Ordinary Meeting, 2006 May 31

 

Let's Collaborate! A Professional's Perspective

Dr Henden remarked in opening that he had always considered himself a professional astronomer, but had also always felt the line between amateurs and professionals to be a very grey one. After all, the word 'amateur' derived from the Latin verb 'amare' (to love), and whilst he was a professional in the sense that he earned his livelihood by his work, was he not also an amateur if he loved doing it? With this thought in mind, he was keen for both astronomical communities to acknowledge the common passion that they shared.

In recent times he could think of many examples where amateur – in the traditional sense of the label – astronomers had made very valuable contributions to the work of professionals. One example was in the SETI@home project, founded in 1999 by a professional team at the University of California, Berkeley. The problem had been this: the Berkeley astronomers had wanted to search data from the Arecibo Radio Telescope for signals which were finely tuned to specific frequencies – too finely so to be of plausible natural origin – and which might thus originate from alien radio communication. The computational demands of such a search, however, were far more than could be met by their own hardware. Their solution had been to invite PC users from around the world to donate computer time. A software package had been devised which allowed users to set their desktop PCs to automatically detect whenever they were sitting idle, and to then switch to performing calculations for SETI@home. Motivated only by the excitement of wondering whether aliens might be seen, nearly a million computer users had taken part since the project's inception, contributing between them a total of two million CPU years since 1999. At present, SETI@home was able to analyse data at a rate of 50 Gb each day; the processing capability offered by their users was comparable to that of the world's fastest supercomputers.

Whilst SETI@home had not found any evidence for extra-terrestial intelligence, it had demonstrated a principle: if the public imagination was suitably caught by a project then so-called 'distributed computing' could offer a tremendous resource for data analysis. In the near future, another Berkeley team, Stardust@home, planned to start a similar project, this time analysing data from NASA's recently returned Stardust probe, sifting through high-resolution images of the probe's aerogel plates for evidence of dust grain impacts.

These projects required little skill on the part of the amateur, but there were other examples where the expertise of amateurs seemed to exceed that of professionals. An example would be the task of searching for comets in images returned by the LASCO solar coronograph on NASA's SOHO satellite. NASA had opted to publish all data from this instrument live on the web – a policy which had been well-rewarded: the dominance of amateur eyes in the art had grown so great that professionals now scarcely tried to compete. The coronograph had recently celebrated its thousandth comet discovery since its launch in 1995.

The rôle of amateurs in astronomy had a long history. The speaker recalled that when Percival Lowell had founded the Lowell Observatory at Flagstaff in 1894, he had done so at his own expense. Through the spectroscopic work of V.M. Slipher – a professional whom Lowell had employed – the Observatory had gone on to discover the expansion of the Universe. Here was a rare example of a professional employed by an amateur. A modern parallel to such philanthropy was being seen in the Allen Telescope Array, a SETI project in California, currently under construction, being part-funded by Microsoft co-founder Paul Allen.

Dr Henden now turned to give his personal perspective on amateur astronomy, and Lowell's Observatory provided a useful link, as he recalled how he had first been enthused into astronomy by the experience of viewing the planets through the 24" refractor there. He went on to recall the books which he had read through his teens, the planetary observations he had made with his first 3" instrument, and the 6" Dynascope through which he had observed Comet Bennett in 1970. By the time of his authorship of Astronomical Photometry (1978), he had been using a 16" Boller & Chivens Cassegrain. In time, his passion for astronomy had led him to obtain his Ph.D. from Indiana University in 1985.

Throughout these years, variable star observation had always been his passion, leading him to become involved with the American Association of Variable Star Observers (AAVSO), of which he had eventually become Director in 2004. The AAVSO would be the subject of the remainder of his talk.

Based in Cambridge, Massachusetts, its history stretched back to 1911. Today, it had 1,200 members, only 15% of whom were professional. The total number of observers who frequently submitted observations, however, was closer to 3,000. From them, around 600,000 observations were typically added each year to the 13 million which were already accessible from the AAVSO website. The speaker wanted to stress that visual observations remained as scientifically valuable to the AAVSO as those made with CCDs; around half of the data received remained in the form of visual observations. He also wanted to stress that the AAVSO was not a 'members only' organisation; in his view, true scientific enquiry knew no boundaries. Data was accepted from all, members and non-members alike.

At the other end of the website, the AAVSO's staff comprised ten paid workers, most of whom were graduate-level, though two held university positions, and one was a post-doctoral research scientist.

Dr Henden turned to outline some of the advantages which he perceived the amateur community to hold over professionals in the monitoring of variable stars. For one, the sheer number of amateur observatories around the globe made it possible to monitor very large numbers of objects. Their good geographic spread was of especial value when constructing light curves for objects which fluctuated on timescales of hours; a world-wide network effectively made 24-hour monitoring possible. Having so many distributed observing sites also alleviated the effects of local weather conditions, which professional survey instruments found hard to escape.

The long history of the AAVSO also brought its own advantages. The degree of continuity in its data archive was hard for professional surveys to rival, operating, as they did, typically for only a few years at a time. To study targets which exhibited variability over timescales of many years, this was invaluable; in some cases it allowed homogeneous light-curves to be constructed over nearly a century. Dr Henden added that perhaps it was also true, if under-appreciated, that amateurs were often simply more competent than professional observers, possessing a much greater degree of familiarity with their instruments.

The objects studied by the AAVSO ranged from classic variable stars to more exotic objects, including supernovae and Gamma Ray Bursters (GRBs), and the speaker discussed the diverse scientific cases for studying each class. He explained that the Association was often approached by research teams requesting data for specific objects, and that the increasing frequency of such approaches in recent times suggested a healthy appreciation of the amateur community among professionals. Observing campaigns were organised in response to such requests, aiming to achieve especially well-sampled light curves for these objects over a few months. Earlier in the year, for example, several campaigns had been run for targets which had been simultaneously being monitored by the XMM-Newton space-based X-ray observatory, in order to provide ground-based optical data to compliment the X-ray variability data.

To close, the speaker listed some of those amateurs who had made especial contributions to the AAVSO, including, perhaps most notably, Edgar Smith, founder of the Calypso Observatory on Kitt Peak, now home to a 1.2-metre instrument which could regularly monitor ~104 targets. Smith hoped to be able to put this large aperture to use in the near future to discover exoplanets: the degree of photometric accuracy which could be achieved was potentially sufficient to detect the slight apparent faintening of stars as planets transited across their disks. This might open up a whole new avenue of research for the AAVSO. While such prospects were very exciting, the speaker also wanted to stress that they should not eclipse the work done by those with more modest equipment: the value of visual observers with binoculars was not to be forgotten.

Following the applause, the President thanked Dr Henden for providing such an authoritative account of the AAVSO's work and invited questions.

A member asked whether the AAVSO accepted spectroscopic observations from amateurs. The speaker replied that they did and that this was a growth area; good spectroscopic equipment was now quite readily available and amateurs could make well-calibrated observations. Mr Maurice Gavin, in the audience, queried this: he remarked that he had submitted some spectra to the AAVSO's website recently, and that they had not appeared in the online archive. In reply, Dr Henden explained that there were some outstanding technical issues with the online retrieval of spectra, but that the submission process was working and filing incoming data correctly.

The President then introduced the evening's second speaker, Prof. Steve Miller of University College, London. In addition to his work as a planetary scientist, Prof. Miller was also a very active communicator of science; he headed the Department of Science and Technology Studies at UCL. Tonight, he would be talking about observations of aurorae in the atmospheres of the solar system's gas giants.

Ashburn

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39.04°N
77.49°W
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