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Marsden, B. G.

Publications and source records attributed to Marsden, B. G..

At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1991

Astrometric observations of comets and asteroids and subsequent orbital investigations

The transformation of the Oak Ridge astrometry from a photographic program to a charge coupled device (CCD) program can now be considered complete, and the number of observations being made is now approaching an order of magnitude greater than in the old photographic program. Astrometric observations with the 1.5-m reflector were made at the Oak Ridge Observatory, and the progress, accomplishments, and projected accomplishments are presented.

Marsden, B. G.↗
NASA NTRS1989

Discovery and follow up of asteroids

After a summary of the increasing activity in steroid discovery during the past few years, the importance of carefully thought out observing strategy is discussed, in particular with regard to target selection, observing frequency, and the time distribution of observations. Problems of cataloging and orbit linkage are outlined, inasmuch as they affect individual observers and orbit computers, as well as the work of the Minor Planet Center. There is some discussion of appropriate two-way communication between observers and the Minor Planet Center.

Bowell, E.↗
NASA NTRS1986

Astrometric observations of comets and asteroids and subsequent orbital investigations

The 155-cm reflector was used for observations of comets and minor planets on 32 nights during April-October. The distribution was fairly uniform, ranging from 45 in June and September to 28 in July: on September 1 a total of 17 observations was made. A table is included which lists the 230 measurements published during the semester. These include six additional measurements going back to 1984 and the republication of a previously misidentified 1976 observation as a new discovery. Thirty-two of the observations refer to comets, 83 to numbered minor planets, and the remainder to unnumbered minor planets. Among the older-numbered minor planets observed were the Earth-approaching objects (3103) 1982 BB, (3199) 1982 RA (Nefertiti), (3361) 1982 HR and (3362) 1984 QA (Khufu), some of which were of interest for radar experiments. Unnumbered Earth-approaching objects observed were 1963 RH, 1983 RD, 1985 TB and 1986 DA, as well as the new discoveries 1986 JK, 1986 LA and 1986 PA.

Mccrosky, R. E.↗
NASA NTRS1986

Astrometric observations of comets and asteroids and subsequent orbital investigations

During the past year some 500 observations were made on 66 nights and published on the MPCs (Minor Planet Circulars/Minor Planets and Comets). In addition, a handful of measurements of earlier plates were completed and published. 121 of the observations published referred to comets. Of special importance were observations of comets (P/Giacobini-Zinner and P/Halley) in connection with the NASA ICE and ESA Giotto missions, but a special effort was made to get good coverage of almost all of the observable comets. Observations were also made of (2060) Chiron and of the earth-approaching objects (1627) Ivar, (1866) Sisyphys, (1943) Anteros, (3362) 1984 QA, 1985 JA, PA, TB and WA, and 1986 DA and EB. 46 minor planets were given permanent numbers entirely as a result of the observations.

Mccrosky, R. E.↗
NASA NTRS1984

Cometary Astrometry

Modern techniques for making cometary astrometric observations, reducing these observations, using accurate reference star catalogs, and computing precise orbits and ephemerides are discussed in detail and recommendations and suggestions are given in each area.

Yeomans, D. K.↗
NASA NTRS1984

Remarks on cometary astrometry

A statistical examination of the astrometric observations made during the past 20 years indicates that there are generally sufficient data on bright and well-publicized comets. On the other hand, astrometric coverage of fainter objects has recently become a severe problem. In spite of an increase in the number of participating observatories, fewer observatories are making significant contributions. Automated methods have generally improved the quality of observations. The timely communication of observations is also discussed.

Marsden, B. G.↗
NASA NTRS1984

Comets and nongravitational forces

The widely procedure used for the allowance of nongravitational effects in the motions of comets is summarized. Some results are mentioned, and an innovative variation of the procedure is discussed.

Marsden, B. G.↗
NASA NTRS1979

Radar observations of asteroid 1580 Betulia

Radar observations of the asteroid 1580 Betulia, made at a wavelength of 12.6 cm, show a mean radar cross section of 2.2 + or- 0.8 sq km and a total spectral bandwidth of 26.5 + or- 1.5 Hz. Combining bandwidth measurements with the optically determined rotation period sets a lower limit to the asteroid's radius of 2.9 + or- 0.2 km.

Pettengill, G. H.↗
NASA NTRS1979

The discovery and orbit of /2060/ Chiron

'Slow-moving Object Kowal' was discovered as an asteroidal object of photographic magnitude about 18 on photographic plates made on October 18 and 19, 1977 with the 122-cm Schmidt telescope at Palomar Observatory. It was determined that the object was located between 14 and 17 AU from the earth in a low-inclination, near-circular orbit. Examination of subsequent plates and earlier observations of the area allowed a more exact calculation of the orbital elements, which suggest the object to be in 3:5 resonance with Saturn at a perihelion of 8.5 AU. The object's orbital behavior suggests that of an inactive comet perturbed by Saturn from a previous orbit, however its magnitude is uncharacteristically large for a comet. It is proposed that object Kowal was once an ordinary minor planet that was deflected into its present orbit by collisions with other minor planets and a series of encounters with Jupiter and Saturn. The object has received the minor planet number (2060) and the name of Chiron has been proposed.

Kowal, C. T.↗
NASA NTRS1979

Comet Halley and history

A history of Halley's Comet is presented. Comets Kohoutek and Ikeya-Seki are discussed.

Marsden, B. G.↗
NASA NTRS1978

New osculating orbits for 110 comets and analysis of original orbits for 200 comets

Osculating orbits are presented for 110 nearly parabolic comets. Combining these with selected orbit determinations from other sources, a total of 200 orbits are considered where the available observations yield a result of very good (first-class) or good (second-class) quality. For each of these, the original and future orbits (referred to the barycenter of the solar system) are calculated. The Oort effect (a tendency for original reciprocal semimajor axis values to range from zero to +100 millionths per AU) is clearly seen among the first-class orbits but not among the second-class orbits. Modifications in original reciprocal semimajor axis values due to the effects of nongravitational forces are considered.

Marsden, B. G.↗
NASA NTRS1977

Orbit of 1976 AA

The orbit of Asteroid 1976 AA is described, with attention given to calculations of its period and its distance from earth, both of which could be accurately and quickly determined by measuring the minor planet's position over wide ranges of hour angle on one to three nights. The geometry of the asteroid's orbit is compared to that of earth's orbit, and the periodicity of the minor planet's approaches to earth is projected. The motion of 1976 AA over an interval of seven centuries into both past and future is also studied; the possibility of its libration with respect to earth or to Venus is examined. Some data on closest approaches of the asteroid to Mars and Venus, as well as to earth, are given.

Marsden, B. G.↗
NASA NTRS1976

The occultation of Kappa Geminorum by Eros

The paper discusses predictions and observations of the occultation of Kappa Gem by (433) Eros on January 24, 1975. Several positive and negative observations made in western New England are described. Local circumstances for the occultation are reconstructed, and the size and shape of Eros are determined analytically as well as graphically. The calculations yield two extremes for the cross section: a circle 23 km in diameter or a somewhat irregular figure 20 km by 6 or 7 km. Arguments based on the expected albedo of the asteroid suggest that the circle should be warped into an ellipse 21 by 13 km or that the irregular figure might be one component of a dumbbell-like profile.

Oleary, B.↗
NASA NTRS1976

The study of the physics of cometary nuclei

A semiannual progress report describing the work completed during the period 1 September 1975 to 29 February 1976 on the physics of cometary nuclei was given. The following items were discussed: (1) a paper entitled ""A speculation about comets and the earth'', (2) a chapter entitled"" The physics of comets'' for ""Reviews of Astronomy and Astrophysics'', (3) continuing work on split comets, and (4) results dealing with a new application of nongravitational solar-radial forces as a measure of comet nucleus dimensions and activity.

Whipple, F. L.↗
NASA NTRS1976

Nongravitational forces on comets

Methods are presented and discussed for determining the effects of nongravitational forces on the orbits of comets. These methods are applied to short-period and long-period comets. Results are briefly described.

Marsden, B. G.↗
NASA NTRS1975

The study of the physics of cometary nuclei

Research in the area of split and hyperbolic comets, orbital calculations, and interstellar comets is discussed. Other topics discussed include the role of comets in galactic chemistry, gamma ray bursts, and predicted favorable visibility conditions for anomalous tails of comets.

Whipple, F. L.↗