152 lines
8.5 KiB
Plaintext
152 lines
8.5 KiB
Plaintext
SUBJECT: THE MARTIAN CHRONICLE FILE: UFO3331
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PART 4
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******************************************************************************
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T h e M a r t i a n C h r o n i c l e
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August 1990 No. 4
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******************************************************************************
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The electronic newsletter by the International Mars Patrol (I.M.P.),
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an observing program of the Association of Lunar and Planetary Observers
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(A.L.P.O.)
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Edited by: J.D. Beish
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------------------------------------------------------------------------------
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Is Mars' South Polar Missing?
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Several observers have reported the disappearance of the Martian south
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polar cap (SPC). Because southern summer began on July 30th. the SPC was in
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rapid retreat during August and should not be very large. For those of us in
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the United States, observing Mars' during mid-August (Central Meridians (CM)
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from 150 - 270 degrees) the south limb will resemble a great "bald spot" where
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the SPC should be. The cap will be very hard to see for Northern Hemisphere
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observers because the cap is offset 7 degrees from the pole towards 30 degrees
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longitude. Therefore, the SPC is on the other side of the planet from us.
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From mid-August, the planetocentric declination of Earth (De) will be -11.2
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deg. and decrease to -3.9 deg. by the end of September. This will also place
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the south polar region of Mars in a difficult position to observe for every
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one.
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The two polar caps of Mars are composed differently. The north cap is a
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water ice cap covered with layers of carbon dioxide ice. While water has been
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detected in the south cap, it is mostly carbon dioxide. Because the atmos
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pheric pressure of Mars is too low for liquid water to exist on its surface,
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frozen materials in the caps do not melt but sublimate at temperatures above
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zero.
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Mars looks strange?
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Are we seeing new dark features on Mars or just changing shadows? Those
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who regularly observe the Moon know that shadows cast by Lunar surface fea
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tures change its surface appearance from day to day. Although certain Martian
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surface features are known to physically change in shape and darkness, shadows
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also effect the appearance of the Red Planet's surface. Shadows have a direct
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effect on the appearance of regions such as Tharsis -- with its steep rise
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from a large valley floor to its 12 and 16 mile high volcanoes -- or Hellas,
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which is shaped like a very large and deep crater. Remember also that shadows
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are longer near the planet's morning and evening limbs or terminator and are
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shorter nearest to the planet's noon hour (sub-solar point). In August, Mars'
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south pole is tilted toward the Sun, so, the shadows will appear to point in a
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more northerly direction. As the Martian seasons change from summer to au
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tumn, these same shadows will change directions as well, giving its surface a
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slightly different appearance.
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However, don't let the shadows fool you, report all changes on the Mar
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tian surface to the ALPO Mars Recorders as soon as possible.
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******************************** DUST STORMS *********************************
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* *
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* Again, we must caution observers not to confuse those Martian white clouds *
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* or bright white surface deposits with dust clouds.We have received several *
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* calls and letters this month from observers claiming to have seen a large *
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* dust storm on Mars. While observing both visually and with sensitive CCD *
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* cameras, the ALPO Mars Recorders can find no trace of dust either on the *
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* Martian surface or in its atmosphere as of August 27, 1990. Remember, dust *
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* clouds are very bright in red light and they usually move about covering *
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* over portions of the Martian surface. *
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******************************************************************************
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*** GUIDELINES FOR IMP OBSERVERS ***
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1. ALPO MEMBERSHIP: Membership in Association of Lunar and Planetary Observ
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ers (ALPO) is not mandatory for the IMP. However, we strongly urge our observ
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ers to join, if for no other reason than they can see the fruits of their
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labor in print in the apparition reports and other papers in The Strolling
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Astronomer. Subscribing to the J.A.L.P.O. also gives one the opportunity to
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read about others' observational techniques and methods of data reduction. In
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addition, the observer may find other fields which stimulate his interest,
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such as observing Pluto. U.S., Canada, and Mexico, send $14 for one year or
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$24 for two years to Harry D. Jamieson, P.O. Box 143, Heber Springs, Arkansas,
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72543. Other countries: $16 for one year, $29 for two.
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2. CORRESPONDENCE: All correspondence should contain an enclosed S.A.S.E.
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Remember that the A.L.P.O. staff is voluntary -- both with time and money!
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OBSERVING AIDS
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************************** MARS OBSERVER'S HANDBOOK **************************
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* *
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* Now available from the Astronomical League is the Mars Observer's Handbook *
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* by Jeffrey D. Beish and Charles F. Capen at a new low price of $8.00. This *
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* very important and informative book is in second printing due to popular *
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* demand. Formerly published for The Planetary Society's Mars Watch '88, the *
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* book was sold out and has been out of print for the past two years. Send *
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* $8.00, check or money order to: Astronomical League Sales, Four Klopfer *
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* Street, Pittsburgh, PA 15209. *
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* *
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******************************************************************************
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a) The A.L.P.O. Solar System Ephemeris: 1990. This contains the complete
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ephemerides for the Sun, Moon, planets and minor planets as well as selected
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comets. This is a "must" if one is to get full enjoyment from his observing.
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Send $6.00 to A.L.P.O., P.O. Box 16131, San Francisco, CA 94116.
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b) Introduction to Observing and Photographing the Solar System, by T.A.
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Dobbins, D.C. Parker, and C.F. Capen. Contains both theoretical and observa
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tional information on Solar System objects. Very detailed chapters on Mars,
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astrophotography, micrometry, etc. Forward by A.L.P.O. founder Walter H. Haas.
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Hardcover, $19.95 from Willmann-Bell, Inc., P.O. Box 35025, Richmond, VA
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23235, (804) 320-7016.
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c) IMP Astronomical Calculator (IMPAC). Computer program containing complete
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ephemerides of Mars and Jupiter for any year and geographical location. Also
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rise and set times, altitude, azimuths for all Solar System objects for
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observer's location. Automatic correction for Daylight Time, lunar phases for
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star party planning, telescope and mirror cell design, and comprehensive
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astrophotography program. Subroutines for color filter calculations and auto
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matic computation of Martian polar cap and Jovian belt latitudes from
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observer's input. For IBM XT, AT and compatibles, monochrome, EGA, or VGA. For
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a 5.25-inch diskette, send $49.95 to J.D. Beish, 9460 Toni Dr., Miami, FL
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33157.
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THE A.L.P.O. MARS SECTION -- 1990
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ALPO Mars Recorders have been assigned to a geographical area. Observers
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should correspond with the recorder in his or her area:
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JEFF BEISH, 9460 Toni Dr., Miami, Fl, 33157: AL, AR, FL, GA, HA, KY, MS, NC,
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SC, TN, and VA.
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HARRY CRALLE, 3902 E. 29th St. (J-4), Bryan, Texas, 77802: AZ, CA, CO, KS, LA,
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MO, NV, NM, OK, TX, UT, and WY.
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CARLOS HERNANDEZ, 2714 Plaza Dr., Woodbridge, NJ, 07095: AK, CT, DC, DE, MA,
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MD, ME, NH, NJ, NY, PA, RI, and VT.
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DON PARKER, 12911 Lerida St., Coral Gables, FL, 33156: U.S. Territories and
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Possessions and all areas outside U.S.
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DAN TROIANI, 629 Verona Ct., Schaumberg, IL, 60193: IA, ID, IL, IN, MI, MN,
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MT, ND, NE, OH, OR, SD, WA, WI, WV.
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*********************************************************************
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* -------->>> THE U.F.O. BBS - http://www.ufobbs.com/ufo <<<------- *
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********************************************************************* |