One of the major technical challenges for ALMA has been to provide a stable Local Oscillator (LO) signal across the wide range of frequencies at which ALMA will operate. The phase of this LO signal must be stable even when delivered to antennas that can be separated by several kilometers. The first unit of the central LO, which is capable of providing this signal to 16 antennas, has now been installed at the 5000 m Array Operations Site (AOS) in the Technical Building. An 84 GHz LO signal has been sent between the newly installed racks and the nearby antenna pad No. 106 and the system appears to be working well. Pad 106 will be the first pad to receive an ALMA antenna when it is moved to the AOS site on 17 September 2009. For more details on the LO installation, see the August 2009 issue of NRAO eNews.
Figure 1: The ALMA Central Local Oscillator installed at 5000m AOS technical building. Image from NRAO eNews August 2009; photo W. Grammar.
Interferometry testing continues at Operations Support Facility (OSF) at 2900 m, now using the second and third accepted antennas as the first antenna is moving to the AOS site. The water vapour radiometers have measured some exceptionally good weather at the OSF (pwv as low as 0.45 mm), which suggests that observations in the high frequency ALMA bands will be possible occasionally from the OSF. Indeed, the first Band 9 (450 micron) observations were made during 3-4 July, 2009 with a detection of the Moon and a scan of Jupiter. During this period the first successful interferometric observation in Band 6 (1.3 mm) was made from the OSF. As this is the first southern hemisphere winter since we have started having antennas in Chile, testers are taking advantage of the cooler night temperatures to investigate the surface performance of some of the antennas which are still in the contractor camps.
Figure 2: Two ALMA antennas being carried by the two ALMA transporters. Image from NRAO eNews August 2009.
In total, there are 16 antennas in various stages of construction and testing at the OSF as well as portions of various other antennas. 16 antennas is the magic number for early science with ALMA! At the AEM antenna area, preparation is continuing for foundations for removable shelters to be installed around pads during the assembly of the antennas. The first two BUS halves for the AEM antenna have been glued together. Integration of its legs, apex and subreflector mechanism has been completed. Lightning protection was installed on the BUS and work on panels and adjusters has been started The yoke arms were also installed. The second quadrant of ALMA correlator in the AOS technical building and progress is being made towards on-site acceptance. If my quarterly ALMA updates are not frequent enough for you, a good source for monthly updates on the ALMA project is the new electronic NRAO newsletter
http://www.nrao.edu/news/newsletters/And don't forget the ALMA observatory web site
http://www.almaobservatory.org/which contains wide range of information about the observatory, including details about science and technology, infrastructure, geographical location, etc. From there, you can also check out and subscribe to the new ALMA electronic newsletter (go to Newsroom and click on Newsletter), which comes out every few months and contains longer articles on various aspects of ALMA as well as recent updates.
http://www.nrao.edu/meetings/galaxies09/For those of us (like me) who cannot attend the meeting, it is likely that most of the talks will be posted on the conference web site. The next ESO-MPE-MPA-USM Joint Workshop, "From circumstellar disks to planetary systems", will be held November 3-6, 2009 in Garching, Germany. The goals of the workshop will be to review the status of the field and to discuss transformational programs that will be made possible with the upcoming facilities, and especially by the combined use of the ESO present and future facilities. To achieve this, the workshop will bring together the communities working with ground based infrared large telescopes and interferometers, with space observatories and millimeter interferometers as well as theorists. The web site for the meeting is
http://www.eso.org/sci/meetings/disks2009/index.htmlBased on the success of the McMaster workshop and the timeline for Early Science observations with ALMA, we plan to hold a half-day meeting in May 2010 to inform the community about Early Science opportunities with ALMA. This meeting will be held in conjunction with the 2010 CASCA Annual Meeting at Saint Mary's University in Halifax. Stay tuned!
http://my.nrao.eduALMA commissioning work in Chile now regularly uses CASA. CASA supports direct import of data in ALMA, VLA, and EVLA formats, and almost any data set that can be written in uv-fits format can also be imported into CASA. The Pipeline team continues to prepare for the next User Test which will focus on improvements to the calibration algorithms for single field interferometry and also the first implementation of mosaics with interferometric data. This User Test is now anticipated to start in November. Chris Wilson firstname.lastname@example.org Canadian ALMA Project Scientist (with input from Gerald Schieven, as well as material from Al Wootten and the NRAO and ALMA newsletters)