AbstractsGeomagnetic activity, the frequency and intensity of magnetic disturbance, is supposed to indicate the influence of solar corpuscular radiation on the Earth. Various schemes for measuring the fluctuations of this phenomenon are in operation, but in connection with direct ionospheric studies by radio methods it was found necessary to provide a new scheme using smaller time-units than a day or half a day. A threehour-range index/( based on the "Potsdarner erdmagnetische

Context. The larger number of models of asteroid shapes and their rotational states derived by the lightcurve inversion give us better insight into both the nature of individual objects and the whole asteroid population. With a larger statistical sample we can study the physical properties of asteroid populations, such as main-belt asteroids or individual asteroid families, in more detail. Shape models can also be used in combination with other types of observational data (IR, adaptive optics images, stellar occultations), e.g., to determine sizes and thermal properties. Aims. We use all available photometric data of asteroids to derive their physical models by the lightcurve inversion method and compare the observed pole latitude distributions of all asteroids with known convex shape models with the simulated pole latitude distributions. Methods. We used classical dense photometric lightcurves from several sources (Uppsala Asteroid Photometric Catalogue, Palomar Transient Factory survey, and from individual observers) and sparse-in-time photometry from the U.S. Naval Observatory in Flagstaff, Catalina Sky Survey, and La Palma surveys (IAU codes 689, 703, 950) in the lightcurve inversion method to determine asteroid convex models and their rotational states. We also extended a simple dynamical model for the spin evolution of asteroids used in our previous paper. Results. We present 119 new asteroid models derived from combined dense and sparse-in-time photometry. We discuss the reliability of asteroid shape models derived only from Catalina Sky Survey data (IAU code 703) and present 20 such models. By using different values for a scaling parameter c YORP (corresponds to the magnitude of the YORP momentum) in the dynamical model for the spin evolution and by comparing synthetic and observed pole-latitude distributions, we were able to constrain the typical values of the c YORP parameter as between 0.05 and 0.6.

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The paper gives three-hour-range indices K for seven observatories for July 1, 1938, to December 31, 1939 (Table 1), world-wide three-hour-range indices K• for 1938 and 1939 (Table 2, which will be used most often), and, based on Ku,, daily indices B (Table 3) and monthly frequencies and averages (Table 4). Section (1) contains all the information necessary for using these Tables in geophysical or ionospheric work. Sections (2) to (5) show how the indices K are standardized by means of keys for transforming/( into reduced indices Kr. The world-wide Kt, is introduced as an average 9 f the reduced indices Kr, in which the Kr from polar stations enter with higher weight than the Kr from equatorial stations. Kw is proposed as a measure of the intensity P of solar corpuscular radiation.Note--Throughout this paper, a superior cross (X) denotes a half unit, thus, 0x =0.5, lx--1.5, etc. õ 1. Description of the current tables and diagrams The three-hour-range index K expresses, by an integer between 0 and 9, the intensity of the magnetic disturbance at an observatory for each of the eight three-hour intervals of the Greenwich day, as described in our first paper, • to which the reader is referred for details; the present paper will, however, be self-contained in that the tables and their use will be explained. Table/--Original K-indices, for July, 1938, to December, 1939, for the seven observatories Si =Sitka (Alaska), Ni = Niemegk (Potsdam, Germany), Ch=Cheltenham (Maryland), Tu=Tucson (Arizona), SJ = San Juan (Puerto Rico), Hu=Huancayo (Peru), and Wa=Watheroo (Western Australia). The first of the eight indices given for each Greenwich day refers to the interval 00 h to 03 h GMT. The indices for January to June, 1938, were given on pages 434-439 of our first paper, x together with those for Ho = Honolulu.In case of incomplete records, indices could easily be estimated from those given by the other observatories for the same intervals. There are again a few cases in which the range was clearly raised by the geomagnetic effect of a solar flare, that is, by a non-corpuscular solar influence' for these intervals, a "non-flare-K" or K' , , , was also estimated

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