productivity and impact of radio telescopes

Productivity and Impact of Radio TelescopesAuthor(s): Virginia Trimble and Paul ZaichSource: Publications of the Astronomical Society of the Pacific, Vol. 118, No. 844 (June 2006),pp. 933-938Published by: The University of Chicago Press on behalf of the Astronomical Society of the PacificStable URL: http://www.jstor.org/stable/10.1086/505182 .

Accessed: 26/05/2014 00:27

Your use of the JSTOR archive indicates your acceptance of the Terms & Conditions of Use, available at .http://www.jstor.org/page/info/about/policies/terms.jsp

.JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range ofcontent in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new formsof scholarship. For more information about JSTOR, please contact [email protected].

.

The University of Chicago Press and Astronomical Society of the Pacific are collaborating with JSTOR todigitize, preserve and extend access to Publications of the Astronomical Society of the Pacific.

http://www.jstor.org

This content downloaded from 195.78.109.99 on Mon, 26 May 2014 00:27:15 AMAll use subject to JSTOR Terms and Conditions

http://www.jstor.org/action/showPublisher?publisherCode=ucpress

http://www.jstor.org/action/showPublisher?publisherCode=astrosocpac

http://www.jstor.org/stable/10.1086/505182?origin=JSTOR-pdf

http://www.jstor.org/page/info/about/policies/terms.jsp


933

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 theHALCA, COBE, andSWAS satellites and a fewballoon-borne detectors. More than 80 telescopes were represented, including 36 that were each responsible forfive or more papers. These papers were cited 11,332 times in 2002, 2003, and 2004, for a mean rate of 13.56citations per paper, or 4.52 citations per paper per year (sometimes called impact or impact factor, and comparedto 5.40 citations per paper per year for optical astronomy papers in the same period and 6.42 for space-basedpapers). We examine here the distributions of papers, citations, and impact factors among subject areas andtelescopes and make some comparisons with the 2100 optical and infrared and 1200 space-based papers publishedand cited in the same years. The single largest item in the optical inventory was, naturally, theHubble SpaceTelescope, with 16% of the papers and 19% of the citations. Radio astronomy houses an even more dominantentity, 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 thanHST 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 and7.51 citations per paper per year, respectively, slightly above the averages for the individual bands. Thus, slightlymore than half of observational astronomy is still optical astronomy, but multiwavelength papers are somewhatmore influential than average. No radio�optical paper went completely uncited during the triennium.

1. INTRODUCTION

In 2005, we reported data concerning about 2100 papers, pub-lished in 18 journals, which had made use of data obtained withground-based optical and infrared telescopes plus theHubbleSpace Telescope (Trimble et al. 2005, hereafter Paper I).About250 telescopes were represented, including 25 with primary-mirror diameters of 3 m or larger. In the next 2 years, 2002and 2003, those papers were cited 24,334 times, for a meanrate of 11.56 citations per paper, or 5.78 citations per paperper year (sometimes called impact or impact factor).HST wasresponsible for the single largest number of papers (346.3) andhad a somewhat larger than average citation rate (13.71 cita-tions per paper). Keck was second, with 104.5 papers and 20.86citations per paper. Remarkably, telescopes with diameters lessthan 1 m contributed 107 papers, but only 5.02 citations perpaper. See Paper I for further details, including citation ratesas a function of subject matter, distribution of papers amongthe journals, and details of the method adopted.

In spring 2005, we decided to extend the analysis to papers

1 Department of Physics and Astronomy, University of California, Irvine,4129 Frederick Reimes Hall, Irvine, CA 92697-4575; and Las Cumbres Ob-servatory Global Telescope, Goleta, California.

2 5901 Sierra Bravo Road, Irvine, CA 92612.3 Current address: P.O. Box 13844, Stanford, CA 94309.

reporting observational data from radio (including millimeterand submillimeter) telescopes and from space facilities oper-ating at infrared, X-ray, and gamma-ray wavelengths, using asnearly as possible the same methods. Because ground-basedradio and optical telescopes generally have lifetimes of manyyears, data concerning them should be comparable. This cannotbe true for the space-based sample, because of the short life-times of most missions. As far as we know, no similar ex-amination of radio astronomy (or space-based) papers and ci-tations has been carried out. Thus, no historical trends can besought, and the present work is a sort of “first epoch” study,with the equivalent of proper motions to be determined 5–10years into the future. In addition, the optical citation numbershave been updated to represent the 3 years of 2002–2005.

We present here the distributions of radio-observation papersas a function of the telescope(s) used and subject matter, makesome comparisons with the optical sample, and look verybriefly at the space-based sample (Trimble et al. 2006, hereafterPaper III).

2. METHODS

As noted in Paper I, an analysis of this sort cannot be donein real time. A facility must be debugged, significant numbersof observations accumulated, and papers written, refereed, andpublished. Only then can the papers be read and cited; and



934 TRIMBLE & ZAICH

2006 PASP,118:933–938

peak citation rates normally occur a year or two after publi-cation. Our data were collected from May to September 2005,and it would thus have been possible to start over and usepapers published in 2002 and cited in 2003 and 2004. The firstauthor simply quailed at the task. At a minimum of 3 minutesper paper, examining 6000 papers, identifying the 4000 ob-servational ones, and recording appropriate information abouteach takes more than 300 hr. Thus, what we have here is allthe observational papers published in 2001 and citations tothem from 2002 to 2004, compiled by the second author fromthe Science Citation Index (SCI)/Web of Science. This appearsto be somewhat more complete than the citation data in theAstrophysics Data System, at least in the sense that fewer pa-pers turn up with no citations at all.

The radio situation is generally analogous to the optical one.Some telescopes were just coming on line (including the newGreen Bank Telescope), and others were probably past theirprime or no longer in existence, although data from them werestill being used (the Cambridge 3C survey at 178 MHz, to takean extreme example). The numbers of papers from these classesare likely to be smaller than their lifetime annual averages, butthe citations per paper may be representative. In the opticalcase, Gemini, the Hobby-Eberly Telescope, and the Italian TNG(Telescopio Nazionale Galileo) were just beginning operation,while the Mount Wilson 100 inch and the Byurakan 2 m wereno longer producing new data.

This time around, in April–May 2005, V. T. went page bypage through the same issues of the same 18 journals (plus afew that had turned up since summer 2004) and identified allthe papers that reported or analyzed data from any ground-based radio, millimeter, or submillimeter telescopes, plus theHALCA (Japanese interferometry),COBE (microwave back-ground), andSWAS (submillimeter) satellites, and a few bal-loon-borne millimeter and submillimeter telescopes, like BOO-MERANG. P. Z. looked up all the citation numbers duringsummer 2005. This is probably the place to confess that theJames Clerk Maxwell Telescope (JCMT) accidentally endedup in the optical sample last time. It has been properly movedto submillimeter this time, and we were careful not to countits papers or citations twice!

The rule, as in Paper I, was that it had to be possible todiscern from the published paper itself which telescopes wereinvolved. Thus, uses of the FIRST survey were credited to theVery Large Array (VLA), but papers that drew a sample ofactive galactic nuclei (AGNs) from several catalogs and men-tioned only the catalogs were not included. The resulting listconsisted of 836 papers, 149 of which had also been in theprevious, optical sample. For consistency, they and their ci-tations were here credited entirely to the radio telescopes used,since they had been credited entirely to the optical telescopesin Paper I.

The journals and paper yields wereApJ (205), A&A (in-cluding Letters, 195), MNRAS (116), ApJ Letters (110), AJ

(85), PASJ (38), ApJS (23), Astronomy Reports (16), Icarus(14), Nature (10), Science (8), J. Astrophys. Astron. (8), PASP(4), Astronomy Letters (3), Ap&SS (1), and none inAstron.Nachr., JRASC, or Acta Astronomica.

For each paper, the following information was recorded:name of first author, number of additional authors, volume andpage number, total number of pages, subject, and identity ofall the telescopes contributing data to the paper, in the orderthey were mentioned by the authors. Subjects were chosen fromthe same list of about 25 used for the optical sample, althougha “radio first” approach might well have led to a somewhatdifferent assortment. The largest number of individual tele-scopes or dishes used in any one paper was 36, and at thispoint the decision was made to count the Very Long BaselineArray (VLBA) and the European VLBI Network (EVN) assingle entities and to accept that there would be a class of“strays” that had contributed only small fractions of the datato one or a few papers. For a few (but only a few) papers, itwas not possible to determine which telescopes were used.These appear only in various totals.

As in the optical case, the subject assignment was based onwhat the authors said they had in mind. Observations of qua-sars, for instance, could have been aimed toward establishinga more precise coordinate system (the “service” class), under-standing the core-jet structure (AGNs), or tracing out 21 cmabsorption along the line of sight (very large scale structure orcosmology). The service areas included catalogs, surveys, andinstrument calibrations, as well as astrometry.

Again as in Paper I, all radio, millimeter, and submillimetertelescopes contributing to the data in a given paper receivedequal credit for the paper and for the citations to it, except thatcitations were credited only in integers. Thus, the last-men-tioned of seven telescopes contributing to a 13 citation paperreceived credit for one citation, each of the others getting two.This was not really very common. And optical, X-ray, orgamma-ray telescopes contributing to the same papers weresimply ignored, just as the radio ones were in Paper I. Wesuspect that the gravest injustice done by this equal-credit sys-tem is toHALCA, the Japanese VLBI satellite. It was typicallyused in combination with two to very many ground-based tele-scopes, but because of the enormous increase in baseline itmade possible, it probably contributed more than 1/N of theweight to most results.

Which telescopes contributed to the 2001 literature, andwhich to keep track of? In the end, the bean-counting approachwon, and although 80 plus telescopes were mentioned at leastonce, we report only the 36 individual facilities that contributedfive or more papers, plus a number of collectivities. The un-listed include some fairly well known places (like Hartebeest-hoek) and others less so (like Qinghai).

How accurate are the data? Several kinds of problems arepossible. Rereading a paper, one sometimes finds some addi-tional observational data (usually near the end!) from additional



RADIO TELESCOPES 935

2006 PASP,118:933–938

TABLE 1The Most Cited Radio Papers

Number of Citations Telescope(s) Journal Subject

298 . . . . . . . . . . . . . . . . . VLA�optical ApJ Letters GRBs224 . . . . . . . . . . . . . . . . . MAXIMA ApJ Letters Cosmology146 . . . . . . . . . . . . . . . . . MAXIMA ApJ Letters Cosmology134 . . . . . . . . . . . . . . . . . JCMT, VLA�optical, and X-ray ApJ Galaxies120 . . . . . . . . . . . . . . . . . 1.2 m millimeter dishes at the Center for Astrophysics and

Cerro Tololo Inter-American ObservatoryApJ ISM

111 . . . . . . . . . . . . . . . . . VLA�X-ray ApJ AGNs91 . . . . . . . . . . . . . . . . . WesterborkSynthesis Radio Telescope MNRAS Galaxies90 . . . . . . . . . . . . . . . . . VLA�X-ray ApJ Letters Clusters of galaxies85 . . . . . . . . . . . . . . . . . Parkes MNRAS Calibration85 . . . . . . . . . . . . . . . . . JCMT ApJ Galaxies

telescopes not caught the first time and not mentioned in theabstract or methods sections. A possible final summary paper(to be submitted elsewhere) will correct the optical data in thisrespect. Some subject assignments are a bit arbitrary, on theedge between young stellar objects (YSOs) and ordinary stars,for instance. And there are occasional anomalies in the SCIdatabase. About 10 papers (of the original 2100 of Paper I)actually showed fewer citations when examined in summer2005 than they had the previous year. One paper’s citationnumbers had jumped from three in 2 years to 53 in 3 yearsand may have represented an injustice in Paper I to one smallbut well-used optical telescope. Error bars of a few percentshould therefore be associated with all the numbers.

3. RESULTS

In Papers I and III, these were grouped under headings re-flecting common misconceptions about the astronomical lit-erature, and this section was originally structured the same wayto facilitate comparisons of the results. In response to requestsfrom the referees, it has been reorganized, and some of theconclusions and predictions have been removed. Copies of theunexpurgated version are available from the first author andcan be sent, on request, in plain brown wrappers.

3.1. The Most and Least Cited Papers

We had not expected radio astronomy to have any one tele-scope responsible for as large a fraction of the papers asHSTis in the case of optical data. Nor did we expect any one paperto stand out in quite the way that theHST Key Project deter-mination of the Hubble constant did (443 citations in 2 years;632 citations in 3 years). The latter expectations proved to becorrect, the former wrong (§ 3.4). The optical standout is Freed-man et al. (2001), which was miscited in Paper I.

Table 1 lists the 10 most cited radio papers, giving the num-bers of citations in 3 years, the telescopes used, the journalsof publication, and the subjects. Eight different telescopes wereinvolved (compared to 10 for the 10 most cited optical papers),and two papers are in both sets, highly cited multiwavelength

studies. The most cited radio papers appeared in only threejournals and concerned seven different subjects (four journalsand four subjects for the optical set). The 10 next most citedpapers bring in some additional telescopes—the Institut de Ra-dioastronomie Millime´trique (IRAM), BOOMERANG, Dwin-geloo, the 30 m at Villa Elisa in Argentina, the Owens ValleyRadio Observatory (OVRO), and the Multi-Element Radio-linked Interferometer Network (MERLIN)—a couple moresubjects (pulsars, interstellar medium), and two additional jour-nals (A&A andApJS).

And some papers are never cited at all: 133 (6.3%) of the2100 optical papers in the first 2 years, dropping to 63 (3.0%)with 3 years of citation data. The radio rate is very similar: 28of 836 papers, or 3.3%, had no citations in the SCI databasein the 3 years following 2001 publication. And none of themultiwavelength (radio�optical) papers ended up completelyuncited. There are also no zeros among the radio�space papers,and only a very few among optical�space papers. Perhaps itis just a matter of having two communities who might wantto mention the work.

The radio zeros are not distributed uniformly over either thejournals or the telescopes, and surprises are few. The mix oftopics is much the same set of active galaxies, normal galaxies,interstellar material, and star formation/YSOs that dominatesthe cited papers, but the uncited appear more often in journalspublished in less prosperous countries, and they often reportdata collected at telescopes in difficult places (Russia, Maur-itius, and India, for instance). But neither the high-profile jour-nals (ApJ, A&A, MNRAS) nor the most productive telescopes(VLA, BIMA, VLBA) are completely exempt.

3.2. Trends

On this point, no information is available. Paper I noted thatthe most productive 3–5 m optical telescopes of a decade beforehad all yielded fewer papers in the new compilation: not justa smaller percent of the papers, but a smaller number, by 10%–40% per telescope. In contrast, the large ground-based infraredtelescopes had produced more papers and more citations in



936 TRIMBLE & ZAICH

2006 PASP,118:933–938

TABLE 2Citation Rates by Topic and Comparison with Optical Numbers

TopicRadio

CitationsRadioPapers C/P

Percentage ofRadio Papers

Percentage ofOptical Papers Optical C/P

Cosmology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1037 37 28.02 0.044 0.051 42.24Clusters of galaxies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 534 22 16.69 0.038 0.040 14.81GRBs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 463 9 51.54 0.011 0.012 30.10AGNs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1944 148 13.36 0.177 0.098 16.56Galaxies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2021 144 14.03 0.172 0.147 23.02Milky Way . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 285 22 12.95 0.026 0.008 29.81ISM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1897 174 10.90 0.208 0.066 10.44SNe/SNR. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 306 36 8.50 0.043 0.021 15.75NS/BH/XRB/PSR. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1109 73 15.19 0.087 0.021 14.43YSO/star formation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 775 53 14.62 0.063 0.041 14.57Stars/clusters/BDs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 389 43 9.05 0.051 0.250 12.24PNe/WDs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87 7 12.43 0.008 0.035 11.22Binary stars/CVs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 6 6.17 0.007 0.108 7.38Solar system. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205 23 8.91 0.028 0.051 11.03Exoplanets/SETI. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65 4 16.25 0.005 0.018 28.48Service (surveys, catalogs, calibrations, astrometry) 178 25 7.12 0.030 0.016 24.95

Totals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11,332 836 13.56 1.000 1.000 16.18

2001–2003 than they had in 1990–1993. Possible reasons weresuggested, and a prediction or two made. We are not aware ofany previous survey of papers and citations from radio, mil-limeter, and submillimeter telescopes with which the presentdata could be compared.

That is not to say that such a survey could not exist. It wouldcurrently be very difficult to assemble the set of papers pub-lished in 2011 and cited in 2012–2014, but there is nothing toprevent one of us (or even one of you) from going back andlooking at the radio papers from 1991 and their subsequentcitation rates. The number of papers would probably be onlyabout 500.

3.3. Distribution by Subject Matter

Table 2 shows the numbers of papers and citations to them,divided by subdiscipline, and using the same subject headingsas in Paper I, except that several topics that appeal to opticalastronomers are so rarely studied in the radio regime that wemerged a few of them in the table. These include star clusters,brown dwarfs, white dwarfs, and all sorts of binary stars. Notsurprisingly, interstellar material, active galaxies, and star for-mation are larger presences in the radio literature than in theoptical.

On average, optical papers are cited more often than radiopapers. (The numbers in Table 2 reflect 3 years of citations,not 2 as in Paper I). High-profile topics in one tend to be high-profile in the other (cosmology, gamma-ray bursts, extrasolar-system planets), and similarly for some low-profile ones (binarystars, solar system). Supernovae and their remnants and theMilky Way garner more citations per paper at optical wave-lengths than radio, and there are a few other differences. Mostof the numbers are not statistically significant in the last digit,but the large differences among subjects are real and can been

seen in some very different data compilations, centered aroundindividual astronomers rather than facilities (Trimble 1985).

We have been assured by a number of colleagues that thisis really just a matter of community size. Lots of astronomersworking on, say, active galaxies means lots of citations perpaper. But the numbers in Table 2 strongly suggest that size isnot the whole story. Gamma-ray bursts and exoplanets appearin very few, but very highly cited, papers, while the largestradio subdiscipline, the interstellar medium, consists of paperscited, on average, less often than the whole field (10.9 vs. 16.2citations per paper).

3.4. Distribution by Facility

Table 3, at long last, reveals the numbers of papers, citations,and citations per paper for the 36 ground-based radio telescopes(including millimeter and submillimeter facilities), balloon-borne detectors, and space missions that contributed at leastfive papers each (in our equal-credit-to-all-telescopes in a paperrubric), plus groups that include the other 44 less productivetelescopes (grouped as “other European” and so forth). Theordering is, first, interferometers and their component disheswhen used separately, plus other single radio dishes and arrays,second, facilities used primarily for cosmology and study ofthe cosmic microwave background, and third, millimeter andsubmillimeter devices. Each is referred to by the name foundmost often in the papers read for this project (frequently alocation), occasionally abbreviated to fit in the column.

Much can be said about the potential unfairness of suchnumbers. Green Bank (NRAO) was in the process of com-missioning a new dish to replace the one that had collapsed,and several other facilities were just coming on line, had alreadyfallen from space, or experienced various other indignities. Andit is probable thatHALCA contributed more strength to the



RADIO TELESCOPES 937

2006 PASP,118:933–938

TABLE 3Papers and Citations Attributable to Radio, Millimeter,

and Submillimeter Telescopes and Satellites

Facility Citations Papers C/P

Interferometers, Parts Used Separately, and Single Dishes

HALCA satellite . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 3.4 7.65VLBI unspecified. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 5.1 7.45VLBA �component dishes. . . . . . . . . . . . . . . . . . . . . . . . . 482 38.25 10.01VLA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3003 181.4 16.55MERLIN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194 18.6 10.43Australia Telescope Compact Array. . . . . . . . . . . . . . . 525 46.8 11.22Parkes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 786 38.3 20.52Other Australia�Deep Space Network. . . . . . . . . . . . 94 11.4 8.25Arecibo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 366 28.0 13.07European VLBI Network . . . . . . . . . . . . . . . . . . . . . . . . . . 106 12.2 8.69Jodrell Bank (several). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112 10.5 10.67Westerbork. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 181 14.1 12.84Effelsberg . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183 21.0 8.71Puschina . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 7.0 3.43RATAN-600 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 6.0 1.00Nancay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 6.2 6.62Other European. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115 17.4 56.61Giant Metrewave Radio Telescope. . . . . . . . . . . . . . . . 40 6.0 6.67Ooty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 6.0 1.67Other Asian . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 9.4 2.77Green Bank (several). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118 8.9 13.26Dominion Radio Astrophysical Observatory. . . . . . 60 8.0 7.50Other Western Hemisphere. . . . . . . . . . . . . . . . . . . . . . . . 53 6.3 8.41

Used Primarily for Cosmology and CMB Studies

COBE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 227 14.6 15.55BOOMERANG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136 5.6 24.29MAXIMA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 456 5.6 81.433C, 6C, 7C surveys. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134 6.8 19.71Other cosmological horns, balloons, etc.. . . . . . . . . . 223 12.4 17.98

Millimeter and Submillimeter Facilities

SWAS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120 8.3 14.46JCMT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 988 46.9 21.07NRAO 12 m . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189 16.5 11.45IRAM 30 m . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 467 31.6 14.78IRAM interferometer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 212 10.75 19.72Caltech Submillimeter Observatory. . . . . . . . . . . . . . . 128 9.4 13.62Five College Radio Astronomy Observatory. . . . . . 164 10.3 15.92Owens Valley Radio Observatory. . . . . . . . . . . . . . . . . 282 21.1 13.36Berkeley-Illinois-Maryland Association. . . . . . . . . . . 302 23.3 13.02Swedish-ESO Submillimetre Telescope. . . . . . . . . . . 169 20.0 8.45Heinrich Hertz Telescope. . . . . . . . . . . . . . . . . . . . . . . . . . 37 5.0 7.40Antarctic submillimeter . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 5.3 7.55Nagoya 4 m . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84 16.1 5.52Nobeyama 45 m. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128 19.2 6.62Nobeyama interferometer. . . . . . . . . . . . . . . . . . . . . . . . . . 34 6.8 5.00Other millimeter/submillimeter. . . . . . . . . . . . . . . . . . . . 260 18.1 14.36

projects in which it was used than is apparent from giving itequal credit with other participating telescopes, because it con-tributed the longest baselines. Papers and citations have, how-ever, been apportioned in the same way, so that the relativelylow rate of citations per paper forHALCA is real.

With all due reservations, one can nevertheless concludeseveral things. First, telescopes on well-supported sites, main-

tained by countries with a long tradition of radio astronomy,tend to do best. Second, the VLA dominated world radio as-tronomy early in this century by an even wider margin thanHST dominated optical astronomy. The VLA was responsiblefor 22% of the papers published in 2001 and 27% of the tri-ennium citations, compared to 16% of the papers and 19% ofthe optical citations forHST.

Another point to be noted is that most of the millimeter andsubmillimeter facilities rank above average in citations per pa-per. An exception is the 12 m in Arizona, formerly owned andoperated by NRAO, then closed down, and then reopened underdifferent management, much of this during the time when datafor 2001 publications would have been being collected. TheJames Clerk Maxwell Telescope and IRAM facilities are re-sponsible for a sizable numbers of papers, while US observingat shorter wavelengths was largely in the hands of universi-ties—Caltech (OVRO), the Five College Radio Astronomy Ob-servatory of Massachusetts (FCRAO, recently closed), and theBerkeley-Illinois-Maryland consortium (BIMA). OVRO andBIMA were very nearly equal in both numbers of papers andcitation rates, support for the wisdom of their ongoing unifi-cation of dishes, budgets, and programs. With the coming ofALMA (the Atacama Large Millimeter Array, an internationalcollaboration), US involvement in this wave band will moveback into public hands.

4. CONCLUSIONS

In 2001, 836 papers published in 15 refereed journals re-ported or analyzed data from radio, submillimeter, and milli-meter telescopes on the ground, in the air, or in space. Thesewere cited 11,332 times in 2002–2004 in journals that formpart of the Science Citation Index/Web of Science database,for an average of 13.56 citations per paper, or 4.52 citationsper paper per year (a bit smaller than the optical number forthe same periods, 5.40 citations per paper per year; the spaceaverage is 6.42).

Some topics included many more highly cited papers thanothers, cosmology, gamma-ray bursts, and exoplanets beingpopular in all wave bands. No one radio paper outweighed allthe rest, in the way that theHST Key Project determination ofthe Hubble constant did among the optical papers, but the VeryLarge Array dominated radio astronomy even more thoroughlythan theHubble Space Telescope did optical astronomy. Nomultiwavelength paper went completely uncited, and the multi-wavelength averages are a bit higher than those in any onewave band.

Although there seem to be no previous studies of radio as-tronomy papers with which this can be compared, it is temptingto suggest trends that might appear in the future, based onoptical data and on overviews such as the decadal reports. All4 m class optical telescopes have become less productive sincethe deployment of several 8 m mirrors, and one might expectALMA to have a similar effect on smaller short-wavelength



938 TRIMBLE & ZAICH

2006 PASP,118:933–938

facilities. The highly cited topics will probably become moreso and the less-cited topics still more obscure, because of thetendency of funding to follow the crowd.

We hope to come back in a decade or so and “do thenumbers” again, but it is perhaps worth noting now that a singlestudy in which all papers and citations are divided among allthe observing facilities used, no matter what the wavelength,may not have the expected effect. The total numbers of papersand citations of course stay the same; they are simply morewidely spread. Thus, the total number of papers for each andevery telescope ever used in multiwavelength studies will comedown, although citations per paper will not change. Because,for instance, the 149 radio�optical papers make up 18% ofthe radio total but only 7% of the optical total, the numbers

of papers per radio telescope will necessarily come downfurther.

The authors are grateful to Major Dawn and Colonel JimDeshafy of the US Air Force Reserve, who, by remarkablechance, brought them together. We are indebted to James Ul-vestad for authorizing, and to NRAO for providing, the pagecharges. The National Radio Astronomy Observatory is a fa-cility of the National Science Foundation, operated under acooperative agreement by Associated Universities, Inc. Amongthe colleagues who read and commented on the first draft ofthis study, special thanks to Richard Hills and Richard Wie-lebinski for thoughtful insights and for catching some errorsthat had eluded us.

REFERENCES

Freedman, W. L., et al. 2001, ApJ, 553, 47Trimble, V. 1985, QJRAS, 26, 40

Trimble, V., Zaich, P., & Bosler, T. 2005, PASP 117, 111 (Paper I)———. 2006, PASP, 118, 651 (Paper III)



productivity and impact of radio telescopes

Documents