MIT Reports to the President 1997-98
The Haystack Observatory, located in Westford MA, is an interdisciplinary research center engaged in radio astronomy, geodesy, atmospheric sciences, and radar applications. The radio astronomy program is conducted under the auspices of the Northeast Radio Observatory Corporation (NEROC), a consortium of 12 educational and research institutions in the northeast. The Observatory receives financial support primarily from federal agencies including the NSF, NASA, and the USAF through MIT Lincoln Laboratory.
The Haystack Observatory instrumentation consists of the following facilities:
RADIO ASTRONOMYAmongst the highlights of the radio astronomy observations using the 37-m diameter radio telescope in the year has been the discovery of a compact outflow towards a very strong molecular gas region, S68N in the Serpens cloud core, by a group led by Grace Wolf-Chase of the University of California, Riverside, and which included Joel Kastner of MIT. The images obtained using the CS tracer line at 98 Ghz were combined with radio interferometric and other observations to identify for the first time the source responsible for the outflow and to establish the exact location of the infall center of the core. The survey for infall motions in dense cores using 160 starless cores was completed during the past year by a group led by Phillip Myers of the Harvard-Smithsonian Center for Astrophysics. Using the CS and the N2H+ lines in the lines in the 3-mm wavelength band, 65 sources were detected that showed a slight excess infall asymmetry in the measured spectra, but most starless cores appear to be static. Dan Clemens of Boston University and his students conducted observations to determine the distances to IR sources from CS-derived velocities observed at Haystack in 10 detected sources, and concluded that these sources are high-mass protostars at large galactic distances. In other staff research using facilities elsewhere, Colin Lonsdale of Haystack and his colleagues studied the extreme luminosity resulting from the collision of two spiral galaxies in Arp 220. New massive young stars formed as a result of the collision are thought to release the luminous energy. In a later stage of evolution, a luminous quasar is expected to form from the black hole at its center.
In May 1998, the Haystack Observatory ended its program as a user facility for radio astronomical research under NEROC's oversight. Under new support from NSF, the Observatory is implementing a program using the Haystack telescope to allow undergraduate students to engage in radio-astronomical research as part of their education. In the past year, 60 students from local area universities including MIT, Harvard, Boston University, University of Massachusetts, Wellesley College and Northeastern University, used the telescope for observational projects associated with courses or independent research programs. Pilot projects have been developed by Haystack staff to allow such educational projects to be undertaken, and workshops have been provided to faculty and students to acquaint them with the radio telescope systems and observational methods in radio astronomy. Web-based tutorials have been started, and a new computer control system has been developed to allow remote operations of the telescope and monitoring of the observations. A small radio telescope, 3 m in diameter, has also been developed to provide students with a direct experience in the construction of a radio telescope, and the telescope will be offered as a kit to interested institutions. This will provide an opportunity for students to perform hands-on observational training prior to the use of the Haystack telescope. With the successful demonstration of the educational value of the program, it is expected that the telescope will be made accessible to students nationwide for research experiences.
VERY LONG BASELINE INTERFEROMETRY
Very Long Baseline Interferometry (VLBI) applied to astronomical observations at 3mm-wavelength has continued successfully at Haystack through the Coordinated Millimeter-VLBI Array (CMVA) project. Eleven radio telescopes, globally distributed in the US, Europe, and South America, participate as part of the CMVA to map galactic cores with angular resolutions of 50-100 microarcseconds, and the data are processed using Haystack's VLBI correlator. While on-going CMVA projects map the evolution of the structure of active galactic nuclei, emphasis at Haystack has recently shifted to spectral-line observations aimed at the study of interstellar maser pumping mechanisms and the determination of maser proper motions. Towards that end, a series of experiments on a short baseline from Haystack to the Five College Radio Astronomy Observatory at Quabbin, MA, have been conducted under the leadership of Shepherd Doelman of Haystack. Methanol masers at 95 and 107 Ghz were detected, indicating that the emission in the source OMC is likely to be thermal. In a new technically-challenging thrust, VLBI observations have been attempted in April 1998 at a wavelength of 1.3 mm, using five telescopes in the US and Europe. Due to poor weather conditions at several of the telescopes, interferometric fringes have not been detected, and the test experiments will be continued with emphasis on short-baseline observations using telescopes in the western US. Instrumentation improvements such as the development of water vapor radiometers to enhance the coherence time for mm-wavelength observations are in progress with the involvement of MIT graduate student David Tahmoush.
Haystack Observatory, in partnership with the MIT Physics Department, Harvard-Smithsonian Center for Astrophysics, Boston University, Brandeis University, and the University of Massachusetts, has participated in a proposal for an NSF Science and Technology Center for Advanced Interferometry. The effort is led by Professor Jacqueline Hewitt of MIT. Based on a successful pre-proposal recently selected by the NSF, a full proposal is now being prepared. The goal of the center is to provide a cohesive and integrated approach to the development of advanced interferometry at all wavelengths. Amongst the proposal components to be carried out at Haystack is the design of a large multi-element correlator system to support the One-Square Kilometer Array project led by Professor B. Burke of MIT Physics, the mapping of GPS satellites in collaboration with Professor Thomas Herring of MIT Earth, Atmospheric and Planetary Sciences, the adaptation of high-speed network links for transmission of VLBI data, the development of lightning detection systems, and the characterization and mitigation of radio-frequency interference. The proposed STC will include strong interactions with industrial firms, national laboratories and international institutions, and will include a strong educational component and public outreach.
The Mark IV correlator system is now in its full production phase using local area industrial firms, and the assembly of correlator boards and other subsystems is in progress. In addition to the Haystack correlator developed under NASA support, copies will be constructed for the US Naval Observatory to support the USNO-NASA geodetic program, the Smithsonian Institution for the Sub-Millimeter Array, the Joint Institute for VLBI in Europe, the Netherlands Westerbork Array and the Max Planck Institute in Bonn, Germany. In the past year, Haystack staff have contributed to the resolution of difficulties encountered with station units designed by an industrial firm in England which have delayed the completion of the Mark IV correlator. The station units are now being replicated in the US. It is expected that the correlators will be completed by mid-1999 and will allow a vastly increased capacity for VLBI data processing.
Implementation of the Mark IV data acquisition system on telescopes worldwide is in progress. This will allow the data to be recorded at high rates for processing with the Mark IV correlator. Haystack technology has been transferred successfully to industry for the replication of these systems, and scientific studies, such as NASA's CORE program (Continuous Observation of the Rotation of the Earth) are now being started. To facilitate the application of the new system, Haystack hosted an international workshop in May 1998 to provide operational training for personnel who will use the new system at their telescopes. Over 100 scientists and engineers from 18 countries took part in this workshop. In addition, a special forum was held following the workshop to discuss the use of high speed networks in the transfer of VLBI data from the telescopes to correlators. Strong international interest was expressed in such a capability.
Feasibility tests of the new thin-film recorder head-arrays developed by Seagate Tape Technology Division were completed in the past year. The measured signal-to-noise ratio of thin film heads in reading recorded data showed a significant advantage over traditionally-used ferrite heads, but some modifications were identified to enhance their writing performance. Prototype head-arrays are now expected from Seagate to allow further development and tests of wide bandwidth recording systems (1-2 Gbits/s) using thin-film heads. The modeling of the head-tape interface is proceeding successfully under an NSF grant, and a gift from Quantum Corporation has allowed further developments in recorder head modeling to proceed.
In the past year, emphasis has been placed on the development of an atmospheric lidar system as part of the cluster of instruments at Millstone Hill to study the coupling between the Earth s middle atmosphere (30-100 km altitude) and the upper atmosphere. The lidar utilizes the Lincoln Laboratory Firepond 1.2m-aperture telescope together with a 25 Watt Nd:Yag laser obtained through a collaborative effort with Clemson University. Through grants obtained from the NSF Major Research Instrumentation and CEDAR programs (Coupling, Energetics and Dynamics of Atmospheric Regions), a Rayleigh-Doppler system is being implemented to measure the neutral density, temperature and wind velocities in the middle atmosphere. Together with the other radar and optical instruments at Haystack, the lidar will allow us to study the effects of tidal and gravity wave propagation from the Earth's lower atmosphere into the upper atmosphere.
Our second initiative in atmospheric science has involved participation in the design and development of the Polar Cap Observatory (PCO) at Resolute Bay, North West Territories, Canada (near the geomagnetic north pole) in response to an NSF solicitation. MIT/Haystack is a partner in a consortium led by SRI International, and which includes Boston University and the University of Michigan. Our joint proposal was peer-reviewed and approved by NSF and the National Science Board. Haystack's responsibility is the design and development of the data acquisition system for the incoherent scatter radar that is the central element of the PCO. This system will remotely control the radar, monitor its data output, and analyze its observations in real time. Regrettably, the location of the facility has become an issue in Congress, and funding has not been released for initiation of the project. Our expectation had been to complete the development by 2001, in order to take advantage of the peak of the solar cycle when important geomagnetic effects will occur. The study of such effects at the Earth's polar cap is crucial to understanding the solar-induced phenomena that influence the Earth's ionosphere and magnetosphere.
EDUCATIONAL PROGRAMSThe program to provide undergraduate students access to the Haystack radio telescope for research projects, described under the radio astronomy program, is a key effort which represents our contribution to strengthen the linkage between education and research. In addition, our summer internship program involves twelve undergraduate students this year, recruited from across the nation. The students are mentored by members of the Haystack staff and participate in the staff's research projects in astronomy, atmospheric science and instrumentation development. Two students from the University of Massachusetts at Lowell are constructing a copy of the small radio telescope for use at the Lowell campus, and a special pilot project to control the Haystack telescope from that campus is being tested. Several graduate students and post-doctoral associates are also engaged in research associated with our radio interferometry program.
In order to maintain our contributions to the local area schools, we have prepared a project on teacher enhancement in science and mathematics. Several teacher-student teams at the high school level are to be mentored by Haystack staff on a specific project which will be initiated during summer internships and then carried into the classroom during the following academic year. The project has been proposed to NSF.
More information about the Haystack Observatory can be found on the World Wide Web at the following URL: http://www.haystack.mit.edu
Joseph E. Salah
MIT Reports to the President 1997-98