**AAS Meeting #194 - Chicago, Illinois, May/June 1999**

*Session 44. Computation and Data Analysis*

Display, Tuesday, June 1, 1999, 10:00am-7:00pm, Southwest Exhibit Hall
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## [44.07] A Model for Readership of Astronomical Journals, From an Analysis of ADS Readership

*M.J. Kurtz, M. Demleitner, G. Eichhorn, C.S. Grant, A. Accomazzi, S.S. Murray (SAO)*

Astronomy is perhaps unique, in that it already has an
integrated electronic information resource (ADS/Urania)
which includes electronic access to nearly all the modern
journal literature, and which is used by a large fraction of
practitioners in the field, worldwide. The combined Urania
logs, including the electronic journals and ADS, probably
represent a fair sample, if not the majority, of the total
readership in the field.

Using the ADS logs we develop a four component model for how
the astronomical literature is read, as a function of the
age of an article, R = N + C + IM + H, where the first
three terms are exponentials with very different time
constants, and the fourth is a low level constant.

R is the total readership; N is the readership of the
latest issue of a journal; C is the readership of the
current literature; I is the fraction of articles which
are intermediate term interesting; M is the frequency of
readership for interesting articles; so IM is the
readership of intermediate term interesting articles; H is
the readership of historical articles.

The overwhelming majority of ADS use can be described
accurately by R = C + IM; where I = I_{0}e^{-0.075T}, T is
the age of the article in years, and I_{0} is about 0.7, M
= M_{0}e^{-.015T}, with M_{0} equal to 2.5 reads per month,
and C = C_{0}e^{-0.85T}, where C_{0} is equal to 5 reads per
month.

Note that after about 4 years, when the C term has become
small, the main factor is I, whether an article is read at
all, not M, how many times an article is read.

If the author provided an email address or URL for general inquiries, it is a
s follows:

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