors over several apparitions and sparse data was used to model shapes for two asteroids: the Mars-crosser (21028) 1989 TO and Hungaria member (32814) 1990 XZ. For 1989 TO, a reasonably reliable spin axis and period of (86°, 0°, 3.66527 h) was found, although one of (292°, -62°, 3.66527 h) canno...
Article
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Using the S-band radar at Arecibo Observatory, we observed thirteen X/M-class asteroids; nine were previously undetected and four were re-observed, bringing the total number of Tholen X/M-class asteroids observed with radar to 29. Of these 29M-class asteroids, 13 are also W-class, defined as M-class objects that also display a 3-μm absorption featu...
Article
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A lightcurve of 788 Hohenstenia was obtained from the Center for Solar System Studies during July and August 2014.
Article
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CCD photometric observations of 16 asteroids were obtained from the Center for Solar System Studies from 2014 July to September.
Article
CCD observations of three asteroids were made at the Center for Solar System Studies in mid-2014. The Hungaria member 1727 Mette is a known binary system. We saw no evidence of the satellite in 2014, which - assuming the satellite's orbit is nearly in the primary's equatorial rotational plane - leads to an estimate for the primary's spin axis orien...
Conference Paper
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Center for Solar System Studies Results As of October 2014, the asteroid lightcurve database (LCDB; Warner et al., 2009) contains 775 near-Earth asteroids with statistically useful rotation rates, about 7% of all known NEAs. The LCDB also contains 54 NEAs that are known or suspected binary or multiple systems, 47 with spin orientations, and 47 tumb...
Article
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Lightcurves for eight Jupiter Trojan a s t e r o i d s were obtained from the Center for Solar System Studies from 2014 January to May. The Jovian Trojan asteroids are found in orbits near the stable L4 and L5 Langrange points of Jupiter's orbit. They are thought to have formed further from the Sun and their composition and collisional history appe...
Article
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CCD photometric observations of 14 asteroids were obtained from the Center for Solar System Studies from 2014 April to June.
Article
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CCD photometric observations of 15 asteroids were obtained from the Center for Solar System Studies from 2014 January to March.
Conference Paper
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The Jovian Trojans are among the most enigmatic objects in the Solar System. They have been studied less than main-belt asteroids because of their low albedos and greater distance from the Sun. Several lines of evidence support a common origin for the Jovian Trojan asteroids and cometary nuclei. Their spectra and low albedos bear a strong resemblan...
Article
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Results from CCD photometric observations are reported for eleven asteroids. These data were obtained from the Center for Solar System Studies (CS3) during 2013 October to December.
Article
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Earlier in 2013 we reported rotational periods for two dozen Jupiter Trojan asteroids. Here we present lightcurves for 24 additional Trojans obtained from the Center for Solar System Studies and Cerro Tololo Inter- American Observatory from July to December 2013.
Article
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Initial analysis of CCD photometry observations in 2013 November from two stations in California made of the near-Earth asteroid (138095) 2000 DK79 found a synodic rotation period of 5.19 h, or 4.62 rotations per Earth day. It was only after adding data from a station on the East Coast of the United States that the more accurate period of 4.243 h (...
Article
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CCD photometric observations of eight asteroids were obtained at the Center for Solar System Studies from 2013 July to September.
Article
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Lightcurves for 16 Hungaria asteroids were obtained at the Center for Solar System Studies (CS3) from 2013 April through June. Most of the efforts were follow-up to observations from previous apparitions to check for the possibility of previously undiscovered satellites and to provide additional data for spin axis and shape modeling.
Article
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CCD photometric observations of the Apollo asteroid (152756) 1999 JV3 were obtained from Lowell Observatory in May 2013. A synodic period of 2.845 ± 0.001 h with an amplitude of 0.32 ± 0.02 was found.