630315Eclipse3_p2

Click on the thumbnail at the bottom right of this page to go to the bitmap scan of this document. The text of this document appears immediately below.

Eclipse Bulletin No. 3 cont'd.

METHODS OF TIMING (cont'd.).

(3) With stopwatch and Short-Wave Radio. Equipped With a stopwatch and short-wave
    radio, the observer can be his own timekeeper. He starts the watch when the
    phenomenon occurs and then stops it at a given time signal. By deducting the
    watch reading from the given time, one obtains tie observed time of the phenon3enon.
    The stopwatch should be stopped on the next time signal possible, preferably with-
    in five minutes, for if it is allowed to ran too long, the accuracy of the watch
    will have to be checked as under (i) above, Method (3) is much more accurate than
    either (1) or (2) but is dependent on good radio reception,

(4) With Short-Wave Radio and Tape Recorder. With radio and tape recorder running
    continuously, both time signals arid the voice of the observer as he calls "Time!"
    are it corded on the tape. This method has both advantages anck disadvantages. It
    can be extremely accurate and the observer can record all other details of this
    observation on the tape. However, reports are not available immediately. Much
    playback time is required before written: reports can be produced. Also, because
    extraneous noise can be a serious handicap, the method is probably better suited
    to a lone observer than a group effort. 

    It can be seen that the timekeeper is a very important member of the team. Both
timekeeper and observer must become thoroughly familiar with the procedure to be foll
owed, the equipment end time signals to be used. It is recommended that several drills
be held well in advance of eclipse day.

REPORT FORMS

    Attached is a copy of Report Form No I that can be adapted to most observations
in this section of the programne ù Where the observer makes a series of observations
of the same nAture, such as the occultation of sun-spots, the information could be
arranged in tabular form on one report. Otherwise, a separate form should,be completed
for each. observation made. (In an drganized field station, some of the work will be
centralized such as recording of seeing conditions, etc. thus relieving the indiv-
idual observers of the necessity of recording this detail. This will be described in
a later bulletin.) 


EYE PROTECTION

    It cannot be emphasized too strongly.that where binoculars or telescopes are to
be used, extreme care must be taken to protect the eyes during the partial phases,''
for permanent blindness eould result if the eyes are exposed even momentarily to the
light of the sun. For binoculars, a welder's glass placed over the objectives would
be sufficient. For telescopes, union one has proper solar equipment an objective
diaphragm, Herschel wedge and solar eyepiece filter - it is safer to use the projection.
method, projecting the sun's image onto. a screen attached by rods to the telescope
tube. A SOLAR FILTER ON THE EYEPIECE IS NOT SUFFICIENT It will quickly crack and
the eye will be exposed to the sun's heat.

    Even those who just want to watch fta partial phases of the eclipse with the
unaided eye should quip themselves with some protection a piece of heatiiy exposed
film or dark glass, preferably welder's glass.

                                         - 2 -