PHOTOELECTRIC PHOTOMETRY OF SATURN’S RINGS: A PROPOSED PROJECT FOR 2003-2004
2002
A team consisting of Walter Haas, Julius Benton, and Fred Pilcher of the
A.L.P.O. have formed an observing project as a subset of the regular
programs of the A.L.P.O. Saturn Section to do photoelectric photometry of
Saturn’s rings. This is a strategy to improve observations to detect and
quantify the curious Bicolored Aspect of Saturn’s Ring A pursuant to the
article written by Thomas A. Dobbins, Alan Heath, and Valeri Dikarev
entitled "Saturn’s Colorful Mystery" in the December 2002 issue of Sky and
Telescope magazine.
The A.L.P.O. Saturn Section project would monitor extremely small brightness
fluctuations in different wavelengths at various position angles around
Saturn’s ring system. The technique suggested by Haas, Benton, and Pilcher
would involve the use of old-style photoelectric photometers of the 1970’s
or early 1980’s vintage, and an aperture of roughly 1.0 to 2.0 arcseconds.
The technique would use the standard Johnson UBV filter set (or perhaps just
B and V), perhaps supplemented with other standard filters such as the Kron
R and G filters. Applied to Saturn’s rings, this would admit the large
amount of light required for very precise magnitude measurements.
Observations at 10 to 15 degree intervals in position angle all the way
around Ring A, calibrated with Ring B measurements, would be repeated at
time intervals of 20 to 40 minutes on a single night. Such measurements
should capture any progressive changes in the rings with the revolution of
Saturn of conjectured underlying structures. Routine observations of this
kind throughout several observing seasons (or apparitions) should provide
quantitative information, currently lacking, which theorists need for model
building.
The greatest difficulty is that photoelectric photometers have largely been
replaced by CCD photometers due to their relative ease of use, but the
latter are also inherently less accurate. The A.L.P.O. team is trying to
locate observers who have older photoelectric photometers who would be
interested in participating in this long term project, slated to begin with
the 2003-2004 apparition of Saturn (which begins soon after Saturn emerges
from conjunction with the Sun on June 24, 2003). It is believed that there
may also be professional and/or university observatories who possess
top-of-the-line photoelectric photometers left over from the 1970’2 or
1980’s that could be brought back into use.
More developments shall be forthcoming on this project, but observers who
are adequately equipped are encouraged to join the team for the 2003-3004
apparition of Saturn. All inquiries should be addressed to the A.L.P.O.
Saturn Section at the following address:
Julius L. Benton, Jr., Ph.D.
Coordinator - A.L.P.O. Saturn Section
c/o ASSOCIATES IN ASTRONOMY
P.O. Box 30545
Wilmington Island
Savannah, GA 31410 USA
Telephone: 912-897-0951
Cellular: 912-661-3924
E-Mail: jlbaina@msn.com
Website: http://www.lpl.arizona.edu/alpo/sat.html
eGroups: Saturn-ALPO@yahoogroups.com