THE ROYAL ASTRONOMICAL SOCIETY OP CANADA

                       1991 SOLAR ECLIPSE EXPEDITION
                                                                   7 May 1991

Dear Registrant(s) No.:	______________________________


          We are writing to provide an update on the status of the Expedition
and to provide additional information to assist in your 
preparations.


STATUS OF EXPEDITION

          We continue to be extremely pleased with Expedition planning. The
contract between La Tur Airlines (our carrier) and Sunquest Incentive Travel
(our travel agent) has been signed, and we have received a guaranteed price
for the charter.

          Two members of the RASC Solar Eclipse Committee will be travelling
to Mexico in June to meet with our hotel and bus company personnel, and with
the Mexican government officials with whom we have been dealing, to ensure
that the final details of the Expedition are settled. We will also be
locating specific back-up observing sites near the eclipse centre line on the
Mexican mainland north of Puerto Vallarta in the event that, for any reason,
we are unable or choose because of weather not to fly to Los Cabos in Baja
California on Eclipse Day.


EXPEDITION COST AND FINANCIAL ARRANGEMENTS

          Most of the Expedition's final costs have been determined, and it
appears that the final per person cost will be $1,280 ($1,152 for registrants
no. 1-92). If you have to date paid $700 (as have most participants), then
your final payment will be $580 ($452 for registrants no. 1-92). If you have
paid an amount to date other than $700 per person (in which case your final
payment must be adjusted accordingly), that amount is indicated here:
_____________, and your final per person payment will be ______________.

          Please send your final payment as soon as possible. WE MUST HAVE
RECEIVED YOUR PAYMENT, AT THE VERY LATEST, BY 24 MAY. This is in order to
allow your cheque to clear the bank in time for us to make the final payment
to La Tur Airlines as required by the tens of the contract.

          Please make your cheque or money order payable to "The Royal
Astronomical Society of Canada". Please send your payment by regular mail
or Canada Post Special Letter. DO NOT SEND PAYMENT BY REGISTERED MAIL OR
PRIORITY POST, because we are not at home during the day, and it is very
difficult for us to pick up mail at the post office during business hours.

INFORMATION RETURN AND EQUIPMENT LIST

          Enclosed you will find an Intonation Return and an Equipment List
(one for each member of your group) that we ask you to complete and return
to us AS SOON AS POSSIBLE. We need this information in order to be able to
contact you quickly should the occasion arise, to arrange appropriate hotel
accommodation and aircraft seating, and to enable us to send a complete list
of all equipment to Mexican customs officials (as is required by Mexican
law). It is essential that one copy of each of these forms PER PERSON be
completed and returned.


MEXICAN CUSTOMS AND IMMIGRATION

          For Canadians entering Mexico, a tourist card (to be provided to
you on the flight) is required, TOGETHER WITH A VALID PASSPORT OR ORIGINAL
BIRTH CERTIFICATE WITH PHOTO IDENTIFICATION. Please obtain these documents
now. The formalities upon entering Mexico are simple and straight forward,
with the exception that all astronomical and photographic equipment must be
approved before arrival, and will be subject to careful inspection.

          Citizens of countries other than Canada should consult their local
Mexican consulates to determine entry documentation and regulations. THIS
IS YOUR RESPONSIBILITY.

          Mexican law provides that, if a minor (ie. person under age 18) is
accompanied by only one parent (or by neither parent), the other parent (or
both parents) must sign a Consent, WHICH MUST BE NOTARIZED, granting


                                    - 2 -


permission for the minor to enter Mexico. If you may fall into this category
(as determined by the Releases that you signed and sent to us), two copies
per minor of the required Consent are enclosed. THIS IS VERY IMPORTANT. DO
NOT RETURN THE CONSENTS TO US. HAVE THEM SIGNED AND NOTARIZED BY A NOTARY
PUBLIC, AND KEEP THEM WITH YOU ON THE EXPEDITION.

LUGGAGE

          Because of the need to maximize the amount of space available for
telescopes and other astronomy equipment, all clothes and personal effects
must be taken on as carry-on luggage aboard the aircraft, and not as checked
luggage. Remember, all checked luggage will remain on board the aircraft
overnight in Puerto Vallarta, and will not be accessible until Eclipse Day.
Please pack all telescopes and tripods in boxes or bags. When completing the
Equipment List, DO NOT UNDERESTIMATE THE WEIGHT OF YOUR EQUIPMENT AS FULLY
PACKED, or else we risk being overweight and having to leave equipment
behind.


ARRIVAL IN AND DEPARTURE PROM TORONTO BEFORE THE ECLIPSE

          The flight will depart from TERMINAL 2 at Toronto International
Airport at 08:30 EDT on Wednesday, 10 July 1991. All members with luggage
to be checked should arrive at Terminal 2 by 06:30 a.m. Members with only
carry-on bags should arrive by 07:00. Proceed to the Sunquest booth in
Terminal 2 to obtain your ticket and boarding pass, before checking in at the
La Tur counter. The early morning departure time will probably require that
all non-Toronto (and immediate region) participants arrive in Toronto on the
day before (that is, Tuesday, 9 July). There are many hotels close to the
Toronto airport. If you wish assistance in making a hotel reservation, we
will be pleased to help you. Please get in touch with the undersigned as
soon as possible.


WEATHER IN MEXICO - AVAILABILITY OF WATER, ETC.

You can expect the weather on the Mexican mainland to be hot (32°
- 38° C.) and humid. The weather in Baja may also be very hot, but extremely
dry and therefore not at all uncomfortable. YOU WILL NOT NEED TO CARRY EXTRA
WATER OR REFRESHMENTS. We are arranging for pack lunches, water, soft
drinks, beer and fruit to be available with us on the buses and therefore at
the observing site.


FURTHER INFORMATION

          We are enclosing as well, for your review, the following
information: (a) suggested packing list; (b) articles on solar eclipse
photography and solar observing safety; (c) an Itinerary for the trip; and
(d) a suggested reading list. Please read all these enclosures as soon as
possible.

          As is indicated in the Itinerary, we plan to hold a one to two-hour
group meeting at the hotel in Puerto Vallarta in the late afternoon before
the eclipse. At that time, there will be talks and discussions concerning
various matters related to the eclipse, including a question and answer
session. This will be an excellent opportunity for everyone to become
acquainted.

          We hope that the information contained in this letter is
sufficient. If you have further questions, please do not hesitate to contact
us. We look forward to seeing all of you in July, and we thank you for
joining our Expedition.

                                          Yours very truly,



                                          Michael S. F. Watson
                                          Expedition Leader
                                          1991 RASC Solar Eclipse
                                          Expedition

                                          Tel. (416) 999-9999 (Bus.)
                                               (416) 999-9999 (Res.)
MSFW: sc



             THE ROYAL ASTRONOMICAL SOCIETY OF CM4ADA


                    1991 SOLAR ECLIPSE EXPEDITION




                              ITINERARY




WEDNESDAY, 10 JULY 1991



06:30 -      Expedition members arrive at Toronto International Airport,
07:00        Terminal 2




07:00 -      Check-in at airport
08:00


08:30        Departure from Toronto Airport for Puerto Vallarta


12:00        Arrival in Puerto Vallarta; clear Mexican customs and
             immigration


13:00 -      Bus transfer to Plaza Vallarta hotel; check-in at hotel
13:30


13:30 -      Afternoon at leisure
17:00


17:00 -      Program in hotel meeting room for entire Expedition
19:30

19:30 -      Balance of evening at leisure; dinner (on your own);
             photographing sunset (19:52 local time) and evening planets
             in twilight



THURSDAY, 11 JULY 1991          ECLIPSE DAY



03:00 -      Wake-up; pack


03:30 -      Buffet breakfast at hotel (provided); check-out
04:30


04:30 -      Bus transfer to airport; checkÄin
05:00


06:00        Departure from Puerto Vallarta for Los Cabos
             (or north toward centre line on mainland, if necessary)



        TIME ZONE CHANGE (SET WATCHES BACK 1 HOUR)



06:00        Land in Los Cabos, unload equipment onto buses



                    - 2 -

FRIDAY. 12 JULY 1991



07:30 -      Bus ride to Santiago (40 km north of airport), or to
             back-up site on Baja west coast (depending on weather)


08:30        Arrive in Santiago; unload buses; set up equipment


10:24.6      First contact; parL.al phase of eclipse starts
             (at Santiago, our primary observing site)


11:49.3      Total phase of eclipse begins


11:56.2      Total phase of eclipse ends


13:20.7      Last contact; partial phase ends


13:00 -      Pack up equipment; load buses
14:00


14:00 -      Brief tour of Santiago
14:30


14:30 -      Bus ride to Cabo San Lucas; stop at Tropic of Cancer marker
15:00        for photograph



15:30 -      Afternoon at leisure (swimming, walking tour, shopping);
21:00        Dinner (on your own)

21:00 -      Depart Cabo San Lucas; bus drive to airport
22:00


22:00        Arrive at Los Cabos airport; check-in
23:50        Depart Los Cabos for Toronto; snack on board flight;
             breakfast on board flight before landing



FRIDAY, 12 JULY 1991



07:20        Arrive at Toronto airport


07:21        Begin planning next eclipse tripl



                               SUGGESTED PACKING LIST
                                  (TRAVEL LIGHT!)

1.    Shorts (1 pr.)
2.    T-Shirts (2)  (remember, you will probably buy some as souvenirs)
3.    Pyjamas
4.    Extra underwear (1 pr.)
5.    Toiletries
6.    Sweat pants or jeans (1)
7.    Sweater or light jacket (1)
8.    Sun hat
9.    Sunglasses
10.   Close toed running shoes or sneakers (1 pr.)
11.   Bathing Suit
12.   Sunscreen Lotion

Other

13.   Blanket to lie down on to observe eclipsed sun in zenith
14.   1 square metre piece of carpeting to kneel on to photograph eclipse
15.   White sheet to protect telescope from heat and dust
16.   White sheet for shadow band observations (optional)
17.   Sun filter
18.   Fresh batteries for all equipment

__________________________________________________________________________

                        SOLAR ECLIPSE READING LIST
SOLAR ECLIPSE


Books

ECLIPSE                                Brian Brewer, 1978, Earth View,
                                       Seattle Washington

ECLIPSE                                David and Carol Allen, 1987, Allen
                                       & Unwin, Boston

TOTAL ECLIPSES OF THE SUN	       J. B. Zirker, 1984, Vos Nostran
                                       Reinhold Company

FIFTY YEAR CANON OF SOLAR              Fred Espenak, NASA REFERENCE
ECLIPSES:  1986-2035                   Publication

TOTALITY:  ECLIPSES OF THE SUN         Mark Littman and Ken Wilcox (see May
                                       '91 SKY & TELESCOPE p. 539)

THE UNDERSTANDING OF ECLIPSES          Guy Ottewell (see May '91 SKY AND
                                       TELESCOPE p. 557)

Periodicals

HOURS OF THE MIDDAY NIGHT              Jay M. Pasachoff, ASTRONOMY, August
                                       1973

SPERLING'S EIGHT SECOND LAW -          Norman Sperling, ASTRONOMY, August
                                       1980


NORTH AMERICAN SOLAR ECLIPSES -        Fred Espenak, ASTRONOMY, November
                                       1980

AN ECLIPSE CHASER'S NOTEBOOK           Fred Espenak, ASTRONOMY, June 1982

SOLAR ECLIPSE DIARY:  1985 - 1995      Jean Meeus, SKY & TELESCOPE, October
                                       1984

CONFESSIONS OF AN ECLIPSE ADDICT       Joel K. Harris, ASTRONOMY, January
                                       1988

WHEN THE SUN AND MOON EMBRACE          Leif J. Robinson, SKY & TELESCOPE,
                                       November 1988

ECLIPSE PROSPECTS FOR THE 1990'S       Jay Anderson, ASTRONOMY, February
                                       1989

OBSERVING PARTIAL PHASES SAFELY

SAFE SOLAR FILTERS                     Ralph Chou, SKY & TELESCOPE, August
                                       1981



EQUIPPED FOR SAFE SOLAR VIEWING          Richard Hill, ASTRONOMY,

TOTAL SOLAR ECLIPSE - 11 JULY 1991

OBSERVERS' HANDBOOK 1991                 RASC (pp. 87-109)

THE BIG ONE IS COMING                    Leif J. Robinson, SKY & TELESCOPE,
                                         February 1989

PREDICTIONS FOR THE TOTAL                Fred Espenak, Journal of The Royal
SOLAR ECLIPSE OF 1991                    Astronomical Society of Canada,
                                         Volume 83, Number 3, 1989

A JOURNEY INTO DARKNESS                  Allan Dyer, ASTRONOMY, July 1990

CHASING THE MOON'S SHADOW                Trudy E. Bell, Science PROBE, April
                                         1991

THE ENIGMA OF SHADOW BANDS               Johanan L. Codona, SKY & TELESCOPE,
                                         May 1991

YOUR GUIDE TO THE GREAT                  Joe Rao (see May `91 SKY & SOLAR
ECLIPSE OF 1991                          TELESCOPE p. 539)

PHOTOGRAPHING SOLAR ECLIPSES

FILM THE ECLIPSE                         Richard Berry, ASTRONOMY, 1978

HOW TO PHOTOGRAPH THE ECLIPSE            Alan Dyer, ASTRONOMY, April 1991

ASTROPHOTOGRAPHY BASICS                  1988, Eastman Kodak Company, Kodak
                                         Publication P-150

PREVIOUS SOLAR ECLIPSES - SAME SAROS CYCLE

THE LONG ECLIPSE:  20 JUNE 1955          SKY & TELESCOPE, February 1955

JUNE ECLIPSE OBSERVERS PARTLY            SKY & TELESCOPE, August 1955
SUCCESSFUL

ECLIPSE IN THE PHILLIPPINES, CEYON       SKY & TELESCOPE, September 1955

SOLAR ECLIPSE:	30 JUNE 1973             SKY & TELESCOPE, March 1973

THE GREAT SOLAR ECLIPSE                  SKY & TELESCOPE, September 1973

ECLIPSE VIEWS                            SKY & TELESCOPE, October 1973

PREVIOUS SOLAR ECLIPSES - VARIOUS REPORTS

7 March 1970             SKY & TELESCOPE           April, May 1970
                         NATIONAL GEOGRAPHIC       August 1970

10 July 1972             SKY & TELESCOPE           September 1972

12 October 1977          SKY & TELESCOPE           January 1978

26 February 1979         SKY & TELESCOPE           April, May, June 1979
                         ASTRONOMY                 May, June, 1979
                         STAR & SKY                April 1979

16 February 1980         SKY & TELESCOPE           May 1980
                         ASTRONOMY                 May 1980
                         STAR & SKY                May 1980

31 July 1981             SKY & TELESCOPE           October 1981
                         ASTRONOMY                 November 1981

11 June 1983             SKY & TELESCOPE           September 1983
                         ASTRONOMY                 September, October 1983
                         DISCOVER                  August 1983

22-23 November 1984      SKY & TELESCOPE           February, March 1985
                         ASTRONOMY                 April 1985


18 March 1988            SKY & TELESCOPE           June, July 1988
                         ASTRONOMY                 July, August 1988


                   PHOTOGRAPHING A SOLAR ECLIPSE

                       BY MICHAEL S. F. WATSON



       Even novice astrophotographers should not have any difficulty
producing acceptable quality photographs of a solar eclipse. A little
planning combined with certain basic minimum equipment are all that is
required. The following are the major considerations in planning to
photograph such an event:

1.	The sun and moon both appear approximately 0.5 degrees in
diameter as seen from the Earth. A standard 50 mm lens on a 35 mm
camera therefore produces an image on the film that is only 0.5 mm in
diameter, which is far too small to show any detail at all. In order
to produce an image size that is large enough to show detail, a
telephoto lens of at least 200 mm focal length is required. Experienced
photographers use lenses or telescopes of 1000 - 2000 mm focal length.
A lens of 2500 nun focal length will just fill the short dimension of the
35 mm frame with the eclipsed sun's image.

2.	It is imperative to mount your camera on a tripod and to use a
cable release. It is next to impossible to hold a camera steady enough
(particularly when pointing virtually straight up - see page 2) to get
a sharp, unblurred picture.

3.	Using very long telephoto lenses (ie. longer that 500 mm focal
length) is difficult unless your camera is mounted on a telescope mount
that is equipped with a motor drive to compensate for the Earth's
rotation. If a 500 mm lens is used on a fixed tripod, the Earth's
rotation will cause the sun's image to drift completely across the frame
of a 35 mm camera in about 15 minutes, constant adjustment is needed to
keep the image centred.

4.	To photograph the uneclipsed or partially eclipsed sun one must
place a safe solar filter in front of the camera lens or telescope.
Suitable filters include proper commercial solar filters (available at
astronomy supply stores and some photo outlets) and number 14 welder's
glass (available at welding supply shops). Neutral density ("ND")
photographic filters are unsafe. The filter can be removed reasonably
safely a few seconds or so before the total phase of the eclipse
actually begins, and the filter should be replaced immediately at the
end of totality. During the total phase of the eclipse no filter of any
kind is required either to photograph or to observe the eclipse.

5.	The solar corona (the delicate outer atmosphere of the sun that
is visible only during the total phase of a solar eclipse) is bright
enough to photograph using moderate speed, black and white or colour
films. Most experienced eclipse photographers use films with ISO speeds
of between 50 and 200. Faster films are unnecessary (and can result in
excessively grainy images), although they do reduce required exposure
times to 1/500 sec. or faster, which may be advantageous if one's tripod
or mount is shaky, or if one's camera shutter is noisy and causes the
camera/lens assembly to vibrate significantly.

6.	The proper exposure for the "diamond ring" effect (at the
beginning and end of totality), the solar chromosphere and the innermost
corona is approximately 1/125 sec. using ISO 50 film and a lens having
a speed of f/8. Other systems will change the required exposure
accordingly. For example, if your lens has a speed (or aperture) of
f/11 instead of f/8, the required exposure will be twice as long, or
1/60 sec. Faster film will decrease the required exposure time
accordingly.

7.	The brightness of the solar corona decreases rapidly as one moves
radially away from the eclipsed sun. Successively longer exposures will
therefore reveal more and more corona, sometimes out to several solar
radii. Use a variety of exposures in order to capture as many aspects
as possible.



                                - 1 -


                                - 2 -



SUN'S ALTITUDE DURING THIS ECLIPSE

	An unusual feature of this eclipse is the extremely high altitude
of the sun. During totality the sun's elevation exceeds 80 degrees
(that is, within 10 degrees of the zenith). Many camera tripods
restrict the movement of their pan heads to not more than about 30
degrees or so above the horizontal, thus making it impossible to aim the
camera lens high enough to point it toward the zenith. YOU MUST CHECK
YOUR TRIPOD NOW TO DETERMINE WHETHER YOU HAVE THIS PROBLEM. If you do,
consider purchasing a tripod that has full 90 degree movement of the pan
head in altitude. An alternative is to build, out of 1/2 inch or 3/4
inch plywood, a right-angled block, one side of which can be bolted to
the tripod pan head, and to the other side of which your camera body can
be mounted pointing straight up.

	Check as well to determine whether you will have difficulty
looking through your camera's viewfinder (in order to focus and frame
the image) when the lens is pointing virtually straight up. Often the
tripod's pan head locking arms get in the way and make it awkward or
even impossible for the photographer to look through the camera in such
a configuration. If you have this problem, then you may (a) remove the
pentaprism from your camera body (if this is possible) so as to be able
to frame and focus while looking horizontally on to the ground glass
focusing screen, (b) purchase a right-angled viewfinder for your camera
(if one is available), or (c) build from plywood an extension plate that
will allow you to move your camera body further above and away from the
tripod pan head.


PRACTISING BEFOREHAND

	There is no substitute for assembling, disassembling and
practising with your intended photographic assembly several times before
Eclipse Day. Failure to do so often leaves lurking, undiscovered until
the hours or minutes before totality, problems that could have been
anticipated and solved with early practice.

	As well, take some experimental photos of the uneclipsed sun
using the lens and filter that you will use during the eclipse. Try a
variety of exposures, and look for the one that shows a slight darkening
at the edge or limb of the sun. This will be within one photographic
stop of the correct exposure for the partial phases.

	Try some experimental photos of the crescent or first-quarter
moon using a cable release and your tripod. Inspect the photos
carefully for image shake caused by camera or tripod vibration. If this
is a problem, then either reduce the focal length of your lens, or rig
up a system of weights (shopping bags filled with earth or stones will
do) to suspend from your tripod to increase its stability.

	It is a common mistake for first-time eclipse-goers to shoot
frantically through an entire roll of film during the first seconds of
totality. Resist this temptation if you can! Plan to shoot no more
than one-quarter to one-third of a roll during the opening diamond ring
phase, so as to leave plenty of frames for totality and the closing
diamond ring phase.

	Mirror or extra long telephoto lenses may focus beyond infinity.
On Eclipse Day, focus on either a distant mountain or on the uneclipsed
sun, then tape down the focusing ring with duct tape, so you will not
inadvertently twist the focusing ring away from infinity during the
excitement of approaching totality or when you remove your solar filter
in the seconds before the total phase begins.

	AND FINALLY: Practise ahead of time, think beforehand about how
you will make your photographs, but don't forget to stop and watch the
eclipse! It is the greatest of all visual spectacles!



OBSERVING THE SUN SAFELY; USE OF SOLAR FILTERS



	Contrary to popular belief, it is no more dangerous to
observe a partial eclipse of the sun (or the partial phases before
or after the total phase of an eclipse) than it is to observe the
sun at any other time. Such observations, especially with optical
aids such as binoculars or a telescope, are EXTREMELY DANGEROUS
and must not be made without a safe solar filter. Alternatively,
one may build and use a "pinhole camera", which is described in
many introductory astronomy handbooks.

	You may be either a novice at astronomical observation
or unsure of safe methods of observing the sun either with or
without optical aid. We strongly urge you to consult any one of
a number of astronomy handbooks and textbooks that are available
in science and astronomy shops, or at your local library. Safe
observation of the sun is simple and easy, provided that the proper
precautions are taken.

	Solar filters are discussed in paragraph 4 of the
enclosed article entitled "Photographing a Solar Eclipse". If you
intend to observe or photograph the partial phases of the eclipse,
you should investigate and acquire your solar filter(s) now. You
must affix your solar filter(s) firmly to the front (not the back)
of your binoculars or telescope. If your filter is not firmly
attached, it may slip from in front of your binoculars or
telescope, allow unfiltered sunlight to enter your eyes (magnified
by the binoculars or telescope) and possibly damage your eyes
irreparably.

	Please do not be alarmed at the foregoing discussion.
It is a simple matter to observe the partially eclipsed sun safely
using solar filters. If you are inexperienced or have concerns,
you may choose to observe the partial phases with only a solar
filter, and without any optical aid such as binoculars or a
telescope. Remember, the six minute, fifty-two second total phase
can be watched perfectly safely without any filter.



___________________________________________________________________