August 1998
With the approval of the National Science Board, the three-year Design and Development phase of the Millimeter Array has begun. On June 1, 1998, much of the NRAO staff who are assigned to the MMA Project were transferred formally onto it so this provides an easily remembered start date for the formal project at the NRAO. We are enormously pleased and very grateful for the efforts of everyone at the NRAO and in the U.S. community who worked to bring this about.
The Design and Development phase of the MMA is meant to provide us with an opportunity to prototype representative modules of some of the technically most demanding instrumentation. A prototype antenna is the most visible example of the effort but many of the other prototyping efforts are equally challenging: these include prototyping SIS mixers that are in fact MIC. SIS circuits on a single chip that incorporate balanced image separation; 4K cryogenics that is reliable and economical even when running at an ambient pressure 70 percent of that at sea level; an optical fiber signal transmission system with 16 GHz bandwidth; and a computing environment that is designed from the outset to be developed, used, and maintained remotely. A primary goal of the MMA D&D effort is to allow us to establish a firm cost basis for the construction phase of the project.
Approximately 20 people at the NRAO are now working on the MMA project, about a third of these people are at each of the Tucson, Socorro, and Charlottesville sites. By the end of the year the number of staff should grow to more than 30 all together; their efforts will be augmented by the design and research efforts of another six people working at the OVRO and BIMA arrays. Advertisements for open positions with the MMA project can be found on the NRAO homepage http://www.nrao.edu.
Personnel assignments to the MMA project at the NRAO have brought about some changes that users of the Observatory will notice. In particular, Brian Glendenning has transferred to the MMA Project from AIPS++ where he worked for many years directing the technical work on that project; Brian is now the Division Head for all of MMA computing. Al Wootten has assumed the role of MMA Project Scientist replacing Frazer Owen. Frazer was the inspiration for much of what is now the MMA, and we are very grateful to him for his seminal insights and efforts.
The burden of organizing initial D&D work, assembling the staff and making the facilities ready for the staff to work effectively, has prevented much progress from being made with potential international partners in the MMA or in that larger, combined array that will subsume the MMA. However, in the weeks ahead discussions and negotiations on possible partnership arrangements will resume with a realistic expectation that a mutually satisfactory, and beneficial, international partnership can indeed be forged.
R. L. Brown
Presence in Chile
NRAO has now consolidated its legal situation in Chile. On June 30, 1998 a decree signed by the President of Chile, Eduardo Frei Ruiz-Tagle, was published granting AUI the same legal status enjoyed since the sixties by AURA and the Carnegie Institution of Washington, the other U.S. organizations operating observatories in Chile. The MMA is not only the first radioastronomical observatory to come to Chile, but NRAO is also the first, new foreign astronomical organization in a generation.
But securing a legal status for NRAO was only the first step needed to build the MMA in Chile. Guaranteed access to the Chajnantor site and protection of the area is an equally essential part of the process. Thanks to the enthusiastic collaboration of the University of Chile, the National Commission for Science and Technology (CONICYT), and the Chilean political authorities at all levels, this has now been accomplished.
The President of Chile signs the decree declaring Chajnantor a scientific preserve. From left to right, Dr. Mauricio Sarrazin Arellano, President of CONICYT; Mr. Sergio Jimenez Moraga, Secretary of Mines; Eduardo Frei Ruiz-Tagle, President of Chile; and Mrs. Adriana Delphiano Puebla, Secretary of Public Properties
In July, the President of Chile issued an invitation for a ceremony to take place in Santiago at La Moneda, the presidential palace. The invitation was for "the signature of a Supreme Decree declaring Chajnantor a Scientific Preserve area and an agreement for the prosecution of radioastronomical projects in fiscal land." The ceremony took place on July 22nd in the presence of close to 100 guests representing the Chilean and foreign resident scientific community, as well as representatives of the government, particularly of the ministries involved in the signature. It was the largest Chilean public act associated with astronomy in memory. We were represented by Martha Haynes, AUI Acting President, Robert Brown, Project Director, and Eduardo Hardy, NRAO resident scientist and AUI legal representative in Chile. The National Science Foundation was represented by Robert Dickman.
Dr. Martha Haynes, president of AUI offers Eduardo Frei Ruiz-Tagle, President of Chile, a satellite picture of the Chajnantor area. The Chilean president is flanked by Drs. Martha Haynes and Eduardo Hardy.
The decree, signed by the President, the Secretary of Mines, Mr. Sergio Jimenez Moraga, and the Secretary of Public Properties, Mrs. Adriana Delpiano Puebla, protects the area from mining claims. The text of the decree, which makes specific references to the MMA, clearly acknowledges that the government of Chile agrees that Chajnantor is the best known place on Earth for millimetric astronomy.
In June, the local authorities of the region of Chile where the MMA site is located (the 2nd Region) had already transferred the administration of the Chajnantor area to CONICYT. The agreement between the ministry of National Properties and CONICYT signed at La Moneda on July 22nd, insures that the land will be devoted to astronomical research. Specific reference was made to the MMA which is considered to be in the development stages there already. A formal agreement between NRAO and CONICYT will follow.
The written texts, as well as the speeches pronounced by the President of CONICYT, Dr. Mauricio Sarrazin Arellano, and Secretary Delpiano contained statements that revealed the degree of interest the government of Chile has taken in our project and in astronomy in general. Chile has said loud and clear that it is waiting for the MMA.
Eduardo Hardy
Oversight Committee Meeting
On August 4th the NSF MMA Oversight Committee (MMAOC) met for the second time to review progress being made by the project. In preparation for the meeting the MMAOC was provided with the following documentation:
- (1) The Recommended Site for the Millimeter Array, an analysis of the
process that led to our recommendation of the Chajnantor site for the
MMA;
- (2) the MMA Project Book, Version 1, a description of the tasks for the Design and Development Phase written by the MMA Division Heads for use by members of the project; and
- (3) the MMA Management Plan, Version 1.
- (2) the MMA Project Book, Version 1, a description of the tasks for the Design and Development Phase written by the MMA Division Heads for use by members of the project; and
The MMAOC endorsed the recommended site and forwarded their endorsement to the NSF. The formal site selection will come from the NSF approval of the recommendation, the MMAOC action is an important aspect influencing the approval. Presentations were made by Peter Napier and John Webber introducing the Project Book to the committee. They also enumerated the issues raised the previous week at the Project Internal Review in Tucson that will modify the initial version of the plan as given the the Project Book. Special emphasis was given to the revised plan for procurement of the first prototype antenna, a revision that derived from suggestions given at the first meeting of the MMAOC. The Management Plan was similarly introduced by Bob Brown and Richard Simon to much spirited discussion about the nuances of what was and was not included in the Project Work Breakdown Structure.
Paul Vanden Bout then summarized for the committee the initiatives underway to secure international partners in the MMA or to join the MMA with similar initiatives being discussed in Europe and Japan. The prospect of enlarging the MMA by the addition of many more antennas, and a commensurate increase in collecting area, was welcomed even though such an enhancement via partnership will modify the current MMA planning.
The committee will issue a formal report to the NSF in a month. The next meeting of the MMAOC is scheduled for November 1998.
R. Brown
August 13, 1998
Al Wootten gave a summary of some points from the MMA Internal. They are as follows:
Imaging:
It is expected that the MMA will often be used in an interactive
observing mode. How important will it be to have on-line images?
The general feeling seemed to be that a reliable pipeline will be
essential for on-line programming decisions, early recognition of
errors (wrong position, wrong LO, etc.), quick evaluation of date
quality, etc. A pipeline will also be essential simply from the
stand point of dealing with the enormous data rate that the MMA
will produce. It is recommended that work on a reliable pipeline
be started as soon as possible so that it will be available
as an integral part of the on-line and early reduction software.
Configurations:
Progress on modeling of the array configurations was noted. In
particular, the D-array subconfigurations are still under consideraton
to satisfy maximum senstivity with minimum shadowing and sidelobes for
a range of observing requirements.
Phase calibration:
The technique of choice is monitoring either the 22 GHz or the 183 GHz
water line. A lot of work has been done on the 22 GHz line at OVRO and
BIMA and there seems to be general agreement that monitoring this line
would provide reliable phase corrections. The problem with this line is
that its feed would fill a large fraction of the focal plane and its beam
would probably be larger than the central hole in the primary dish.
The 183 GHz line would not suffer from these problems but it has not been
extensively tested as a phase calibrator. Plans are underway to do this
at the Chilean site, but it will probably take until January at least to
get the system set up.
Jack Welch has pointed out that the 183 GHz line might be problematic when clouds are present because of the frequency squared dependence of emission in the water lines.
Amplitude calibration:
The main activity here is the search for new secondary calibration sources
including: stars; solar system objects such as asteroids, moons, etc.; and
a two-load calibration system. The goal is to achieve an accuracy of 1-5%.
Two corrections to the Internal Review report that Jean and I sent out last week:
-
1) A nutating subreflector is planned only for the two prototype antennae. A
decision on whether all antenna will have one will depend on scientific
requirements.
- 2) The prototype antennae will also be outfitted with 230 GHz receivers for testing at the VLA site in addition to the 30 and 90 GHz recievers.
Correlator:
The present correlator design has a highest resolution at 230 GHz of
0.02 km/s with steps of two in bandwidth and corresponding decrease
in resolution.
Receivers:
The list of recommended receivers generated by Al Wootten's committee
was based on a study of the astrophysically most important atomic and
molecular lines presently known and maintaining a frequency ratio of
1.30 or less.
Peter Napier reported on the results of the meeting with the NSF Oversight Committee.
- 1) The Chilean site was accepted by the committee.
- 2) The committee was enthusiastic about collaboration with the Europeans.
- 3) They want more detailed project management plans. In particular, more detailed budget, manpower, and scheduling plans.
- 2) The committee was enthusiastic about collaboration with the Europeans.
Richard Hills was concerned about altitude effects at 5000m and asked about the possibility of doing some tests by adding oxygen to a room at the site. Peter Napier said that tests are already being conducted in California by an expert on the physiological and psychological effects of altitude. He is testing human responses in a room whose air composition can be adjusted to mimic that of the atmosphere at a specified altitude.
We will have a MAC meeting this Fall. September is too soon to get onto calendars and October seems to be too busy with various meetings and some members have told me that the first weekend in November is not possible for them. I am thinking of trying for the second weekend in November. I don't want to put it off any later than this if we can avoid it. Let me know if this is absolutely impossible for any of you. I still have to clear this with NRAO and I'm sure we will not be able to fit everyone's schedule, but we will do the best we can.
E. Churchwell
The impact of MMA development activities in Tucson is growing and is welcomed by all. The site testing interferometers in operation in Chile, designed and built by Tucson engineers and scientists, continue to be operated and maintained from Tucson. A submillimeter tipper is now operational at this test site. Earlier this year we hosted an international gathering of European, Japanese, Chilean, and U.S. groups to discuss existing and future millimeter and submillimeter site testing activities. MMA receiver development and production are scheduled to take place in Tucson, using mixer blocks supplied from the Central Development Lab (CDL). In collaboration with the CDL, an orthomode transducer for the MMA has been built in Tucson; this prototype is designed for 90 GHz, but the goal is to extend the principle up to 300 GHz. MMA cryogenics design and development are also centered in Tucson under the guidance of Larry D'Addario. The MMA antenna group is based in Tucson, headed by Peter Napier in Socorro. An experimental laser local oscillator system is being developed in Tucson, and if successful, potentially provides a simpler, cheaper, and more reliable local oscillator system for the MMA; we will report on the progress of this project in later Newsletters.
The additional staff in Tucson now supporting the MMA has already strained the available office and lab space; more MMA employees will be added by the end of this year. To accommodate this expansion, we are looking at various options of increasing the space available to NRAO at the University of Arizona.
D.T. Emerson
In case you may be interested, Millimeter Wave Report web site has a millimeter wave event calendar which list symposia, conferences etc, a few of which may interest MMA staff. The web URL is http://www.mmwrpt.com/calendar.htm
Please send questions or comments to
kweather@nrao.edu, Editor/Webmaster