UC Irvine UC Irvine Previously Published Works Title Productivity and impact of radio telescopes Permalink https://escholarship.org/uc/item/3xb98207 Journal Publications of the Astronomical Society of the Pacific, 118(844) ISSN 0004-6280 Authors Trimble, V Zaich, P Publication Date 2006 DOI 10.1086/505182 License https://creativecommons.org/licenses/by/4.0/ 4.0 Peer reviewed eScholarship.org Powered by the California Digital Library University of California Publications of the Astronomical Society of the Pacific, 118: 933–938, 2006 June ᭧ 2006. The Astronomical Society of the Pacific. All rights reserved. Printed in U.S.A. Productivity and Impact of Radio Telescopes Virginia Trimble1 and Paul Zaich2,3 Received 2005 October 18; accepted 2006 April 18; published 2006 June 14 ABSTRACT. In 2001, 836 papers appearing in 15 journals reported and/or analyzed data collected with ground- based radio, millimeter, and submillimeter telescopes, plus the HALCA, COBE,andSWAS satellites and a few balloon-borne detectors. More than 80 telescopes were represented, including 36 that were each responsible for five or more papers. These papers were cited 11,332 times in 2002, 2003, and 2004, for a mean rate of 13.56 citations per paper, or 4.52 citations per paper per year (sometimes called impact or impact factor, and compared to 5.40 citations per paper per year for optical astronomy papers in the same period and 6.42 for space-based papers). We examine here the distributions of papers, citations, and impact factors among subject areas and telescopes and make some comparisons with the 2100 optical and infrared and 1200 space-based papers published and cited in the same years. The single largest item in the optical inventory was, naturally, the Hubble Space Telescope, with 16% of the papers and 19% of the citations. Radio astronomy houses an even more dominant entity, the Very Large Array (VLA), responsible for 22% of the papers and 27% of the citations. The VLA is, therefore, proportionately even more influential in world radio astronomy than HST is in world optical astronomy. A third paper in this series looks at papers and citations in the area of infrared, X-ray, and gamma-ray space- based astronomy and planetary missions. Of the “radio” papers, 149 were also optical papers and 76 were also “space” papers, in the sense of reporting or analyzing data in both bands. Their impact factors were 5.71 and 7.51 citations per paper per year, respectively, slightly above the averages for the individual bands. Thus, slightly more than half of observational astronomy is still optical astronomy, but multiwavelength papers are somewhat more influential than average. No radioϩoptical paper went completely uncited during the triennium. 1. INTRODUCTION reporting observational data from radio (including millimeter In 2005, we reported data concerning about 2100 papers, pub- and submillimeter) telescopes and from space facilities oper- lished in 18 journals, which had made use of data obtained with ating at infrared, X-ray, and gamma-ray wavelengths, using as ground-based optical and infrared telescopes plus the Hubble nearly as possible the same methods. Because ground-based Space Telescope (Trimble et al. 2005, hereafter Paper I). About radio and optical telescopes generally have lifetimes of many 250 telescopes were represented, including 25 with primary- years, data concerning them should be comparable. This cannot mirror diameters of 3 m or larger. In the next 2 years, 2002 be true for the space-based sample, because of the short life- and 2003, those papers were cited 24,334 times, for a mean times of most missions. As far as we know, no similar ex- rate of 11.56 citations per paper, or 5.78 citations per paper amination of radio astronomy (or space-based) papers and ci- per year (sometimes called impact or impact factor). HST was tations has been carried out. Thus, no historical trends can be responsible for the single largest number of papers (346.3) and sought, and the present work is a sort of “first epoch” study, had a somewhat larger than average citation rate (13.71 cita- with the equivalent of proper motions to be determined 5–10 tions per paper). Keck was second, with 104.5 papers and 20.86 years into the future. In addition, the optical citation numbers citations per paper. Remarkably, telescopes with diameters less have been updated to represent the 3 years of 2002–2005. than 1 m contributed 107 papers, but only 5.02 citations per We present here the distributions of radio-observation papers paper. See Paper I for further details, including citation rates as a function of the telescope(s) used and subject matter, make as a function of subject matter, distribution of papers among some comparisons with the optical sample, and look very the journals, and details of the method adopted. briefly at the space-based sample (Trimble et al. 2006, hereafter In spring 2005, we decided to extend the analysis to papers Paper III). 2. METHODS 1 Department of Physics and Astronomy, University of California, Irvine, As noted in Paper I, an analysis of this sort cannot be done 4129 Frederick Reimes Hall, Irvine, CA 92697-4575; and Las Cumbres Ob- servatory Global Telescope, Goleta, California. in real time. A facility must be debugged, significant numbers 2 5901 Sierra Bravo Road, Irvine, CA 92612. of observations accumulated, and papers written, refereed, and 3 Current address: P.O. Box 13844, Stanford, CA 94309. published. Only then can the papers be read and cited; and 933 934 TRIMBLE & ZAICH peak citation rates normally occur a year or two after publi- (85), PASJ (38), ApJS (23), Astronomy Reports (16), Icarus cation. Our data were collected from May to September 2005, (14), Nature (10), Science (8), J. Astrophys. Astron. (8), PASP and it would thus have been possible to start over and use (4), Astronomy Letters (3), Ap&SS (1), and none in Astron. papers published in 2002 and cited in 2003 and 2004. The first Nachr., JRASC,orActa Astronomica. author simply quailed at the task. At a minimum of 3 minutes For each paper, the following information was recorded: per paper, examining 6000 papers, identifying the 4000 ob- name of first author, number of additional authors, volume and servational ones, and recording appropriate information about page number, total number of pages, subject, and identity of each takes more than 300 hr. Thus, what we have here is all all the telescopes contributing data to the paper, in the order the observational papers published in 2001 and citations to they were mentioned by the authors. Subjects were chosen from them from 2002 to 2004, compiled by the second author from the same list of about 25 used for the optical sample, although the Science Citation Index (SCI)/Web of Science. This appears a “radio first” approach might well have led to a somewhat to be somewhat more complete than the citation data in the different assortment. The largest number of individual tele- Astrophysics Data System, at least in the sense that fewer pa- scopes or dishes used in any one paper was 36, and at this pers turn up with no citations at all. point the decision was made to count the Very Long Baseline The radio situation is generally analogous to the optical one. Array (VLBA) and the European VLBI Network (EVN) as Some telescopes were just coming on line (including the new single entities and to accept that there would be a class of Green Bank Telescope), and others were probably past their “strays” that had contributed only small fractions of the data prime or no longer in existence, although data from them were to one or a few papers. For a few (but only a few) papers, it still being used (the Cambridge 3C survey at 178 MHz, to take was not possible to determine which telescopes were used. an extreme example). The numbers of papers from these classes These appear only in various totals. are likely to be smaller than their lifetime annual averages, but As in the optical case, the subject assignment was based on the citations per paper may be representative. In the optical what the authors said they had in mind. Observations of qua- case, Gemini, the Hobby-Eberly Telescope, and the Italian TNG sars, for instance, could have been aimed toward establishing (Telescopio Nazionale Galileo) were just beginning operation, a more precise coordinate system (the “service” class), under- while the Mount Wilson 100 inch and the Byurakan 2 m were standing the core-jet structure (AGNs), or tracing out 21 cm no longer producing new data. absorption along the line of sight (very large scale structure or This time around, in April–May 2005, V. T. went page by cosmology). The service areas included catalogs, surveys, and page through the same issues of the same 18 journals (plus a instrument calibrations, as well as astrometry. few that had turned up since summer 2004) and identified all Again as in Paper I, all radio, millimeter, and submillimeter the papers that reported or analyzed data from any ground- telescopes contributing to the data in a given paper received based radio, millimeter, or submillimeter telescopes, plus the equal credit for the paper and for the citations to it, except that HALCA (Japanese interferometry), COBE (microwave back- citations were credited only in integers. Thus, the last-men- ground), and SWAS (submillimeter) satellites, and a few bal- tioned of seven telescopes contributing to a 13 citation paper loon-borne millimeter and submillimeter telescopes, like BOO- received credit for one citation, each of the others getting two. MERANG. P. Z. looked up all the citation numbers during This was not really very common.