PART 1





T H E M A R T I A N C H R O N I C L E
March 1990 (Edited by J.D. Beish for ASTROFORUM) No. 1

Mars is back! Throughout 1990 the Red Planet will become more prominent in
the morning sky until it reaches opposition on November 27. Although Mars' apparent diameter will not be as great as it was in 1988, it will still be
a most respectable 18.1 arc-seconds, permitting high resolution photography
and quality visual observations of surface features, clouds, and the South Polar Cap (SPC). The planet will be very favorably placed in the sky for northern hemisphere observers, remaining north of the celestial equator
between mid-June, 1990 and September, 1991 and attaining a declination of
+22 degrees during the 60-day period around opposition.

Practically speaking,the apparition will commence on April 7, when Mars
attains an apparent disk diameter of 6 arc-sec, allowing quality telescopic observations. However, A.L.P.O.'s International Mars Patrol (IMP) astronomers are encouraged to make observations even when the planet appears smaller.
While little or no fine detail can be discerned when the planet is low and of small apparent size, gross features, such as Syrtis Major, can be seen. If the observer has been regularly recognizing such features and suddenly notes their disappearance, one is led to suspect an obscuration, such as a dust storm. In the past, such sightings made independently by several observers have shed new light on the history of Martian dust storms, even when the planet subtended an angle of less than 6 arc-seconds. A red (Wratten 25 or equivalent) filter is strongly recommended since it improves image contrast and reduces the apparent seeing effects, since red wavelengths are refracted less.


MARTIAN SEASONS

During most of the 1990-91 apparition Mars' South Pole will be tilted earth- ward with most of Southern Hemisphere spring and all of summer and part of southern autumn being observable. Thus astronomers can again study the regress- ion of the SPC and follow both Martian antarctic and arctic meteorology. This apparition should also allow careful scrutiny of the summer SPC remnant. As Mars will have an apparent diameter of over 13 arcseconds at southern autumnal equinox (Jan. 5, 1991), there will be an excellent opportunity to determine whether the remnant disappears completely or, as was the case in 1988-89, it remains throughout southern summer.

IMP astronomers will have an unusual opportunity in early 1991 to watch for
the possible reformation of the SPC. During early Martian southern autumn (January to April TD) the planet's apparent size will remain respectable and its south pole will be tilted earthward, permitting detailed study of antarc- tic regions. Does the South Cap expand during this period, or are its secrets hidden beneath the south polar hood? In fact, does a hood actually form, or
are hoods phenomena restricted to the North? We hope that the IMP can provide some answers to these questions in 1991.


SURFACE FEATURES

Several regions have displayed long-term, or secular, changes in recent years and should be monitored closely during the 1990-91 apparition. These include Solis Lacus (85W, 28S), Daedalia-Claritas (115W, 30S), Phasis (109W, 30S), eastern Sirenum M. (145W, 35S), southern Memnonia and Zephyria, Trivium Charontis (198W, 20N), Cerberus II (212W, 10N) and III (240W, 18S), Elysium (215W, 80N), Hyblaeus (230W, 30N), Nilosyrtis, and Syrtis Major. In addition the Libya-Isidis (275W, 10N) area should be scrutinized to see whether Nodus Laocoontis (246W, 20N) and Thoth-Nepenthes (265W, 15N) are still markedly faded.


DUST STORMS -- A REVISED VIEW

Mars will reach perihelion on June 29, 1990, at which time it will have a respectable apparent diameter of 7.8 arc-seconds. Classically, perihelion passage, which occurs in late southern spring, heralds a period when global dust storms occur. Martian dust storms have been the subject of much media- hupe recently, but in point of fact there have been only five well-document-
ed GLOBAL dust storms on the Red Planet: in 1956, 1971, 1973, and 1977 (two). Furthermore, the concept of a true "dust storm season" on Mars is now open to question: it may well be that dust clouds can occur at any season on Mars. However, Beish's comprehensive analysis of IMP data reveals that there is increased probability of seeing dust storms soon after the planet's perihe- lion passage, with a second peak occurring in mid southern summer. Thus the 1990-91 apparition will present an excellent opportunity for monitoring the occurrence (or non-occurrence!) of dust clouds. This is of considerable importance for our understanding of Martian climate and meteorology and for future space exploration.

The dust storms of Mars have once again become the subject of much study among professional planetary astronomers. However these men and women have neither the funding nor manpower for a 24-hour worldwide surveillance of the planet. A.L.P.O.'s IMP can provide considerable support in this regard as it did dur- ing the 1988 apparition. Thanks to recent developments in communication tech- nology, we can now have virtually instantaneous alerts for unusual Martian phenomena. When such an event is sighted the observer contacts one of the Mars Recorders who then informs the rest of the IMP network. Upon verification the appropriate professional astronomers are contacted so that they can conduct detailed investigations.

STORM WARNING. To facilitate communication Beish and Parker will monitor Compuserve daily during the apparition. Please send messages to both Parker, 72317,3157 and Beish, 72317,3306. If you have no access to a modem, Dan
Troiani has kindly volunteered his phone number: (708) 529-1716. Professor Asada, 71701,1534, in Japan is now on the Compuserve network, which provides us with virtually instant communication with our friends in the O.A.A. We hope that our other observers abroad will be able to avail themselves of this service.

*** DANGER ***

The one thing that must be avoided in reporting dust storms is a false alarm. Our mentors in the professional community take a dim view of wasting consider- able time and money on spurious information. Thus, after consultation with professionals, we have revised our criteria for Martian dust activity.

The astute reader will note that nowhere in this chronicle has the adjective "yellow" been applied to dust. In the past we have referred to dust storms as "yellow clouds" and "yellow dust storms." We feel that this is misleading. First, it is virtually impossible to see or even photograph accurate colors on Mars without employing very specialized techniques. Traditionally, observers have employed yellow filters to better reveal dust clouds. The problem is that nearly EVERY light feature on Mars is bright through a yellow filter! In November, 1989, we were fortunate to have a professional Mars astronomer spend several days in Miami reviewing IMP dust storm data. Under his guidance we have revised our definition of dust clouds/storms.

*** NEW CRITERIA FOR MARTIAN DUST STORMS ***

1. They must appear bright in red light. Dust clouds can be bright in all spec- tral regions, including violet, but if they are not bright in red, they are most likely not dust. This means that observing and photographing Mars through a red filter is a "must" for IMP astronomers. A Wratten 23A will suffice for instruments of 20 cm ( 8 inches) or less in aperture, while a W-25 or even 29 should be employed with larger instruments.

Photographing Mars through filters presents problems to the amateur observer because exposure times are often prolonged beyond the capabilities of his or her drive and the limits of seeing conditions. In such cases observers are strongly requested to photograph Mars on color slide film. They can than re- photograph them through appropriate filters onto black-and-white film. This technique is fully discussed in Parker, et al., Journal of the Association of Lunar and Planetary Observers (J.A.L.P.O., Vol. 31, Nos. 9-10, July, 1986,
and in "Introduction to Observing and Photographing the Solar System." Those who are unable to use this technique are encouraged to send the recorders quality copies of their slides for analysis. Copies should be made on Kodak Slide Copy film 5071 to insure good grain and color balance. Commercial copies are suggested for this film. If copies are made at home, we suggest Fujichrome CDU film. Following the advice of John Sanford, we have tried this film and have found it much easier to use than Kodak 5071. If originals are submitted, we cannot guarantee their return. We commend those observers who have regularly submitted color filter photographs of Mars during past apparitions. These include B. Flach-Wilken (Germany), B. Adcock (Australia), and Japan's T. Akutsu, T. Ishibashi, N. Matsumoto, and T. Nakugami.

2. The sine qua non of Martian yellow clouds is movement with obscuration of previously well-defined albedo features. Absence of this criterion disqualif- ies a candidate from inclusion under dust clouds.

3. When these clouds reach heights of several kilometers, we have proposed that they may cast shadows that are observable from Earth. There are numer- ous reports of anomalous transient dark surface markings appearing near yellow clouds, especially when the solar phase angle was reasonably large. Anomalous dark markings were in fact seen in conjunction with both 1988 dust storms.

THE A.L.P.O. MARS SECTION -- 1990

We wish to take this opportunity to thank the 300 IMP observers who sub- mitted over 7,000 drawings, photographs, and micrometer measurements of Mars during the 1987-1989 apparition. Such an effort is most gratifying but has re- quired some reorganization of the Mars Section. In addition to taking on more recorders, we have assigned each recorder to a geographical area. Observers should correspond with the recorder in his or her area:

JEFF BEISH, 9460 Toni Dr., Miami, Fl, 33157
AL, AR, FL, GA, HA, KY, MS, NC, SC, TN, and VA.

HARRY CRALLE, 3902 E. 29th St. (J-4), Bryan, Texas, 77802
AZ, CA, CO, KS, LA, MO, NV, NM, OK, TX, UT, and WY.

CARLOS HERNANDEZ, 2714 Plaza Dr., Woodbridge, NJ, 07095
AK, CT, DC, DE, MA, MD, ME, NH, NJ, NY, PA, RI, and VT.

DON PARKER, 12911 Lerida St., Coral Gables, FL, 33156
U.S. Territories and Possessions and all areas outside U.S.

DAN TROIANI, 629 Verona Ct., Schaumberg, IL, 60193
IA, ID, IL, IN, MI, MN, MT, ND, NE, OH, OR, SD, WA, WI, WV.


*** GUIDELINES FOR IMP OBSERVERS ***

1. Observations. Submit these to your appropriate recorder. If you want to be assured of their arrival, enclose a stamped, self-addressed postcard with your material. This is the cheapest and easiest way. We cannot acknowledge all the observations received. Drawings should be made on 42-mm diameter disks, or on the standard B.A.A. 2-inch disks. We employ overlay templates for data reduct- ion, and other sizes are unacceptable. Photographs should be approximately 1-inch diameter, so that they can be published properly. However, any photos will be welcome! Do not send negatives. We welcome videotapes (VHS or Super VHS), but do not send originals. Please edit videos -- no more than 5 minutes per observation. We fall asleep easily. Please include date, times.

2. Observing Forms. Send a stamped, self-addressed envelope (SSAE) to Beish or Parker. They will return it with an A.L.P.O. Mars Section observing form en- closed from which you can make copies. A copy of Ebisawa's excellent map of Mars will also be included upon request.

All observations must have the observer's name, the U.T. date, the starting
and ending U.T.'s, and the telescope, magnifications, and filters employed. Mark drawings and photos with "South" and "Preceding" so that we know the orientation. Other information, such as C.M. and Ls, is not required but is appreciated.

3. Correspondence. All correspondence should contain an enclosed SSAE. Remem- ber that the A.L.P.O. staff is volunteer -- both with time and money!

4. Martian Chronicles. Those who wish to subscribe should send 6-8 SSAE's to Beish or Parker. Overseas members cannot send stamps but often send internat- ional postal certificates with their envelopes. We wish to thank the many observers abroad who did this during the last two apparitions. Their help was much appreciated!

5. A.L.P.O. Membership in A.L.P.O. is not required for the IMP. However, we strongly urge our observers to join if for no other reason than they can see the fruits of their labor in print in the apparition reports and other papers in The Strolling Astronomer. Subscribing to the J.A.L.P.O. also gives one the opportunity to read about others' observational techniques and methods of data reduction. In addition, the observer may find other fields which stimulate his interest, such as observing Pluto. U.S., Canada, and Mexico, send $14 for one year or $24 for two years to Harry D. Jamieson, P.O. Box 143, Heber Springs, Arkansas, 72543. Other countries: $16 for one year, $29 for two.

6. Observing Aids.

a) Mars Observer's Handbook, by J.D. Beish and C.F. Capen. This is being re- published by the Institute for Planetary Research Observatories. It is a 55- page, copiously illustrated book on Mars observing techniques, including how
to make drawings and micrometer measurements, tips on photography, use of filters, etc. Send $10.00 to Jeffrey D. Beish, 9460 Toni Drive, Miami, Florida 33157.

b) The A.L.P.O. Solar System Ephemeris: 1990. This contains the complete ephemerides for the Sun, Moon, planets and minor planets as well as selected comets. This is a "must" if one is to get full enjoyment from his observing. Send $6.00 to A.L.P.O., P.O. Box 16131, San Francisco, CA 94116.

c) Introduction to Observing and Photographing the Solar System, by T.A. Dobbins, D.C. Parker, and C.F. Capen. Contains both theoretical and observat- ional information on Solar System objects. Very detailed chapters on Mars, astrophotography, micrometry, etc. Forward by A.L.P.O. founder Walter H. Haas. Hardcover, $19.95 from Willmann-Bell, Inc., P.O. Box 35025, Richmond, VA
23235, (804) 320-7016.

d) IMP Astronomical Calculator (IMPAC). Computer program containing complete ephemerides of Mars and Jupiter for any year and geographical location. Also rise and set times, altitude, azimuths for all Solar System objects for observ- er's location. Automatic correction for Daylight Time, lunar phases for star party planning, telescope and mirror cell design, and comprehensive astro- photography program. Subroutines for color filter calculations and automatic computation of Martian polar cap and Jovian belt latitudes from observer's input. For IBM XT, AT and compatibles, monochrome, EGA, or VGA. For a 5.25- inch diskette, send $49.95 to J.D. Beish at above address.

Again, many thanks to the dedicated IMP observers for their excellent work in the past. In the past, some observers have not sent in their observations be- cause they felt their work inadquate, please send them, especially those color photographs -- how many discoveries go undetected............................?

The Association of Lunar and Planetary Observers -- International Mars Patrol
Good Seeing in 1990-91!

Don Parker Jeff Beish Carlos Hernandez
Harry Cralle Dan Troiani

Eddie,
telnet://ricksbbs.synchro.net:23
http://ricksbbs.synchro.net:8080
---
þ Synchronet þ Rick's BBS telnet://ricksbbs.synchro.net:23

PART 2





******************************************************************************
T h e M a r t i a n C h r o n i c l e
April 1990 No. 2 ******************************************************************************
The electronic newsletter by the International Mars Patrol (I.M.P.),
an observing program of the Association of Lunar and Planetary Observers
(A.L.P.O.)
Edited by: J.D. Beish ------------------------------------------------------------------------------
INTRODUCTION

The International Mars Patrol (IMP) is a cooperative program by planetary

observers located around the Earth, that makes possible a 24-hour surveillance

of all Martian longitudes. The IMP was organized during the early 1960's by

the late Charles F. Capen and cataloged nearly 20,000 visual observations,

more than 3,000 black & white and color photographs, and thousands of Martian

surface measurements contributed by amateur and professional planetary astro- nomers.

The Association of Lunar and Planetary Observers (A.L.P.O.) is an international group of students of the Sun, the Moon, the major planets, minor planets, me- teors, and comets. Our goals are to stimulate, coordinate, and generally pro- mote the study of these bodies using methods and instruments that are available to amateur astronomers. Observations carried out by professionals or with pro- fessional equipment are also welcome. We provide a service for the advanced amateur specializing in particular investigations, for the novice who wishes to develop techniques and general knowledge, and for the professional scientist interested in group studies and systematic patrols of our Solar System neigh- bors. All interested persons are welcome as members. Our activities are on a

volunteer basis and each member can do as much or as little as she or he wish- es. Of course, the A.L.P.O. gains in stature in proportion to how much and also how well each member contributes.

The Mars Section Recorders coordinate and instruct 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 Mars Section receives thousands of individual observations of visual 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 obs- erving 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 a simple, efficient and standard Mars Observing Report Form has been prepared by the Mars Recorders. This Standard Form can be used for reporting all types of observations such as; micrometry, transit tim- ings, intensity estimates, etc. Photographs may also be attached to the top or back of the forms 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.


The A.L.P.O. was founded in 1947, by Walter H. Haas, and now enrolls over 700 members, of which about 160 live in foreign countries on six continents. Our group is organized into Observing Sections that study each Solar System body or type of body.

We have held conventions every year beginning in 1956, usually together with the meetings of the Astronomical League or of the Western Amateur Astronomers. Our chief means of communication is our quarterly Journal ("The Strolling As- tronomer"), although several of our Observing Sections also publish their own newsletters and handouts.

Membership dues in the A.L.P.O. include a subscription to our Journal and are $14.00 per year for members in the United States, Canada, and Mexico; and $16.00 per year for other countries. (2-year rates are $24.00 and $29.00 re- spectively.) Payment should be by check or money order payable to "A.L.P.O."

If our organization sounds of possible interest to you, write to:
Harry D. Jamieson, A.L.P.O. Membership Secretary,
P.O. Box 143, Heber Springs, Arkansas 72543. -----------------------------------------------------------------------------
***IDENTIFYING A MARTIAN DUST STORM***

Although immense global dust storms are firmly entrenched in Martian lore, they may be rare. Lowell Observatory's Leonard Martin has written that there have been only five well-documented "planet-encircling" Martian storms. These storms occurred in 1956, 1971, 1973, and two storms in 1977 (these were dis- covered by Viking Spacecraft). However, smaller dust storms or dust clouds are observed on Mars. These dust clouds are very difficult to identify in their beginning stages and, in some cases, go undetected even after they have fully developed.

Numerous reports of yellowish hazes have appeared in the literature and in the International Mars Patrol archives. Mars observers frequently report "albedo features" lacking in contrast, the planet is "washed out," or Mars' atmosphere is "dusty." These terms have been employed in the past by the A.L.P.O. Mars Recorders. While such descriptions may have merit, generalized yellow hazes and temporary losses in surface contrast is usually omitted in our reports. Photographic evidence for these phenomena is also weak, since the proper sen- sitometric calibration is usually lacking.

While working with Leonard Martin (Planetary Research Center, Lowell Observa- tory, Flagstaff, Arizona) and Richard W. Zurek (JPL) on problems of correctly identifying and classifying Martian dust clouds or storms, new guidelines have been established by the A.L.P.O. Mars Recorders for interpreting Martian dust clouds and dust storms, they are classified as:

I. Type of Observation.

1. White cloud or bright area mistaken for dust cloud.
2. Visual observation(s) of dust clouds in a dust storm.
3. Instrumental observation(s) of dust cloud/storm (Includes
photographic, polarimetric, spacecraft data, or other data
obtained by instrumental means).


Table I (con't)

II. Martian dust clouds.

1. Obscuration -- Not sure if surface or atmospheric.
2. Dust Haze -- Partial obscuration with displacement.
3. Bright dust cloud -- Bright obscuration with displacements.
4. Limb projection/terminator protrusion by dust cloud.

III. Martian dust storms.
1. Local -- Dust storm with major axis not to exceed 2000 km
(1,243 miles or less than 34 degrees).
2. Regional -- Dust storm with major axis that exceeds 2000 km
(1,243 miles or less than 34 degrees) but not encircling either
or both hemispheres.
3. Planet Encircling -- Dust storm with major axis that completely
encircles either one or both hemispheres of Mars.


Confusion over the colors of Mars is nothing new. When the bright planet Mars is observed against a nighttime sky, the planet's predominantly orange colored surface becomes highly saturated to the eye. The darker albedo features, when observed against this saturated background are perceived as complementary hues. This effect is known as "simultaneous contrast" and is explained the May 1989 Sky and Telescope Magazine, Vol. 77, No. 5, page 474, inset "Mars from Mauna Kea" in an article by W.K. Hartmann, "What's New on Mars?".

COLOR FILTERS

A full set of photo-visual color filters is a most important observing aid the planetary astronomer can have in his or her arsenal of telescopic accessories. Color filters help overcome image deterioration caused by atmospheric scatter- ing of light, permit separation of light from different levels in a planetary atmosphere, increase hue contrast between areas of differing color, and reduce irradiation within the observer's eye. All of these factors increase the sharpness of surface and cloud details that are seen on the planet Mars.

Using color filters at the telescope can be a most challenging an rewarding ex- perience, although several weeks of practice may be necessary to condition the observer to detect those subtle wisps of clouds and hazes often observed in the

Martian atmosphere. Without the aid of these filters, many interesting phenom- ena may go undetected.

Table I. Eastman Kodak Wratten Color Filters used for visual and
photographic observations of Mars. Transmission Characteristics
are given.

RED (W25,29) -- Gives maximum contrast of surface features, polar
cap edges, enhances fine surface details, and dust cloud bound-
aries.

ORANGE (W21,23A) -- Further increases contrast between light and
dark features, penetrates hazes and most clouds, and brightens
dust clouds.

Table I (con't)

YELLOW (W8,12,15) -- Brightens desert regions, darkens blue and
brown features.

GREEN (W56,57) -- Darkens red and blue features, enhances frost
patches, surface fogs, polar projections,and polar cap boundaries.

BLUE-GREEN (W64) -- Enhances ground fogs, limb and polar hazes.

BLUE (W80A,38A)-- Shows atmospheric clouds, discrete white clouds,
and limb hazes, and darkens reddish features, which probably con-
tributes to the illusion of blue or violet haze.

VIOLET (W47) -- Shows blue and blue-white clouds,limb hazes,equa-
torial cloud bands, polar cloud hoods, and dark dust clouds,and
aids in the detection of the Violet Clearing phenomenon.

MAGENTA (W30,32) -- Enhances red and blue features, darkens green
features.


THE MARS RECORDERS

To participate in our Mars observing program, receive the Martian Chronicle, an observing form (to copy as many times as required) -- please send 8 Self Ad- dressed Stamped Envelopes to the individual listed below that corresponds to

your local area. Each of the following ALPO Mars Recorders will be responsible

for receiving and corresponding with observers in a specific geographic area:

Jeff D. Beish, 9460 Toni Drive, Miami, Florida 33157 (CompuServe 72317,3306) -- Alabama, Arkansas, Florida, Georgia, Hawaii, Kentucky, Mississippi, North

Carolina, South Carolina, Tennessee, and Virginia.

Harry Cralle, 3902 E. 29th Street (J-4), Bryan, Texas 77802
-- Arizona, California, Colorado, Kansas, Louisiana, Missouri, Nevada, New Mexico, Oklahoma, Texas, Utah, and Wyoming.

Carlos Hernandez, 2714 Plaza Drive, Woodbridge, New Jersey 07095
-- Alaska, Connecticut, D.C., Delaware, Massachusetts, Maryland, Maine, New Hampshire, New York, New Jersey, Pennsylvanian, Road Island, and Vermont.

Don C. Parker, Coral Gables, Florida 33156 (CompuServe 72317,3157) -- Overseas and U.S. Territories.

Dan Troiani, 629 Verona Ct., Schaumburg, Illinois 60193
-- Idaho, Illinois, Indiana,Iowa, Michigan, Minnesota, Montana, Nebraska, North Dakota, Ohio, Oregon, South Dakota, Washington, West Virginia, and Wisconsin.






CALENDAR OF EVENTS -- MARS, 1990-91

03/06/90 -- Martian Southern Spring Equinox. South Polar Cap (SPC) should be

near maximum diameter. Is South Polar Hood (SPH) present? Look for North Polar

Hood. Disk diameter only 4.9 arcseconds ("). Mars rises approx. 2.5 hours

before Sun.

04/01/90 -- Disk diameter 5.4". Mars rises over 3 hours before Sun. Can the major albedo features be seen? SPC large and bright. Is the eastern border of

Syrtis Major withdrawing? In violet light are orographic clouds present over Tharsis-Amazonis? April Fool's Day!

04/27/90 -- Disk diameter 6". SPC rifts developing. Watch for those Martian dust clouds (red filter), orographics clouds (violet filter).

05/12/90 -- Novissima Thyle appears as a bright SPC projection. However disk diameter still small.

05/21/90 -- Southern hemisphere mid-spring. Any dust clouds yet? Orographics over the Tharsis volcanoes -- W-Cloud? Maximum earthward tilt of Martian South

pole for this apparition, affording good views of SPC. Has Novissima Thyle sep- arated from SPC to become Mountains of Mitchel? At disk diameter of 6.6" are

the Rima Australis and Magna Depressio visible in SPC?

06/05/90 -- Disk diameter is now 7". Rapid SPC retreat. Quality micrometer me- asurements of SPC possible.

06/29/90 -- Mars at perihelion (closest to Sun). Disk diameter now 7.8". Views of surface details better. Rapid SPC retreat. W-clouds possible. Dust clouds?

Is Novus Mons (Mts. of Mitchel) detached from SPC?

07/15/90 -- Late Southern spring. SPC now more than 20 degrees diameter. Watch for dust clouds (red filter!). Numerous white patches possible on surface.

07/30/90 -- Martian Southern Summer Solstice. SPC continues to retreat poleward Disk diameter 9".

08/16/90 -- Disk diameter is now 10". Some photography now possible. Discrete (white) clouds and white areas should be minimal. SPC small, offset from pole.

09/01/90 -- SPC retreat slowing--stable polar remnant. Is Syrtis Major narrow? Blunted? Possibility of dust storms again increasing. Large northern winter

North Polar Hood (NPH) should be prominent. Measure latitude of NPH -- does it retreat or disappear when dust storm present?

09/14/90 -- Disk diameter 12". Begin high resolution visual observations and high quality photography begins.

10/17/90 -- High probability of dust storms. Disk diameter 15.4". Tilt of Mars now affording good view of both polar regions: large NPH. Look for tiny SPC

remnant near South limb. SPC offset, so easier to see when CM near 30 degrees. Is SPC remnant present in mid-summer?



CALENDAR OF EVENTS -- MARS, 1990-91 (con't)

11/09/90 -- Continued alert for dust storms. SPC remnant visible? Antarctic hazes present? Is NPH variable, occasionally bright? (Use a violet filter for

NPH measurements, observations.)

11/20/90 -- Closest approach (0400 UT) to Earth. Disk diameter 18.1".

11/27/90 -- Opposition (2028 UT). Disk diameter 17.9". Late Southern summer: Is SPC remnant still present. Photographs needed of SPC. NPH still observable.

Watch for signs of NPH thinning. Are South polar hazes present?

12/17/90 -- Disk diameter 16". NPH should be easily visible if present. Close- ly monitor hood from now on. When does it disappear and the NPC appear? Is SPC

remnant still present? Any evidence of SPH? Watch Syrtis Major for signs of

expansion to east.

01/05/91 -- Southern hemisphere autumnal equinox. Carefully monitor antarctic region for evidence of SPC remnant and/or hazes. Will SPH form? N. hemisphere

vernal equinox. Monitor arctic closely for date of disappearance of NPH. Watch

for possible reformation of polar hood. NPC at maximum extent with edge near 55

degrees areocentric latitude. Disk diameter 13.2". Begin micrometer/reticle NPC

measurements, using red/orange filters.

02/01/91 -- Disk diameter 10". Photography difficult but visual observations and NPC measurements still possible. Monitor antarctic for SPC remnant, hazes.

Are Hellas, Argyre brightening?

02/24/91 -- Disk diameter rapidly shrinking--now 8". Early Northern hemisphere spring. Continue NPC measurements. Is North Cap fairly static or entering rapid retreat phase? South polar regions becoming difficult to observe. Any signs

of SPH?

3/14/91 -- Disk diameter 7". Limb clouds/hazes should start to increase. Look for them in violet light. What is size, shape of Syrtis Major?

04/04/91 -- Disk diameter 6". N. hemisphere mid-spring. Is NPC beginning rapid retreat? Are limb arcs increasing in frequency, intensity. Use filters! Ant-

arctic hazes, hood? Cloud activity increases.


For complete details for the physical and geocentric positions of Mars send for the "A.L.P.O. Solar System Ephemeris," $6.00 in the U.S, Canada, and Mexico; $8.50 in other countries. Write to: John E. Westfall, A.L.P.O. Director/Editor, P.O. Box 16131, San Francisco, CA 94116.

Eddie,
telnet://ricksbbs.synchro.net:23
http://ricksbbs.synchro.net:8080
---
þ Synchronet þ Rick's BBS telnet://ricksbbs.synchro.net:23