7. Commission de l’Astronomie Dynamique et des Tables Astronomiques

There do not appear to be at the present moment any problems in dynamical astronomy of which the solutions call for combined action and international organisation rather than private efforts of mathematicians. The only possible contents of a report of the commission under these circumstances would be a historical survey of the work done in the subject since the last meeting. I do not think that a review of this nature is the proper function of such a report. My conviction that the subject of dynamical astronomy does not at the present moment stand in need of international co-operation, has been strengthened by the fact that a circular letter sent to all members of the commission has elicited only two replies, one of which expressed doubt regarding the usefulness of international co-ordination of the subject, whilst the other intimated that the writer had no remarks to offer.</jats:p

31. Commission de l’Heure

Sur la proposition du Comité exécutif, l’Assemblée générale du 13 juillet 1928, réunie à Leyde, adopta la résolution suivante: “Le Comité exécutif espère que d’ici à la fin de la présente convention (31 décembre 1931) la direction du Bureau de l’Heure pourra être exercée par le Directeur de l’Observatoire de Paris, et qu’après cette date l’activité actuelle du Bureau pourra être conservée sans faire appel aux fonds limités de l’Union, peut-être avec la coopération d’observatoires et autres institutions.”</jats:p

20. Commission Pour l’Observation des Positions et le Calcul des Éphémérides des Petites Planètes, des Comètes, et des Satellites

In accordance with suggestions made by members of the Commission further consideration of the following topics is proposed:(1)Improvement of the present plan for distribution of observations and computations relating to minor planets and comets, with special reference to those which depart considerably from their ephemerides.(2)Designation of a central bureau to supervise any accepted plan for coordination of observations and computations. It is suggested that separate bureaus be established for Minor Planets and for Comets.(3)Systematic investigations of the orbits of the recently discovered objects designated as minor planets: Reinmuth 1932 HA, and Delporte 1932 EA1( and other objects of similar interest.(4)Financing of proposals (2) and (3).(5)Standard equinoxes as proposed by Comrie (1950.0) and by Bower (1900.0).(6)Designation of published residuals as observed residuals rather than referring to the epoch of the comparison star.(7)Greater adherence to the convention “That the dates used in giving the osculation epochs of elements for comets and minor planets shall be the midnight following an integral Julian date which is exactly divisible by 40, and for ephemerides, divisible by 8 (or 4, etc.),” to facilitate intercomparison of ephemerides and elements.(8)Inauguration of complete residuals of comets, similar to those of minor planets with provision for their continuation.(9)Inclusion in astronomical telegrams of some information of a descriptive nature to indicate the accuracy of the measured position, in confirmation of previous action.(10)Greater emphasis on accurate rather than on approximate positions, particularly in (9), or preliminary orbits.</jats:p

31. Commission de l’Heure

Depuis la dernière réunion, notre commission s’est transformée en une commission internationale mixte dépendant à la fois de l’Union astronomique et de l’Union géodésique et géophysique internationales.On se rappelle que l’Assemblée générale, réunie à Leiden, a émis le vœu que le Président de l’U.A.I. s’entretienne avec le Président de l’Union de Géodésie et de Géophysique et le prie d’examiner s’il serait possible que celle-ci apporte quelque contribution aux dépenses du Bureau international de l’Heure. Comme suite à ce vœu, l’Assemblée générale de cette dernière Union, réunie à Lisboa en 1933, a adopté la résolution suivante:“L’Union géodésique et géophysique internationale décide qu’une subvention régulière annuelle sera allouée par elle au Bureau international de l’Heure, dans les limites de ses crédits et des besoins du Bureau.</jats:p

31. Commission de L’heure

Durant la période de 1933 à 1936 le Bulletin Horaire a donné les heures définitives des signaux horaires d’après la moyenne de 15 observatoires. A partir du Ier janvier 1937 on introduit trois observatoires en plus (Kharkov, Manille et Tokyo), qui communiquent régulièrement leurs résultats au B.I.H.Au Bureau International de l’Heure certains perfectionnements sont actuelle ment en voie de réalisation. Il s’agit d’une horloge à diapason d’une part, et, de l’autre, d’un ensemble nouveau pour l’émission des signaux horaires. M. Lambert va donner une communication sur ce sujet.</jats:p

20. Commission Pour l’Observation des Positions et le Calcul des éphémérides des Petites Planètes, des Comètes, et des Satellites

In accordance with action taken by the Commission at the 1932 meeting of the Union, the President has taken steps to ascertain the general opinion of computers and observers in regard to the co-operation of the Nautical Almanac offices in furnishing data for the equinox of 1900. The question under discussion is that of the adoption of the standard equinox to which observations and elements should be referred, e.g. 1900, 1950, etc. The opinion is being ascertained through a questionnaire, the results of which will be reported at the meeting. In this connection Commission 4 proposes discussion of the following resolution in co-operation with Commission 20:“That, as from 1938 January 1, the equinox used for expressing the elements of cometary orbits and for cometary ephemerides shall be that of 1950.0. Further that, as from the same date, the equinox used in giving observed positions of comets shall be that of 1950.0, unless the observer, for good reasons, used some other equinox and expressly draws attention to the equinox used.”</jats:p

27. Commission des Étoiles Variables

The Commission again subscribes to a number of the good resolutions it has made in the past, for example, to follow the almost universal practice of counting the observed times, either in decimals of a day or in hours and minutes, from Greenwich mean noon, even though one is convinced that the rest of the world should adopt U.T.; and to prepare a chart, identifying the variable and the comparison stars, to form a part of the discovery announcement of a variable which cannot be easily identified through a Durchmusterung number and which is bright enough to invite further observation.</jats:p

27. Commission des Étoiles Variables

It is well-nigh impossible to give, in a short report, an adequate idea of the enormous activity in Variable-Star Astronomy during the past three years. Without attempting to be complete I shall give a summary of the most important recent occurrences in this field of research.Statistical data for eclipsing binaries were given by Gaposchkin (Veröff. Berlin-Bab. 9, Heft 5), for long-period variable stars by Ludendorff (Sitz.-ber. Ak. d. Wiss. Berlin, 1932), Thomas (Veröff. Berlin-Bab. 9, Heft 4) and Sterne and L. Campbell (Harvard Annals).Some valuable catalogues have been issued: a Finding List for Observers of Eclipsing Variables by Dugan (Princeton Contr. No. 15), a Catalogue of Eclipsing Variables, together with a Program of Investigations, by Martinoff (Engelhardt Obs. Bull. No. 2), a Catalogue and Ephemeris of Short-period Cepheids by Zessewitsch (Len. Un. A. 0. Bull. No. 3).</jats:p

27. Commission des Étoiles Variables

Fourteen members of the committee have failed to respond to correspondence; nearly all of the others have expressed the definite opinion that non-responsive members should be dropped from committee membership when a new list is prepared a few correspondents indicating however, that the policy should be adopted for Commission 27 only if generally adopted for all commissions of the Union.</jats:p

20. Commission des Positions et des Mouvements des Petites Planètes, des ComÈtes, et des Satellites

In view of the considerable ground covered by the Commission at its Paris meetings and the fairly complete record of the activities of institutes and observatories, etc. published in the Minutes, it has not been deemed profitable by the president to call for further reports in advance of the Stockholm meeting. At the Paris meeting it was agreed that such reports be printed independently before each meeting of the Union and that reprints of or references to the published reports be sent to the president. It is hoped that all such reports if ready will be made available before the Stockholm meeting so that they may be summarized by the representatives in attendance or by the president and recorded in the Minutes. With reference to the pronouncement at the Paris meeting “that it is eminently desirable that more attention be given to the development of accurate general perturbations and mean elements on the basis of accurate osculating elements”, the president has visited the Planeten-Institut at Frankfurt and the Rechen-Institut at Berlin and has been in correspondence with the Leningrad Institute. From these sources particularly valuable material has been received.</jats:p