OBSERVATORY MOVES TO SOUTH AFRICA

As a result of long careful study of Climatic and atmospheric conditions in different parts of the Southern Hemisphere, the Harvard Observatory had decided to transfer its southern station from Arequipa, Peru, to a site in South Africa, probably in or near Bloemfontein. It is expected that observations will begin there within a few months.

Although many successful results have been obtained at Arequipa during the past 35 years, the meterological conditions during the southern summer are rather unfavorable to astronomical observations. For this reason the Observatory has been experimenting in various South African regions for the past few years. After extensive observations, it appears, according to the scientists investigating the subject that during the cloudy season, the sky of the South African plateau is much clearer than that prevailing in Peru.

Several sections of the Dark Convent have been investigated under the superintendance of Professor Harlow Shapley, Director of the Harvard Observatory; Hanover, Johannesbury, and Bloemfontein have all been found favorable for stellar observations. The last-site mentioned is on the whole the best of the three, according to the authorities, and will probably be selected.

Arequipa, the present observation site, has had a long and varied history. An elevated site about 25 miles east of Lima was temporarily chosen in 1889, principally as a point of observation from which to continue the work in photometry and spectroscopic survey begun in the Northern Hemisphere at the University. But Mount Harvard, as this spot was named, proved almost impossible for observations during the rainy season from October to May; when clouds cover the sky almost continuously. Other points in Peru and Chile were visited, and Arequipa was on the whole found to be the only practical choice. for although a station at Pampa Central, on the desort of Altacama in Chile, seemed to possess somewhat better climatic conditions, the living conditions were practically impossible.

Pickering Picks Arequipa

Professor Pickering, Director of the Observatory at that time, finally authorized the recommendation that Arequipa be chosen as the permanent Southern station. For on this site there was not only almost as good a sky as in any part of South America, but excellent living facilities were obtainable for members of the Observatory's staff. In 1890, the main equipment for the station was sent to Arequipa. Throughout the years since then the Peruvian government has in every way possible assisted the efforts of the Observatory.

The need for a Southern Observatory is apparent if a complete survey of the stellar universe is desired. In discussing this subject in a recent issue of the Harvard Alumni Bulletin, Professor S. I. Bailey '88, Professor Emeritus of Astronomy says:

"Since the world's important observatories are situated neither on the equafor nor at the poles, let us see what the actual conditions for observation really are. It is a familiar rule, and easy to remember that the attitude of the celestial pole above the horizon is equal to the latitude of the place; for example, at the equator they are both equal to zero, and at the pole to 90 degrees, as we have seen. We may take Cambridge as an example of a typical Northern Observatory. Its latitude is North 42 degrees, but for simplicity let us call the latitude of our Observatory 45 degrees, or just half way between the pole and the equator. This is about the latitude of Montreal, and the conditions are much the same, and the quantities will be easier to remember. At latitude 45 degrees, the north celestial pole is at an altitude of 45 degrees above the northern horizon. From this pole to the equator is naturally 90 degrees, making 155 degrees: and since it is 10 degrees from any point of the horizon through the zenith to the opposite point, i. e., half a circle, we have left 15 degrees, the distance to which one can see below the equator at that latitude. That is one can see just hal way from the equator to the south pole.

Two Stations Better Than One

"In this way an observer during the course of the year can see all the stars in the sky except those within 45 degrees of the south pole. These never rise above out horizon. Without working too near the horizon where observations are unfavorable, a person at Cambridge can observe about three-fourths of the sky, and for the most part under very favorable conditions. Stars within 45 degrees on the north pole never set, so that they may be observed as continuously as the Sun permits. The position of the Earth is a good one except for for southern stars and for these one must go below the equator. It is on this account that for a long time northern one servatories have established more or less permanent branch stations in the Southern Hemisphere, and southern colonies and nations have established observatories of their own, or have encouraged their establishment by private institutions.

"In reality two stations are better than any possible single station, since at the equator, as we have seen, stars near both poles will always be too near the horizon for good observations, while at either pole, an observer would never see more than half the celestial sphere. Perhaps no better combination of two stations is possible than one anywhere in the southern temperate zone, cooperating with one similarly placed in the northern hemisphere. This has ben accomplished approximately for many years by the Harvard Observatery with its auxiliary station at Arequipa, Peru."MILKY WAY The cut of the galaxy reproduced above was made from a photograph taken at the Harvard Observatory at Arequipa, Peru. It shows the southern Milky Way with the Southern Cross and the Coal Sack in the middle. The Observatory is to be moved in the near future to Bloemfontein, South Africa, where it has been found climatic conditions are better for astronomical observation.