PLANETARY SECTION

Bulletin No 2                                                    February 7, 1962.

PROGRESS   To date I have received replies to my first Bulletin from seven of the Centres
REPORT     of the R.A.S.C. I will here list the names of my contacts:

     Centre        Contact               Address

     Halifax       B. W. Allen           419 Windsor St., Halifax, N.S.

     Hamilton      Edward Ostrosser      70 Sussex Ave., Hamilton, Ont.

     Kingston      G. M. Steed           13 Chestnut St., Kingston, Ont.

     Montreal      Geoffrey Caherty, Jr  636 Sydenham Ave., Montreal 6, Que.

     Niagara Falls Grayson C. Gardner	 488 Philip St., Niagara Falls, Ont.

     Ottawa        Dr W. L. Orr          1952 Fairbanks St., Ottawa 1, Ont,

     Quebec        Rene Doucet           650 Blvd des Prairies, Cap de la
                                              Madeleine, Co. Champlain, Que.

Observations have already been received from Hamilton, Quebec, and Montreal, and I
have been promised some drawings by the Ottawa Centre. The other Centres, while not
engaged in systematic planetary work at the present time, have expressed interest in
participating in the Section's program as it develops.

Regarding: the responsibilities of the contacts, they are expected to pass on the inform-
ation in this and future Bulletins to members of their Centre particularly interested
in planetary problems and if possible to the general membership as well (i.e. at meetings
of the Centre or via the Centre's newsletter where such exists). The exact means is
left to the good judgement of the individual, although I will be glad to do anything
within my power to help. (In this respect I can supply a limited number of extra copies
of these Bulletins.) The contact will also be responsible for keeping me posted on
local activities. The details of this will be worked out in practice.

JUPITER	  I will shortly begin preparing a report on 1961 observations of Jupiter as
          mentioned in Bulletin No 1. I would appreciate it if any further observations
were sent to me as quickly as possible for inclusion in this report. From the considerable
amount of material on hand it should be possible to obtain some very interesting results
from one of the most active apparitions in recent years.

OBSERVING   Initially there will be a deliberate concentration on observations of the
PROGRAM     planet Jupiter. Some of the reasons for this are:

     (a)  It is observable over a large part of the year and in particular will be
          well placed for most of 1962.
     (b)  Any good telescope of 3 inches aperture or greater will show detail worth
     (c)  There is a wide variety of observation programs to suit practically every
     (d)  The experience gained will make observations of other planets much more

Detailed instructions and suitable report forms will be available in a few months.
In the meantime I will briefly describe some of the types of observation possible.

Bulletin No 2 (continued)	                                        Planetary Section

Drawings, With practice almost anyone can learn to draw well enough to record the
appearance of astronomical objects. The idea is to copy the telescopic image accurately,
not to strive for "pretty" effects. The value of a drawing can be greatly increased
by the addition of semi-quantitative data such as estimates of conspicuousness, intensity,
and. colour as described below.

Conspicuousness Estimates. This involves estimating the relative ease with which the
belts or zones can be seen. The telescope's eyepiece is racked out of focus to present
a featureless disk. As it is refocused the order in which the belts (or zones) reappear
gives a good measure of their conspicuousness.

Intensity Estimates. The relative intensities of the belts and zones can be estimated
using a 0-10 scale. The information revealed by these observations is quite different
from that obtained from conspicuousness listings; here the actual shade of the feature
is estimated rather than its overall impression.

Colour Estimates. These are necessarily subjective but nonetheless of use if great
care is taken to eliminate spurious effects. A reflector is almost obligatory for this
sort of work.

Central Meridian Transits. The observer times to the nearest minute the tranaits of
bright and dark markings across the central meridian of Jupiter's disk (estimated by
eye). Although the accuracy of a given timing may be low, a sufficient number of timings
of the same feature on various occasions during a month or more yields a rotation period
of accuracy at least equal to the best spectroscopic work. Almost all our knowledge
of Jupiter's atmospheric currents over the last 70 years is based on amateur observations
of this type. Except for the most prominent markings a 6-inch or larger is required.

Photography. Good photographs provide a useful check on visual observations and also
can be measured to derive the latitudes of the belts. Due to the limitations of the
photographic process, a 6Äinch is probably the minimum for successful results.

Satellite Phenomena. Observations have shown that the phenomena of Jupiter's satellites
predicted in the Handbook are frequently in error by several minutes. The exact nature
of these variations from theory has yet to be determined; timings to the nearest 0.1
minute of occultations, eclipses, and transits can therefore be of value.

Lest the sheer quantity of programs frighten those who have done little along these
lines, I certainly do not expect everyone to participate in all fields! My own method
of getting started was to make drawings (a lot of them pretty horrid) at every opport-
unity until I could honestly feel that I was making a fair representation of what my
telescope could show. The serious planetary observer must have the ability to consider
his work objectively; unless he continually seeks to maintain the highest standards,
his observations will be of value to no one.

In spite of the emphasis I have placed on Jupiter, I do of course welcome any observations
of the other planets. As the Section's program gains momentum it will be expanded to
include these, and this in turn will lead to the appointment of Assistant Co-ordinators.

It is my hope that this Bulletin will stimulate further interest in planetary work.
Your comments and suggestions will shape the ultimate form which our program will take.

                                               Geoffrey Gaherty, Jr, National Co-ordinator,
                                               Planetary Section, Standing Committee
                                                    on Observational Activities.
                                               636 Sydenham Avenue, Montreal 6, Que.
Planetary Section Bulletin No. 2
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