The San Francisco call., 1910-05-18
OBSERVERS FIX TINE
OF COMETS TRANSIT
By A. o. LEUSCHNER

Director Students Observatory, University of
California.
RKELEY, May 1.-THE first part
of the calculation on Halleys comet,
undertaken by the Berkeley astrono-
mical department of the University of
California at the request Of the As
Economical and Astrophysical Society
of America was completed today. These
calculations were conducted on pro-
gram decided upon by Professors
Leuschner and Crawford. but practi-
cally all the numerical work involved
with carried out by Professor Crawford.
with the assistance of w. +. Meyer and
other members of the department.
The work just completed refers to a
timely prediction of the phenomena of
the transit of the nucleus of the comet
across the suns disk May is. These
predictions require a very accurate de-
termination of the motion of the comet
at the present time.
As the first step, the famous calcula-
tions of Messrs. Cowell and Crommelin
of the Greenwich observatory were
made the basis of the computation of
an orbit of the comet during the pres
ent apparition- The obserVational ma
terial needed for this purpose was Sc
cured by special arrangement with the
Lick and Yerkes observatories, the re-
quired observations being made by
the aid of this orbit the disturbing
effects of the planet Venus and of the
earth We're calculated.
APPROACH TO VENUS
The closest approach of Venus took
place Nav ,. and the closest approach
TO the earth will occur May 10. These
effects are not very significant, but
they varied with such irreguarity as
to render the calculations quite COM
plicated-
Owing to the very rapid apparent
motion of the comet at the present
time it was necessary to test the com
puted positions of he comet by OBJ
servaions secured as close to the transit
across the sun as possible. The final
position required for this purpose was
secured yesterday morning at the Lick
observatory by Astronomer Aitken. On
the basis of this observation a final
correction was applied to the adopted
time of perihelion passage and to the
periheliOn distance. The adopted value
of the former was found to require
correction of only two minutes. The
main result of the calculation is that
the prediction of a transit is fully
verified. The comet will cross the sun
minutes of arc above the suns center
from west to east.
TINE OF CONJUNCTION
The instant Of geocentric conjunc-
tion is May Is. is hrs. 7 min. 8 sec,
Greenwich meridian time.
For the Lick observatory the in
stants of the nucleus on the suns disk
and egress have also been calculated.
These times viii be practically the
same for the whole Pacific coast.
Ingress viii occur at hrs. 80 min.
10 sec. Pacific standard time.
The middle of the transit will occur
al hrs. min. 46 see, Pacific standard
time.
Egress will occur at s hrs 81 min
46 Sec, Pacific standard time.
The position angles at ingress wifi
be 27S degrees minutes and IS de-
grees 5 minutes respectively.
Unfortunately, however. none of
these phenomena are observable in San
Francisco and vicinity. as they will oc-
cur shortly after sunset. which takes
place at about 1920, Pacific standard
time. nor viii the phenomena be OBJ
servable in any part of the United
States.