Chapter 3 Use of Observing Time and
USE OF TELESCOPE TIME
The available observing time on the ING telescopes is allocated between
British, Dutch and Spanish time allocation committees, the CCI International
Time Programmes (ITP), service and discretionary nights, and scheduled stand-down
and commissioning time.
The ING Board has delegated the task of time allocation to British astronomers
to the PPARC Panel for the Allocation of Telescope Time (PATT), and to Dutch
astronomers to the NFRA Programme Committee (PC). It is the responsibility
of the Instituto de Astrofísica de Canarias (IAC) to allocate the
Spanish time via the Comité para la Asignación de Tiempos (CAT).
For committee membership please see Appendix I.
The ratio of UK PATT : NL NFRA PC : SP CAT : ITP is nominally 60 : 15 :
20 : 5. This ratio is monitored and small differences in these proportions
in any one year are corrected over a number of observing seasons.
The PPARC makes 27 nights per year of its share on the JKT available to
the National Board of Science and Technology of Ireland (NBST) and the Dublin
Institute for Advanced Studies (DIAS).
The aim of the ING service programme is to provide astronomers with a way
to obtain small sets of observations, which would not justify a whole night
or more of telescope time. For each telescope and instrument several nights
per month are set aside especially for this purpose. During those nights,
ING support astronomers perform observations for several service requests.
Stand-down and discretionary nights are used for major maintenance
activities, minor enhancements, calibration and quality control tests, etc.,
and partly for astronomy, for example, as compensation for breakdowns or
for observations of targets of opportunity. A careful record of service observations
per nationality is kept.
The way the available observing time on the ING telescopes has been shared
in 2000 and 2001 is summarised in Table 1.
NL NFRA PC
Instrument Builders’ Guaranteed Time
Table 1. Allocation of nights from
semester 2000A to semester 2001B. UK PATT allocation on the JKT includes
Irish time, and Portuguese time to semester 2000B. Service nights include
UK and NL service time, and SP CAT time includes also Spanish service time.
USE OF INSTRUMENTATION
Figure 1 shows the allocation of nights per instrument on the WHT in 2000
and 2001. As in previous years, the ISIS spectrograph and polarimeter was
the most popular instrument but also remarkable is the increase in the use
of the ING infrared imager INGRID, which became the second most popular
instrument in 2001. Private instruments included LDSS, SAURON, and SCAM.
On the INT, dark time periods were almost exclusively used for CCD imaging
with the Wide Field Camera (60.3% and 52.9% in 2000 and 2001 respectively).
The rest of the time was for the use of the IDS spectrograph (33.4% and
39.9%) and ocassional private instruments like CIRSI, Musicos or the Texas
Photometer (6.3% and 7.2% all private instruments). The JKT was a single
instrument telescope for CCD imaging.
Figure 1. Left: Use of instrumentation
in semesters 2000A and 2000B on the WHT. [ JPEG
| TIFF ] Right: The same for semesters 2001A
and 2001B. Commissioning nights are excluded. The abbreviations are explained
in Appendix K. [ JPEG | TIFF ]
During the year 2000 and 2001 the ING telescopes again performed very well,
with downtime figures due to technical problems averaging at 2.1%, 3.0%,
and 2.7% in 2000 and 3.3%, 1.1% and 1.2% in 2001 on the WHT, the INT, and
the JKT respectively. These figures meet the target value of a maximum of
5 percent technical downtime. Down time due to poor weather averaged 22.8%
in 2000 and 24.6% in 2001. The historical trends of technical down time and
weather down time by semester are plotted in Figures 2 and 3. Figure 4 shows
the seasonal average.
An important metric of the success of ING telescopes is the publication rate
in refereed journals and for this reason the ING Bibliography (see Appendix
I) is updated on a yearly basis. Traditionally this bibliography has
been compiled by visually scanning all articles in many journals and identifying
those which make use of data from our telescopes. However most journals are
now published electronically and often have quite sophisticated search engines
associated with them and it is therefore appropiate to conduct the search
with the help of these facilities.
Our selection process identifies papers that make direct use of observations
obtained with the ING telescopes. in order to qualify. Papers which refer
to data presented in earlier papers (derivative papers) are not counted.
When we analyse ING publications for the five years between 1995 and 1999
inclusive it can be seen that more than 95% of articles are published in
a small number of core journals. These core journals consist of the British
journal MNRAS, the American journals ApJ, ApJL, ApJS, AJ and PASP, plus the
European journal A&A (including the now defunct A&AS). We also include
Nature and Science as core journals due to their perceived high impact. Journals
making up the remainer of publications are widely spread among such journals
as Icarus and the Irish Astronomical Journal to name a few. The bibliography
for the years 2000 and 2001 was compiled from only the core journals listed
above for reasons of efficiency. Search engines were used to select papers
and the resulting list of papers visually inspected to ensure that they satisfied
the selection criteria described above (the journal Astronomy & Astrophysics
still had to be visually inspected).
Our initial results indicated a fall in the total number of journals compared
with the previous few years, with 162 being found for 2000 and 162 for 2001
compared to the typical total of more than 220 found for the previous four
An analysis of these results indicated that this drop was due largely to
a fall in the ApJ publication rate for 2000 by a factor of about 2. An immediate
concern was that the electronic search process was missing articles.
However, a check against previous years indicates that only few papers, if
any are missed this way.
An analysis of these numbers follows (see Figures 5 – 9 and Table 2). Note
that if a paper makes use of more than one telescope we count that paper
for each telescope. Also, concerning perceived nationality we use the nationality
of the first author’s institution although in a few cases two institutions
are credited. Similarly, if a paper makes use of more than one instrument,
that paper is counted against each instrument.
Figure 5. Number of refereed papers
per telescope since first light. [ JPEG | TIFF ]
Figure 6. Total number of refereed
papers per year and telescope. [ JPEG | TIFF ]
The fraction of papers attributed to the ISIS spectrograph from 1998 until
2001 (the years for which this information exists) varied from 39%, 50%,
54% to 39%. Clearly ISIS is still our most productive instrument by a long
way. Over the same period the UES echelle spectrograph figures are 20%, 15%,
17% and 24% indicating the continuing demand for high resolution spectroscopy
by our community. Papers from the newly commissioned IR imager INGRID made
a welcome appearance in 2001 with a total of 4 papers being attributed to
this instrument. Interestingly the number of papers from visitor instruments
on the WHT has increased from a few in previous years to 5 or 9 papers a
Figure 7. Use of instrument data in WHT papers.
[ JPEG | TIFF ]
On the INT the papers are split very evenly between IDS spectrograph and
the Wide Field Camera as might be expected from the split of observing time
between these instruments, roughly 50–50.
It is heartening to note that the JKT still contributes to 25 to 30 scientific
papers per year.
Figure 8. Use of instrument data in INT papers.
[ JPEG | TIFF ]
Concerning the nationality of the first author’s institution, there is little
change, at least considering the fluctuations from year to year. The UK share
is steady around 40%, the Spanish share increased to 25% in 2000 but in 2001
was back at 20%. The NL share also showed little systematic change.
There is a clear decrease in the total number of papers published with a
nearly 30% drop for the WHT. We believe our selection methods are sound but
maybe more strictly applied than in previous years. Although some papers
may have been missed by our more restrictive search, we expect that the main
reason for the reduced publication rate is related to the advent of the 8-m
Encouragingly, ING telescopes continue to play an important role and in this
respect we note the impact which the Wide Field Camera has had with an important
paper in Nature concerning the merger of a satellite galaxy M31 (Ibata
et al, 2001, Nature, 412, 49).
In an attempt to measure the quality of the ING science, an analysis of the
scientific productivity of large telescopes over the last decade (Benn and
Sánchez, 2001, PASP, 113, 385) puts the WHT in the lead over all other
4-m class and smaller telescopes, judging by counts of papers in Nature;
and in close second place, after the Canada-France-Hawaii Telescope, judging
by counts of citations to the 1000 most-cited astronomy papers world-wide
(see Figure 10). This study also showed that during the 1990s, smaller telescopes
accounted for half as much scientific output as did 4-m class telescopes,
which bodes well for the continued productivity of the WHT in the era of
Figure 10. Result from a citation index study of
the 1000 top-cited astronomy papers (125 top papers per year) from 1995 to
1998. [ JPEG | TIFF ]
THE ING ARCHIVE
All data taken with the ING telescopes is archived in the UK, at the Institute
of Astronomy, Cambridge. The data archive is managed by the Cambridge Astronomy
Archival data from the ING telescopes is made available to anyone upon request,
after a one-year proprietory period. The number of archive retrieval requests
has remained high over the past two years, with around 500 requests per year.
The historic trend of the archive requests can be seen in Figure 11. This
level of archive use underlines the importance of the ING archive as a general
tool for astronomy research.
Figure 11. Number of archive requests. [ JPEG | TIFF ]