NATIONAL RADIO ASTRONOMY OBSERVATORY Observing Summary - 1985 Statistics February 1986 NATIONAL RADIO ASTRONOMY OBSERVATORY Observing Summary - 1985 Statistics February 1986 Some Highlights of the 1985 Research Program A radio image of the Cassiopeia A supernova remnant showing unprecedented detail was produced, which is the most complex image yet made by a radio-interferometer. Six centimeter observations from all four VLA configurations were combined and deconvolved by means of a supercomputer in order to produce a 0.2 arcsecond resolution image of the large diameter 6.1 arcminute field. Images from future epochs will allow detailed tracking of the expansion of the remnant and monitoring of the compact knots of emission that appear throughout as a result of the catastrophic explosive event that created the remnant approximately 300 years ago. The 1400-MHz continuum survey of the entire sky within the -5° < 6 < + 82° declination band that was carried out on the 300-ft telescope in 1983 has produced a confusion limited atlas containing approximately 3000 sources per steradian stronger than 0.15 Jy. Available on FITS tapes that can be readily displayed and analyzed with standard AIPS programs, the atlas is comparable to the Palomar Sky Survey, its optical counterpart, as a standard reference for source identifications and variability studies. The VLA continued to participate in ongoing search for gravitational lens candidates chosen from the 6-cm MIT-Green Bank survey with the 300-ft telescope. The seventh candidate to pass all the preliminary radio and optical observational tests was identified in 1985 as the complex triple source, 0023 + 171, with z = 0.946 and total angular separation of 5 arcseconds. Although the object is the closest gravitational lens candidate yet discovered, deep optical images do not reveal the faint lensing mass. Observations at 18.3 GHz with the 140-ft telescope were critical to the identification of the C3H2 molecule (cyclopropenylidene) in the interstellar medium. The ubiquitous occurrence of this small organic ring molecule in the Galaxy makes it an important new tracer of physical and chemical conditions. A survey of a large number of sources detected the line in emission in cold dust clouds and in absorption in the direction of the galactic center. One-hundred forty foot observations have also detected the line in absorption in Cen A, suggesting that C3H2 may be widespread enough to study in many galaxies. The first detailed maps of the distribution of OH in Halley's Comet were made by the VLA. While no OH was seen toward the coraetary nucleus, the molecular emission in the coma was non-uniformly distributed in several clumps. The detailed maps support comet models which predict the vaporization of coraetary H2O ice from the nucleus and the eventual dissociation of H2O into H and observable OH once it has been expelled from the immediate vicinity of the nucleus. The detection rate of molecular shells surrounding Infrared, bright, evolved, red giant stars increased greatly as a result of the newly improved l-mm receiver on the 12-111 telescope. These shells provide ideal laboratories for studying the mass losing stages of stellar evolution through the measurement of mass loss rates, isotopic abundance ratios, molecular abundances, and dust-to¬ gas ratios. They contribute significant amounts of carbon and oxygen to the interstellar medium, as well. Observing Hours 30 est-jest. est, est, est, est, 1976 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 Calendar Year 1300-Foot 140-Foot ■ 12-Meter WM Interferometer W&VLA Fig. 1. This figure shows the hours scheduled for observing on each telescope during the last decade. Distribution of Scheduled Observing Time 12-Meter 140-Foot 300-Foot VLA 1976 77 78 79 80 81 82 83 84 85 1976 77 78 79 80 81 82 83 84 85 1976 77 78 79 80 81 82 83 84 85 1981 82 83 84 85 Calendar Year Calendar Year Calendar Year Calendar Year \NRAO Staff I Visitors IB Testing and Calibration Fig. 2. These graphs show the number of hours scheduled for calibration and for observing by the NRAO staff and by visitors on each telescope system during the last decade. 12-Meter Radio Telescope Summary 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 Calendar Year •Observing Installation, Maintenance and Calibration Equipment Failure, Weather and Interference Fig. 3. This summary for each quarter of the calendar year shows the percentage of time the telescope was scheduled for observing, for routine calibration, maintenance, and installation of new experiments, and the percentage of time lost due to equipment failure, bad weather, and radio interference. The telescope is removed from service for a period of 4-6 weeks each summer during the wet season. This period is used for maintenance and upgrading of the instrument. During the last half of 1982 and most of 1983, the telescope was out of service for the replacement of the reflecting surface and its backup structure. 140-Foot Radio Telescope Summary 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 Calendar Year Observing Installation, Maintenance and Calibration Equipment Failure, Weather and Interference Fig. 4. This summary for each quarter of the calendar year shows the percentage of time the telescope was scheduled for observing, for routine calibration, maintenance, and installation of new experiments, and the percentage of time lost due to equipment failure, bad weather, and radio interference. Maior improvements to the telescope system include: 1977 - data processing computer and installation of the maser Cassegrain system; 1978 - tests of the deformable subreflector; 1980 - installation of the Model IV auto¬ correlation receiver; 1982 - beam efficiency and pointing tests at 1.3 cm; 1983 - brake overhaul and installation of the second channel of the upconverter/maser receiver. 300-Foot Radio Telescope Summary 100 "S -\ A ^ A* -^ KS /^ ^^ - A A /- - ^- "\ ^ - V V V / r / ^ 80 A f V \,V - \ i- 60 vV U - V - o- 40 { - \ - / L > \ 20 A AA SS /\ /" ~N v_ / _^ ^N ^ V -J ^ >1 \_ ■—■ 7 — — s - — -^ — -—. ^< y \: ^ ^ 0 y Calendar Year •Observing Installation, Maintenance and Calibration Equipment Failure, Weather and Interference Fig. 5. This summary for each quarter of the calendar year shows the percentage of time the telescope was scheduled for observing, for routine calibration, maintenance, and Installation of new experiments, and the percentage of time lost due to equipment failure, bad weather, and radio interference. During 1980 a new traveling feed was installed, in 1983 cables were replaced and the telescope was painted, and during 1985 N-S motion was added to the traveling feed. Very Large Array Telescope Summary 1977 1978 1979 1980 1981 1982 1983 1984 1985 Calendar Year — Construction Initial Observing and Testing • Observing Testing, Maintenance and Calibration Downtime Fig. 6. This summary for each quarter of the calendar year shows the percentage of time the telescope was scheduled for observing, for routine system testing, maintenance, and calibration and the percentage of time lost due to hardware or software failure, power failure, or bad weather. During 1977 and 1978 no distinction was made between astronomical and test observing. Time scheduled for completion of the construction was reduced to zero after the first quarter of 1981. Full-Time Permanent Employees 450 400 350 300 &250 E ^ 200 150 100 50 1957 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 Fiscal Year Calendar Year Fig. 7. This figure shows the total number of NRAO full-time, permanent employees at the end of each year, projected into the future. Number of People Observing With NRAO Telescopes 1959 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 89 90 Calendar Year Fig. 8. This bar chart shows for each calendar year the number of NRAO permanent research staff and the number of research associates who use the telescopes. In addition, it shows the total number of visitor-users of NRAO telescopes and the number of institutions from which the NRAO visitors come. The significant jump in these last two categories for 1981 reflects the increased use of the VLA. 10 Distribution of Telescope Time by Per Cent 12-meter 140-foot 300-foot VLA 1985 Summary Visitors 50% 61% 45% 58% 54% Students 8% 7% 17% 8% 10% Permanent Staff 10% 17% 7% 8% 10% Research Associates 1% 0% 7% 3% 3% Tests and Calibrations 10% 7% 3% 13% 8% Maintenance and Installation 20% 6% 12% 9% 12% Holidays and Unscheduled 1% 2% 9% 1% 3% 11 Distribution of Scheduled Observing Programs in Various Research Areas, by Percent 12-meter 140-foot 300-foot VLA Overall I. SOLAR SYSTEM -- Sun, Planets, Satellites, and Comets 3% 4% 5% 5% 4% II. STELLAR — Pulsars, X-ray Sources, Planetary Nebulae, 18% 7% 9% 27% 15% Circumstellar Shells, Supernova Remnants, Masers. Novae, Supernovae, and Stars III. GALACTIC Galactic Structure, Center, Molecular 45% 33% 5% 15% 25% Clouds, HII Regions, Star Formation, Molecules, and Interstellar Medium IV. EXTRAGALACTIC — Normal and Active Galaxies, Radio Galaxies, 34% 56% 81% 53% 56% Clusters, Quasars, VLB Studies, Extra- galactic Molecules, and Cosmology 12 Institutions from which Visitors Came to Use NRAO Telescopes during 1985 Telescope Institution 12-m 140-ft 300-ft VLA 1. Anglo Australian Observatory 2. Aerospace Corp. (CA) 3. Alabama, U. of 4. Arcetri Ap. Obs. (Italy) 5. Arizona, U. of - Steward, L & P Lab. 6. Arizona State Univ. 7. Athens, U. of (Greece) 8. Beijing Ast. Obs. (P.R.