T h e M a r t i a n C h r o n i c l e December 1990 No. 7

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                    T h e   M a r t i a n   C h r o n i c l e

December 1990                                                            No. 7

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     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

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                          The Last Martian Chronicle

     Due to the ever increasing cost and work load the  editor  is  forced  to

suspend publication of the Martian Chronicle newsletter (mailed and electronic 

versions).  This will be the last IMP Martian Chronicle  published.     Please

except the editor's apology to all those who have enjoyed reading this  humble

newsletter over the past 18 years.

                               MISSING REPORTS!

     Following a most successful observing program in  1988,  cataloging  more

than 7,000 observatons from 311 astronomers, the 1990 Mars apparition will  go

down as the worst in the IMP's history.  So far  only  27  observers  have re-

sponded with 337 observations of Mars!  During the first  months  of  1988  we

collected thousands.  The main problem  apparently  stems  from  a  change  of

address for the IMP last year.  Since over half of IMP's observers  either  do

not belong to ALPO (and receive our journal, The Strolling Astronomer) or   do

not receive the Martian Chronicle, for one reason or the other,  it  is diffi-

cult for the Mars Recorders to notify  observers  of  these  changes.   It  is

probable that many of their observations are being "round filed"  or  returned

by the post office. 

     We experienced a similar situation during the late 1970's  when  many  of

our experienced observers gave up reporting their Mars observations because of 

the spaceflights to Mars.  They felt that since Viking had seemingly  answered

all questions about the  Red Planet it was useless  to  continue  ground-based

telescopic study.  

     With the Hubble Space Telescope, poised in space  ready  to  answer  what

questions NASA was unable to answer before, we may see a replay of the 1970's. 

Also, we must not forget that the CCD camera has all but  replaced  the  human

eye and the photographic plate (sic)!

                              NOVEMBER DUST CLOUD

                                            

     While using the University of Hawaii's 24-inch  telescope  at  Mauna  Kea

Observatory, Beish received a call from Don Parker with an alert of yet anoth-

er dust storm.  He was on Mauna Kea during 30 October through 7 November  1990

photographing Mars for Lowell Observatory's  International  Planetary  Patrol.

On 4-5 November he recorded in color  three  dust  clouds  moving  across  the

Aurorae Sinus-Solis Lacus regions.

     John Rogers of the BAA and ALPO's Frank Melillo were  the  first  to  see

this small dust storm.

                                       

                                 COLOR FILTERS

     A set of photo-visual color filters is the most important  observing  aid

the planetary astronomer can have in his/her  arsenal  of  telescopic accesso-

ries.  Color filters help overcome image deterioration caused  by  atmospheric

scattering 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  in

crease the sharpness of surface and cloud details that are seen on the  planet

Mars.

     Standard color Wratten Filters for scientific research are made  by  East

man Kodak Co., and they may be ordered in 3x3-inch square thin gelatin  sheets

from Kodak photo dealers or may be purchased from major telescope  dealers  in

glass with threaded mounts for attachment to the eyepiece.   A  basic  set  of

tricolor filters useful for color image comparison or "Blinking"  at  the  eye

piece is a must for the planetary observer, e.g., yellow  (Wratten-12),  green

(W-58), and blue (W-80A) or W-38A).  An advanced set  would  also  contain  as

orange (W-21 or W23A), red (W-25), violet (W-47),  and  magenta  (W-30,  minus

green)

     Using color filters at the telescope can be a  most  challenging  and re-

warding experience, 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 phenomena may go undetected.  

     Bright Martian atmospheric clouds and hazes are classified by  the  color

of light in which they are best observed.    Standard  color  Wratten  Filters

produced by Eastman Kodak Co. for scientific research are systematically  used

by observers either at the eyepiece or in combination with  a  camera  at  the

telescope.  Observers using filters other than Kodak Wratten Filters  supplied

their respective filter characteristic curves to insure compatibility.

     During all observations with permissible seeing conditions, Kodak Wratten 

color filters were systematically  used  to  detect  suspected  meteorological

activities.  Blue-white clouds appear bright in blue and  violet  light.   Red

and green filters are used to search for low fog's and hazes with close atten-

tion to discrete bright  areas  accompanied  by  surrounding  yellowish  haze.

Checks are made from time to time  with a yellow filter to either  confirm  or

dispel  any suspected yellow dust clouds.

     While longer wavelength light reveals low altitude meteorology or surface 

white frost areas, green  and  blue-green filters  also enhance seasonal white 

clouds.  

     Due to the scattering of blue light  by  Mars'  atmosphere,  blue  filter

observations with frequent cross checking with  red filters aid in  the detec-

tion of higher cloud formations and hazes.  Alternating from blue to red light 

(blinking) is a tried and proven way to detect cloud  activity.   The  use  of

light blue and violet filters will surely  bring  out  those  subtle  and  low

intensity blue and blue-white clouds often observed near the Martian  equator.

Without the aid of color filters, planetary system cloud banding and other low 

contrast meteorology is almost impossible to detect.

     Several atmospheric conditions and physical effects are modified  by  the

use of color filters at the telescope:

SCATTERING interposes a luminous veil between the  observer  and  his/her sub-

ject.  Scientists have shown that for particles in a planet's atmosphere of  a

given size, the scattering is inversely proportional to the  fourth  power  of

the wave length of the light.  Hence, violet light  of  400  nm  is  scattered

about 16 times more than deep red light of 800 nm; Earth's daytime sky is blue 

as a result of this property.  The Martian atmosphere scatters  light  in  the

same manner and thus allows us to observe Martian aerosols  at  the  different

relative atmospheric depths.

PRISMATIC  DISPERSION by our atmosphere is most evident when a star or  planet

is seen near the horizon.  It results  from  refraction  being  less  for  the

longer wave lengths where the red appears nearer the horizon and violet toward 

the zenith.

ATMOSPHERIC PENETRATION.  To explore an atmosphere similar to our's to various 

depths,  molecular scattering  can  be  exploited.   Since  the  shorter  wave

lengths are scattered more, it follows that ultra violet light  scarcely pene-

trates an atmosphere at all, violet light penetrates to some depth, blue still 

deeper, while blue-green may reach the solid surface.

COLOR CONTRAST is affected by sharpness of boundaries and  by  differences  in

color and shade.  Light yellow and orange filters are useful  in  judging  the

colors of the low-hue cloud belts and zones of Jupiter and Saturn.   To  bring

out a white area on a reddish background, a green filter is useful. 

IRRADIATION occurs between adjoining areas of unequal brightness.  The  amount

the bright area appears to encroach upon  the  fainter  one  is  approximately

proportional to their intensity difference.  This is evidently a physiological                                              

effect, originating within the eye itself.  A deep red  or  orange  filter re-

duces this effect while observing a planet at the telescope.  

                                Observing Aids. 

************************** MARS OBSERVER'S HANDBOOK **************************

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* Now available from the Astronomical League is the Mars Observer's Handbook * 

* by Jeffrey D. Beish and Charles F. Capen at a new low price of $8.00. This * 

* very important and informative book is in  second printing due to  popular * 

* demand. Formerly published for The Planetary Society's Mars Watch '88, the * 

* book was  sold out and has been out of print for the past two years.  Send * 

* $8.00,  check or money order to:  Astronomical League Sales,  Four Klopfer * 

* Street, Pittsburgh, PA 15209.                                              *

*                                                                            *

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******** Introduction to Observing and Photographing the Solar System ********                          

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     I wish to thank all those who have participated in the ALPO International 

Mars Patrol and hope our dedicated Mars observers continue to send us their 

most helpful observations of the Red Planet Mars..........

                                 =Jeff Beish=

te bright  areas  accompanied  by  surrounding  yellowish  haze.