(meteorobs) Origin of ZHR: Getting closer?

[Richard Taibi]

I want to acknowledge everyone's contributions to this topic.  They have 
been helpful!

In particular, I received suggestions from Ed Cannon and Alastair McBeath, 
VP of the IMO, that seem to point to the possibility that 1951 or 1952 was 
when "zhr" was conceived and employed in publications reducing visual meteor 
rates.  I was referred to two astronomers who, if they themselves did not 
originate the concept, they must surely have been in association with other 
astronomers who developed it.

1) Zdenek Ceplecha published "Statistical Observations of Meteors 1951," in 
1952.  In this article, he improved on an hourly rate computation used by 
Vladimir Guth (1905-1980), in 1941, by adding another term for "transferring 
the (meteor) frequencies to the position of the radiant in zenith."

2) Eva Ahnert-Rohlfs (born Rohlfs, 1912-1954), an associate of Cuno 
Hoffmeister, published a study in 1952 too.  Ed Cannon cited a secondary 
source that reported Dr. Ahnert-Rohlfs published a study about the Perseids 
in which "hourly rates were corrected to a zenithal value..."  I do not have 
access to the original article in Veroffentlichungen der Sternwarte in 
Sonnenberg, Akademie Verlag Berlin, volume 2, part 2, pp. 5-38.  Another 
source gives 1956 as the publication date of this article.  I must confess 
that even if the article were available to me, I do not read German.  
Perhaps one of our colleagues who does read German could help us out?

In any case the term "zhr" became more widely used in 1954 articles, and as 
we have seen, in Sidgwick's 1955 tome.

So, this interim report points to 1951 as the latest date when the concept 
of zenithal hourly rate was developed.  Note that Ceplecha's 1952 article 
was submitted for publication in 1951.  It also seems that the concept was 
in the meteoric "zeitgeist" in Germany and Czechoslovakia at that time.

Does anyone have information about earlier uses of the concept?  Perhaps 
some German-reading meteor student could pursue the Ahnert-Rohlfs article 
and determine who she references, if anyone.

Best wishes,

Richard Taibi
Maryland, USA