NATIONAL RADIO ASTRONOMY OBSERVATORY
1973 I-
NATIONAL RADIO ASTRONOMY OBSERVATORY
HISTORY AND PLANS TABLE OF CONTENTS
Pag;e Observing Hours...... 1
Observing Time Distribution...... ******** *...... 2
36-foot Radio Telescope Summary...... 3
140-foot Radio Telescope Summary...... 4 300-foot Radio Telescope Summary...... 5
Interferometer Radio Telescope Summary...... 6
Full-time Permanent Employees ...... ************. 7...... 7
Number of People Engaged in Research at NRAO...... 8...... 8
Visitor Representation by Institution...... 9 Distribution of Scheduled Telescope Time by Percent ...... 10 Institutions from Which Visitors Came to Use NRAO Telescopes During 1972 ...... 11 Doctoral Theses for Which Major Work Was Done at NRAO...... 14 NRAO Student Program...* * *...... 15 NRAO Summer Student Program...... ,...... 16 Telescopes and Receiver Systems...... 17 NRAO Front-End Boxes...... 18 VLA Performance Data...... ,...... 20 VLA Construction Program...... 22
Millimeter Wave Antenna...... 23 Observatory Report...... 26 Staff and Visitor Publications...... **.**** ...... 32 OBSERVING HOURS
VL A ---
36'-fl TELESCOPE IMPROVEMENTS I ~ti~'////////////////lllllllllllll~'~llI Cr) 85 - 3- z I I~'///////////////////////////////////// z 14 0'-- wL I ~'/////////~'///////////////I/////////// Fz 85-2 - I IEi~'//////////////~'/////////////////// 185-7 300 '-- ~ji~'////////////////llllllllllll~"lllll L I 13j~-//////////////////////////////////I _ 1959 '1960 196111962 I 1963 11964 11965 1966 11967 '1968 111969 1970 1 1971 '1972 11973 1974 1975 11976 11977 1978 1979 L 40
30 0 0 0
20
O0
OL
1303 I9(1 V LE' I (U iy rr I IiTe Ilr1 I('4 ftUr1 IJ 1 lyre FISCAL YEAR CALENDAR YEAR
Fig. 1. The upper figure shows the year in which existing (black) or planned (shaded) telescope systems are incorporated into the NRAO observing program. The lower figure shows the total number of hours of observing time during each year. OBSERVING TIME DISTRIBUTION
300 -FOOT INTERFEROMETER 140-FOOT 36-FOOT
0 0 0 x
Cf) ID 0 -I
1965 1966 1967 1968 1969 1970 1971 1972 1966 1967 1968 1969 1970 1971 1972 1968 1969 1970 1971 1972 FISCAL CALENDAR FISCAL CALENDAR CALENDAR YEAR
- PERMANENT STAFF VISITORS STESTING AND CALIBRATION
Fig. 2. These graphs show the number of hours devoted to calibration and testing and to observing by NRAO permanent staff members and by visitors on each telescope system during each year the telescope has been operative. 36-FOOT RADIO TELESCOPE SUMMARY
wz L
0-L
CALENDAR YEAR
Fig. 3. This summary for each quarter of the calendar year shows the per- centage of time the telescope was scheduled for observing, for routine maintenance and installation of new experiments, and the percentage of time lost due to equipment failure, bad weather, and radio interference. 140-FOOT RADIO TELESCOPE SUMMARY
zF- w C) ELL0
CALENDAR YEAR
Fig. 4. This summary for each quarter of the calendar year shows the per- centage of time the telescope was scheduled for observing, for routine maintenance and installation of new experiments, and the percentage of time lost due to equipment failure, bad weather, and radio interference. 300-FOOT RADIO TELESCOPE SUMMARY
F- L .C) LU 0
CALENDAR YEAR
Fig. 5. This summary for each quarter of the calendar year shows the per- centage of time the telescope was scheduled for observing, for routine maintenance and installation of new experiments, and the percentage of time lost due to equipment failure, bad weather, and radio interference. INTERFEROMETER RADIO TELESCOPE SUMMARY 100
80 z 60 wLU
w 40
20
0
CALENDAR YEAR
Fig. 6. This summary for each quarter of the calendar year shows the per- centage of time the telescope was scheduled for observing, for routine maintenance and installation of new experiments, and the percentage of time lost due to equipment failure, bad weather, and radio interference.
6 FULL- TIME PERMANENT EMPLOYEES 80
LL
LL I- 60 U) - 40 l-0
IL 0 20
0
0
FISCAL YEAR CALENDAR YEAR
400 _ ___~~___
300 i BASIC RESEARCH AND TECHNICAL L- ALL OTHER 200 zzD
100 -'l
0 1957 1958 1959 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 FISCAL YEAR CALENDAR YEAR
Fig. 7. The lower figure shows the total number of NRAO full-time, permanent employees at the end of each year, projected into the future. The upper figure shows the percentage of these employees each year that are in the basic research staff (lower curve) or who are either research or technical (upper curve). NUMBER OF PEOPLE ENGAGED IN RESEARCH AT NRAO 400
350
NUMBER OF INSTI TUTIONS m:; PERMANENT S TAFF 300 EE' E"E-, El RESEARCH ASSOCIATES lillil VIS/ TORS
- - 't,., 250 -- _ '".."- -- ",. .,r cc
CWen :3 200 cos ID 2:- . .. .
"" ""' 150 """'''" "''''' """' ""'''' ""''''' ""' ;t; "" i'"' """' ;r;. . 100 ;;. .;t ;; ; .;t..;, 50 ;;; ..s ::-: ::j:::- -- fi. I ::2~i:-i.-.. -~' ' -I"" ' 0 - ---~- 1959 1960 1961 1962 1963 1964 1965 1966 1967 1969 1970 1971I 1972I 1973ll 1974IL 197511 1976 197711 1978ft 1979 CALENDAR YEAR
Fig. 8. This bar chart shows for each calendar year the size of the NRAO permanent research staff and the number of research associates on one or two year appointments. In addition it shows the total number of visitor-users of NRAO telescopes and the number of in- stitutions from which the NRAO visitors come. VISITOR REPRESENTATION BY INSTITUTION
Domestic Institutions No. Individuals Dome .stic Institutions N 4o. Individuals 1. Maryland (11) 20 23. Florida (1) 2. M.I.T. (8) 20 24. Hampshire 3. Illinois (6) 10 25. Minnesota (1) 4. Cal Tech (2) 9 26. N.B.S. 5. Harvard (4) 8 27. Stanford (1) 6. Massachusetts (3) 8 28. Unaffiliated 7. Smithsonian Ap. Obs. 7 29. Alabama 8. Virginia (4) 6 30. Brandeis 9. Bell Tel. Labs 5 31. Brookhaven Nat'l Lab 10. NASA-Greenbelt 5 32. Columbia (1) 11. NAIC 5 33. Eastern Mennonite 12. SUNY-Albany (1) 5 34. Haystack Facility 13. Berkeley 4 35. Indiana (I) 14. NASA-Inst. Space Studies 4 36. Iowa State 15.. Princeton (2) 4 37. Lockheed Corp. 16. Aerospace Corp. 3 38. N.S.F. 17. Chicago (2) 3 39. New Mexico State (1) 18. Cornell (1) 3 40. Puerto Rico Univ. 19. J.P.L. 3 41. Rochester 20. N.R.L. 3 42. SUNY-Stony Brook 21. Arizona (2) 2 43. Texas (1) 22. D.T.M.(Carnegie Inst.) 2 44. UCLA
Foreign Institutions No. Individuals
1. Max Planck Inst., Germany (1) 9 2. Toronto, Canada (1) 5 3. Chalmers Instit. Tech.,Sweden 4 4. Jodrell Bank, England 3 5. Queens, Canada 3 6. Nat'l. Research Council, Canada 2 7. Queen Mary, England (1) 2 8. Stockholm, Sweden 2 9. Budapest, Hungary (1) 10. Byurakan Ap. Obs.,USSR 11. Pulkovo Obs., USSR 12. Tata Institute, India
Note: Numbers of students are shown in parentheses. 9 Distribution of Scheduled Telescope Time By Per Cent
140-ft 300-ft 36-ft Interferometer 1972 Summary
Visitors 61% 49% 64% 41% 52.4%
Students 11 19 10 12 13.3
Permanent Staff 15 14 16 24 17.7
Research Associates 8 16 4 14 11.4
Test Time 4 1 6 9 5.2 INSTITUTIONS FROM WHICH VISITORS CAME TO USE NPAO TELESCOPES DURING 1972
Telescope
Institution 36-foot Interferometer 140-foot 300-foot
1. Aerospace Corp. X X 2. Alabama X 3. Arizona X X 4. Bell Telephone Laboratories X X X 5. Berkeley X X X X
6. Brandeis X 7. Brookhaven National Lab X 8. Budapest, Hungary X 9. Byurakan Ap. Obs., USSR X X X X 10. Calif. Inst. of Tech. X X
11. Chalmers Inst. Tech., Sweden X 12. Chicago X X X X 13. Columbia X X 14. Cornell X X 15. Dept. Terrestr. Magnetism, Carnegie X
16. Eastern Mennonite X 17. Florida X X X 18. Hampshire X X 19. Harvard X X 20. Haystack Facility X
21. Illinois X X X 22. Indiana X X 23. Iowa State X 24. Jet Propulsion Lab X X 25. Jodrell Bank, England X X
11 Telescope
Institution 36-foot Interferometer 140-foot 300-foot
26. Lockheed Corp. X 27. Maryland X X X X 28. Massachusetts X X X 29. Mass. Inst. of Tech. X X X 30. Max Planck Inst., Germany X X X
31. Minnesota X X 32. NASA-Goddard (Greenbelt) X X X X 33. NASA-Goddard (NYC) X 34. National Astronomy and Ionosphere Ctr. X X X X 35. National Bureau of Standards X X
36. National Res. Council, Canada X X 37. National Science Foundation X X 38. Naval Research Lab X X X 39. New Mexico State X 40. Princeton X X
414 Puerto Rico, Univ. X 42. Pulkovo Obs., USSR X 43. Queen Marvy, England X 44. Queens, Canada X 45. Rochester X
46. Smithsonian Astrophys. Obs. X X 47. Stanford X 48. Stockholm, Sweden X X 49. SUNY, Albany X X X 50. SUNY, Stony Brook X
12 Telescope
Institution 36-foot Interferometer 140-foot 300-foot
51. Tata Institute, India X 52. Texas X 53. Toronto, Canada X X 54. Unaffiliated Scientists X X X 55. UCLA X
56. Virginia X X X X
No. Institutions 26 25 39 23
No. Visitors 44 52 83 34 No. Students 10 16 23 14 No. Research Associates; 2 8 7 7 No. Permanent Staff 7 13 10 6
Total Observers : 63 89 123 61
13 DOCTORAL THESES FOR WHICH MAJOR WORK WAS DONE AT NRAO
Cr uJ cro z
1969 1970 1971 CALENDAR YEAR
Fig. 10. This bar chart shows the number of doctoral dissertations pro- duced each calendar year by Ph.D. students where the major work on the theses was done at the NRAO.
14 NRAO STUDENT PROGRAM
wL 50
40
30
20
10
O- 1959 CALENDAR YEAR
Fig. 11. This figure shows for each calendar year the number of Ph.D. students (salaried and non-salaried), co-op students, and summer undergraduate and graduate students who observed or worked at the NRAO during that year.
15 N R AO SUMMER STUDENT PROGRAM
Argentina - / Egypt - / Germany - / Germany - / Mala/asia - / South Africa - / Netherlands - / Hong Kong - 7 Mex/co - / South Vietnam - / South Africa - / /nd/a - / Netherlands - / Sweden - 4 Sweden - 4 /ta/y - 2 Nigeria - / Ta/wan - 2 United Kingdom - 4 Korea - / Puerto Rico - / United Kingdom - 4
Home States College-University Affiliation
Fig. 12. This figure shows the total number of graduate and undergraduate students by home state or country and by college location who did summer work at the NRAO since the beginning of the summer student program in 1959. Telescopes and Receiver Sysems
T system X cm (°K) Bandwidth 36-ft 140-ft 300-ft Interf.
0.25 - 0.4 1500 100 MHz X 0-,.3 4000 1 GHz X 0.35 1500 1 GHz (X) 0.3 - 0.45(line) 4000 100 MHz X 0.60 - 0.90 1500 100 MHz X 0.65 150 i00 M1Hz (X) 0.95 1100 400 MHz X [X] 0.95 1500 100 MHz X [X] 1.35 (line) 600 50 lz X X 1.7 - 2.5 (line) 1500. 200 11Hz 1.95 1200. 2 GHz X x 2.05 100 500 MHz 3 - 6 (line) 400: 50 MHz x 3 75 300 MHz X 3 and 11 100 30 X MHz X 6 90 200 MHz x 6 70 300 MH z 11 50 250 MHz (X) (X) 11 (3 beam) 120 50 X 7.5 - 30 (line) 100-300 45- MHz x X 18 (line) 150 20 l.._11Hz z X X 18 70 50 MHz x X 21 (line) 120 60 x X 21 (4 beam) 150- 60 MHz X 21 50- 50 MHz x X 30 - 60. 150 20 M Hz (x) (x) 40. 500 90 MIHz [X] x
50 170 4 MHz [X] X
75 400 8 .IHz X 60 - 150 400 300 MHz X 120 400 3 MHz X 200 400 100 1-Hz X 300 - 30 300-600 Octave X
Key: X Avai lab le (x) On order or planned December 1972 [X] Available, not optimum 17 NRAO FRONT-END BOX STATUS
Technical Data Sheet No. 12 NovemDer l972 Page 1 of 2
Person Applicable Frequency Amplifier System Bandwidth Feed Calibration Temperature Polarization Switching System Remarks Telescope (MHz) Type (K)(MHz) Type Value in ("K) Charge
300' Tuned Simultaneous Adjustable No Dicke switch. Designed for pulsar and line work. 110-500 MHz Brundage ° ° ° Fixed 50-80 > 350 30 Crossed- 0 , 45 , 90", 50* to Total power or fre- feeds can be rotated 90" for polarization work. ° on Dipole 135* Linear, 2000 . quency switching. Usable with 4-channel multi-bandwidth receiver and Travel- Broadband RCP and all NRAO line receivers. ° ing 110-250 Transistor - 200 140 Crossed- LCP. Feed Dipole Broadband 250-500 >200" 250 Broadband Crossed- Dipole
140/300' 500-110 Paramp Ch X 100° 20 Broadband Single Linear- 10 °K or Frequency switching. Traveling feed box for 300' can be used on 140' as Brundage Crossed- all frequencies. 100 OK Load switch can be clip on. Available Feb. 1973. Multiple polari- 610-740 Paramp Ch Y Dipole Dual Linear- installed. zation with IF polarizer on 300' at 610 MHz. 610 MHz. 140/300' 740-880 Paramp Ch X 100" 20 Broadband Single Linear- 10 'K or Frequency switching. Traveling feed box for 300' can be used on 140' as Brundage Crossed- all frequencies. 100 OK Load switch can be clip on.. Available Feb. 1973. Multiple polari- 835-1000 Paramp Ch Y Dipole Dual Linear- installed. zation with IF polarizer on 300' at 835 MHz. 835 MHz. ° 140' 100 to Transistor 300 to Limited by Tunable Dual Linear 50 "K Frequency. ° Line work and VLB. Balister 1000 500 feed to 5 Dipole 300/140' 1400 x 4 Paramp 150" 60 Linear ° 4 Horns 4 "K and 300 load or fre- Line or continuum from control room. Fleming Scalar Dual Linear 15 "K quency switching.
140/300' 1420 Paramp 120 60 ° Horn Linear 10 K Freq./load switching. Simultaneous operation; both feeds on axis. 750 Transistor Fleming 600 20 Dipole Load switching.
° ° 140/300' 1410 Dual Cooled 50 25 Scalar Dual Linear t 5 Frequency switching. Paramps independently tunable over 1375-1435 MHz . Fleming Channel Param Total power. ° 140/300' 1610-1720 Cooled 60 30 Scalar Dual Linear 4 "K Normally frequency Can be remotely tuned anywhere in frequency range Dual Paramp switched. Can be 1610-1720 MHz. Two channels can be used simul- Channel polarization taneously at different frequencies. Six polarization s Moore switched, are available simultaneously with IF polarimeter. Will tune 1540-1780 with higher noise temperature outside range 1610-1720 MHz.
° ° 140/300' 1000 to Paramp 270 30 1-2 GHz Linear 10 "K 300 load or fre- Tuning over a 200-400 MHz range is from control Payne 2000 Scalar quency switching. room. Larger frequency changes require paramp ° 140/300' 2000 to Paramp 270 to 30 2-4 GHz Linear 10 "K 300 load or fre- module change approximately 2 hours. Box, includ- ° 4000 350 Scalar quency switching. ing feed, changed at 2000 MHz. Control room equipment will drive either. Change time approxi- Payne mately 4 hours. Any 2295 Paramp 100" 50 Horn Circular 10 "K None. Packaged in small temperature-stabilized box. Can Payne be installed on other telescopes with little effort. ° 140/300' 2695 x 4 Degenerate 120" 100 3 Horns Dual Circular 4 "K 300 load or Continuum receiver. On-axis horn has paramps on Fleming Paramp DSB or Dual Linear polarization, both polarizations. 140/300' 2695 Paramp 200" ° 40 TRG Dual Linear 3 "K 300 load sky horn, Choice of switching system from control room. Scalar other polarization. Behrens
18 NRAO FRONT-END BOX STATUS
No. 12 Technical Data Sheet Page 2 of 2 November 1972 Person System Bandwidth Feed Calibration Applicable Frequency Amplifier Temperature Bandwidth Feed Polarization Calibration Switching System Remarks in Telescope (MHz) Type (MHz) TValue Charge
° Feed change requires 3 hours. Dual horns are used 140' 4750-5100 AIL 80 line 225 TRG Dual Linear 4 'K Any two of: be mounted off-axis Behrens Cooled Scalar or Orth. Linear 60 "K load, sky for beam switching. A horn can is high, approxima - Paramp 135 2 Horns horn, other beam. to scalar feed, but beam spacing tely 30'. ° Two feed arrangements are available: (1) Scalar Behrens 140' 4500-5200 TRG 70 Scalar 400 2 Horns Orth. Linear 5 'K Other beam or Cooled Feed or 25 °K load and (2) dual horns for beam switching ° Paramp 100 Horns Scalar ° Packaged in small temperature-controlled box. Can Payne Any 4600-5100 Paramp 150 20 Horn Linear 10 'K None. be installed on other telescopes with little effort.
° in 2 bands about 7 GHz. Moore 140' 5.2-10. 4 Paramps 300 to 40 Horn Linear 20 "K Frequency switching. Set of 7 tunable paramps ° Band change 3 hours. GHz 400 Paramp change 1 1/2 hour. ° Packaged in small temperature-controlled box. Can Any 10,695 Paramp 250 20 Horn Linear 10 'K None. Payne be installed on other telescopes with little effort.
° Behrens 140' 10,300- TRG Cooled 100 300 2 Horns Orth. Linear 5 "K Other beam or Two feed arrangements available: (1) Scalar and 11,000 Paramp or Scalar 25 'K load. (2) dual horns for beam switching. ° Moore 140' 14.4-14.9 Paramp 70 500 2 Horns Orth. Linear 5 "K Correlation, dual Under development. Available November 1972. Dual Ch. or Scalar Dual Circular beam or polarization. ° 140' 15,400- TDA 1100 3 GHz Horns Linear 17 "K Beam or Can be installed on 140' telescope in front of existin g ° Dolan 5000 TDA 1100 400 Horns Linear 8 'K load switching. box in 2 hours. Box may be removed in a similar time, allowing lower frequency programs to continu e when weather is too bad for 15 GHz observations. ° Dolan 36' 15,375 TDA 1600 2 GHz 2 Horns Parallel 5"K Other beam or Original 2 cm receiver repackaged in 36' box. Linear sky horn. ° 12. 4-18 TDA' s 1000 50 Frequency switching. Contains LO system tunable 12.4 - 18 GHz. on GHz (1 GHz continuum) Tunnel diode amplified continuum receiver Balister 140' 14.4Horn14. 4-14. 9 Horn OrthOrth. Linearinear 10 KK Load switching orthogonal polarization (used for pointing). GHz Paramp 500' 70 continuum. ° 36/140' 22-24 Degenerate 300 100 Horn Linear 20 'K Load, beam, or Stabilized LO system. Cochran GHz Paramp DSB DSB frequency. ° 36' 31-50 Mixer 1500 100 Horn Linear 250 "K Chopper wheel or Line receiver. Ross GHz SSB frequency. ° 36' 31.4 Mixer 1100 400 2 Horns Variable 28 oK Other beam or load. Ross GHz DSB ° 36' 45. 6 Degenerate 150 1000 Horn Linear 10 'K Beam, load. Under development. Estimate completion Weinreb GHz Paramp DSB DSB August 1973. ° 36' 85 Mixer 4000 1 GHz 2 Horns Variable 28 OK Other beam or load. Single horn mechanically position-modulated or Ross GHz DSB ferrite switch. ° 36' 85 Mixer 4000 100 Beam Linear 30 "K Beam or frequency. Stabilized LO for line work. Can be used with Ross GHz SSB Switch some difficulty over the 67-101 GHz range. Cassegrain system under development. ° 36' 85 Mixer 1500 1 GHz Horn Linear -- Nutating Available February 1973. Kerr GHz DSB subreflector ° 36' 75-120 Mixer 1500 100 Horn Linear --- Chopper wheel Under development. Four plug-in front-end plates. Kerr GHz SSB or frequency. 85-95 GHz. Available December 1972.
19 VLA PERFORMANCE DATA
The VLA performance given in Table I is based on an array consisting of 27
antenna elements, each 25 m diameter, distributed along three arms of a wye. Each arm of the wye is 21 km long. The distribution of antenna elements is not sym- metric, nor is the distance between elements equal. The positions of the antenna
elements have been optimized for best performance (low sidelobes) over the sky above -15 ° declination.
The basic VLA operates at one frequency only (6.3 cm), but both circular polarizations are available.
The addition of equipment will extend this capability to other frequencies. Then one polarization at each of two frequencies, or both polarizations at one of the frequencies, will be available simultaneously.
Table I shows the basic performance specifications for the VLA. The reso-
lution and the fields of view given in the table correspond to the maximum reso- lution available with 21 km arms. There will be a total of 100 stations available which will permit operation at a total of 4 different resolutions.
20 TABLE I
Field of View Maximum Side- at Maximum lobe Within Mean Distant System IF Sensitivity f A Resolution Resolution Field of View Sidelobe Temperature Bandwidth 12-hour Tract 2 (GHz) (cm) (arc sec) (arc sec) (dB) 1 (dB) (°K) (MHz) (W m- 2 Hz - 1
1.50 20.0 2 240 -15 -30 - 35 75 6x10 - 3 1
4.75 6.3 0.6 72 -15 -30 40 75 7x10 -3 1
14.90 2.0 0.2 24 -15 -30 200 75 4x10 - 3 0
22.50 1.3 0.13 15 -15 -30 250 75 5x10 - 3 0
1 At declinations above -15 °
2 About 5 times the rms noise level
21 Very Large Array (VLA) Construction Program
CY 1973 (First Year) CY 1978 (Sixth Year)
Detail Design and Procure Prototype Add 5 Antenna Systems (18 Total) Antenna System Add 5 Miles of Track (24 Total) Acquire VLA Site
CY 1979 (Seventh Year) CY 1974 (Second Year) Add 5 Antenna Systems (23 Total) Build and Evaluate Prototype Add 2 Miles of Track (26 Total) Design and Procure Site Facilities
Design Track System CY 1980 (Eighth Year) Add 4 Antenna Systems (27 Total) CY 1975 (Third Year) Add 7 Miles of Track (33 Total) Procure 4 Antenna Systems
Complete Site Facilities CY 1981 (Ninth Year) Construct 5 Miles of Track Add 6 Miles of Track (39 Total) Phase. Into Full Operation CY 1976 (Fourth Year)
Add 4 Antenna Systems (8 Total) CY 1982 (Tenth Year)
Add 8 Miles of Track (13 Total) Full Operation Start Partial Operation
CY 1977 (Fifth Year) Add 5 Antenna Systems (13 Total)
Add 6 Miles of Track (19 Total)
22 65-meter Telescope Design Specification
Dish diameter 65 meters (213 feet)
Mounting Altitude-Azimuth Sky cover Complete--but no tracking inside a small zone near zenith
*RMS surface accuracy 0.22 mm (0.009 inches)
*Short wavelength limit 3.5 mm (86 GHz) *Tracking accuracy 3 arc seconds RMS
Slew rates (both axes) 200 per minute
Optics Prime focus f/D = 0.42 Cassegrain--subreflector diameter 3.7 m (12 feet) Instrument cabins Behind prime focus: behind Cassegrain focus Equipment room Rotates in azimuth
*This performance is only possible under benign environmental conditions.
23 65-meter Telescope Cost Estimate (1974 dollars)
Thousands of $
Fabrication of reflector and tower structure, including counterweight 1,657
Fabrication of intermediate structure 496
Erection of complete telescope 1,213
Surface plates, installation and adjustment 1,730 Azimuth, trucks, gear boxes and motors 382
Pintle bearing 56
Elevation bearings 107 Elevation gear, gear boxes, drive motors 213
Foundation and track 164
Feed and subreflector supports, subreflector instrument cabins 281
Optical position reference system 517
Servo control system 562
Telescope control computer, including software 225 Ladders, walkways, hoists, cable trays 47 Telescope cabling 112
Painting, start-up and test 225
Site preparation 712
Project management and engineering 505
9,204
Add 15% contingency 10,585
24 65-meter Telescope -- Operating Cost Estimate (1974 dollars)
Totals $ On-Site Personnel
Site manager, administrative assistant, clerk, secretary 4 55k
Electronic engineer (3) and electrical/mechanical 4 67k
Technicians, electronic (3) and computer (1) 4 45k
Telescope operators 6 67k Telescope mechanics 2 22k
Programmer 1 17k
Laborers/handymen/driver 2 14k Guards (night only) 2 14k
Housekeeper/cook 1 6k Part-time, temporary, overtime -- 10% 31k
TOTALS 26 338k
Salaries of on-site personnel 338k
Benefits, 15% 51k Travel 17k
Utilities--telephone 5k; power 15k 22k
Materials, services and supplies -115k
One-third cost of painting telescope (paint every three years) 36k
TOTAL ANNUAL OPERATING 579k
25 OBSERVATORY REPORTS
National Radio Astronomy Observatory, Charlottesville, Virginia, Green Bank, West Virginia, and Tucson, Arizona.
This report covers the period July 1971 through June visitors, including 46 students, observed on NRAO tele- NRAO-sponsored symposia on Interstellar Molecules 1972. scopes. They came from 53 different institutions. The and High Velocity Clouds were held in the fall of 197 1. following table summarizes, by telescope, the numbers I. FACILITIES of visitors, students, and NRAO permanent staff who V. PERSONNEL observed on each instrument, as well as The National Radio Astronomy Observatory is funded the number of Additions to the NRAO scientific staff included D. different institutions from which they came: by the National Science Foundation under a management C. Backer, P. L. Baker, B. Balick, J. R. Fisher, R. H. contract with Associated Universities, Inc. The NRAO Tele- Visi- Stu- Gammon, P. J. Napier, and G. S. Shostak as Research facilities are available to any qualified scientist or grad- NRAO Total No. of scope tors dents Staff Inst. Associates. Visiting appointments were made to P. uate student, and visitors are assigned at least 60% of the Brosche (Heidelberg, W. Germany), C. A. Gottlieb observing time on the telescopes for research programs, 36-ft 46 9 10 65 27 (Harvard), and H. M. Tovmassian (Byurakan Observatory, which they may conduct independently or cooperatively Interfero- 36 13 8 57 19 USSR). C. Bignell (Canada) joined NRAO on an NRC with staff members. meter Fellowship. Leaving NRAO during this period to take The major Observatory telescopes include a 300-ft positions elsewhere were M. M. Davis, J. J. Broderick, meridian transit telescope, a 140-ft fully steerable tele- 140-ft 74 30 10 114 33 S. T. Gottesman, R. N. Manchester, E. H. Tademaru, and scope, a three-element interferometer consisting of 85-ft 300-ft 30 12 5 47 16 J. F. C. Wardle, while F. Biraud (Meudon, France), P. telescopes that can operate in conjunction with a remote Brosche (Heidelberg, W. Germany), C. A. Gottlieb (Har- portable 42-ft antenna, and a 36-ft millimeter-wave an- Ten co-op students and 28 undergraduate and grad- vard), C. E. Heiles (Berkeley), T. K. Menon (Tata Insti- tenna located on Kitt Peak in Arizona. Receivers are uate students worked at NRAO on the 1971 summer tute, India), H. S. Murdoch (Sydney, Australia), and available for observing programs that cover the wave- student program. On 31 December 1971, there were 231 T. Nakano (Kyoto, Japan) returned to their respective length range from 3 mm to 3 m. Autocorrelation and full-time, permanent employees, of whom 15 were on the institutions. K. J. Gordon (Hampshire) and J.F. C. War- multichannel receivers are available for studies that re- permanent scientific staff in the basic research group, die (Brandeis) held summer appointments to the scientif- quire frequency discrimination. Each telescope is equip- 10 held research associate appointments, and 27 were ic staff that were assigned to recent recipients of the ped with on-line computers that provide telescope control structural, mechanical or electronics engineers. Ph.D. whose primary academic-year appointments involve and real-time data analysis. Data are recorded on mag- Visiting colloquia were delivered by R. S. Booth, teaching. netic tape for further processing by general purpose com- W. N. Brown, Y. L. Chow, P. S. Conti, R. D. Davies, T. Williams, Head of the Green Bank Plant Mainten- puters, an IBM 360/50 located in Charlottesville and N. H. Dieter, J. E. Felten, F. F. Gardner, J. Heidmann, ance Division, retired and was succeeded by D. D. Mad- a CDC 6400 located in Tucson. C. E. Heiles, J. G. Hills, G. R. Knapp, H. van der Laan, ron. J. W. Hawkins resigned as Head of the Green Bank Visitors from other institutions may apply for ob- S. Mitton, V. Radbakrishnam, K. W. Riegel, S.E. Strom, Administrative Services Division. J.Marymor returned serving time by writing to the Director, National Radio J. H. Taylor, R. B. Tully, W. J. Welch, G. Wynn-Williams, to NRAO as Contracts Manager. Astronomy Observatory, Edgemont Road, Charlottes- N. J. Wolff, G. T. Wrixon, H. Eichhorn von Wurmb, and ville, Virginia 22901. The NRAO will send to any po- A. Yahil. VI. RESEARCH PROGRAMS tential observer, on request, information sheets that IV. JANSKY LECTURESHIP; COMMITTEES; give brief descriptions of each major telescope, receiver, The following section is a brief summary of resident feed, and computer system, that provide a general SYMPOSIA staff, students, and visitor scientific activity. Visitor familiarization with Observatory procedures and that The sixth annual Karl G. Jansky Lectureship was activities will usually be found in more detail in the advise how to prepare an observing proposal. awarded to Charles H. Townes, University Professor of Reports of their own institutions. the University of California at Berkeley. Townes II. NEW INSTRUMENTATION delivered the lecture entitled "Exploring for the Crea- A. Solar System Two new receiver front-ends are now available. One tion" in October 1971. The Jansky Lectureship, es- 1. Solar Studies: The Stony Brook observers M. tablished is a dual-channel cooled parametric-amplifier system op- by the AUI Trustees in 1966, is awarded an- Simon and P. Berger searched for solar recombination nually to an outstanding erating in the 1350-1430 MHz range and providing a scientist, usually chosen for lines at 85-95 GHz on the 36-ft telescope. F. Shimabuk- 0 his contribution 70 K system temperature on the 140-ft or 300-ft tele- to astronomy. It is named in honor uro (Aerospace) searched for solar recombination lines of Karl G. Jansky, scopes. The second is a mixer receiver which provides who pioneered the field of radio as- at 109-115 GHz and undertook a study of 300-sec solar tronomy. 15000 single-sideband receiver temperature over 33-50 oscillations at 85 GHz. Together with E. Mayfield (Aero- The six-man NRAO GHz; this front-end will be used for spectral-line obser- Visiting Committee, appointed space), and S. Edelson (NASA-Ames), Shimabukuro in- vations at the 36-ft telescope. A new 50-channel, 1.2 by the AUI Board of Trustees to review the management vestigated nonthermal processes in solar active regions and research MHz per channel filter bank receiver has been com- programs of the Observatory, consisted at 31 GHz. Using the dual-frequency NRAO interfero- of the pleted for use at the 36-ft telescope. Equipment has following individuals between October 1971 and meter, studies of the structure of solar active regions been added to the 140-ft and 300-ft telescopes to facili- October 1972: C. H. Mayer (Chairman), A. T. Moffet, were made by W. Webster, R. Hobbs, and S. Jordan (all L. Woltjer, tate the frequency-shifting, monitoring, and distribution H. van der Laan, H. C. Ko, and W. J. Welch. NASA-Goddard). Using the 36-ft telescope, M. Kundu of IF signals. The NRAO Users' Committee, which meets twice (Maryland) and D. Gergely (Maryland) observed solar The Observatory has completed the development of each year to advise the NRAO Director and staff on the prominences, and the brightness and polarization distri- a laser distance measuring instrument for use in survey- future needs for instrumentation and facilities, consisted bution in solar active regions at 85 GHz. Two observers ing the surface of large paraboloids. The instrument can of the following members on 30 June 1972: A. Barrett, from the Crimean Astrophysical Observatory, USSR, I. -4 B. Burke, W. Dent, measure up to 60 m with an rms accuracy of 10 m in J. Dickel, J. Douglas, F. Drake, W. Moiseev and V. Efanov, undertook observations of the a measuring time of 2.5 sec. Erickson, S. Goldstein, C. Heiles, D. Jauncey, F. Kerr, circular polarization of the quiet Sun and active regions H. C. Ko, M. Kundu, A. E. Lilley, C. Mayer, P. Palmer, at 85 GHz. III. VISITORS, STUDENTS, AND STAFF K. Riegel, A. Smith, L. Snyder, G. Swenson, J. Taylor, 2. Solar Wind and Interplanetary Scintillation: D. De P. Thaddeus, A. R. Thompson, J. Warwick, G. Westerhout, Young and A. J. Hundhausen (High Altitude Observa- From 1 January through 31 December 1971, 175 D. Williams, R. Wilson, and B. Zuckerman. tory) have calculated the propagation of flare-associated 26 disturbances in the solar wind. city clouds. The Maryland observers, F. Kerr, W. Sullivan, of the OH in dust clouds associated with H II regions D. Backer, G. Zeissig (San Juan), and R. Lovelace and G. Kaplan, observed high-velocity I-tl clouds and are now being reduced. (Cornell) conducted single-epoch, multifrequency ob- studied an unusual feature found in one of the high-velocity b. Special Studies: servations of the interplanetary scintillations of 3C 279 clouds in Hulsbosch's Complex A. Observations of high- (1) Clouds. B. Turner has detected OH in regions and 3C 273 with the 140-ft and Arecibo telescopes to velocity cloud A were made by R. Davies ( Jodrell Bank) of unprecedented low optical extinction (1 to 5 mag) investigate the irregular spectrum in the solar wind. and D. Buhl on the 140-ft telescope. The Maryland ob- that are several square degrees in size. C. Heiles and M. 3. Planets: The following programs were carried out servers F. Kerr, G. Knapp, and D. Ball used the NRAO Gordon investigated the distribution of OH, H, and The observations on the NRAO interferometer. Observations at 1410 MHz interferometer to make 21-cm observations of continuum H2 CO in the dark cloud in Taurus. were undertaken by J. Basart (Iowa State), G. Wrixon sources in the directions of high-velocity clouds in a were all made with identical beam sizes. (Bell Laboratories), and D. Buhl to measure the polar search for hydrogen-line absorption. A. Barrett (MIT) and P. Myers (MIT) mapped three heating of Venus. In separate programs, F. Drake (Cor- c. Special studies: W. M. Goss and A. Winnberg galactic dark clouds at the 1667-MHz OH line fre- nell) and F. Briggs (Cornell) made observations at 1420 (both MPI, W. Germany) used the NRAO interferometer quency that are known to contain OH and H 2 CO MHz to study Mars, Jupiter, Saturn, and Mercury, and to measure Ill absorption in local gas in front of about molecules. brief observations of Neptune and Uranus, and observed 70 sources. The Maryland observers, G. Westerhout, (2) IR stars and stellar objects. The 18-cm OH the major satellites and thermal features of Jupiter at R. Harten, and G. Mader calibrated the Maryland-Green emission from 36 infrared stars was monitored on the 8085 MHz. E. Olsen (JPL) studied the structure and Bank 21-cm line survey by taking 1I1 observations at 140-ft telescope by J. Ball (Harvard), K. Bechis (MIT), polarization of Jupiter. constant latitude on the 300-ft telescope. D. Cesarsky W. Wilson (Aerospace), and P. Schwartz (NRL). D (Caltech) and E. Chaisson (Harvard) undertook a study Dickinson (Smithsonian) and E. Chaisson (Harvard) B. GALACTIC STUDIES of recombination line emission at 1683 MHz originating attempted to detect far infrared sources in the 18-cm in neutral hydrogen regions. G. Knapp (Maryland) made OH line on the 140-ft telescope. A search for weak 1. Hydrogen Line Studies and the Interstellar Medium a series of high-frequency resolution maps of Il i distribu- 18-cm OH emission in the direction of several globular a. HI distribution: W. B. Burton and G. Ver- tion in dust clouds. Knapp and CG.Verschurr mapped a clusters was made by the Maryland observers G. shuur completed a survey with the 300-ft telescope of number of cold hydrogen emission clouds at 21 cm. Knapp and F. Kerr to determine OH-to-dust ratios. hydrogen associated with spiral arms extending to large In collaboration with C. Heiles (Berkeley), G. Knapp (3) 6-cm OI. B. Zuckerman (Maryland) and P. Palmer (Chicago) = z-distances. G. Wrixon (Bell Laboratories) collaborated observed HI in dust clouds and measured the beam observed the 27r3/ 2 J 5/2 state of in this investigation by observing a selected region with efficiency of the 300-ft telescope. OH at 6.017, 6.030, 6.049, and 6.065 GHz on the 140- the 20-ft horn of the Bell Telephone Laboratories. Bur- The Maryland observers, F. Kerr, W. Rose, and G. ft telescope, searching for broad emission in Sagittarius ton utilized 21-cm line profiles' extreme sensitivity to Knapp, searched for 21-cm neutral hydrogen in globular B2. velocity variations to derive the kinematic structure of a clusters, and Knapp, Kerr, and P. Bowers (Maryland) in- (4) Other work. P. Palmer (Chicago), C. Gottlieb region of the Milky Way. His kinematic method is being vestigated a peculiar Ill feature near Messier 92. F. Kerr (Harvard), and B. Zuckerman (Maryland) searched on applied to a larger region of the galaxy. A comparison and G. Knapp continued their program to derive a catalog the 140-ft telescope for the four hyperfine split lambda is being made between the radio and optically derived of H i profiles in directions towards the Kapteyn Selec- doublet values for the V=1 state of OH. The same three ted Areas. A. Milman (Maryland) studied the 21-cm observers in collaboration with H. Radford (Smithsonian) galactic kinematics by Burton and T. Bania (Virginia). Il 1 W. B. Burton and P. Baker identified characteristics of distribution in L134 and L1547/L1 552 in a series of de- searched for the O" H molecule at 1624 and 1625 MHz, tailed mapping and high-velocity 018 16 neutral hydrogen observations attributable to saturation resolution studies. the molecule at 1639 MHz, and the 0 H molecule effects, and are analyzing these characteristics in terms E. Grayzeck (Maryland) observed hydrogen-line profiles at 1667 MHz in the external galaxy M82. Polarization of the distribution of temperature in the neutral toward positions of hot luminous stars and x-ray studies of the main 1667-MHz OH lines in ten weak hydrogen gas. Burton and M. True (Indiana) examined sources. sources were made by D. Dickinson (Smithsonian) and the response of 21-cm profiles to varying the basic galac- d. Continuum structure and the interstellar medium: B. Turner. A pumping model for Type I anomalous OH tic rotation curve at distances from the galactic center During the past year, R. Brown has considered the im- emission has been completed by B. Turner, W. Gwinn greater than that of the Sun. portance of charge transfer reactions in determining the (Berkeley), G. Blackman (Berkeley), and W. M. Goss The Maryland observes R. Harten and G. Mader ionization equilibrium of atomic species in the interstellar (MPI, W. Germany). took a series of 300-ft H I scans to compare and aid in gas. Particular emphasis has been placed on processes combining data taken in the northern and southern affecting the relative calcium and sodium abundances. 3. Supernova remnants, StellarRadio Astronomy G. Westerhout (Maryland) undertook a 300-ft program hemispheres. Together with G. Knapp (Maryland), G. a. Supernova Remnants; M. Kundu (Maryland) Verschuur mapped all the physical parameters in two to measure the polarization of the galactic background at 1400 and 2695 MHz. and T. Velusamy (Maryland) undertook a series of mea- localized cold -lI clouds using the 140-ft telescope. surements at 6 and 11-cm on the 140 and 300-ft tele- Further high-resolution observations were made by scopes in order to measure the polarization and fluxes Verschuur with the 300-ft telescope to map 20 2. OH Studies of known and suspected supernova remnants. In a high-velocity clouds in collaboration with R. Giovanelli a. Survey work: B. Turner has continued his similar program the Illinois observers, J. Dickel, A. and T. Cram. galactic OH survey. The study of the correlation with Willis, and W. Boughton searched for 6- and 11-cm P. Baker has analyzed hydrogen-line emission profiles H2 CO, continuum sources, and other molecules is con- recombination lines and made polarization measurements to show the extent of cold, optically thick HI layers tinuing, and will involve the examination of galactic in a number of supernova remnants. The study of H I whose detection is complicated by the similarity of the radiation around the supernova structure derived from both OH and H2 CO observations. remnant HB21 was spin temperature and background emission temperature. A study of the satellite lines of the OH1emission sources carried out by G. Assousa (DTM) and J. Erkes (SUNY, In addition, examples of kinematic disturbances in the found in B. Turner's survey has been continued by Albany). Using the 300-ft telescope, D. Williams interstellar medium are being tabulated by Baker to find Turner and D. Dickinson (Harvard) using the 85-ft Agassiz (Berkeley) observed at 21 cm to study ionization holes their frequency of occurrence and a qualitative classifi- Station telescope. around supernova remnants and the absorption spectra cation scheme. Observations of OH absorption in front of strong of the associated sources. At the OH-line frequencies b. High-velocity clouds: G. Veschuur undertook galactic sources have been made by E. Fomalont, W. M. 1667 and 1720 MHz, T. Wilson (MPI, W. Germany) an observing program on the 300-ft telescope at 21-cm Goss (Bonn, W. Germany), and 1. Lockhart (Caltech). observed supernova remnants with the 140-ft telescope. wavelength to map several high and intermediate velo- Observations to determine the brightness distribution b. Novae, x-ray stars, stars: The MIT observers
27 B. Burke, J. Spencer and G. Murthy monitored the W3 at high resolutions. The H93ca-line (v = 8045 MHz) in the interstellar emission from Sco X-l using the NRAO interferometer. medium in the direction of pulsars. was observed on the NRAO interferometer. The The Maryland observers R. Hjellming and C. Wade used the interferometer to M. Kundu and T. Velusamy data are now being analyzed. observed at 2695 MHz detectradio emission from two eclipsing binaries, i3 on the 300-ft telescope to Harvard observers A. Dupree and search Persei (Algol) and 3 Lyrae. E. Chaisson obser- for weak extended sources in the direction of ved the a and ( recombination lines of carbon A survey by B. Balick of 32 0, B, and Wolff-Rayet in NGC pulsars that are known to have long periods. '024 and W3 at 2704 and 2726 MHz on the stars on the NRAO interferometer failed to detected 140-ft tele- 7. Other Line Studies scope. Observations at 6-cm unresolved radio sources coincident with any of the wavelength of the H O09a recombination a. H CO (Formaldehyde): M. Gordon and B-. stellar positions. line in eight sources in the Cyg X region, 2 and a 6-cm recombination line search in the diffuse in- Hoglund (Chalmers, Sweden) attempted to map large H. Tovmassian (Byurakan, USSR) observed AE Cap- terstellar medium were undertaken on the 140-ft tele- sections of the galactic plane by searching for H CO ricorni at 20 cm to test whether its radio characteristics 2 scope by Y. Terzian (NAIC) and A. Parrish (NAIC). absorption against the microwave background. P. ate similar to BL Lac, which is optically similar. W. Harvard observers E. Chaisson and L. Goad searched Solomon and N. Scoville (both Minnesota) mapped Wilson (Aerospace) and P. Schwartz (NRL) took 36-ft at 18-cm wavelength for H, He and C along the line of the distribution and excitation of the 4830-MHz for- observations of HCN, CO, CN, and X-ogen in late-type maldehyde line sight toward K3-50. Chaisson and J. Ball (Harvard) in- in the large molecular cloud associated stars. Using the dual-frequency interferometer, J. vestigated an anomalous recombination line near 1683 with NGC 2024, mapped W3 and W3 OH, and observed Broderick (NAIC) and E. Fomalont attempted to detect MHz in the direction of W3 and DR 21. dark clouds and continuum sources to determine a quan- emission irom the globular clusters M3, M13, and M15. titative relation M. Gordon and T. Cato (Chalmers, Sweden) mapped between the strength of the H2 CO line Two observers from SUNY, Albany, J. Erkes and A.G.D. and interstellar recombination line radiation from diffuse interstellar gas extinction. T. Wilson (MPI, W. Germany) Phillip, searched for thermal radiation from globular over a large section of the plane of the galaxy. Observa- mapped H2 CO in the source W5 1,and measured the clusters at 6 cm on the 140-ft telescope. tions of the Rosette Nebula in recombination line excitation temperature of formaldehyde near W40 and c. Infrared stars and continuums R. Gammon radiation near 1400 MHz were undertaken by W. NGC 2024. H. Dickel (Illinois) mapped 4830 MHz collaborated with R. Treffers (Berkeley) and J. Gaustad Altenhoff and T. Wilson (both MPI, W. Germany). A. E. absorption in W44 and W3. (Berkeley) in observations of the "10p excess" emission Lilley, J. Ball, D. Cesarsky, and A. Dupree (all Harvard) E. Fomalont and L. Weliachew (Meudon, France) in several late-type stars at high (Av = - resolution 4 cm ), investigated a narrow 21-cm recombination line com- have observed formaldehyde absorption in front of using a scanning Michelson interferometer at the Coudi ponent in W3, W51, and NGC 2024. In a low-frequency strong galactic sources. focus of the Lick 120-inch telescope. B. Zuckerman survey on the 300-ft telescope, R. C. Gordon (Hamp- b. Other Studies: D. Buhl and L. E. Snyder (Vir- (Maryland), P. Palmer (Chicago), and D. Buhl attempted shire), and J. Lockman (Massauchusetts) investigated a ginia) obtained further results in their study of the to detect IRC+10216 at 6 cm on the 140-ft telescope. number of strong I l regions at 385 MHz in an attempt hydrogen cyanide (HCN), X-ogen and hydrogen iso- Several H II regions identified as intense sources of to detect low-frequency recombination lines. cyanide (HNC) lines. Isocyanic acid (HNCO) has been 100p far infrared radiation were studied at 3.55 mm studied in Sgr B2 on the 36-ft telescope at 3 mm and with the 36-ft telescope by R. Brown and J. Broderick 5. Planetary Nebulae on the NRL 85-ft telescope at 1.4-cm (NAIC). wavelength. An analysis of radio recombination line observations The Aerospace observers W. Wilson and E. Epstein, together 4. HII Regions has been completed by B. Balick and Y. Terzian (Cornell). with P. Schwartz (NRL) studied hydrogen R. Rubin (Illinois) in collaboration with J. Cahn cyanide emission in carbon stars at 88 GHz on the 36- a. Continuum studies: B. Balick completed ft. telescope. (Illinois), made flux density measurements of selected Together with W. Fogarty (Arizona), the synthesis maps of DR 21, W51, W33, and other H II same three observers searched - planetary nebulae with the dual-frequency interfero- for carbon monoxide regions. Fine structure with scale sizes of 10 .5 and cyanogen emission -3 meter, and in collaboration with B. Turner, searched in late M-type stars at I 10-1 16 pc, densities of 104. cm ,and temperatures of 104 GHz. for recombination lines at 1.35 cm in NGC 7027 on Schwartz and the Aerospace observers joined H. K were observed in some of these nebulae. the These results 140-ft telescope. Weaver and D. Williams (both Berkeley) in a 36-ft. agree well with recombination line analyses. Such study of galactic spiral arm structure using the CO line. structure must be deemed enigmatic since it will disperse 6. Pulsars P. Solomon (Minnesota) and the Bell Laboratory observers in a few thousand years unless either confined or re- Statistical analyses of pulsar radiation have been K. Jefferts, A. Penzias and R. Wilson observed CS toward supplied. Y. Terzian (Cornell) and A. Parrish (Cornell) conducted by D. Backer using single pulse polarization the galactic center and selected Hii regions and IR observed the Cygnus X region with the 36-ft telescope data from Arecibo and single pulse, multifrequency objects. A. Barrett, P. Myers, and R. Martin (all at 31 GHz. data from the 300-ft. A program to measure the flux den- MIT) observed H II regions and IR stars at the 48-GHz b. Recombination line studies. The H, line He, and sity spectra of pulsars by simultaneous observations at of methyl alcohol. C85a lines (v = 10.522 GHz) were mapped in the direc- a number of radio frequencies was started. Backer At the Haystack Observatory, B. Turner, tion of Orion A by B. Balick, L. M. Doherty (NRC, also undertook 140-ft observations at 6 cm to measure Gordon, and G. Wrixon (Bell Labs) searched the X9-mm Canada), and H. Tovmassian (Byurakan, USSR). The the radio spectra of pulsars. R. Manchester (Massachu- region of the spectrum for a variety of molecular lines. H and He line ratios and velocities were found to be setts) continued his pulsar polarization and timing mea- W. Howard and H. Hvatum searched normal throughout the nebula. unsuccessfully for There are clear indi- surements program on the 300-ft telescope in the fre- strong spectral lines in the range 85-95 GHz. R. cations that the CII distribution is quite different quency range 200-500 MHz. Manchester and R. Gammon collaborated with D. Johnson than that of the H Il and Hell; (NBS), and the carbon line is Huguenin, and J. Taylor (both Massachusetts) measured F. Lovas (NBS) in laboratory measurements of meta- quite strong northeast 3 of the trapezium (towards the polarization, pulse profiles, and timing character- stable a CO at 3 mm. the dark bay and M43), 1r and is undetectable 5 min of istics of known pulsars in the frequency range 100-500 arc to the southwest. No evidence HC N, CS, and CH OH were studied by B. Turner, of ionized species MHz and searched for new pulsars in, or associated 3 3 heavier than carbon was observed to M. Morris (Chicago), P. Palmer (Chicago), and B. a level of 0.01 K. with, selected objects on the 300-ft telescope. W. M. Goss and E. Churchwell (both MPI, W. Zuckerman (Maryland). Several pulsars known to have relatively flat spectra P. Germany) undertook a detailed study at 3 cm of the Stickney (Arizona) and R. Gammon are doing were observed at 9.5 mm by E. Conklin, R. Hobbs region of the Norma-Scutum Arm (.= 300) statistical equilibrium calculations (with variable kinetic in the H85a- (NASA-Goddard), S. Maran (NASA-Goddard), and recombination line. First attempts were made by temperature, density, and collisional selection rules) in B. H. Chiu (NASA Institute Space Studies). J. Lockman Balick and T. Wilson (MPI, W. Germany) to study an attempt to find the physical conditions consistent with a (Massachusetts) attempted to detect hydrogen-recom- radio recombination line in Orion A, M17, M41 and the full set of observations for a given molecule, bination lines in the range and 150-500 MHz, that originate to predict the most favorable transitions for further 28 observations. Gammon is currently studying the ap- 19, 26, 49, 56), HCOCH 2 OH (3, 12, 41, 50), C H OH radio and optical behavior. The source OJ+287 was plicability of chemical thermodynamic equilibrium to 2 5 (1, 17, 27, 39), CH 3 CH 2 CH 3 (3, 12, 14, 17, 41, 50), observed intensively in January 1972 by E. Conklin, T. the observed relative abundances of interstellar mol- C 6 HsCN (11, 51), C 6 HsNO (11, 51), C 6 H 5 OH (11, Kinman (KPNO), B. Andrew (NRC, Canada), J. ecules, and predicting transition frequencies of observed 51), C6 H5 C2 H (1 1, 51), C6 Hs NO 2 (11, 51), pyrimidine Wardle (Brandeis), and K. Kellermann. E. Epstein (Aero- and expected molecules. (44,45), pyridine (44,45), and a search for fine structure space) and W. Fogarty (Arizona) used the 36-ft telescope c. Summary: In the next two subsections are listed: linesof atomic hydrogen (9, 36). to search for short-term variations in 3C 1 20 and BL (1) other known moledules for which one or more lines Lac at 85 GHz, and with J. Montgomery (Aerospace), have been observed during this report interval, and (2) C. Discrete Sources searched for short-term time variations in QSO's at molecules for which searches for one or more lines 85 GHz. W. Dent (Massachusetts) and R. Hobbs (NASA, have been conducted in the same interval. Following 1. Occultations Goddard) continued their measurements of flux densities each molecule are indicated the names of all observers N. Sarma and T. Menon (both Tata Institute, India) of variable sources at 31 and 85 GHz. K. Johnson connected with the study, the numbers corresponding to used the 300-ft. telescope to measure 11, 20, and 40- (Arizona) monitored the flux density of 3C 120 for the names, below, In each subsection, the molecules cm flux densities of a large number of radio sources variability at 31 and 85 GHz, and with K. Kellermann, are listed in order of increasing complexity. Engaged that have been observed by occultation techniques with monitored 30 sources for variations in flux density on in this work have been: J. Ball (1), A. Barrett (2), R. the Ooty radio telescope in India at a wavelength of 92 the NRAO Interferometer. Benson (3), R. Bernheim (4), D. Buhl (5), F. Clark (6), cm. A group of x-ray astronomers from MIT, W. Zauman, T. Cram (7), R. de Zafra (8), D. Dickinson (9), E. G. Murthy, and S. Rappaport, collaborated with R. Epstein (10), J. Fertel (11), W. Flygare (12), W. Fogarty 2. Polarization Hjellming and C. Wade to detect a variable radio counter- (13), R. Gammon (14), P. Giguere (15), M. Gordon Virginia observes S. Goldstein and F. Gauss observed part to the x-ray source GX9+1. J. Findlay has made (16), C. Gottlieb (17), J. Hagen (18), C. Heiles (19), strong radio sources to obtain the position angle and more measurements at 1440 MHz over the past three R. Hobbs (20), R. Hubel (21), K. Jefferts (22), D. amplitude of the linear polarized flux at discrete points years of the flux density of Cas A and its rate of de- Johnson (23), W. Klemperer (24), S. Knowles (25), M. over a 1250-1450 MHz frequency range. J. Wardle crease. An observational program using the NRAO in- Kutner (26), A. E. Lilley (27), H. Liszt (28), M. Litvak (Brandeis) measured linear polarization of radio sources terferometer to search for variability in Cyg A, Vir A, (29), F. Lovas (30), R. Martin (31), J. McGurk (32), M. at 31 GHz on telescope, the 36-ft and he used the dual and Cas A at 11 and 3.7 cm has been completed by D. Morris (33), P. Myers (34), P. Palmer (35), H. Penfield frequency interferometer to obtain high-resolution De Young and D. Hogg. (36), A. Penzias (37), T. Phillips (38), H. Radford (39), observations of source polarization. Wardle and R. L. Rickard (40), R. Rubin (41), P. Schwartz (42), N. Sco- Sramek made linear polarization measurements of 24 4. Source Surveys ville (43), M. Simon (44), M. N. Simon (45), L. Snyder normal galaxies with the dual frequency interferometer. a. Interferometer: E. Fomalont, A. Bridle (Queens, (46), P. Solomon (47), P. Swanson (48), P. Thaddeus Wardle and P. Kronberg (Toronto, Canada), obtained in- Canada), M. Davis, and J. Lequeux (Meudon, France) (49), H. Tigelaar (50), B. Turner (51), H. Weaver (52), terferometer polarization measurements of approxima- have completed a "Two-flux Unit Catalog." Observa- D. Williams (53), R. Wilson (54), W. Wilson (55), R. tely 100 quasistellar sources, and in a separate program, tions of 21-cm hydrogen and helium recombination Zare (56), and B. Zuckerman (57). Kronberg measured the polarization structure of extra- lines in galactic HII regions, and observations of 21-cm (1) Known Molecules. The following molecules were galactic radio sources. neutral hydrogen in absorption in order to make kine- studied by the individuals noted in parentheses (see E. Seaquist (David Dunlap Observatory, Canada) matic distance estimates of galactic sources have been Key, above): CN (10, 13, 22, 28, 37, 38, 42, 47, 54, 55), and F. Biraud (Meudon, France) observed simultaneously carried out on the NRAO interferometer by T. Wilson CO (10, 13, 22, 23, 28, 30, 37, 42, 43, 47, 52, 53, 54, with the dual frequency interferometer and the 140- and J. Wink (both MPI, W. Germany), K. Riegel (UCLA), 55), CS (22, 28, 33, 35, 37, 43, 47, 51, 54, 57), SiO (9, ft telescope the spectrum of circular polarization of several and W. Webster (NASA-Goddard). Interferometer ob- 17, 20, 25, 57), HCN (3, 5, 6, 10, 12, 15, 22, 26, 33, 35, sources at 1666 MHz, 2695 MHz, and 8085 MHz. servations of 180 normal galaxies have been completed 37, 38, 41, 42, 46, 49, 50, 51, 54, 55, 57) H O (33, 2 35, Later, F. Biraud used the 36-ft telescope to search for by R. Sramek at 4 and 1 1 cm. The confusion level of 51, 57), H2 S (22, 26, 37, 49, 54), OCS (14, 22, 37, 47, circular polarization in compact sources at 31 GHz. faint sources has been investigated by means of anal- 51, 54), HNCO (3, 5, 12, 35, 41, 46, 50, 51, 57), NH E. Fomalont, M. Wright, 3 and J. Hogbom (Stockholms, ysis of observations at 8085 MHz on the dual-frequency (33, 35, 51, 57), HC N (33, 3 35, 51, 57), HCOOH (9, Sweden) continued their analysis of the linearly polarized interferometer by B. Dennison (Louisville) and E. Foma- 27, 39), CH CN (22, 37, 47, 54), CH OH (1, 2, structure of extragalactic 3 3 16, radio sources. Observations lont. The MIT observers W. Zaumen, S. Rappaport, 17, 27, 31, 34, 36, 39, 51), NH at 4 and 1 1 2 CHO (3, 12, 17, 35, 40, cm (NRAO), and 6 and 21 cm (Westerbork) J. Spencer, and C. Canizarias measured the positions 41, 50, 57), CH CCH (5, of - 40 sources 3 46), CH 3CHO (3, 12, 41, 50), are being made. and intensity variations with time of a number of x- U89.2 E. or X-ogen (5, 6, 15, 33, 35, 46, 51, 57), and U90.6 Conklin and L. Matveyenko (Cosmic Space Inst., ray sources. or "HNC" (5, 56). USSR) mapped the polarization distribution in the Crab E. Fomalont and M. Davis have completed source (2) Molecule Searches. One Nebula or more lines of the at 3.5 mm. C. Bignell analyzed the linear polari- counts of high brightness and low brightness radio following molecules were searched for by the individuals zation observations of 44 radio sources (26 were sources. noted in parentheses (see Key, above): CH (51, 57), variable in flux density) obtained at wavelengths of 2.8 b. 36-ft Telescope: Twenty-nine Markarian galaxies CQO (35, 51, 57), MgO (14, 51), SiN (20, 25, and 4.5 cm using 57), CH 2 the 150-ft radio telescope at the were observed at 9 mm by H. Tovmassian (Byurakan, (4, 18, 48), CO (14, 17), HCO (1, 9, 17, 22, 26, 27, 2 Algonquin Radio Observatory in Canada. USSR) on 37, 39, 49, 54), HCP (14, 51), NCO (33, 35, 51,57), the 36-ft telescope. c. 300-ft Telescope: M. Davis, K. Kellermann, and HCNO (3, 12, 41, 50), HNCS (35, 51, 57), C H (14, 3. Spectral Studies and Time Variations 2 2 I. Pauliny-Toth (MPI, W. Germany) have extended their 17), CH N (3, 12, 35, 41, 50, 57), CH F (9), H C 0 2 2 3 2 2 I. Pauliny-Toth and K. Kellermann have completed 6-cm source survey by using the 300-ft telescope to in- (14), NH CN (3, 12, 41, 50), CH NOH (3, 12, 41, 50), 2 2 their analysis of the radio spectra of very weak sources clude a total of about 4 ster. The sources detected in CH NC (3, 12, 41, 50), CH NO 3 3 (3, 12, 41, 50), CH 3 SH based on new observations at 6 and 11-cm. 11. Murdoch this survey are being reobserved at NRAO and Bonn (1, 14, 17, 27, 39), HC OH (35, 51, 3 57), SiH 3 CN (3, (Sydney, Australia) made 11- and 21-cm observations on at a number of wavelengths to determine their spectra 12, 33, 35, 41, 50, 51, 57), CH 2 CHCN (3, 12, 41, 50, the 300-ft telescope to obtain the spectra of sources and accurate positions. 51), CH NH (1, 17, 27, 29, 35, 39, 3 2 57), CNCH 2CN contained in the Molonglo 408-MHz survey. Identification work is being done by K. Johnson (3, 12, 41, 50), OHCH2 CN (24, 27), CH 2 CHCHO Joint radio and optical observations of a number of (Arizona). A 6-cm survey of 1 100 normal galaxies in (3, 12, 41, 50), CH CHNO (3, 12, 41, 2 2 50), CH 3 COOH QSO's and other short period variables were begun, to the de Vaucouleurs catalog was made by R. Sramek (3, 12, 41, 50), CH3 SiH (33, 35, 51, 57), C Hs N (8, 3 2 search for periodicities and correlations between the using the 300-ft telescope. J. Webber (Illinois) observed 29 at 11 cm a large sample of weak radio sources in the NASA-Goddard (T. Clark), NASA-JPL (G. Downs, fluxes from radio galaxies using the dual-frequency Vermillion River Observatory Catalog. J. Wardle and P. Reichley), NRL (K. Johnston, S. Knowles, P. interferometer. Two galaxies of the M82 type (NGC M. Wright have made a search for continuum emission Schwartz), Smithsonian (J. Moran), and Virginia (P. 520 and NGC 5363), which were expected to have from peculiar galaxies at 11 cm. Hemenway). definite structure in the nuclear region, were observed W. M. Goss and A. Winnberg (both MPI, W. Germany) The VLB programs generally covered one or more of by H. Tovmassian and R. Sramek on the interferometer. observed neutral hydrogen profiles of 66 extragalactic the following studies: (1) The investigation of structure sources. At Cambridge, England, H. Murdoch worked or variations in structure of compact radio sources and 2. Line Studies with C. Hazard on optical identifications of the quasars, and the spatial structure of emission line G. S. Shostak completed the synthesis of H I distribu- Molonglo survey sources he observed at Green Bank. He sources, (2) The collection of general astrometric and tions in the galaxies NGC 2403, NGC 4236 and IC 10, is investigating the radio spectra from the observations geodetic data, (3) Measurements of the extent of bend- using the Owens Valley interferometer. Similar observa- at Green Bank and Arecibo of 100 previously identi- ing of radio waves at the solar limb to test the general tions and analyses were completed for the late-type fied sources from Hoskins, Murdoch, Hazard, and theory of relativity, (4) The monitoring of the apparent galaxies NGC 6946 and IC 342 in collaboration with D. Jauncey (CSUAC 261). In addition, Hazard has ob- angular size and pulse shape of the Crab Nebula pulsar, Rogstad (Caltech) and A. Rots (Groningen, Netherlands). tained redshifts for many of the survey identifications. and (5) The measurement of pulsar position, and the A study of the large-scale properties of Scd galaxies, investigation of the extent of their proper motions and 5. Individual Sources based in part on the above data, was made by Shostak parallaxes. and Rogstad. a. Galactic Center Region: Synthesis observations B. Clark has constructed a continuum, very long of selected regions of the galactic center were begun baseline interferometer software system to handle the J. Gallagher (Wisconsin)searched for HI in elliptical at 4 and 11-cm wavelength by B. Balick and R. Hjellming. data output from the NRAO Mark II tape recorder inter- galaxies. Using the interferometer at 21 cm, C. Heiles On the 140-ft telescope, B. Zuckerman (Maryland) ferometer system. (Berkeley), K. Reigel and D. Elliott (both UCLA), S. and P. Palmer (Chicago) investigated a broad weak line Gottesman (Caltech), W. B. Burton, M. Roberts, and M. near 4660 MHz in Sgr B2. Recombination line observa- 7. Theory Wright conducted observations of six galaxies in a two- tions at 6-cm of sources near the galactic center were P. Napier has studied the interpretation of inter- dimensional synthesis program, I 8 galaxies in fan-beam carried out by E. Churchwell and P. Mezger (both MPI, ferometric data for use in radio synthesis work. Two synthesis program, and have made absorption measure- W. Germany), and T. Pauls (New Mexico State) to in- problems of interest were: (1) the use of computational ments in selected galactic and extragalactic radio sources vestigate the rotation of the inner part of the nuclear schemes to remove phase errors from synthesis maps in with both a two-dimensional and fan-beam synthesis disk cloud. Massachusetts observers J. Taylor and J. cases where the modulus of the fringe visibility function program. Lockman observed a region near the galactic center to is known more accurately than the phase, and (2) in M. Wright and D. Rogstad (Caltech) have observed M33 map the 18-cm H158a recombination line. The Maryland cases where no phase information is available, the and M83 in the hydrogen line at Owens Valley to look observers F. Kerr and J. Carlson used the 1420 and 1425- interpretation of the modulus information to yield un- for density-wave perturbations. L. Weliachew (Cal- MHz H I and H167a line to search for a "black hole" in ambiguous brightness temperature distributions. tech), S. Gottesman, and M. Wright conducted interfero- the direction of the galactic center. D. De Young has completed a study to determine the meter observations to measure hydrogen in absorption b. Other Sources: M. Wright, K. Riegel (UCLA), C. distribution of synchrotron radiation from a relativis- in front of NGC 253 and M82. Wright and G. Seielstad Heiles (Berkeley), S. Gottesman (Florida), and D. tically expanding radio source as seen by a distant ob- (Caltech) have made line aperture synthesis maps of Elliot (UCLA) have made aperture synthesis maps of server. IC 2574, NGC 7640, and Maffei 2. G. S. Shostak and hydrogen-line absorption in Cas A, Cyg A and other J. Rather has worked on the development of a theory L. Weliachew (Caltech) completed Hi observations of sources. of quasar and galactic nucleus energy sources. Maffei 2 using the Owens Valley interferometer K. Kellerman has investigated the cosmological im- with a 6. Very Long Baseline (VLB) Surveys 400-ft N/S baseline. M. Roberts continued his observing plications of radio source counts and other radio program to determine the neutral hydrogen distribution Three NRAO staff members (B. Clark, K. Kellermann, observations. in galaxies using and R. Sramek) and 37 visitors participated in one or the 300-ft telescope, and on the 140-ft telescope, more VLB experiments that employed different pairs D. Galaxies conducted observations to search for high- velocity of 14 telescopes located throughout the world. Three H I clouds in other galaxies and to search for 1. Continuum Studies HI emission from the galaxies Maffei 1 and Maffei 2. spectral line (1.3-cm H3 0, 6-cm OH, and 18-cm OH) and eleven continuum (2.8, 2.5, 3.7, 3.8, 6, 13, 20, 21, J. Wardle and M. Wright conducted a search at 11 cm 50, 150, and 270 cm) wavelengths were used. The on the 300-ft telescope for radio emission from peculiar 3. Other Studies; Supernovae; Intergalactic Medium following telescopes were involved in VLB experiments: galaxies. F. Biraud (Meudon, France) used the inter- D. Wilkinson and E. Groth (both Princeton) searched Westford 60 ft, Chalmers (Sweden) 84 ft, NASA-JPL ferometer to measure accurate radio positions of those for short-time scale pulsations or bursts in extragalactic 85 ft, NRL 85 ft, Ft. Davis 85 ft, NRAO 85-ft inter- Zwicky Compact Galaxies that are radio sources. F. sources to find and measure dispersion due to inter- ferometer, Owens Valley 90-ft interferometer, Hay- Owen (Texas) began a program to observe Abell galactic ionized hydrogen over the frequency range stack 120 ft, Owens Valley 130 ft, NRAO 140 ft, clusters of galaxies at 20 cm on the 300-ft telescope. 250-500 MHz, using the 300-ft telescope. NRL-Sugar Grove 150 ft, NASA-JPL 210 ft, NRAO Observations of giant E and SO galaxies were con- 300 ft, and the Arecibo 1000-ft telescopes. tinued at 9.5 and 3.5 mm, by E. Conklin and D. Heeschen. D. De Young and W. Saslaw have completed an in- Visitor participants, by institution, were: Aerospace H. Tovmassian (Byurakan, USSR), searched for milli- vestigation of compact extragalactic objects in which (W. Wilson), Caltech (W. Cannon, M. Cohen, M. meter-wave emission from Markarian galaxies at 31 Ghz. implications of a physical association between Markarian Ewing, E. Hardebeck, A. Moffet, D. Muhleman, G. Pur- Measurements of the emission from Hii regions, in the 205 and the nearby galaxy NGC 4319 are considered. cell, D. Shaffer), Chalmers, Sweden (J. Elder, B. Hans- galaxies M31 and M33, and detailed studies of other The starlike object in the region of the galaxy NGC 4319, son, B. Ronnang, O. Rydbeck), Cornell-NAIC (J. regions in M31 were undertaken on the dual-frequency and the galaxy Markarian 205 has been observed with Broderick, D. Jauncey), Cosmic Space Inst., Moscow, interferometer by B. Burke and J. Spencer (both MIT). the 200-inch telescope by Tovmassian and B. Oke (Hale USSR (L. Matveyenko), Harvard (J. Ball, D. Harris, Continuum maps of M31 and M33 were made at 11 Observatories). A. Maxwell), Maryland (W. Erickson, G. Resch, N. cm on the 300-ft telescope by B. Balick and Y. Terzian W. Saslaw and S. Aarseth (Cambridge, UK) have Vandenberg), MIT (B. Burke, P. Crane, C. Knight, (Cornell). E. Fomalont and M. Wright have made aper- investigated the uncertainties inherent in various methods G. Papadopolous, A. Rogers. 1. Shapiro, A. Whitney), ture synthesis maps of the polarized distribution of used to determine galactic masses. 30 E. Miscellaneous has been done by a design group of 14 NRAO scientists R. Sramek and E. Fomalont continued their measure- and engineers, aided by contracted studies from several ment of the gravitational deflection of 3C 279 by the companies. The results show that a fully steerable tele- sun. scope of this size,operating exposed to the climate, can R. Whitehurst (Alabama) and M. Roberts have give good performance under benign atmospheric con- searched for recombination lines originating from ditions to wavelengths as short as 3.5 mm (a frequency excited quark-proton configurations. of 86 GHz). The design has made full use of the prin- W. Saslaw has developed expressions for the growth ciples of homology, as worked out by S. von Hoerner. It also incorporates an optically controlled of correlations in isotropic systems of gravitating point platform to give a stable reference to the pointing system. Methods particles. These are applied to investigate the early evolution of clusters and density fluctuations in an by which the surface can be manufactured, installed, and measured to the required accuracy expanding universe. have been developed. The estimated cost, M. Wright and C. Moore in 1972 dollars, is have developed a new inter- ten million dollars. ferometer reduction program for polarized and line data. The package uses a direct access data set, and maps are C. 140-ft Telescope Improvement stored on disk for display on the printer or plotter or interaction through a graphics terminal. The original telescope control system has been replaced After completion of the design of the 65-m millimeter- by a new design based on a H316 mini-computer. The wave homology telescope, S. von Hoerner continued his new system provides higher pointing accuracy, automatic work on general studies related to the optimization of operation and the ability to handle sophisticated point- structures. ing programs.
D. 300-ft Telescope Building Addition VII. CONTINUING PROJECTS The addition to the 300-ft control building was com- A. Very Large Array (VLA) pleted in November 1971. The added 1000 ft available for the operations console and receivers approximately Funds for the first phase of the construction of a doubles the operating space, and permits more rapid change Very Large Array (VLA) were included in the NSF of radiometer systems. budget request for FY 1973. NRAO is developing de- tailed plans for the construction of the array. The Plains E. 36-ft Instrumentation Development of San Augustin, about 45 miles west of Socorro, New J. Rather Mexico, has been chosen as the VLA site. has continued the development of a liquid helium cooled broadband detector system for use in the B. 65-m Millimeter-Wave Telescope Design 1.6 and 0.8 millimeter wavebands on the 36-ft telescope. .The design of a 65-m telescope for millimeter wave- lengths has been completed, and the results will shortly D. S. HEESCHEN be published in an Observatory monograph. The work Director
31 NRAO - STAFF AND VISITOR PUBLICATIONS 1972
Backer, D. C., "Pulsar Flux-Density Spectra", Astrophys. J., 174, L157-L161, 1972. (B320)
Balick, B., "Fine Structure in HII Regions: Synthesis Observations at 11 and 3.7 Centimeters", Astrophys. J., 176, 353-365, 1972. (B332)
Balick, B., "Radio Observations of Early Type Stars", Astrophys. Letters, 12, 21-23, 1972. (A267)
Barrett, A. H., Martin, R. N., Myers, P. C., and Schwartz, P. R., "Observations of Methanol in Sgr B2 at 48 GHz", Astrophys. J., 178, L23-L27, 1972. (B347)
Berger, P. S. and Simon, M., "Solar Radio Recombination Lines", Astrophys. J., 171, 191-200, 1972. (B290)
Biraud, F., "A Search for Circular Polarization in Compact Sources at 9 mm Wavelength", Astron. & Astrophys., 19, 310-311, 1972. (A257)
Bridle, A. H. and Davis, M. M., "The N(S) Relationship at 1400 MHz", IAU Symposium, 44, 437-443, 1972. (B301)
Bridle, A. H., Davis, M. M., Fomalont, E. B., and Lequeux, J., "Counts of Intense Extragalactic Radio Sources at 1400 MHz", Nature-Phys. Sci., 235, 123-126, 1972. (A243)
Bridle, A. H., Davis, M. M., Fomalont, E. B., and Lequeux, J., "Flux Densities, Positions and Structures for a Complete Sample of Intense Radio Sources at 1400 MHz", Astron. J., 77, 405-443, 1972. (A259)
Bridle, A. H. and Kesteven, M. J. L., "Distance Estimates for Two Thermal Galactic Radio Sources", Astrophys. J., 77, 207-209, 1972. (A252)
Briggs, F. H. and Drake, F. D., "Interferometric Observations of Mars at 21 cm Wavelength", Icarus, 17, 543-547, 1972. (B346)
Broderick, J. J., Kellermann, K. I., Shaffer, D. B., and Jauncey, D. L., "High-Resolution Observations of Compact Radio Sources at 13 Centimeters. II.", Astrophys. J., 172, 299-305, 1972. (B299)
Brown, R. L., "The Charge Transfer Reaction C+2+-HHe +C and its Application to the Interstellar Medium", Astrophys. J., 174, 511-516, 1972. (B325)
Brown, R. L., "Chemical Composition of the Interstellar Gas: X Ray Determinations", Astrophys. & Space Sci., 17, 123-127, 1972.
32 Brown, R. L., "Ionization Equilibria of Calcium and Sodium in Interstellar Clouds", Astrophys. J., 173, 593-599, 1972. (B315)
Brown, R. L., "Near Resonant Charge Transfer Processes at Thermal Energies", Astrophys. & Space Sci., 16, 274-283, 1972. (B330)
Buhl, D., Snyder, L. E., and Edrich, J., "An Interstellar Emission Line from Isocyanic Acid at 1.4 cm", Astrophys. J., 177, 625-628, 1972.
Burns, W. R., "The Confusion Error on the Flux Estimate of a Point Source", Astron. & Astrophys., 19, 41-44, 1972. (A253)
Burton, W. B., "Comments on a Paper by K. Rohlfs", Astron. & Astrophys., 16, 158-160, 1972. (A234)
Burton, W. B., "On the Kinematic Distribution on Galactic Neutral Hydrogen", Astron. & Astrophys., 19, 51-65, 1972. (A254)
Conklin, E. K., Andrew, B. H., Wills, B. J., and Kraus, J. D., "Spectra of Some Ohio Radio Sources: List III" Astrophys. J., 177, 303-307, 1972. (B339)
Dent, W. A., "A Flux-Density Scale for Microwave Frequencies", Astrophys. J., 177, 93-99, 1972.
De Young, D. S., "The Distribution of Radiation from Relativistically Expanding Radio Sources", Astrophys. J., 177, 573-577, 1972.
De Young, D. S., "Possible Evidence for an Intergalactic Medium in Clusters of Galaxies", Astrophys. J., 173, L7-L11, 1972. (B312)
Dickinson, D. F. and Turner, B. E., "Classification of New OH Sources", Astrophys. Letters, 11, 1-5, 1972. (A248)
Downs, G. S. and Thompson, A. R., "The Distribution of Linear Polarization in Cassiopeia A at Wavelengths of 9.8 and 11.1 cm", Astron. J., 77, 120-133, 1972. (A246)
Doxsey, R., Murthy, G. T., Rappaport, S., Zaumen, W., and Spencer, J., "Radio Search for the Pulsing X-Ray Source in Hercules", Astrophys. J., 176, L15, 1972.
33 Edrich, J., "Low Noise Parametric Amplifiers Tunable Over One Full Octave", IEEE J. of Solid State Circuits, SC7, 32-37, 1972. (A235)
Epstein, E. E., Fogarty, W. G., Hackney, K. R., Hackney, R. L., Leacock, R. J., Pomphrey, R. B., Scott, R. L., Smith, A. G., Hawkins, R. W., Roeder, R. C., Gary, B. L., Penston, M. V., Tritton, K. P., Bertaud, C. H., Veron, M. P., Wlrick, G., Bernard, A., Bigay, J. H., Merlin, P., Durand, A., Sause, G., Becklin, E. E., Neugebauer, G., and Wynn-Williams, C. G., "3C 120, BL Lac, and OJ 287: Coordinated Multiwavelength Observations of Interday Variability", Astrophys. J., 178, L51-L60, 1972. (B342)
Erickson, W. C., Kuiper, T. B. H., Clark, T. A., Knowles, S. H., and Broderick, J. J., "Very Long Baseline Interferometer Observations of Taurus A and Other Sources at 121.6 MHz", Astrophys. J., 177, 101-114, 1972. (B334)
Evans, N. J. II, Hills, R. E., Rydbeck, 0. E. H., and Kollberg, E., "The Statistics of the Radiation from Astronomical Masers", Phys. Rev. A., 6, 1643-1647, 1972. (A260)
Felli, M. and Churchwell, E., "Radio Emission at 1400 MHz from Galactic HII Regions", Astron. & Astrophys., 5, 369-432, 1972.
Findlay, J. W., "The Flux Density of Cassiopeia A at 1440 MHz and Its Rate of Decrease", Astrophys. J., 174, 527-528, 1972. (B322)
Fomalont, E. B., "Radio Components with a Circumferential Magnetic Field Configuration in 3C219 and 3C353", Astrophys. Letters, 12, 187-192, 1972. (A270)
Gallagher, J. S., III, "A Search for HI in Elliptical Galaxies", Astron. J., 77, 568-572, 1972. (A265)
Gordon, M. A., "The Effect of the Interstellar Gas on the Continuum Spectrum of 3C391", Astrophys. J., 174, 361-363, 1972. (B324)
Gordon, M. A., Brown, R. L., and Gottesman, S. T., "The Latitude Extent of Diffuse Ionization in the Galaxy", Astrophys. J., 178, 119-124, 1972.
Gordon, M. A. and Cato, T., "A Longitude Survey of Radio Recombination Lines from the Diffuse Interstellar Medium", Astrophys. J., 176, 387-396, 1972. (B333)
Goss, W. M., "Low Frequency Turnover in the Spectrum of 3C391", Astron. & Astrophys., 18, 484-486, 1972.
34 Gottesman, S. T., Broderick, J. J., Brown, R. L., Balick, B., and Palmer, P., "First-Epoch Radio Observations of Supernova 1970g", Astrophys. J., 174, 383-388, 1972. (B323)
Gregory, P. C., Kronberg, P.P., Seaquist, E. R., Hughes, V. A., Woodsworth, A., Viner, M. R., Retallack, D., Hjellming, R. M., and Balick, B., "The Nature of the First Cygnus X-3 Radio Outburst", Nature-Phys. Sci., 239, 114-117, 1972.
Gwinn, W. D., Turner, B. E., Goss, W. M., Blackman, G. L., "Excitation of Interstellar OH by the Collisional Dissociation of Water", Astrophys. J., 179, 789-813, 1972.
Heeschen, D. S., "Annual Report-National Radio Astronomy Observatory, July 1970-June 1971", Bull. Amer. Astron. Soc., 4, 140-149, 1972. (A240)
Hinteregger, H. F., Ergas, R., Knight, C. A., Robertson, D. S., Shapiro, I. I., Whitney, A. R., Rogers, A. E. E., and Clark, T. A., "Precision Geodesy via Radio Interferometry: First Results", Science, 178, 396-398, 1972.
Hjellming, R. M., "13 Persei: Radio Star and Probable X-ray Star", Nature-Phys. Sci., 238, 52-55, 1972. (B341 )
Hjellming, R. M. and Balick, B., "More Unusual Radio Events in Cygnus X-3", Nature-Phys. Sci., 239, 135-136, 1972.
Hjellming, R. M. and Balick, B., "Unusual Radio Events in Cygnus X-3", Nature, 239, 443-446, 1972.
Hjellming, R. M., Hermann, M., and Webster, E., "Radio Observations of Cygnus X-3", Nature-Phys. Sci., 237, 507-508, 1972. (A263)
Hjellming, R. M., Wade, C. M., and Webster, N. E., "Radio Variations of Beta Persei and Beta Lyrae", Nature- Phys. Sci., 236, 43-46, 1972. (A247)
Hjellming, R. M., Webster, E., and Balick, B., "Radio Behavior of 1 Persei", Astrophys. J., 178, L139-L144, 1972. (B340)
Johnston, K. J., Knowles, S. H., and Schwartz, P. R., "Microwave Celestial Water-Vapor Sources", Sky and Telesc., 44, 88-90, 1972.
Kellermann, K. I., "Intercontinental Radio Astronomy", Sci. Amer., 226, 72-83, 1972. (A249)
35 Kellermann, K. I., "Radio Emission from Compact Objects", IAU Symposium, 44, 190-213, 1972. (B302)
Kellermann, K. I., "Radio Galaxies, Quasars, and Cosmology", Astron. J., 77, 531-542, 1972. (A262)
Kerr, F. J. and Knapp, G. R., "A Search for Neutral Hydrogen High Velocity Clouds in the Directions of Six Globular Clusters", Astron. J., 77, 354-359, 1972. (A255)
Kerr, F. J. and Knapp, G. R., "Upper Limits on the Atomic Hydrogen Abundance in 12 Globular Clusters", Astron. J., 77, 573-576, 1972. (A266)
Knapp, G. R., "Research Note: An HI Velocity-Longitude Diagram for the Southern Milky Way", Astron. & Astrophys., 21, 163-165, 1972.
Knapp, G. R. and Kerr, F. J., "An Upper Limit on the OH Abundance in the Intercloud Medium", Astron. J., 77, 649-651, 1972. (A268)
Knapp, G. R. and Verschuur, G. L., "HI Clouds with Spin Temperatures Less Than 25 0 K-II. Physical Properties of Two Neutral Hydrogen Clouds", Astron. J., 77, 717-725, 1972. (A271)
Kundu, M. R., "Observations of Prominences at 3.5 Millimeter Wavelength", Solar Phys., 25, 108-115, 1972. (B331)
Kundu, M. R. and Becker, R. H., "Observations of the Cygnus Loop at 6 Centimeter Wavelength", Astron. J., 77, 459-473, 1972. (A258)
Kundu, M. R. and Velusamy, T., "Brightness and Polarization Structure of Four Supernova Remnants 3C58, IC 443, W28 and W44 at 2.8 Centimeter Wavelength", Astron. & Astrophys., 20, 237-244, 1972. (A264)
Lantos, P. and Kundu, M. R., "The Quiet Sun Brightness Distributions at Millimeter Wavelengths and Chromo- spheric Inhomogeneities", Astron. & Astrophys., 21, 119-124, 1972. (A269)
Manchester, R. N., "Pulsar Rotation and Dispersion Measures and the Galactic Magnetic Field", Astrophys. J., 172, 43-52, 1972. (B295)
Manchester, R. N., Huguenin, G. R., and Taylor, J. H., "Polarization of the Crab Pulsar Radiation at Low Radio Frequencies", Astrophys. J., 174, L19-L23, 1972.
Manchester, R. N. and Peters, W. L., "Pulsar Parameters from Timing Observations, Astrophys J., 173, 221-226, 1972. (B311)
36 Margon, B., Spinrad, H., Heiles, C., Tovmassian, H., Harlan, E., Bowyer, S., and Lampton, M., "IC3576: An Unusual Spiral Galaxy in Virgo", Astrophys. J., 178, L77-L80, 1972.
Maslowski, J., "A Green Bank Sky Survey in Search of Radio Sources at 1400 MHz. II. Spectral Properties of the 5C1 and 5C2 Sources", Astron. & Astrophys., 16, 197-203, 1972. (A229)
Mattauch, R. J., "A Simple Vacuum System Substrate Heater", Rev. Sci. Instrum., 43, 148-149, 1972. (A236)
Matveyenko, P. N. and Conklin, E. K., "Distribution of the Polarized Radio Brightness of the Crab Nebula at 3.5 mm Wavelength", Soviet Astronomy & Astronomicheskii Journal, 49, 895-897, 1972.
Miley, G. K. and Macdonald, G. H., "The Radio Structure of Quasars", IAU Symposium, 44, 216-221, 1972. (B303)
Nakano, T. and Tademaru, E., "Decoupling of Magnetic Fields in Dense Clouds with Angular Momentum," Astrophys. J., 173, 87-101, 1972. (B308)
Pauliny-Toth, I. I. K. and Kellermann, K. I., "Measurements of the Flux Density and Spectra of Discrete Radio Sources at Centimeter Wavelengths. III. Observations of Weak Sources at 2.7 and 5 GHz", Astron. J., 77, 560-568, 1972. (A261)
Pauliny-Toth, I. I. K. and Kellermann, K. I., "The NRAO 5 GHz Radio Source Survey. III. The 140-ft. 'Strong' Source Survey", Astrophys. J., 77, 797-809, 1972. (A273)
Pauliny-Toth, I. I. K., Kellermann, K. I., and Davis, M. M., "Number of Counts and Spectral Distribution of Radio Sources at Centimeter Wavelengths", IAU Symposium, 44, 444-452, 1972. (B300)
Pauliny-Toth, I. I. K., Kellermann, K. I., Davis, M. M., Fomalont, E. B., and Shaffer, D. B., "The NRAO 5 GHz Radio Source Survey. II. The 140-foot 'Strong', 'Intermediate', and 'Deep' Source Surveys", Astron. J., 77, 265-284, 1972. (A256)
Penzias, A. A., Jefferts, K. B., and Solomon, P. M., "1 3 C160/12C180 Ratios in Nine HII Regions", Astrophys. J., 178, L35-L38, 1972. (B343)
Penzias, A. A., Jefferts, K. B., and Wilson, R. W., "Interstellar CN Excitation at 2.64 mm", Phys. Rev. Letters, 28, 772-775, 1972.
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