Vol.. 6, 1920 INTERNATIONAL ASTRONOMICAL UNION 379 
has chosen T, followed by a number, but it might be anything distinctive. 
It is advisable that this always be preceded with the year of discovery, 
thus, 1917 Wld, 1912 ri6, etc. This will enable an asteroid to be re- 
ferred to by a distinctive designation in current discussion and in indexes, 
thus facilitating such discussion and the looking up of references. 
3. That this provisional designation of asteroids should be retained 
until undoubted identification with an old asteroid or until identified 
at a second opposition, when it may be given the permanent number 
designation. This would prevent holes in the consecutive numbering 
such as (132) Aethra, etc. 
4. That the term "astrographic," as first used in Greenwich Observa- 
tions 1910, be more generally adopted to denote the position of an object 
obtained from a photographic plate, by using in the reduction the mean 
places of comparison stars at the beginning of the year. Neglecting the 
differential apparent place reduction, it is identical with the position ob- 
tained by applying Aa and A5 directly to the mean place of the comparison 
star, as mentioned in (1). 
5. That observers be urged to publish observation times in decimal of 
day, G. M. T. (Greenwich Civil Time after 1925, if the present agitation 
results in discontinuance of astronomical mean time). For this G. M. T. 
decimal of day is the form which most computers use, since it is most 
convenient, because the national ephemerides use G. M. T. 
6. That the ephemerides give the rectangular solar coordinates at the 
beginning of the year, since they are most made use of by orbit computers 
who almost universally use mean place at beginning of year, and also to 
give these coordinates in the usual manner so that they may be readily 
differenced. The Berliner Jahrbuch has done this since 1868. The re- 
duction to some other epoch such as 1900 or 1925 would also be useful. 
In addition to the coordinates the velocities of the coordinates per one- 
tenth of a day should also be given to facilitate interpolation and orbit 
computation by Laplacean methods. 
7. That 1900.0 be adopted for the publication of positions of asteroids 
and for orbit computation. Many times more reference stars for both 
photographic and visual purposes will be referred to 1900.0 when the 
astrographic program is completed than to any other equinox. Perhaps 
more photographic positions of asteroids are now published than visual 
and probably in a few years they will greatly outnumber the visual. Since 
it is easier for the photographic observer to derive positions in the equinox 
of the catalog, it would seem that in the long run, more computation 
will be saved by this cooperation of observer and computer than by the 
adoption of any other equinox or equinoxes. 
A. O. Lkuschner, Chairman, E. W. Brown, G. H. P^t^rs. 
