660921Occultation1_p2

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Lunar Occultations Section, Bulletin No.1                                        -2-



estimate of the predicted occultation time for your site is obtained by applying the
"a" and "b" corrections given in the OBSERVER'S HANEBOOK. The same information is
supplied in SKY AND TELESCOPE in its yearly supplement on occultations.

With all preliminaries completed, you are now seated at the telescope; select an
eyepiece so that any sky haze does not affect your viewing (use higher powers when
there are hazy conditions). With experience, you can control the "notion" of the
moon so that the occultation occurs when the star is in the midile of the field of
view. Just prior to the event, determine the position angle of the star with
respect to the limb of the moon. Then with your storwatch fully wound, start the
watch at the moment of disappearance of the star. Immediately after this the
short-wave time signals from WWV (5, 10, 15 and 20 megacycles) or CHU (3.330, 7.335,
14.670 megacycles) should be used to stop the watch at the beginning of a known time
signal. By subtracting your watch time from the radio time you obtain the actual
time of the occultation. Where the star is approaching the moon's limb at right
angles, this should take less than 10 minutes. If the radiO signal is heard more
than 5 minutes after the watch is started, then prior calibration of your stopratch
aver longer time periods is desirable. Sometimes observers prefer to reverse this
procedure - stopping the watch upon seeing the occultation.

The information should then be transferred to our special form; mail these to the
National Co-ordinator at the end of each month. A sample report form is attached;
additional copies are available upon request.


The next bulletin will include a list of observers, the local contact in your Centre,
as well as sane "tricks of the trade" useful to the new observer. Good viewing
until then!
                                                          Franklin C. Loehde,
                                                          National Co-ordinator,
                                                          Lunar Occultations Section,
                                        Standing Committee on Observational Activities,
                                                          8332 Jasper Avenue,
21 September, 1966.                                       Edmonton, Alta.