|
Документ взят из кэша поисковой машины. Адрес
оригинального документа
: http://www.adass.org/adass/proceedings/adass96/jennesst.html
Дата изменения: Tue Jun 23 21:16:08 1998 Дата индексирования: Tue Oct 2 02:49:25 2012 Кодировка: Поисковые слова: п п п п п п р п р п р п р п р п р п р п р п |
Next: WinTICS-24 Version 2.0 and PFITS-An Integrated Telescope/CCD Control Interface
Previous: The JCMT Telescope Management System
Up: Real-Time Systems
Table of Contents - Index - PS reprint - PDF reprint
Tim Jenness, Frossie Economou, R. P. J. Tilanus1
Joint Astronomy Centre, 660 N. A'ohoku Place, University Park,
Hilo, HI 96720
1Netherlands Foundation for Research in Astronomy (NFRA)
WORF allows astronomers to eavesdrop on their data using the Netscape
browser with minimal impact on observatory staff and computer
systems. The UKIRT implementation has been extended to meet the differing
expectations of the JCMT community, and has many additions including a
telescope status screen, the ability to access the observation log and the use
of a conferencing tool between the observer and the eavesdropper(s).
The James Clerk Maxwell Telescope (JCMT) is a UK-Canada-Netherlands 15-m submillimetre telescope situated on the summit of Mauna Kea, Hawaii. In order to use good observing conditions more efficiently, the JCMT is moving to full flexible-scheduling. This will result in fewer astronomers travelling out to Hawaii, and more observations taken by observatory staff. It also implies that astronomers may only be given a few hours notice before observations in their program are taken. Although JCMT users understand the advantages of flexible scheduling, they are reluctant to relinquish the ability to modify observing strategy on-the-fly as new data come in.
We are anticipating the community's requirement for a way to monitor remotely their observations by developing the World Wide Web Observing Remotely Facility (WORF). WORF had been developed previously for the United Kingdom Infra-Red Telescope (UKIRT), where the HTTP based implementation was shown to have clear advantages (Economou et al. 1995); the JCMT specific development has become known as WORF2.
Figure: The structure of the WORF2 system. Original PostScript figure (9kB).
Each successful proposal for JCMT time is assigned a user name and password at the beginning of the semester. The first thing the potential eavesdroppers have to do is authenticate themselves, as access to data directories is restricted. They can then enter the WORF2 system, whose user interface consists of four Web pages (the locations of which are shown in Figure 1):
is also used so that the
observer and astronomer(s) can discuss details of the run using both text and diagrams.
The data previewing CGI backend is written entirely in Perl5 (Wall, Christiansen, & Schwartz 1996). JCMT observations are stored in a telescope specific GSD format originally developed for single-dish radio telescopes. Using the flexible Perl extension mechanism, we first had to develop a module allowing access to the C GSD library. Data from the JCMT digital autocorrelation spectrometer (DAS) needs to be processed before being displayed in a manner meaningful to an astronomer. The processed data is plotted into a GIF image via pgperl, the Perl PGPLOT module, and is then served via HTTP.
File naming conventions do not provide sufficient information for the eavesdropper to determine the type of observation contained in a file. Rather than reading in every file in the data directory to extract this information, an observing log generated by the scientist at the telescope is used instead. In the absence of such an observing log, only observation numbers are displayed.
Data privacy is a subject dear to the heart of many an astronomer. The eavesdropper is authenticated by the HTTP server and the login name thus provided is compared against the ownership of each individual file requested thereafter (data ownership is determined by an entry in the file header). This takes advantage of the way observations from different projects are taken and stored at the JCMT.
We use the public domain Easy Web Group Interaction Enabler (EWGIE) conferencing tool. This Java based tool provides a ``chat area'' as well as a ``whiteboard'' allowing diagrams to be exchanged between multiple participants over HTTP.
The data preview component of WORF2 will run on most graphical WWW browsers.
EWGIE requires Java support. The observation log and telescope status screens
make use of client pull in order to automatically update, a feature which is
not currently supported by many browsers other than Netscape
. These pages can, of course, be updated manually by reloading the page.
JCMT has recently taken delivery of SCUBA, a much anticipated submillimetre bolometer array, which will provide our users with imaging data for the first time. Data from SCUBA is stored in the Starlink N-dimensional Data Format (NDF), which is widely used in the UK community. We have already developed a Perl module allowing access to the FORTRAN Starlink libraries, and intend to take full advantage of the on-line data reduction pipeline written for SCUBA.
WORF2 is already in use, mainly by Dutch astronomers who were the first JCMT partner to move to flexible scheduling. We expect it will be used more widely as the British and Canadian allocated telescope time switches to flexible scheduling later this year.
We are in the process of adding more features to WORF2 but, as with WORF, other aspects of the software group's work are of higher operational priority.
A demo of the data preview component of WORF2 is also available.
Economou, F., Bridger, A., Daly, P. N., & Wright, G. S. 1996, in Astronomical Data Analysis Software and Systems V, ASP Conf. Ser., Vol. 101, eds. G. H. Jacoby and J. Barnes (San Francisco, ASP), 384
Wall, L., Christiansen, T., & Schwartz, R. L. 1996, Programming Perl, 2nd edn. (Sebastopol, CA: O'Reilly)
Next: WinTICS-24 Version 2.0 and PFITS-An Integrated Telescope/CCD Control Interface
Previous: The JCMT Telescope Management System
Up: Real-Time Systems
Table of Contents - Index - PS reprint - PDF reprint