1998-1999 Apparition

Linking Amateur and Professional Mars Observing Communities.

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The International MarsWatch Electronic Newsletter

Volume 3; Issue 4
April 27, 1998
Circulation: 1447

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Dear Marswatch participant,

Mars Global Surveyor continues to return spectacular images and other data during its orbit-lowering maneuvers. Initial scientific results were reported in the March 13, 1998 issue of Science magazine, and an array of spectacular new images (including pictures from the south pole, Cydonia, and Viking Lander regions) and other data can be found on the JPL Mars Global Surveyor WWW site, or at the home page for the Mars Orbital Camera investigation.

A new site where a large number of educational and other Mars resources have been compiled can be found at The "Educational Tools" link should be particularly interesting for K-12 teachers and other educators interested in hand-on classroom activities related to Mars and Planetary Science.

While our favorite planet is far on the other side of the solar system, now is the time to start planning for the next round of telescopic observations. To get you started, here is the first of a four-part series of Marswatch emails dedicated to preparations for the 1998-1999 observing season. The series was written by Jeff Beish and other experienced Mars-observing colleagues who are involved with the Association of Lunar and Planetary Observers. Enjoy!

--Jim Bell
Cornell University

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1998-1999 Aphelic Apparition of Mars: Part 1

By: Jeffrey D. Beish
With Donald C. Parker, M.D., Daniel Troiani, and Daniel Joyce


Recent Spacecraft missions into our Solar System have sparked renewed public interest in planetary sciences. The Mars Global Surveyor space mission will bring the first close-up surveillance of the Red Planet Mars since the Viking I and II visits during the mid-1970's and early 1980's. While the past accomplishments of U.S. space missions throughout the Solar System has yielded extensive volumes of scientific information we never the less ponder many questions about the Earth-like planet Mars.

Some of those questions remain unanswered today: Are the polar climates static or are they changing over long periods of time? Can surface wind directions be inferred from cloud formations and movements? Are equatorial water ice crystal clouds seasonal? If so, can their appearance and locations be predicted? What causes the secular (long-term) changes in dark albedo features? Are their locations topographically controlled or result from unseasonable winds? These are just a few of the important questions remaining in the Martian mystery.

Still an intriguing world, Mars offers the casual and serious observer both alike many challenges and delights. This planet offers astronomers a free laboratory for the study another planet's atmosphere: the behavior of condensates and effects on its atmosphere. Mars is similar to Earth in that it has four seasons, exhibits global climates, changing weather patterns, annual thawing of polar caps, storm clouds of water ice, howling dusty winds, and a variety of surface features which predictably change with color and size and move around the surface over long periods of time.

The A.L.P.O. and the I.M.P.

The International Mars Patrol (I.M.P.) is an international cooperative effort between individual observers and members of observing groups located around the world. Established in the late 1960's by the late Charles F. Capen, the IMP has contributed more than 30,000 observations of Mars. Contained within the archives of the Association of Lunar and Planetary Observers (A.L.P.O.) Mars Section library are the records of fifteen apparitions of Mars covering a span of 35 years.

From the late 1960's, interested amateur and professional astronomers located in 47 foreign countries and U.S. territories cooperated in a 24-hour watch on the Red Planet Mars. Additional support is provided by the British Astronomical Association (B.A.A.), the Arbeitskreis Planetenbachter (Germany), and Japan's Oriental Astronomical Association (O.A.A.).

The A.L.P.O./I.M.P. Observing Program for Mars

The I.M.P. coordinates and instructs the cooperating observers in using similar visual, photographic, photometric, and micrometric techniques employing color filters and standard methods for reporting their observations, which results in homogeneous sets of observing data that have good analytic value.

Each apparition the A.L.P.O. Mars Section receives thousands of individual observations consisting of visual disk drawings made with the aid of color filters, black-&-white and color photographs, intensity estimates of light and dark albedo features, color contrast estimates, and micrometer measurements of polar caps, cloud boundaries, and variable surface features during the 10 to 12 month observing period. The chronological filing of this large quantity of data requires the observation information obtained for each night Universal Date be recorded on one or two standard observing report forms!

It is with this regard that the A.L.P.O. Mars Coordinators have prepared a simple, efficient and standard Mars observing Report Form. This Standard Form, or its format, can be used for reporting all types of observations such as; micrometry, transit timings, intensity estimates, etc. Photographs may also be attached to the top or back of the form and the relevant information blanks to be filled in at the telescope. Planetary aspects blanks can be filled in at other times than while observing [Capen et al, 1981].

Observational data consist of color filter photography, visual disk drawings, visual photometry (intensity estimates on the standard ALPO scale: 10 = polar brightness, 8 = desert mean brightness, 0 = night sky), micrometry, and CCD imaging. Great emphasis is placed on quality photographs in red, blue, and violet light, full disk drawings using standard color filters, polar cap measurements made with the astronomical micrometer, and with modern observing techniques such as full disk photometry and CCD imaging.

It is highly recommended that all observers, visual as well as photographers and CCD camera users, use at least a basic set of tricolor filters according to the following guide: Red or Orange (W-25 or W-23A); Green (W58); Blue-Green (W-64); Blue (W-38A or W-80A); and Violet (W-47). Observers with smaller telescopes, such as 3 to 6-inch apertures may find a Yellow (W-15) useful and may provide better performance than the deep red filter (See Table 1). Those employing larger instruments, such as 8 to 16-inch apertures, will find the deep Red and Blue filters most useful for fine surface details or atmospheric cloud detection [Capen, et al, 1984].

Table 1. Eastman Kodak Wratten Filters used by A.L.P.O. observers.

Characteristics for Mars Observations:

Yellow (W12, W15) to brighten desert regions, darkens bluish and brownish features.

Orange (W21, W23A) further increases contrast between light and dark features, penetrates hazes and most clouds, and limited detection of dust clouds.

Red (W25, W29) gives maximum contrast of surface features, enhances fine surface details, dust clouds boundaries, and polar cap boundaries.

Green (W57) darkens red and blue features, enhances frost patches, surface fogs, and polar projections.

Blue-Green (W64) helps detect ice-fogs and polar hazes.

Blue (W80A, W38, W38A) and deep blue (W46, W47) shows atmospheric clouds, discrete white clouds, and limb hazes, equatorial cloud bands, polar cloud hoods, and darkens reddish features. The W47 is the standard filter for detection and evaluation of the mysterious blue clearing.

Magenta (W30, W32) enhances red and blue features and darkens green ones. Improves polar region features, some Martian clouds, and surface features.

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Jim Bell will continue to maintain the email distribution list as well as the various Cornell and JPL Marswatch-related WWW archives. If you are receiving duplicate copies of the International MarsWatch Electronic Newsletter, or you want your name added to or removed from the distribution list, please send him an email at

Jim Bell
Cornell University
Department of Astronomy
Center for Radiophysics and Space Research
424 Space Sciences Building
Ithaca, NY 14853-6801
Phone: 607-255-5911; fax: 607-255-9002

Read the Next MarsWatch Newsletter (Volume 3; Issue 5; August 20, 1998)

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This page is maintained by David Knighton for the International MarsWatch. The 1998-1999 MarsWatch site it hosted by the Astronomical League as a service to the astronomical community. Comments, corrections, and suggestions can be addressed to This page last updated January 17, 1999.