Observatories - Wilcox

Wilcox Solar Observatory

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ngwilcox100@gmail.com

John Marsh Wilcox (1925 – October 14, 1983) was an American geophysicist. He worked at the University of California, Berkeley at the Space Sciences Laboratory from 1964 to 1971. He was an adjunct professor at Stanford University from 1971 until his death.

Wilcox received his Ph.D. at the University of California at Berkeley in 1954 under the supervision of Prof. Burton Jones Moyer. The title of his dissertation was "A direct measurement of the nuclear internal momentum distributions of protons in light nuclei."

John M. Wilcox
Born1925
DiedOctober 14, 1983 (aged 58)
Puerto Peñasco, Sonora, Mexico
NationalityAmerican
Alma materUniversity of California, Berkeley
Iowa State College
Known forWilcox Solar Observatory
Scientific career
FieldsGeophysics
InstitutionsUniversity of California, Berkeley
Doctoral studentsAndrew S. Tanenbaum

Wilcox developed many innovative techniques to extract signals from the variety of noisy data that often plague researchers in Solar Terrestrial physics. John had perception in attacking fruitful problems and the persistence to devote himself to difficult physical puzzles from which others might shy away. Over the past decade, he and his associates established the as-yet-unexplained connection between the sector boundaries of the interplanetary magnetic field and areas of strong vorticity at the lower boundary of the Earth's statosphere. The effect, though small and of variable magnitude, has been independently confirmed and may be of great importance in weather and climate models.

John Wilcox recognized the value of international cooperation and exchanges. He arranged extended visits to Stanford by researchers from many countries, including the USSR, China, Japan, England, France, Italy, Denmark, and Sweden. These collaborations led to exciting and enlightening cultural exchanges, as well as important scientific results. He also organized and participated in many national and internaltional scientific meetings, where he not only contributed his own exciting results, but engaged in discussions on the wide variety of subjects in which he maintained interest. He was active in meetings and symposia of the International Astronomical Union and the International Union of Geodesy and Geophysics. He also chaired the US participation in the US-USSR Bilateral Cooperation under Environmental Working Group VIII from 1973 to 1979. He was a Fellow of the American Association for the Advancement of Science, the Americal Physical Society, and The Royal Astronomical Society (London); and a member of the Americal Geophysical Union, the American Astronomical Society, the Astronomical Society of the Pacific, the International Astronomical Union, and the American Meteorological Society. He served on numerous advisory committees for solar physics, space science, and solar-terrestrial relations.

John was known to his scientific associates not only for his research accomplishments and stimulating ideas, but for his gentle manner of giving help to others. He was a talented clarinet player, and deeply loved chamber music. At home and wherever he travelled, he always made time for musical events.

John Marsh Wilcox died while swimming in the Sea of Cortez near Puerto Penasco, Mexico on 14 October 1983. He is survived by his wife Ann, daughter Sharon, and son David.

Location of Wilcox Solar Observatory

Alternative namesWSO Edit this at Wikidata
Named afterJohn M. Wilcox
Part ofStanford University
Location(s)California
Coordinates37°24′33″N 122°10′04″WCoordinates: 37°24′33″N 122°10′04″W Edit this at Wikidata
OrganizationStanford University
Telescope styleoptical telescope
solar telescope
Diameter33 cm (1 ft 1 in) Edit this at Wikidata
Websitewso.stanford.edu

The Wilcox Solar Observatory (WSO) is a solar observatory in Stanford, California that is used to produce daily observations of the magnetic and velocity field at the Sun's surface. It began daily observations of the Sun's mean magnetic field in May 1975. Formerly known as the Stanford Solar Observatory, it is operated by Stanford University and is located 2 kilometers (1.2 mi) south of the Stanford University campus. It would later be named after solar physicist John M. Wilcox. WSO has historically been funded by NASA Heliophysics, the National Science Foundation, and the Office of Naval Research.

WSO uses a Littrow spectrograph together with a Babcock magnetograph on the 5250 Å iron-1 spectral line, which it compares to the close by and magnetically insensitive iron-1 line at 5124 Å, to estimate the line-of-sight photospheric magnetic field to within 0.04 gauss.

Synoptic charts of the solar magnetic field are assembled from individual magnetograms observed over the course of a solar rotation. The contour maps show the distribution of magnetic flux over the photosphere. The field above 70 degrees is not resolved. Missing data are printed as XXX in the text files. Missing data are interpolated in the F.txt files.

A reduced sample of Carrington Rotation 1642 (June 1976).
Blue, light shading shows the positive regions.
The neutral line is black. Contours are indicated.
Inverted carets show times of contributing magnetograms.

WSO generates data about the Sun's magnetic field in the following forms:

MAGNETOGRAMS
Magnetograms are magntic maps of the Sun's surface. The Sun rotates every 27 days and the features change with time, so the maps change from day to day.

The GIF files show regions of strong positive and negative field as blue and red areas.

The Postscript files are contour maps of the magnetic field on the visible solar disk. Dashed contours are negative.

SYNOPTIC CHARTS
Synoptic Charts are magnetic maps of the whole Sun. Magnetograms taken over a solar rotation are
combined to give a complete picture of the solar field. The Earth is near the solar equator, so we never
get a very good look at the Sun's poles.

The solar magnetic field postscript files are contour maps of the magnetic field for particular Carrington Rotations. Carrington Rotations are a convenient coordinate system for locating positions on the sun. The first Carrington Rotation was in 1853. CR 1891 began on the last day of 1994.

CORONAL FIELDS
The field in the corona can not be measured directly. However the field can be modeled because it's basic structure is determined by the conditions in the photosphere. We use a potential field model to compute the field about 1.5m solar radii above the Sun's surface. That's the height at which the field
pattern becomes fixed. That pattern is carried out into interplanetary space by the solar wind. It takes about 4 days for the pattern to reach the Earth. The model isn't very good at predicting dynamic changes in the corona.

The coronal synoptic charts are postscript contour plots of the magnetic field at the source surface.

The "los" (line-of-sight) method has been used and published for many years; that model assumes that the field measured in the photosphere may be nonradial. It requires a polar field correction that is observatory and temporally dependent.

The "rad" (radial) method is probably preferable. It assumes that the photospheric field is radial in the photosphere. The method does not require a polar field correction. The best source surface radius is 2.5, though 3.25 gave a little better result when comparing with high latitude Ulysses measurements in 1994. During the extended minimum at the end of Cycle 24 the source surface was probably best set even lower.

HARMONIC COEFFICIENTS
The photospheric and coronal field can be decomposed into spherical harmonics. The monopole, dipole, quadrupole, etc. components can be used to reconstruct the field at any height between the photosphere and source surface. There are no plots, but you can get the coefficients in tables. The harmonics computed using the two models described above are slightly different.

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Designed by Nigel G Wilcox