MPEC 2010-W10 : BRIAN MARSDEN (1937 Aug. 5-2010 Nov. 18)

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M.P.E.C. 2010-W10                                Issued 2010 Nov. 18, 15:41 UT

     The Minor Planet Electronic Circulars contain information on unusual
         minor planets and routine data on comets.  They are published
   on behalf of Commission 20 of the International Astronomical Union by the
          Minor Planet Center, Smithsonian Astrophysical Observatory,
                          Cambridge, MA 02138, U.S.A.

         Supported in part by the Steven and Michele Kirsch Foundation
             Prepared using the Tamkin Foundation Computer Network

                              MPC@CFA.HARVARD.EDU
          URL http://cfa-www.harvard.edu/iau/mpc.html  ISSN 1523-6714

                      BRIAN MARSDEN (1937 Aug. 5-2010 Nov. 18)

   Brian Geoffrey Marsden was born on 1937 August 5 in Cambridge, England. His
father, Thomas, was the senior mathematics teacher at a local high school.  It
was his mother, Eileen (nee West), however, who introduced him to the study
of astronomy, when he returned home on the Thursday during his first week in
primary school in 1942 and found her sitting in the back yard watching an
eclipse of the sun.  Using now frowned-upon candle-smoked glass, they
sat watching the changing bite out of the sun.  What most impressed the budding
astronomer, however, was not that the eclipse could be seen, but the fact that
it had been predicted in advance, and it was the idea that one could make
successful predictions of events in the sky that eventually led him to his
career.

   When, at the age of 11, he entered the Perse School in Cambridge he was
developing primitive methods for calculating the positions of the planets.
He soon realized that earlier astronomers had come up with more accurate
procedures for doing this over the centuries, and during the next couple of
years this led to his introduction to the library of the Cambridge University
Observatories and his study of how eclipses, for example, could be precisely
computed.  Together with a couple of other students he formed a school
Astronomical Society, of which he served as the secretary.  At the age of 16 he
joined and began regularly attending the monthly London meetings of the British
Astronomical Association.  He quickly became involved with the Association's
Computing Section, which was known specifically for making astronomical
predictions other than those that were routinely being prepared by professional
astronomers for publication in almanacs around the world.  Under the watchful
eyes of the director and assistant director of the Computing Section, this led
him to prepare and publish predictions of the occasions when one of Jupiter's
moons could be seen to pass directly in front of another.  He also calculated
the gravitational effects of the planets on the dates and sky positions of
the returns of some periodic comets.  He carried out these computations using
seven-place logarithms.  After all, this was long before pocket calculators had
been invented, and the construction of large electronic computers was still
then very much in its infancy.  He always maintained that making such
computations by primitive means significantly increased one's understanding of
the science involved.  During his last year of high school he also became a
junior member of the Royal Astronomical Society.

   He was an undergraduate at New College, University of Oxford.  In his first
year there he persuaded the British Astronomical Association to lend him a
mechanical calculating machine, allowing him thereby to increase his
computational productivity.  By the time he received his undergraduate degree,
in mathematics, he had already developed somewhat of an international
reputation for the computation of orbits of comets, including new discoveries.
He spent part of his first two undergraduate summer vacations working at
the British Nautical Almanac Office.  He also responded to an inquiry from
Dorothy L. Sayers involving the ancient Roman poet Lucan.  Incensed by what
she perceived as grossly unfair criticism of Lucan by A. E. Housman and Robert
Graves, she elicited his assistance during the last year of her life to
support her view that Lucan's understanding of astronomy and geography was
reasonably valid.  Dr. Sayers' extensive correspondence in the course of this
study is included in the last volume of her collected letters.

   After Oxford, he took up an invitation to cross the pond and work at the Yale
University Observatory.  He had originally planned to spend just a year there
carrying out research on orbital mechanics, but on his arrival in 1959 he was
also enrolled as a Yale graduate student.  With the ready availability of the
university's IBM 650 computer in the observatory building, he had soon
programmed it to compute the orbits of comets.  Recalling his earlier interest
in Jupiter's moons, he completed the requirements for his Ph.D. degree with a
thesis on "The Motions of the Galilean Satellites of Jupiter".

   At the invitation of director Fred Whipple, he joined the staff of the
Smithsonian Astrophysical Observatory in Cambridge (MA) in 1965.  Dr. Whipple
was probably best known for devising the "dirty snowball" model for the nucleus
of a comet a decade and a half earlier.  At that time there was only rather
limited evidence that the motion of a comet was affected by forces over and
above those of gravitation (limited because of the need to compute the orbit by
hand), and the Whipple model had it that those forces were due to the comet's
reaction to vaporization of the cometary snow or ice by solar radiation.  Dr.
Marsden therefore developed a way to incorporate such forces directly into the
equations that governed the motion of a comet.  Application of a computer
program that included these nongravitational effects to several comets soon
gave results that were nicely compatible with Dr. Whipple's original idea.
Continued refinement of the nongravitational terms, much of it done in
collaboration with Zdenek Sekanina, a Czech astronomer and friend of
Dr. Marsden whom he and Dr. Whipple succeeded in bringing to the U.S. as a
refugee following the Soviet invasion of Prague in 1968, resulted in a wealth
of improved computations of cometary orbits by the time Dr. Sekanina moved to
California in 1980.  It is noteworthy that the procedure devised and developed
by Dr. Marsden is still widely used to compute the nongravitational effects of
comets, with relatively little further modification by other astronomers.

   The involvement of the Smithsonian Astrophysical Observatory with comets had
been given a boost, shortly before Dr. Marsden's arrival there, by the
transfer there from Copenhagen of the office of the Central Bureau for
Astronomical Telegrams, a quaintly named organization that was established by
the International Astronomical Union soon after its founding in 1920.  The
CBAT is responsible for disseminating information worldwide about the
discoveries of comets, novae, supernovae and other objects of generally
transient astronomical interest.  It is the CBAT that actually names the
comets (generally for their discoverers), and it has also been a repository
for the observations of comets to which orbit computations need to be fitted.
Dr. Marsden succeeded Dr. Owen Gingerich as the CBAT director in 1968.  He was
joined by Daniel Green as a student assistant a decade later, and Dr. Green
took over as CBAT director in 2000.  Until the early 1980s the Bureau really
did receive and disseminate the discovery information by telegram (with
dissemination also by postcard Circular), although e-mail announcements then
understandably began to take over.  The last time the CBAT received a telegram
was when Thomas Bopp sent word of his discovery of a comet in 1995.  Since
word of this same discovery had already been received from Alan Hale a few
hours earlier by e-mail, the object was very nearly just named Comet Hale,
rather than the famous Comet Hale-Bopp that beautifully graced the world's
skies for several weeks two years later.

   The comet prediction of which he was most proud was of the return of comet
Swift-Tuttle, which is the comet associated with the Perseid meteors each
August.  It had been discovered in 1862, and the conventional wisdom was that
it would return around 1981.  He followed that line for much of a paper he
published on the subject in 1973.  He had a strong suspicion, however, that
the 1862 comet was identical with one seen in 1737, and this assumption
allowed him to predict that Swift-Tuttle would not return until late-1992.
This prediction proved to be correct, and this comet has the longest orbital
period of all the comets whose returns have been successfully predicted.

   Although the CBAT also traditionally made announcements of the discoveries
of asteroids that came close to the earth, the official organization for
attending to discoveries of asteroids (more than 99% of which are located in
a belt between Mars and Jupiter) is the Minor Planet Center.  Also operated
by the International Astronomical Union, the MPC was located until 1978 at the
Cincinnati Observatory.  In that year the director, Dr. Paul Herget, was
retiring, and it was necessary for the Center to find a new home.  Accordingly,
the IAU asked Dr. Marsden also to take over the direction of the MPC.  Thanks
to the transfer of associate director Conrad Bardwell with the MPC records
from Cincinnati, this task was rendered easier.  While the CBAT and the MPC
still maintained their separate entities, there was a lot of common ground
between them.  Dr. Marsden was therefore able to introduce some efficiencies
into their combined operation.  On Mr. Bardwell's retirement at the end of
1989, Gareth Williams joined the MPC staff and later became associate director.

   The advances in electronic communication during the 1990s also permitted
improvements in MPC operation. Perhaps the most important of these was the
development, in 1996, of the Internet "Near-Earth Object Confirmation Page".
This draws attention to candidate earth-approaching objects in need of
follow-up observations as soon as they have been reported to the MPC,
following the derivation by Dr. Marsden of a particularly ingenious method
for estimating the uncertainty of the prediction by automatically computing a
series of orbits that represent just the first and the last observations.  In
1998 he developed a certain amount of notoriety by suggesting that an object
called 1997 XF11 could collide with the earth.  He did this as a last-ditch
effort to encourage the acquisition of further observations, including
searches for possible data from several years earlier.  The recognition of
some observations from 1990 made it  quite clear that there could be no
collision with 1997 XF11 during the foreseeable future.  Without those 1990
observations, however, the object's orbit would have become very uncertain
following a close to moderate approach to the earth in 2028; indeed, Dr.
Marsden correctly demonstrated that there was the possibility of an earth
impact in 2040 and in several neighboring years.  He was thereby able
eventually to persuade his principal critics routinely to perform similar
uncertainty computations for all near-earth objects as they were announced.
Again, as more data accrue, it is almost certain to happen that all possible
impacts with moderately large objects (i.e., those at least several hundred
feet across) during the next century, say, will disappear.  While the
production of such computations was directly due to his encouragement, it was
always with some amusement that he saw cases where further data forced his
former critics sheepishly to withdraw their earlier frightening statements
about a potentially dangerous object.

   Dr. Marsden was particularly fascinated by the appearance of a group of
comets that passed close to the sun.  Known as members of the Kreutz group,
after a German astronomer who studied them in the late nineteenth century, the
discovery of three more of these sungrazing comets in the mid-twentieth
century led him to undertake a detailed examination of how the individual
comets may have evolved from each other.  He published this examination in
1967, following it up with a further study in 1989 involving a more recent
bright Kreutz comet, as well as several much fainter objects that had been
detected from sun-observing coronagraphs out in space.  Beginning in 1996,
these were being found by the SOHO coronagraphs at rates ranging from a few
dozen to more than one hundred per year.  Unfortunately, the faintness of the
comets and the poor accuracy with which they could be measured made it
difficult to establish their orbits as satisfactorily as Dr. Marsden would
have liked. More significantly, however, he was able to recognize that the
SOHO data also contained another group of comets with similar orbits, these
comets now known as members of the "Marsden group".  Unlike the individual
Kreutz comets, which have orbital periods of several centuries, it seems that
the Marsden comets have orbital periods of only five or six years, leading
him to try and recognize the same object at different passages near the
sun and thereby predict future returns.  Two other well-populated groups have
also been detected in the SOHO data.

   Another series of astronomical discoveries that greatly interested him were
what he always called the "transneptunian objects", although many of his
colleagues have insisted on calling them "objects in the Kuiper Belt".  When
what those same colleagues considered to be the first of these was discovered
in 1992, Dr. Marsden immediately remarked that this was untrue, because Pluto,
discovered in 1930 and admittedly somewhat larger in size, had to be the
first.  More specifically, he was the first to suggest, correctly, that three
further transneptunian objects discovered in 1993 were exactly like Pluto in
the sense that they all orbit the sun twice while Neptune orbits it thrice.
This particular recognition set him firmly on the quest to "demote" Pluto.
Success required the discovery of transneptunian objects more comparable to
Pluto in size, something that finally happened in 2005 with the discovery of
the object that came to be known as Eris.  At its triennial meeting in 2006
in Prague, the IAU voted to designate these objects, together with two
further transneptunian objects now known as Makemake and Haumea, as well as
the largest asteroid, Ceres, members of a new class of "dwarf planet".

   It was also at the IAU meeting in Prague that Dr. Marsden stepped down as MPC
director, and he was quite entertained by the thought that both he and Pluto
had been retired on the same day.  While he remained working at the MPC (and
also the CBAT) in an emeritus capacity, the directorship was passed to
Dr. Timothy Spahr, whom he had brought to the MPC in 2000.

   Dr. Marsden served as an associate director of the Harvard-Smithsonian Center
for Astrophysics (the combination of the Smithsonian Astrophysical Observatory
and the Harvard College Observatory) for 15.75 years from the beginning of 1987
(the longest tenure for any of the Center's associate directors).  He was chair
of the Division of Dynamical Astronomy of the American Astronomical Society
during 1976-1978 and president of the IAU commissions that oversaw the
operation of the minor Planet Center (1976-1979) and the Central Bureau for
Astronomical Telegrams (2000-2003).  He continued to serve subsequently on the
two solar-system nomenclature committees of the IAU, being the perennial
secretary of the one that decides on names for asteroids.  He also continued
to publish a "Catalogue of Cometary Orbits", the first of these having
appeared in 1972 and its successors roughly at intervals of two years.

   Among the various awards he received from the U.S., the U.K. and a handful of
other European countries, the ones he particularly appreciated were the 1995
Dirk Brouwer Award (named for his mentor at Yale) of the AAS Division on
Dynamical Astronomy and the 1989 Van Biesbroeck Award (named for an old friend
and observer of comets and double stars), then presented by the University of
Arizona, now by the AAS, for service to astronomy.

   Dr. Marsden married Nancy Lou Zissell, of Trumbull, Connecticut, on 1964
December 26, and fathered Cynthia (who is married to Gareth Williams,
still MPC associate director), of Arlington, Massachusetts; and Jonathan,
of San Mateo, California.  There are three Californian grandchildren,
Nikhilas, Nathaniel and Neena.  A sister, Sylvia Custerson, continues to reside
in Cambridge, England.

Gareth V. Williams           (C) Copyright 2010 MPC           M.P.E.C. 2010-W10

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• 1997-B01 (the full form)
• J97B01 (the packed version of the full form)
• B01 (the abbreviated form)