Edited by Peter Lawson
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Editorial: 2 March 2000
Peter R. Lawson.
2 March 2000
News from the CHARA Array
As can be seen from recent photographs, the weather has been predictably
poor this winter season on Mount Wilson (snow on Mount Wilson and rain in
Pasadena). The past few months have been spent working on commissioning
the optics for new baselines, implementing new device drivers,
and aligning optics in the OPL building for the additional baselines.
News from the VLTI
The December 1999 issue of the ESO Messenger (No. 98) contains the article ``The VLTI - The Observatory of the 21st Century," by A. Glindemann et al. describing progress with the
VLTI. Some of the near-term deadlines for the VLTI, described in the article,
are summarised here.
- Siderostats to be delivered to Paranal in January 2000.
- Implementation of siderostat control software by May 2000.
- First two delay lines installed in July 2000.
- Vinci to be delivered to Paranal in October 2000.
- First fringes with Vinci and the two siderostats in December 2000.
- Third delay line installed in December 2000.
MIDI (the 10 micron instrument) is to be delivered in June 2001 and to
have first light with the siderostats in September 2001.
AMBER (the 1 to 2.5 micron instrument) is to be commissioned with the
siderostats beginning in February 2002.
News from PTI
This past weekend the process has begun to bring PTI back on-line for the
2000 observing season. (It has been snowing at Palomar as well.)
A new detector based on the HAWAII chip is being tested on the secondary
table. If the tests prove satisfactory the detector will be moved to
the primary table, which is the table principally used for single-baseline
science observations.
A paper describing the 1999 season's narrow angle astrometric observations
is currently in preparation.
Michelson Summer School
My work on the 1999 Summer School is now overlapping with preparations
for the August 2000 Summer School. I am still encouraging contributions
from the missing lectures, and creating them where they are unlikely
to ever exist!
- Almost all the lecture overheads have been turned into PDF files,
although these have yet to be linked to the Michelson Summer School
Web site, they will be within a week.
- A preliminary agenda has been set for the 2000 Summer School. This
will be an astrophysics-only school, with the number of participants
limited to 35 students/postdocs. The invited speakers
should be confirmed before the end of March.
Real Time Control with RTLinux
I have started work on a testbed interferometer at JPL to implement a
cryogenically cooled delay line and beam-combiner for direct detection
interferometry at a wavelength of 100 microns (should you be interested,
the technology development is being done with TPF, SPIRIT, and SPECS in mind).
This testbed requires a real-time control system for the delay line.
After considering the alternatives, I've decided to build the testbed
following the model at CHARA of using Red Hat Linux with the
Real-Time Linux (RTLinux) extensions. Theo ten Brummelaar at CHARA has implemented the
real-time control system of the Array using Real Time Linux.
Everything at CHARA is running on RTLinux except the delay
lines, so unfortunately Theo will not have done all the work for me.
The advantage of this system is that it can be built around PCs, is capable of
hard real-time with a latency of 30 microseconds, and (at least for me) will
be relatively simple to implement compared with programming a VxWorks-based
system. With this I will be acquiring a Zygo ZMI 2000
metrology system whose metrology board will plug into the ISA bus of a PC.
If you would like to know more about writing device drivers under Linux and
using RTLinux, have a look at the following hyperlinks, articles etc...
Peter Lawson
March 2, 2000
Maintained by Peter Lawson
MS 306-388
Jet Propulsion Laboratory
4800 Oak Grove Drive
Pasadena, CA 91109
USA
