NATIONAL RADIO

S U M M A R Y

ASTRONOMY OBSERVATORY 1991 STATISTICS Cover: The peculiar NGC 7252. This galaxy is a result of a recent merger, or collision, of two . The starlight from the merged galaxy is shown as red in this image, light from scattered by the force of the collision, or stars unrelated to the galaxy, is shown as green and the radio emission from neutral atomic hydrogen gas is indicated by blue shading. This image demonstrates that when galaxies collide their gas is removed; the final merged system is nearly devoid of gas. The radio image was made with the NRAO radio telescope. The optical image was obtained at the CTIO 4m telescope. VLA Observers: John Hibbard Jacqueline van Gorkom Linda Schweizer NATIONAL RADIO ASTRONOMY OBSERVATORY

Observing Summary 1991 Statistics

February 1992 SOME HIGHLIGHTS OF THE 1991 RESEARCH PROGRAM

The 12 m telescope has been used to detect CO in by far the most distant object to date-the diffuse galaxy IRAS10214+4724, whose optical is 2.29. At so high a redshift, the infrared emission corresponds to a luminosity as great as that of the most luminous QSOs, about 1014 solar luminosities, which if thermal dust emission, correspond to 1010 solar masses of dust. Such a large amount of dust is expected to be accompanied by a still larger mass of (molecular) gas. The CO J=3-2 transition which was detected at the 12 m is shifted from its usual frequency of 345 GHz to 105 GHz, and its 4 mK intensity and 400 km/s width correspond to nearly 1012 solar masses of molecular gas. The detection was confirmed by detecting the redshifted J=2-1 transition at the 12 m, and the J=3-2 transition at the IRAM 30 m. These results suggest that the earliest stages of galaxy formation are preceded by, or contemporary with, the onset of molecular gas and the formation of the first few generations of stars.

The first evidence for a primordial "pancake"~a large, flattened agglomeration of hydrogen formed early in the history of the universe-has been detected with the VLA. The object has a redshift of 3.4, and a mass of 3x1014 solar masses, the mass of a large cluster of galaxies. It is interpreted as a protocluster of galaxies undergoing (probably its first) collapse as predicted by Zel'dovich in his "top-down" model in which early matter fluctuations lead first to large structures, which subsequently fragment into smaller structures, eventually galaxies themselves.

• The strongest interstellar maser emission yet detected was observed at the 140 ft telescope in 1991 June. It arises from the 51->60 A* transition of methanol (CH3OH) at 6.668 GHz, and it is now seen in 177 Galactic sources, in many at a strength exceeding several thousand Jy. Nearly all CH3OH masers are associated with interstellar OH masers. The new maser will serve as an important tool for the study of proper motions, both in the Milky Way and in external galaxies.

The VLA has discovered a previously undetected radio source near the Galactic Center, about 35 arcsec from the powerful Sgr A* source, thought by some to be a massive . The new object was not present in early 1990 December, increased to a maximum in 1991 January, and has decreased (with rapid fluctuations) thereafter. At its strongest, it exceeded Sgr A* in flux. The emission is non-thermal, and is likely synchrotron. The source is verified by HI studies at 21 cm to lie physically close to the Galactic Center, and it also coincides with a strong clump of molecular ammonia near the Center. Such molecular clouds are normally associated with rapid formation, but in this case they may be responsible for fueling the nucleus of the Galaxy. The nature of the new object remains enigmatic.

1 The first extraterrestrial silicon-nitrogen molecule, SiN, has been detected in the circumstellar envelope of IRC 10216. SiN occurs in the outer envelope, with an abundance SiN/SiQ = NH3/C2H2, indicating that SiN is formed by reaction of Si* with NH3. Since both NH3 and QHj arise in the dense inner core, an efficient means of transporting silicon to the outer envelope must operate. The likely carrier is silane (SiH4). Although these findings indicate considerable quantities of gaseous Si in the outer envelope, the net loss of refractory elements such as Si to the from such mass-losing evolved stars as IRC 10216 is almost entirely in the form of grains.

• High resolution VLA observations have detected a that is "caught in the act" of escaping from the debris created during its violent formation only 15,000 years ago. Using specially designed electronics, a compact at the tip of an unusual protuberance directly outside the arc-shaped radio emission from the SNR G5.4-1.2 was found to harbor the pulsar PSR 1757-24. The young age of the pulsar was measured from its spin-down rate. If the pulsar and the SNR were created in the same event then the current speed of the pulsar is 2400 km/sec, the highest value known for any pulsar.

Two eclipsing binary are known that appear to be evaporating their companions; the evolution of such systems depends directly on the evaporation rate, which has been poorly known. Recent measurements of the pulsar of PSR 1744- 14A in the Terzan 5 made with the 140 ft telescope and the VLA at 1.67 GHz reveal that the eclipse is not total, but the pulsar signal is substantially delayed during the eclipse and suffers a maximum attenuation by the ablating material of about 70 percent. Models of the free-free absorption and dispersion of the pulsar signal in an ionized wind explain the frequency dependence of the eclipse duration but predict an evaporation rate such that the companion star is unlikely to be fully ablated in less than a Hubble time, so that in this case ablation may not ultimately form an isolated millisecond pulsar. OBSERVING HOURS

1979 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 Calendar Year

MO-Foot 12-Meter iH Interferometer \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 VLA

o X

Z3 O

1982 83 84 85 86 87 88 89 90 91 1982 83 84 85 86 87 88 89 90 91 1982 83 84 85 86 87 88 89 90 91 Calendar Year Calendar Year Calendar Year

\ NRAO Staff | Visitors Kl 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

100 A - ^■ "x r m / \ \ i ^s f 80 X A +r> \ r »• \ r > 1 r s n A ^ ^ A / - ] \ J A / ] ( \ \ \ / \ ^ / /■ £ 60 ) ] f A ' A A A \ A ) A f' f k 1 \ - Q- 40 - \ 0 \ V / V V / I V \ / \ \ V \ • 20 J }v/ 1 ^ V J V jJ u V >r > ^ »< ^--^ ■j f .> ^ ^ V ). ^x > v J .'\ s* »^ .y \ > _.--' 0 i/. i I x*' '»' y 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

100

80

^ 60 u £ 40

20

1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 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. Major improvements to the telescope system include: 1980 - installation of the Model IV autocorrelator receiver; 1982 - brake overhaul and installation of the second channel of the upconverter/maser receiver; 1987 • holographic surface tests and panel readjustments. VERY LARGE ARRAY TELESCOPE SUMMARY

- - 80 s , "\ A Sfc " * **" " s -^ '^- ^ ^x *s s^ -^ "^ "*■* -*■"' -" - ^ ^ ^ V >/ - - * 40 -^ — — -> .^ ^ -^ , - ^ /" - ./ N s,. 20 ^x ^.

^. —■ ^ : —. — ^* r: ■ .-- *-«, ^^ — — .-. ^.- -—. _ --— — ■-- ^^ — — """^»." .-. *'■" --H r 0 ~+-

Calendar Year — Construction Observing Testing, Maintenance and Calibration Downtime

Fig. 5. 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. Time scheduled for completion of the construction was reduced to zero after the first quarter of 1981. FULL-TIME PERMANENT EMPLOYEES

500

200

150

100 50 0 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 Calendar Year

V/SkVLA Construction Research and Operations VLB A Construction ESSSl 6BT Construction

Fig. 6. This figure shows the total number of NRAO full-time, permanent employees at the end of each year, projected into the future.

8 NUMBER OF PEOPLE OBSERVING WITH NRAO TELESCOPES

1000

1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 Calendar Year

Fig. 7. This bar chart shows for each calendar year the number of NRAO permanent research staff and the number of research associates who used 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 came. The significant jump In these last two categories starting in 1981 reflects the increased use of the VLA.

9 DISTRIBUTION OF TELESCOPE TIME BY PERCENT

12-M 140-Fr VLA 1991 Summary

Visitors 38% 62% 53% 51%

Students 10% 6% 11% 9%

Permanent Staff 15% 15% 9% 13%

Research Associates 1% 1% 2% 1%

Test and Calibration 32% 8% 12% 17%

Maintenance and Installation 2% 7% 11% 8%

10 DISTRIBUTION OF SCHEDULED OBSERVING PROGRAMS

IN VARIOUS RESEARCH AREAS, BY PERCENT

12-M 140-FT VLA OVERALL I. SOLAR SYSTEM -

Sun, Planet, Satellites, and Comets 3% < 1% 6% 4%

II. STKUAR-

Pulsars, X-ray Sources, Planetry Nebulae, 3% 20% 25% 21% Circumstellar Shells, Supernova Remnants, Masers, Novae, Supernovae, and Stars

III. GAIACllC-

Galactic Structure, Center, Molecular Clouds, HII Regions, 62% 32% 21% 29% Star Formation, Molecules, and Interstellar Medium

Normal and Active Galaxies, Radio Galaxies, 32% 48% 48% 46% Clusters, , VLBA Studies, Extragalactic Molecules, and Cosmology

11 INSTITUTIONS FROM WHICH VISITORS CAME TO USE NRAO TELESCOPES DURING 1990

TELESCOPES INSTITUTION 140-FT 12-M VLA

1. Air & Space Museum x 2. Alabama, U. of x x 3. American Institute of Physics (N.Y.) x x 4. Amsterdam, U. of - Astronomy Institute x 5. Anglo Australian Observatory - UKSTU (Schmidt) x

6. Applied Research Corporation x 7. Arcetri Astrophysical Observatory (Italy) x x x 8. Arizona, U. of - Steward Obs., L & P Lab. x x x 9. Arizona State University x 10. AURA, Inc. x

11. Barcelona, U. of (Spain) x 12. Beijing Astronomical Observatory (P.R. of China) x x x 13. Bell Laboratories (New Jersey) x 14. Birmingham, U. of (U.K.) x 15. Bloomsburg State College (PA) x

12 TELESCOPES INSTITUTION 140-FT 12-M VLA

16. Bologna, U. of (Italy) X X 17. Bonn U. (FRG) X X 18. Bordeaux Observatory (France) X X 19. Boston U. X X 20. Brandeis University X X

21. British Columbia, U. of (Canada) X 22. Calgary, U. of (Canada) X 23. California, U. of, Davis X 24. California, U. of; Berkeley - Hat Creek Obs. X X X 25. California, U. of, LA. X X

26. California, U. of, San Diego X X 27. California, U. of, Santa Barbara X X 28. Caltech - OVRA, Mt Palomar X X X 29. Cambridge University - Cavendish, Mullard, IOA X X 30. Carleton College X X

31. Catania U. (Italy) X 32. CFA (Harvard + SAO) X X X 33. CNRS, France (CEN, Saclay) X 34. Chalmers-Onsala Space Observatory (Sweden) X X X

13 TELESCOPES INSTITUTION 140-Fr 12-M VLA

36. Chile, U. of X 37. CITA - Canadian Institute of Theoretical Astrophysics X 38. Colgate University X 39. Colorado, U. of - JILA (Boulder) X X 40. X

41. Cornell University X X X 4Z CSIRO (Australia) X X 43. CTIO (Cerro Tololo Inter. Observatoiy) X 44. DAO (Dominion Astrophysical Observatory) X 45. DRAO (Dominion Radio Astrophysical Observatory) X

46. DTM - Carnegie Institute X X 47. Durham, U. of (U.K.) X 48. ESO (European Southern Observatoiy - FRG, Chile) X 49. Florida, U. of X 50. Georgia, U. of X X X

51. Gorky Radio Physical Observatoiy (USSR) X 52. Grenoble, U. of X X 53. Groningen, U. of - Kapteyn Lab. X X 54. Hamburger Stemwarte (FRG) X

14 TELESCOPES INSTITUTION 140-FT 12-M VLA

56. Hawaii, U. of - Institute of Astronomy x x x 57. Haystack Observatory - NEROC x x 58. Helsinki, U. of * 59. Heidelberg Observatory x 60. High Altitude Observatory - NCAR x

61. Hofstra University x 62. IAR, Buenos Aires (Argentina) x 63. lAS-Frascati (Italy) x 64. Illinois, U. of - Vermillion River Observatoiy x x x 65. Institute of Astrophysics (Granada) x x

66. Institute for A & A Andaluda x x 67. Institute for Space Research (USSR) x x 68. Institute for Molecular Science (Japan) x 69. INTA - NASA (Madrid) x x 70. Interferometrics, Inc. x x

71. Institute of Space & Aeronautical Sciences (Japan) x x 72. Iowa, U. of x x 73. Iowa State University x 74. IPAQ Pasadena x x 75. IRAM (France, Spain) x x

15 TELESCOPES INSTITUTION 140-Fr 12-M VLA

76. Itapetinga Observatoiy (Brazil) X X 77. Johns Hopkins University X X 78. JPL - Goldstone X X 79. Kentucky, U. of X X 80. Kolii,U.of(FRG) X

81. Kyung Hee University (Korea) X 82. KPNO - NOAO (National Solar Observatoiy) X 83. Lafayette College X 84. taval, U. of (Canada) X 85. Lebedev Physics Institute (USSR) X

86. Leicester, U. of (U.K.) X 87. Leiden, U. of - Huygens Labs. X X 88. Lockheed Research laboratory X 89. Los Alamos Scientific Laboratory (LANL) X 90. Lowell Observatoiy X

91. Madrid Observatoiy X X 92. Maine, U. of X 93. Manchester, U. of - Jodrell, Nuffield X X 94. Marseille Observatory X

16 TELESCOPES iNsnrunoN MO-FT 12-M VLA

96. Massachusetts, U. of - Five College Observatory x x x 97. Meudon Observatoiy x x 98. Mexico, U. of - Institute of Astronomy (UNAM) x 99. Michigan State University x 100. Michigan, U. of x

101. Middlebury College x 102. Milano (Italy) x 103. Minnesota, U. of x 104. MIT - Lincoln Laboratories x x 105. MMTO - Multimirror Telescope Observatoiy x

106. Monash University (Australia) x 107. Montreal, U. of x 108. MPIPA (Munich, FRG) x 109. MPIR (Bonn, FRG) x x x 110. MPIfEP, Garching (FRG) x

111. Mt. Stromlo Observatoiy (Australia) x x 112. Mt. Wilson & Las Campanas - Carnegie x 113. NAIC - Arecibo Observatoiy x x x 114. Nagoya University (Japan) x 115. NASA, Ames x

17 TELESCOPES INSTITUTION 140-FT 12-M VLA

116. NASA/GSFC - Goddard x x 117. NASA/MSFC - Huntsville x x 118. NFRA (Netherlands Foundation for Radio Astronomy) x x 119. NMIMT (New Mexico Institute of Mining Technology) x x 120. New Mexico, U. of x

121. New Mexico State University x 122. Nobeyama Observatoiy (Japan) x x 123. Nigeria, U. of x 124. North Carolina State University x 125. Northwestern University x x

126. NRC - Algonquin, Herzberg x 127. NRL (Naval Research Laboratories) x x x 128. Oberlin College x x 129. Oklahoma, U. of x 130. Oxford University (U.K.) x

131. Padua, U. of (Italy) x 132. Penn State University x x x 133. Pennsylvania, U. of x 134. Pittsburgh, U. of - Allegheny Observatory x 135. Preston/Lancashire Polytechnic (U.K.) x

18 TELESCOPES INSTITUTION 140-FT 12-M VLA

136. - Institute Advanced Studies x x 137. Pulkovo Observatory (USSR) x 138. Purple Mountain Observatoiy (China) x 139. Queen Maiy College (U.K.) x 140. Queens University (Canada) x

141. Radiophysics, Inc. (Boulder) x 142. Raman Institute (India) x x 143. Rensselaer Polytechnic Institute x 144. Rice University x 145. Royal Greenwich Observatory (U.K.) x

146. Royal Observatory - UKIRT (Scotland) x x 147. SERC, Rutherford Appleton Lab. (U.K.) x 148. Solar Physics Research Corporation x 149. Southampton, U. of x 150. Science Institute x x

151. Stanford University - Institute Plasma Research x 152. St. Lawrence University x 153. SUNY (all campi) x x 154. SFIT, ETH- Swiss Federal Institute of Technology x x 155. Sydney, U. of (Australia) x

19 TELESCOPES INSTITUTION 140-FT 12-M VLA

156. Tasmania, U. of (Australia) x 157. Tata Institute - TIFR, RAC (India) x x 158. Tel-Aviv University - Wise Observatoiy x 159. Texas, U. of - McDonald Observatoiy x x x 160. Tokyo University - Tokyo Astronomical Observatoiy x x

161. Toronto, U. of - David Dunlap Observatory x x 162. Trinity College (Texas) x x 163. Tuebingen University (Germany) x 164. Tufts University x 165. Union College (New York) x

166. University College Cardiff x 167. University College London x 168. USNA - United States Naval Academy x 169. USNO - United States Naval Observatoiy x x 170. Utrecht, U. of - Astronomical Institute (Netherlands) x x

171. Vermont, U. of x 172. Victoria, U. of (Canada) x 173. Virginia, U. of x x 174. VPI & SU x 175. Washington, U. of x

20 TELESCOPES SUMMARY 140-FT 12-M VLA

176. Waterloo, U. of (Canada) 177. Wisconsin, U. of - Washburn Observatory 178. Wyoming, U. of 179. Yale University 180. Yebes Observatory - CAY (Spain)

181. York University (Canada)

Number of Institutions 80 43 156

Number of Visitors 95 76 529 Number of Students 24 23 105 Number of Research Associates 5 2 9 Number of Permanent Staff 39

Total Observers 237 110 682

All told, 775 visitors, including 131 students, from 181 institutions.

21 NRAO STUDENT PROGRAM

200

teM Summer Undergraduate 180 mi co-op YZA Summer Graduate wmph.o. 160 est.

140 lli | ijtfti ^ 120

f 100 % w^w 80 n i

60 1 Ipl^l^l I I E

40 mii i i

20 9 i i Ii 1 E 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 Calendar Year

Fig. 8. This figure shows for each calendar year the number of PhD students (salaried and non-salaried), co-op students, and summer undergraduate and graduate students who observed or worked at the NRAO during that year. Beginning in 1987 the majority of the undergraduate summer students were funded by a separate NSF Grant for Research Experience for Undergraduates.

22 TECHNICAL DATA SHEET NO. 12 FEBRUARY 1992 PAGE 1 OF 4

SYSTEM 3 dB PERSON(S) AMPLIFIER CALIBRATION SWITCHING RECEIVER APPLICABLE FREQUENCY TEMPERATURE BANDWIDTH FEED TYPE POLARIZATION REMARKS IN VALUE SYSTEM NAME TELESCOPE (OH*) TYPE (KELVIN) (MHz) CHARGE

WCKE SWITCH: REFERENCE OPEN ORTHOGONAL TEMPERATURE 60-86 HIGH SLEEME ADJUSTABLE DYNAMIC 38 LINEAR MHz 300 CROSSED FROM FEED CHANGES FROM 60-88 MHz TO RANGE WPOLE fla + REMOVABLE 100 TO 100.000K 110-240 MHz OR TO 450-600 MHz TRANSISTOR NORROO DUAL Taky QUAD HYBRID ADJUSTABLE REQURE TWO HOURS. 50-600 MHi AT FEED FOR OR 140 FT CHANNEL 2 T0 2SOOK (OUVER) ItK BROADBAND RCP ANOLCP FREQUENCY 110-240 130 CROSSED MHz WPOLE SMTCH

CAWIY RCP BACKED FREQUENCY 460-600 FET 60-60 60 AND 460-600 MHz AMP IN 60-250 MHz Rx MHz AMP CROSSED SMTCH WPOLE LCP

280-350 280-350 70 350-410 MHZ 450-600 QASFET AMP 60-100 CAMTY DUAL BACKED 360-420 CHANNEL 60 MHz CROSSED WPOLES ONE OF THE SIX FEEDS COOLED 600-760 SCALAR DUAL 280-350 MHz 500-760 OASFET AMP ORTHOGONAL 60-70 260 WTH 300-420 MHz NORROO MHz DUAL UNEAR 460-600 MHz 300-1000 CHANNEL CROSSED FREQUENCY 140 FT WPOUS 6K 600-760 MHz (SHANK) MHt RN SWTCHINQ 75O-850 MHz OR RF HYBRID 760-1000 MHz COOUD FOR RCP CAN BE USES. TO CHANGE FEEDS REQUIRES 760-660 750-060 QASFET AMP 46-80 100 CROSSED AND LCP TWO HOURS. MHZ DUAL WPOIE CHANNEL

750-1000 COWED SCALAR 780-1000 QASFET AMP 80-70 260 WH TO CHANGE BCTWEN 760-880 AND MHz DUAL 760-1000 RK REQWRES 6 DAYS CROSSED CHANNEL WPOLES COOLED FRCOUENCY 1.00-1.48 SINGLE OASFET 35-40 450 ORTHOGONAL SMTCHINQ (25 CM) BEAM UNEAR 4K TO 6K DUAL SCALAR CHANNEL NOISE ADDING NORROO 6/25 CM ORTH CIRCULAR OTHER FEED CHANGE REQUIRED TO SMTCH BANDS 140 FT SINGLE BEAM 1.4K Rx COOLED OR ORTH UNEAR POLARIZATION TAKES TWO HOURS. (SHANK) 4.47-5.05 OASFET 60-00 660 DUAL BEAM IDENTICAL OR OR (ecM) DUAL ORTH CIRCULAR CHANNEL OFFSET BEAM SMTCHINQ 3 MPBW OR IDENTICAL 12.8K UNEAR

23 TECHNICAL DATA SHEET NO. 12 FEBRUARY 1992 PAGE 2 OF 4 SYSTEM 3 dB PERSON(S) SWITCHING RECEIVER APPLICABLE FREQUENCY AMPLIFIER TEMPERATURE BANDWIDTH FEED TYPE POLARIZATION CAUBRATION REMARKS IN NAME TFVFSCOPE (CH*) TYPE (KELVIN) (MHi) VALUE SYSTEM CHARGE THREE 2HE 2K FREQUENCY OTHER ORCULAR OR UNEAR POLARIZATIONS UP TO 120 ««« "tAM ORTHOGONAL OR ARE SEIECTABLE. CIRCULAR POLARIZATION DUAL NORROD POLARtZATION REQUIRES ADJUSTMENTS FROM THE CONTROL 1.3-1.6 GHz 140 FT 1.30-1.80 CHANNEL 18-25 AND i££W 1.36-1.43 OR SMTCHMQ ROOM. BAND CHANGE REQURES 2 TO 3 Rx COOLED HEMT (CHESTNUT) UMIIU> 1.60-1.72 _, CIRCULAR OR 200K HOURS. OBSERVATIONS OUTSIDE STATED FEED (ZEEMAN 1.36-1.43| NOISE ADDBIQ BANDS POSSIBLE AT REDUCED EPnOENaES. CONTINUUM RECEIVER. ON-AXIS HORN HAS UNCOOLED 110 DSB CIRCULAR 300 K LOAD OR RECEIVERS ON BOTH POLARIZATIONS. FOUR NORROO 11 CM. 2.64-2.75 130 3 HORNS OR 4K POLARIZATION 140 FT QASFET (F 6-56) HOURS TO CHANGE POLARIZATION. FIXED S-FEED Rx UNEAR OR BEAM 4 CHANNEL LO AT 2.685 GHz. (CHESTNUT)

UP TO 250 TWO 2HE DUAL 2K BAND CHANGE REQUIRES FEED CHANCE. THIS SINGLE BEAM ORTHOGONAL CHANNEL 38*4 AND TAKES 2-3 HOURS. FREQUENCY SMTCHMQ 2.8-3.4 FEED 2.80-3.1 UNEAR COOLED FET 18aK REQUMES 60 MS BLANKMO TME. UNITED 3.20-3.4 FREQUENCY BEHRENS 2-6 GHz 140 FT SMTCHMQ Rx UP TO 200 NOISE ADDMO (CHESTNUT) DUAL ONE 2HE 3K RECEIVER BAND UNITED BY 4.4-4.8 GHz FEED. 4.6-6.0 CHANNEL 28*6 SMGLE BEAM AND FREQUENCY SMTCHMQ REQUIRES 60 MS FEED CIRCULAR COOLED HEMT 4.6-4.6 150K BLANKMO TIME UNITED

COOLED 7 CORRUGATED BEHRENS HEMT DUAL CONTINUUM USE ONLY. 6 CM. 140 FT 4.4-6.1 36-46 600 HORNS 4K NONE FOURTEEN OROULAR TOTAL POWER RF DETECTION. 7-FtED Rx 3 HPBW (CHESTNUT) CHANNEL APART

FRFOUFMCY J»»* FIXED UNEAR FREQUENCY OR UPCOtOCRTER 30-50 60-300 CASSEGRAM 3-7K 4.7-7.2 ORCULAR NIB NUT A FOR BEAM 4.7-4.6 40-80 MASER 4.8-6.6 30-40 6.6-7.2 40-60

UPCONNERTER FIXED UNEAR FREQUENCY OR 7.4-8.5 50-80 7.6-11.2 35-80 80-300 CASSEGRAM 3-7K MASER CIRCULAR VLB NUTATOR BEAM 8.5-11.2 36-45

CASSEGRAM UPCONVERTER 140 FT 12-16.2 50-80 80-300 CASSEGRAM FIXED UNEAR 3-7K FREQUENCY OR 12.0-16.2 50-80 MASER NUTATOR BEAM A AND B BROCKWAY COOLED FREQUENCY OR ONE RECOVER AVAJUBLE NOW 12-18 40-80 600 CASSEGRAM FIXED UNEAR 3-7K RECEIVERS HEMT NUTATOR BEAM TWO RECOVERS READY 1682 (OUNBRACK)

FIXED UNEAR FREQUENCY OR 18.2-25.2 MASER 40-70 •0-300 CASSEGRAM 2-6K 18.2-25.2 40-70 ORCULAR *B NUTATOR BEAM

COOLED FREQUENCY OR 25-35 60-60 600 CASSEGRAM F1XFD UNEAR 3-7K ONE RECEMK HEMT NUTATOR BEAM

SUBREFLEC TOR CORRECTS FOR 1ELESC0PI . ASUGMAHSM AND LATERAL OFFSET. BEAM SPUTTER AVAILABIE 6 TO 26 GHz. NUTATWO TRAI MSmON TME 50 MHUSECONt >S. 6 Hz MAXIMUM BEAM SHFT - MUTATOR FOUR HOURS FOR BAND CHANGE. FREQUENCY . BEAM SHIFT DmECTTCN FIXE0. 0-18 ARC MK NOISE ADDMO AVAlLABlf. RECEIVER! 2. 1.5' SOUTH OF 1EAST. 4 RECOVER: 22. 1* MORIM OF MEST.

24 TECHNICAL DATA SHEET NO. 12 FEBRUARY 1992 PAGE 3 OF 4

RECOVER CONTINUUM 3 dB PERSON(S) SWITCHING APPLICABLE FREQUENCY AMPLIFIER lEMPERATURE SENSITIVITY BANDWIDTH FEED TYPE POLARIZATION CAUBRATION REMARKS IN TtLESCOPE (GHx) TYPE (KELVIN) JANSKY V5CC (MH2) VALUE SYSTEM CHARGE

APPROX. 100 TORE 800 MHz HORN-LENS DUAL 10 K NUTATMO LAMB 12 M 68-116 SIS BSB MEASURED UNEAR SUBREFIECTOR SMGLE SRXBAND MIXERS 180-300 DUAL NUTATMO NOT 800 MHz HORN-LENS SMGLE SDEBANO MIXERS LAMB 12 M 200-270 sn SS8 MEASURED UNEAR - SUBREFIECTOR 1000-2000 DUAL NUTATMO 270-305 COOLED NOT 600 MHz HORN-UENS LAMB 12 M MIXER SS8 MEASURED UNEAR - SUBREFIECTOR

25 TECHNICAL DATA SHEET NO. 12 FEBRUARY 1992 PAGE 4 OF 4

SYSTEM 3 dB PERSON(S) APPLICABLE FREQUENCY AMPLIFIER TEMPERATURE BANDWIDTH RED TYPE POLARIZATION CAUBRATION SWITCHING REMARKS IN VALUE TELESCOPE (MHz) TYPE (KELVIN) (MHi) SYSTEM CHARGE 3 MHz DUAL NOSE INJECTION. 30O- UNCOOLED PRIME VLA 150 (UMTEDBY FOCUS ORTNOQONAL 10 6.6 Hz. UUE 343 TRANSISTOR HTERFERENCC) ORCULAR 50 PERCENT CYCLE. DUAL NOISE MJECTKH 1340- VLA 60 55 CASSEGRAM ORTNOQONAL 4 t.a Hz. 17 ANTENNAS HUE 1730 FET CIRCULAR 60 PERCENT CYCLE. DUAL NOISE MJEC1KM. 1340- COOLED 10 ANTENNAS: & 4» 11, 2* 21. 2A> 24k VLA 35 55 CASSEGRAM OKTHOOONAL 4 8.6 Hz. UUE 1730 HEMT SO PERCENT CYCLE. 281 26 ft 27

DUAL NOISE INJECTION. 4600- COOLED VLA 60 65 CASSEGRAM ORTHOGONAL 4 6.6 Hz. UUE 8000 HEMT CIRCULAR 60 PERCENT CYCIF.

DUAL NOSE MJECTKH 8000- COOLED VLA 35 66 CASSEGRAM ORTNOQONAL 4 6.6 Hz. UUE 8600 HEMT CIRCULAR 60 PERCENT CYCLE.

NOSE INJECTION. 14400- COOLED DUAL VLA 110 65 CASSEGRAM 7 15400 FET ORTHOOONAL 6.6 Hz. UUE CIRCULAR 60 PERCENT CYCLE.

COOLED DUAL NOSE INJECTION. 2200O- 130 65 CASSEGRAM 10 VLA 24000 HEMT ORTHOOONAL 8.6 Hz, UUE CIRCULAR 60 PERCENT CYCLE.

26 NRAO - STAFF AND VISITOR PUBLICATIONS 1991

AAQUIST, O. B. and KWOK, S. "High-Resolution Radio Continuum Observations of Compact Planetary Nebulae." Astrophys, J* W, 599-610,1991. AKUJOR, C E. and GARRINGTON, S. T. "MERLIN and VLA Observations of the 1150+497." MfflLUflL Roy. Astron. Soc,, 25a 644-649,1991. AKUJOR, C E. and MCGRUDER, C H. III. "Is Quasar 1038+064 Rotating?" In: Variability of Active Galactic Nuclei. Ed. H. R. Miller and P. J. Wiita. (Cambridge: Cambridge University Press, 1991) 169-171. AKUJOR, C E.; SPENCER, R. E.; and SAIKIA, D. J. "3C43: A Jet Deflected by Dense Gas?" Astron. Astrophys.. 212,337-340,1991. AUSSANDRAKIS, C E.; KUNDU, M. R.; and SHEVGAONKAR, K. R. "VLA Observations of Solar Active Regions at 6 and 20 cm." Astron. Astrophvs.. 251, 276-284,1991. ALLOIN, D.; BARVAINIS, R.; ANTONUCCI, R.; and GORDON, M. "CO Emission From the Radio-Quiet Quasar E 1821+64 at z=0301: Implication Regarding the Origin of Its Far Infrared Radiation." IAU Colloq.. 122, 371-372,1991.

ANANTHARAMAIAH, K. R.; DESHPANDE, A. A.; RADHAKRISHNAN, V.; EKERS, R. D.; CORNWELL, T. J.; and GOSS, W. M. "Source-Noise in Radio Synthesis Images." IAU Colloq.. 131. 6-9, 1991.

ANANTHARAMAIAH, K. R.; PEDLAR, A.; EKERS, R. D.; and GOSS, W. M. "Radio Studies of the Galactic Centre - II. The Arc, Threads and Related Features at 90 cm (330 MHz)." Mon. Not. Rov. Astron. Soc.. 242, 262-281, 1991. ANDERSSON, B.-G.; WANNIER, P. G.; and MORRIS, M. "Warm Neutral Halos Around Molecular Clouds. III. Interpretation of H I and CO J « 1-0 Data." Astrophvs. J.. 366. 464-473, 1991.

ANDERSON, M.; RUDNICK, L; LEPPIK, P.; PERLEY, R.; and BRAUN, R. "Relativistic Electron Populations in ." Astrophvs. J.. 373. 146-157,1991.

27 ANDRE, P.; PHILLIPS, R. B.; LESTRADE, J.-F.; and KLEIN, K.-L "Direct VLBI Detection of the Magnetosphere Surrounding the Young Star SI in p Ophiuchi." Astrophys. J- 2Z& 630-635, 1991.

ANGLADA, G.; ESTALELLA, R.; RODRIGUEZ, L F.; TORRELLES, J. M.; LOPEZ, R.; and CANTO, J. "A Double Radio Source at the Center of the Outflow in L723." Astrophys. J.. 2Z& 615-617,1991.

ANGLADA, G.; ESTALELLA, R.; RODRIGUEZ, L F.; TORRELLES, J. M.; CANTO, J.; and HO, P. T. P. "VLA Observations of the High-Density Gas Around the Exciting Source of HH34N-S." In: SkylinfiS. Ed. A. D. Haschick and P. T. P. Ho. (San Francisco: Astronomical Society of the Pacific, 1991) 279-283.

BAATH, L B. and BOOTH, R. S. "mmVLBI - High Resolution Imaging." IAU Colloq.. HI, 326-329, 1991.

BAATH, L B. and ZHANG, F. J. "The Radio Fine Structure of the BL Lacertae Object 0735+178." AslIQIL AslDBRtaS* 24! 328-332, 1991.

BACHILLER, R.; ANDRE, P.; and CABRIT, S. "Detection of the Exciting Source of the Spectacular Molecular Outflow L 1448 at A. A. 1-3 mm." Astron. Astrophvs.. 241 L43-L46,1991.

BAGRI, D. and THOMPSON, A. R. "Hardware Considerations for High-Dynamic-Range Imaging." IAU Colloq.. HL 47-54,1991.

BARNBAUM, C; MORRIS, M.; LIKKEL, L; and KASTNER, J. H. "Carbon Stars Associated With Oxygen-Rich Circumstellar Envelopes: EU Andromedae, BM Geminorum and V778 Cygni." Astron. Astrophys., 2519 79-91, 1991.

BARTER N.; RUPEN, M. P.; SHAPIRO, 1.1.; PRESTON, R. A.; and RUIS, A. "A High-Resolution Radio Image of a Young Supernova." Nature. 350. 212-214, 1991.

BASTIAN, T. S. "Solar Radio Microbursts at 1.4 GHz." Astrophys. J.. 370. L49-L52, 1991.

BAUDRY, A.; DIAMOND, P.; and HENKEL, C. "The OH and H20 Masers in the Messier 82." Adv. Space ]tes„ 11(2), 369-372, 1991.

BAUDRY, A. and DIAMOND, P. J. "VLBI Observations of 4765 MHz OH Emission in Compact H II Regions." Astron. Astrophvs.. 241 551-555, 1991.

28 BAUM, S. A. and O'DEA, C. P. "Multifrequency VLA Observations of PKS 0745-191: The Archetypal 'Cooling Flow' Radio Source?" Mon. Not. Rov. Astron. SO

BECK, R. "Magnetic Fields and Interstellar Gas Clouds in the NGC 6946." Astron. Astrophys.. 251, 15-26, 1991.

BECKER, R. H.; WHITE, R. L; and EDWARDS, A. L "A New Catalog of 53,522 4.85 GHz Sources." Astrophvs. J. SmL 25.1-229,1991.

BELL, M. B. and FELDMAN, P. A. "Detection of 13C Isotopomers of HQN (J = 9-8) in the Circumstellar Envelope of IRC +10216." Astrophvs. J.. 367. L33-L36, 1991.

BENZ, A. O. and ALEF, W. "VLBI Observations of YZ CMi - a Single dMe Star." Astron. Astrophys^ 252, L19-L22, 1991.

BIBGING, J. H.; GOSS, W. M.; and WILCOTS, E. M. "VLA Observations of 21 Centimeter HI Absorption Toward Qissiopeia A." Astrophys, J. SuppL 35, 999-1010,1991.

BIEGING, J. H.; WILNER, D.; and THRONSON, H. A. JR. "The Molecular Envelope of NGC 7027." Astrophvs. J- 222, 271-279,1991.

BIETENHOLZ, M. F.; FRAIL, D. A.; and HANKINS, T. H. "Does the Vela Pulsar Have 'Wisps'?" Astrophys. J.. 226, L41-L44, 1991.

BIBNTBNHOLZ, M. F. and KRONBERG, P. P. "Faraday Rotation and Physical Conditions in the ." Astrophys. J.. 268,231-240,1991. BIETENHOLZ, M. F.; KRONBERG, P. P.; HOGG, D. E.; and WILSON, A. S. "The Expansion of the Crab Nebula." Astrophvs. J.. 373. L59-L62, 1991.

BIRETTA, J. A.; BARTEL, N.; and DENG, J. "Dual Frequency Synthesis VLBI Observations of 3C84 at 18 cm Wavelength." IAU CpHoq., 12L 334-337,1991.

29 BIRETTA, J. A.; STERN, C. P.; and HARRIS, D. E. "The Radio to X-ray Spectrum of the M87 Jet and Nucleus." AsttQBLL, M, 1632-1646, 1991.

BRAUN, R. "The Distribution and Kinematics of Neutral Gas in M31." Astrophvs. J.. 222, 54-66,1991.

BRIDLE, A. H.; BAUM, S. A.; FOMALONT, E. B.; FANTI, R.; PARMA, P. and EKERS, R. D. "WSRT and VLA Observations of the B2 0326+39 at 0.6, 1.5 and 5 GHz." Astron. Astrophvs.. 245. 371-392, 1991.

BROUILLET, N.; BAUDRY, A.; COMBES, F.; KAUFMAN, M.; and BASH, F. "M81: CO Omtent and Interaction With Its Companion Galaxies." Astron. Astrophys., 242. 35-48, 1991.

BROWN, R. L "The Millimeter Array." IAU Colloq.. 121, 410-414, 1991.

BROWN, R. L; KERR, A. R.; THOMPSON, A. R.; and SCHWAB, F. R. "High-Resolution Imaging Spectroscopy at Terahertz Frequencies." IAU Colloq.. 123. 509-515, 1991.

BROWN, R. L and VANDEN BOUT, P. A. "CO Emission at z - 2.2867 in the Galaxy IRAS F10214+4724." Astron, Jn 102,1956-1959,1991.

BUHL, D.; CHIN, G.; and GOLDSTEIN, J. J. "Discovery of a Doppler-Limited CO Line in the Upper Mesosphere of Venus: A New Dynamical Probe." Astrophvs. J.. 369. L17-L20, 1991.

CABRIT, S. and ANDRE, P. "An Observational Connection Between Circumstellar Disk Mass and Molecular Outflows." Astrophys. J.. 379. L25-L28,1991.

CAILLAULT, J.-P. and DRAKE, S. "Full Phase Coverage of BY Dra With the VLA." IAU Colloq.. 12a 494-497, 1991.

CARILLI, C L; BARTEL, N.; and UNFIELD, R. P. "VLBI Observations of the Nuclear Jet in Cygnus A." Astron. J.. Ifl2, 1691-1695, 1991.

CARILLI, C. L; PERLEY, R. A.; DREHER, J. W.; and LEAHY, J. P. "Multifrequency Radio Observations of Cygnus A: Spectral Aging in Powerful Radio Galaxies." Astrophys. J.. 383. 554-573,1991.

30 CARLSTROM, J. E. and KRONBERG, P. P. "H II Regions in M82: High-Resolution Millimeter Continuum Observations." Astrophys. J.. 266, 422-431, 1991.

CASERTANO, S. and VAN GORKOM, J. H. "Declining Rotation Curves: The End of a Conspiracy?" Astron. J.. 101. 123M241, 1991.

CERSOSIMO, J. C and ONELLO, J. S. "Radio Recombination Lines From Diffuse Interstellar Gas in the Galaxy." Astrophys. J., 220, 225-227, 1991.

CLARK, F. O. "Young Stellar Objects Detected by IRAS." Astrophvs. J. Suppl.. 25, 611-628,1991.

CLARK, F. O. and LAUREUS, R. J. "Dust and Molecular Properties of the Low-Opacity Cloud Lynds 1563." Astrophys. J„ 220,237-242,1991.

CLEGG, A. W. and CORDES, J. M. "Variability of Interstellar Hydroxy! Masers." Astrophys. J.. 374.150-168, 1991.

COMINS, N. F. and OWEN, F. N. "The Extraordinary Radio Source 3C 442." Astrophys. J.. 282,108-114, 1991.

CONDON, J. J. "Radio Luminosity Functions." In: Interpretation of Modem Synthesis Observations of Spiral Galaxies. Ed. N. Duric and P. C Crane. (San Francisco: Astronomical Society of the Pacific, 1991) 113-123.

CONDON, J. J.; ANDERSON, M. L; and HELOU, G. "Correlations Between Far-Infrared, Radio, and Blue Luminosities of Spiral Galaxies." Astrophys. J.. 376. 95-103, 1991.

CONDON, J. J. and BRODERICK, J. J. "Radio Properties of Extragalactic IRAS Sources." Astron. J.. 102.1663-1679, 1991.

CONDON, J. J.; BRODERICK, J. J.; and SEIELSTAD, G. A. "A 4.85 GHz Sky Sunrey. II. Maps Covering -40* <6< +5, &<5<2(V." Astron. J.. Iffi, 2041-2046, 1991.

CONDON, J. J.; FRAYER, D. T.; and BRODERICK, J. J. "UGC Galaxies Stronger Than 25 mJy at 4.85 GHz." Astron. J., 101,362-409,1991.

31 CONDON, J. J.; HUANG, Z.-P.; YIN, Q. F.; and THUAN, T. X. "Compact Starbursts in Ultraluminous Infrared Galaxies." Astrophys. J.. 225, 65-76, 1991.

COOKE, B. A. and PONMAN, T. J. "A Variable Radio Source in the Error Box of the Bright Galactic X-ray Source GX 349+2." Astron. Astrophys., 244,358-362,1991.

COOL, A. M. and HO, P. T. P. "Structure and Kinematics of NH3 Cores in G 10.6-0.4." In: SkyUflCS. Ed. A. D. Haschick and P. T. P. Ho. (San Francisco: Astronomical Society of the Pacific, 1991) 233-240.

CORNWELL, T. J. "Array Configurations and Image Processing - Design Issues." In: Radio Schmidt Telescope. (Penticton: Dominion Radio Astrophysical Observatory, 1991) 209-215.

COWAN, J. J.; GOSS, W. M.; and SRAMEK, R. A. "The Radio Recovery of SN 1970G in M101." Astrophvs. J- 379. L49-L51,1991.

CRANE, P. C and HILLENBRAND, L. A. "Estimating Harmful Levels of Radio-Frequency Radiation." IAU Colloq.. 112, 258-266, 1991.

CRUTCHER, R. M.; LOUSHIN, R.; BIEGING, J.; and TROLAND, T. H. "BIMA and VLA Observations of S106." In: Skylines. Ed. A. D. Haschick and P. T. P. Ho. (San Francisco: Astronomical Society of the Pacific, 1991) 381-385.

D'ADDARIO, L R. "Time Synchronization in Orbiting VLBI." IEEE Tr. Instrum. Meas.. IM-40. 584-590, 1991.

DAHLEM, M.; KORIBALSKI, B.; WIELEBINSKI, R.; and MEBOLD, U. "Mass Outflow From the Nuclear Region into the Halo of NGC 1808." IAU Symp.r 144 (poster vol.), 39-40,1991.

DAHLEM, M.; WIELEBINSKI, R.; KORIBALSKI, B.; and MEBOLD, U. "A Molecular Gas Ring in NGC 1808." IAU Smu 14& 283, 1991.

DE PATER, I. "Radio Images of Jupiter's Synchrotron Radiation at 6, 20, and 90 cm." Astron. J.. 102, 795-805, 1991.

DE PATER, I. and DICKEL, J. R. "Multifrequency Radio Observations of Saturn at Ring Inclination Angles Between 5 and 26 Degrees." Icarus. 24, 474-492, 1991.

32 DE PATER, I.; ROMANI, P. N.; and ATREYA, S. K. "Possible Microwave Absorption by H^ Gas in Uranus' and Neptune's Atmospheres." Icarus. 21.220-233, 1991.

DETTMAR, R.-J.; KEPPEL^ J. W.; ROBERTS, M. S.; and GALLAGHER, J. S. "The Diffuse Ionized Gas Perpendicular to the Plane of NGC 891." IAU Symp.r 144. 295-298, 1991.

DETTMAR, R. J.; KEPPEL, J. W.; ROBERTS, M. S.; and GALLAGHER, J. S. "Observations of the Diffuse Ionized Gas Perpendicular to the Plane of NGC 891." IAU Svmp.. 144 (poster vol.), 43-44,1991.

DEWDNEY, P. E.; COSTAIN, C. H.; MCHARDY, L; WILUS, A. G.; HARRIS, D. E.; and STERN, C P. "An X-ray and Radio Study of Steep-Spectrum Radio Sources. II. Four Fields From a 22 MHz Polar Cap Survey." Astrophys. J. SyppL 26,1055-1066,1991.

DEWDNEY, P. E.; ROGER, R. S.; PURTON, C. R.; and MCCUTCHEON, W. H. "IRAS 23545+6508, a Dissociating Star: Prototype for a New Observational Class?" Astrophvs. J.. 370. 243-256, 1991.

DICKEL, J. R.; VAN BREUGEL, W. J. M.; and STROM, R. G. "Radio Structure of the Remnant of Tycho's Supernova (SN 1572)." Astron. J.. M, 2151-2159, 1991.

DICKEY, J. M. and GAVAZZI, G. "H I Mapping of Galaxies in the Ouster A1367." Astrophys. J.. 373.347-353,1991.

DICKINSON, D. F. and TURNER, B. E. "New OH Main-Line Detections of OH/IR Stars." Astrophys. J. SuppL 25, 1323-1336,1991.

DOUGHERTY, S. M.; TAYLOR, A. R.; and WATERS, L B. F. M. "Radio Variability of Be Stars." Astron. Aslrophysu 248,175-178,1991. DRAKE, S. A.; JOHNSON, H. R.; and BROWN, A. "A Radio Search for Continuum Emission From S-Type Red Giants With Companions." Astron. J.. 101. 1483-1488, 1991.

DRAKE, S. A.; UNSKY, J. L; JUDGE, P. G.; and ELTTZUR, M. "Radio-Continuum Observations of a Variety of Cool Stars." Astron. J.. 101.230-236,1991.

33 DUBNER, G. M.; BRAUN, R.; WINKLER, P. F.; and GOSS, W. M. "VLA Observations of the Puppis A at 327 and 1515 MHz." AsttonJL 1QL 1466-1471,1991.

DULK, G. A. and BASTIAN, T. S. "Imaging the and the Planets With a Radio Schmidt Telescope." In: Radio Schmidt Telescope. (Penticton: Dominion Radio Astrophysical Observatory, 1991) 123-154.

DURIC, N. "Cosmic Rays in Spiral Galaxies." In: Interpretation of Modem Synthesis Observations of Spiral Galaxies. Ed. N. Duric and P. C. Crane. (San Francisco: Astronomical Society of the Pacific, 1991) 17-26.

ELIAS, N. M. II and STRUBLE, M. F. "Discovery of Two Radio Galaxies in the Zwicky Ouster 14373+6436." AstosmJL 102,30-33,1991.

EMERSON, D. T. "Imaging Characteristics of the Proposed NRAO MMA, With and Without a Single Large Element, and a Pointing Correction Algorithm." IAU Colloq.. 121 441-444, 1991.

ESTALELLA, R.; ANGLADA, G.; RODRIGUEZ, L F.; and GARAY, G. "Multifrequency VLA Observations of Radio Continuum From IRAS 16293-2422." Astrophys. J.. 22L 626-630, 1991.

FELU, M. and MASSI, M. "VLBI Observations of HD 193793." Astron. Astrophys., 246, 503-506,1991.

FELLI, M.; MASSI, M.; and CATARZI, M. "Intercontinental VLBI Observations of O1 Ononis A." Astron. Astrophvs.. 248,453-457,1991.

FERNINI, I.; LEAHY, J.P.; BURNS, J.O.; and BASART, J.P. "Depolarization Asymmetry in the Quasar 3C 47." Astrophys. J,, 28163-71,1991. FEY, A. L; SPANGLER, S. R.; and CORDES, J. M. "VLA and VLBI Angular Broadening Measurements: The Distribution of Interstellar Scattering at Low Galactic Latitudes." Astrophys. J.. 222,132-160,1991.

FICH, M. and SILKEY, M. "Abundances in H II Regions at the Edge of the Galaxy." Astrophys. J.. 2i& 107-114, 1991.

HNDLAY, J. "I.U.CA.F. and Frequencies for Radioastronomy." IAU Colloq.. 112,194-197, 1991.

FISHER, J. R. "The Nature, of RFI and Some Lines of Defense." IAU Colloq.. 112, 240-248, 1991.

34 FOMALONT, E. B. and GELDZAHLER, B. J. "The Radio 'Lobes' of Scorpius X-l Are Unrelated Background Sources." Afitrophys. Jn 282,289-294, 1991.

FOMALONT, E. B.; LOWENTHAL, J.; PARTRIDGE, R. B.; and WINDHORST, R. A. "Fine-Scale Microwave Fluctuations at X*3.6 cm." In: After the First Three Minutes. Ed. S. S. Holt, C L Bennett, and V. Trimble. (New York: AIP, 1991) 140.

FOMALONT, E. B.; WINDHORST, R. A.; KRISTTAN, J. A.; and KELLERMANN, K. I. The Micro-Jansky Radio Source Population at 5 GHz." Astron. J.. 1Q2, 1258-1277, 1991.

FOSTER, R. S.; FAIRHEAD, L; and BACKER, D. C "A Spectral Study of Four Millisecond Pulsars." Astrophys. J* 228,687-695,1991.

FRAIL, D. A.; CORDES, J. M.; HANKINS, T. H.; and WEISBERG, J. M. "H I Absorption Measurements Toward 15 Pulsars and the Radial Distribution of Diffuse Ionized Gas in the Galaxy." Astrophvs. J.. 282, 168-181, 1991.

FRAIL, D. A. and HJELLMING, R. M. "Distance and Total Column Density to the Periodic Radio Star LSI+61° 303/ AstlwJL IflL 2126-2130, 1991.

FRAIL, D. A. and KULKARNI, S. R. "Unusual Interaction of the High-Velocity Pulsar With the Supernova Remnant G5.4-1.2." Maiurs, 252, 785-787,1991.

FULLER, G. A.; MYERS, P. C; WELCH, W. J.; GOLDSMITH, P. F.; LANGER, W. D.; CAMPBELL, B. G.; GUILLOTEAU, S.; and WILSON, R. W. "Anatomy of the Barnard 5 Core." Astrophys. J.. 22fc 135-149,1991.

GARCIA-BARRETO, J. A.; DETTMAR, R.-J.; COMBES, F.; GERIN, M.; and KORIBALSKI, B. "The Nuclear Ring of the Barred Galaxy NGC 1326." Rev. Mex. Ast. Astrof.. 22, 197-212, 1991.

GARCIA-BARRETO, J. A.; DOWNES, D.; COMBES, F.; CARRASCO, L; GERIN, M.; and CRUZ-GONZALEZ, I. "Circumnuclear Star Formation in the Barred Galaxy NGC 1022." Astron. Astrophvs.. 252, 19-26, 1991.

GARCIA-BARRETO, J. A.; DOWNES, D.; COMBES, F.; GERIN, M.; MAORI, C; CARRASCO, L; and CRUZ- GONZALEZ, I. "The Nuclear Ring of the Barred Galaxy NGC 4314." Astron. Astrophvs.. 244, 257-272, 1991.

35 GARCIA LARIO, P.; MANCHADO, A.; RIERA, A.; MAMPASO, A.; and POTTASCH, S. R. "IRAS 22568+6141: A New Bipolar ." Astron. Astrophvs.. 242, 223-232, 1991.

GARRINGTON, S. T.; CONWAY, R. G.; LEAHY, J. P. "Asymmetric Depolarization in Double Radio Sources With One-Sided Jets." Mon. Not Roy. Astron. Soc. 250, 171-197,1991.

GAUME, R. A.; JOHNSTON, K. J.; NGUYEN, H. A.; WILSON, T. L; DICKEL, H. R.; GOSS, W. M.; and WRIGHT, M. C H. "NGC 7538 IRS 1: Subarcsecond Resolution Recombination Line and "NHj Maser Observations." Astrophys. J„ 226,608-614,1991.

GAUME, R. A.; JOHNSTON, K. J.; NGUYEN, H. A.; WILSON, T. L; DICKEL, H. R.; GOSS, W. M.; and WRIGHT, M. C H. "NGC 7538 IRS 1: Subarcsecond Resolution Recombination line and "NHj Maser Observations." In: Skylines. Ed. A. D. Haschick and P. T. P. Ho. (San Francisco: Astronomical Society of the Pacific, 1991) 171-175.

GIOVANNINI, G.; FERETTI, L; and STANGHELUNI, C The Radio Source 1253+275, Revisited." Astron. Astrophys., 252,528-537,1991.

GOLLA, G. and BECK, R. "Radio-Continuum Emission of the Edge-On Galaxy NGC 5775." IAUSympT 144 (poster volume), 47-48, 1991.

GOMEZ, Y.; RODRIGUEZ, L F.; GARAY, G.; and MORAN, J. M. The Dense Molecular Envelope Around the Compact H II Region G5.89-0.39 (W28 A2)." Astrophvs. J.. 377. 519-525, 1991.

GOPALSWAMY, N.; WHITE, S. M.; and KUNDU, M. R. "Large-Scale Features of the Sun at 20 cm Wavelength." Astrophvs. J.. 379. 366-380, 1991.

GORDON, M. A. "Detection of CO Emission in the Elliptical Galaxies NGC 3265 and NGC 5666." Astrophys. J.. 221, 563-567,1991.

GRAY, A. D.; CRAM, L E.; EKERS, R. D.; and GOSS, W. M. "A Filamentary Radio Source Near the Galactic Centre." Nature. 252, 237-239,1991.

GREGORY, P. C. and CONDON, J. J. The 87GB Catalog of Radio Sources Covering 0° < 6 < +75° at 4.85 GHz." Astrophys. J. SMPPU 25,1011-1291,1991.

36 GRIFFITH, M.; LANGSTON, G.; HEFLIN, M.; CONNER, S.; and BURKE, B. The Fourth MIT-Green Bank 5 GHz Survey." Astrophys. J. SuppL 25, 801-833, 1991.

HABBAL, S. R. and GONZALEZ, R. D. "First Observations of Macrospicules at 4.8 GHz at the Solar Limb in Polar Coronal Holes." Astrophys. J- 226, L25-L27, 1991.

HANKINS, T. H.; IZVEKOVA, V. A.; MALOFEEV, V. M.; RANKIN, J. H.; SHITOV, Y. P.; and STTNEBRING, D. R. "Microstructure-Determined Pulsar Dispersion Measures and the Problem of Profile Alignment" Astrophys. J.. 222, L17- L21,1991.

HAYNES, M. P. and GIOVANELU, R. The Distribution of Galaxies Around NGC 5846." AfiUmJ* 102, 841-863, 1991.

HAYNES, M. P. and GIOVANELU, R. "Neutral Hydrogen Observations of Galaxies in ." Astrophys. J. SsfflpL 21 331-362, 1991.

HEESCHEN, D. "Reminiscences of the Early Days of the VLA." IAU Colloq.. 121,150-159,1991.

HILL, G. J. and LILLY, S. J. "A Change in the Ouster Environments of Radio Galaxies With Cosmic Epoch." Astrophys. Jo 262,1-18,1991.

HJELLMING, R. M. "Images and Light Curves of the Radio Remnants of Novae." IAU Colloq.. 122.169-178,1991.

HJELLMING, R. M. " Herculis 1991." JALLCfct, 5224, 9 April 1991.

HO, L C; SZCZEPANSKI, J. C; HO, P. T. P.; JACKSON, J. M.; and ARMSTRONG, J. T. "A Molecular Shell Surrounding the Galactic Center." In: Skylines. Ed. A. D. Haschick and P. T. P. Ho. (San Francisco: Astronomical Society of the Pacific, 1991) 177-181.

HO, P. T. P.; HO, L C; SZCZEPANSKI, J. C; JACKSON, J. M.; ARMSTRONG, J. T.; and BARRETT, A. H. "A Molecular Gas Streamer Feeding the Galactic Centre." Nature. 350. 309-312, 1991.

HOLDAWAY, M. "Imaging Characteristics of a Homogeneous Millimeter Array." IAU Colloq.. 131. 437-440, 1991.

37 HOWARTH, I. D. and BROWN, A. "Radio Observations of Massive OB Stars." IAU Symp.. 142,315,1991.

HUGHES, V. A. Time-Dependent Radio Sources in the Star-Forming Region Cepheus A (East)" Astrophys. J.. 282, 280-288, 1991.

HUMMEL, E.; BECK, R.; and DAHLEM, M. The Magnetic Field Structure in the Radio Halos of NGC 891 and NGC 4631." Astron. Astrophysn 248,23-29,1991.

HUMMEL, E.; BECK, R.; and DETTMAR, R.-J. "An Effelsberg/VLA Radio Continuum Survey of an Optically Selected Sample of Edge-On Spiral Galaxies." Astron. Astrophys. SuppL £2, 309-317,1991.

HUMMEL, E.; DAHLEM, M.; VAN DER HULST, J. M.; and SUKUMAR, S. The Urge-Scale Radio Continuum Structure of the Edge-On Spiral Galaxy NGC 891." Astron. Astrophys.. 246. 10-20, 1991.

HUMMEL, E. and SAIKIA, D. J. The Anomalous Radio Features in NGC 4388 and NGC 4438." Astron. Astrophys.. 242,43-56,1991.

IRWIN, J. A. and SEAQUIST, E. R. "Heiles Shells in NGC3079." IAU Symp.. 144 (poster volume), 53-54,1991.

IRWIN, J. A. and SEAQUIST, E. R. The Neutral Hydrogen Distribution of NGC 3079." Astrophvs. J- 221 111-130, 1991.

JACKSON, J. M.; ECKART, A.; CAMERON, M.; WILD, W.; HO, P. T. P.; POGGE, R. W.; and HARRIS, A. I. The Interstellar Medium of the Hot-Spot Galaxy NGC 2903." Astrophvs. J.. 375. 105-115, 1991.

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49 TIFFT, W. G. "Properties of the Redshift II. Radial Variation." Astrophys. J.. 268,105-111,1991.

TIFFT, W. G. "Properties of the Redshift. III. Temporal Variation." Astrophvs. J.. 282, 396-415, 1991.

TURNER, B. E. "A Molecular Line Survey of Sagittarius B2 and Orion-KL From 70 to 115 GHz. II. Analysis of the Data." Astrophvs. J. SuppL 26, 617-686, 1991.

TURNER, B. E. "Observations and Chemistry of Interstellar Refractory Elements." Astrophys. J.. 226,573-598, 1991.

TURNER, B. E. and LUBOWICH, D. A. "H2CO in IC 443G: Unusual Excitation and a Diagnostic of Shock Astrochemistry." Astrophvs. J.. 2SL 173-180, 1991.

ULVESTAD, J. S. and ANTONUCCI, R. J. R. "Second-Epoch VLA Observations of Compact Radio Sources in NGC 253." AslTOIki, 102, 875-881, 1991.

UMANA, G.; CATALANO, S.; and RODONO, M. "A Microwave Survey of Selected Algol Systems With the VLA." Astron. Astrophys., 242,217-222,1991. UMANA, G.; TRIGIUO, C; HJELLMING, R. M.; CATALANO, S.; and RODONO, M. "Cbronal Magnetic Fields of Algol Binaries From Microwave Spectra." IAU Colloq.. 12Q, 498-500, 1991.

USON, J. M.; BAGRI, D. S.; and CORNWELL, T. J. "333 MHz Observations at the VLA: A Search for Pancakes." IAU Colloq., 12L 223-226,1991.

USON, J. M.; BAGRI, D. S.; and CORNWELL, T. J. "Radio Detection of Neutral Hydrogen at Z - 3.4." Physics Rev. LfilL, 61 3328-3331, 1991. USON, J. M.; BAGRI, D. S.; and CORNWELL, T. J. NA Search for Redshifted Neutral Hydrogen From Protoclusters of Galaxies." Astrophys. J.. 222, L65-L68,1991.

USON, J. M. and BOUGHN, S. P. "Large-Aperture BVRJK Photometry of Rich Abell Ousters: Constraints on Dark Matter." Astrophvs. J.. 262, 38-45, 1991.

USON, J. M.; BOUGHN, S. P.; and KUHN, J. R. "Diffuse Light in Dense Ousters of Galaxies. I. R-Band Observations of Abell 2029." Astrophys. J.. 369. 46-55, 1991.

50 USON, J. M. and CORNWELL, T. J. "Observational Test of the Homogeneous Array Concept: An X-Band Image of the Crab Nebula." IAU Colloq.. 12L 260-263, 1991.

VAN DER HULST, J. M.; VAN GORKOM, J. H.; HASCHICK, A. D; and TUBBS, A. D. "VLA HI Observations of the Radio Galaxy Centaurus A." In: Warped Disks and Inclined Rings Around Galaxies. Ed. S. Casertano, P. D. Sackett, and F. H. Briggs. (Cambridge: Cambridge University Press, 1991) 13-14.

VAN DISHOECK, E.; BLACK, J. H.; PHILIPS, T. G.; and GREDEL, R. "CO J - 3-2 Observations of Translucent and High-Latitude Molecular Oouds." Astrophys. J.. 366. 141-162, 1991.

VAN DRIEL, W.; VAN DEN BROEK, A. C; and DE JONG, T. "A Study of Southern Extreme IRAS Galaxies. II. Radio Continuum Observations." Astron. Astrophys. SuppL 90, 55-82, 1991.

VAN LANGEVELDE, H. J. and COTTON, W. D. "Visibility Based Continuum Subtraction." IAU Colloq.. 12L 264-267, 1991.

VAN LANGEVELDE, H. J. and DIAMOND, P. J. "Interstellar Scattering of OH/IR Stars at the Galactic Centre." Mon. Not. Roy. Astron. Soc. 242,7p-l0p, 1991.

VANDEN BOUT, P. A. "National Radio Astronomy Observatoiy (Annual Report, July 1989 - June 1990)." BAASr 22, 535-558, 1991.

VANDEN BOUT, P. A. "The Very Long Baseline Array and the Green Bank Telescope." Adv. Space Res.. H (2): 387-395,1991.

VELUSAMY, T; BECKER, R. H.; and SEWARD, F. D. "G33.6+0.1: A Shell Type Supernovae Remnant With Unusual Structure." Astron. J.. M2, 676-682, 1991.

VELUSAMY, T. and ROSHI, A. "High-Resolution Radio Images of the Crab Nebula." Current ScL 60,120-123,1991.

51 WAGNER, R. M.; STARRHELD, S.; CASSATELLA, A.; GON2^ALEZ-RIESTRA, R.; KREIDL, T. J.; HOWELL, S. B.; HJELLMING, R. J.; HAN, X.-H.; SHRADER, C; SONNEBORN, G.; COLLINS, G. W.; BERTRAM, R.; BUIE, M. W.; BOND, H. E.; JOHNSON, J.; HARRISON, T.; GEHRZ, R. D.; CORDOVA, F. A.; SZKODY, P.; MARGON, B.; MACDONALD, J.; and FRIED, R. "The 1989 Outburst of V404 Cygni: A Very Unusual X-ray Nova." IAU CQltoq., 122, 429-430,1991. WAGNER, S. J.; SANCHEZ-PONS, F.; ANTON, K.; QUIRRENBACH, A.; and WTTZEL, A. "Microvariability in the BLLac Object 0716+71." In: Variability of Active Galactic Nuclei. Ed. H. R. MUler and P. J. Wiita. (Cambridge: Cambridge University Press, 1991) 120-122. WALKER, R.C "The VLBA as a New Tool for Geodesy." In: Geodetic VLBI: Monitoring Global Change. NOAA Technical Report NOS 137 NGS 49. (Rockville, MD: National Oceanic and Atmospheric Administration, 1991) 25-34. WALKER, R.C. "VLBI With the Radio Schmidt Telescope." In: Radio Schmidt Telescope. P. Dewdney and T. Landecker. (Penticton: Dominion Radio Astrophysical Observatory, 1991) 197-208. WALTMAN, E. B.; FIEDLER, R. L; JOHNSTON, K. J.; SPENCER, J. H.; FLORKOWSKI, D. R.; JOSTIES, F. J.; MCCARTHY, D. D.; and MATSAKIS, D. N. "Daily Observations of Compact Radio Sources at 2.7 and 8.1 GHz: 1979-1987." Astrophys. J. SuppL. 22, 379-404, 1991. WANNIER, P. G.; ANDERSSON, B.-G.; MORRIS, M.; and LIGHTEN, S. M. "Warm Neutral Halos Around Molecular Oouds. II. H I and CO (J=1-0) Observations." Astrophvs. J. SuppL. 25, 987-998, 1991. WEHRLE, A. E.; KEEL, W. C; and JONES, D. L "The Enigmatic Jets of NGC 1097." In: Interpretation of Modem Synthesis Observations of Spiral Galaxies. Ed. N. Duric and P. C Crane. (San Francisco: Astronomical Society of the Pacific, 1991) 251-261. WEILER, K. W.; PANAGIA, N.; and SRAMEK, R. "A Supernova With a Difference, SN 1986J." In: Supernovae. Ed. S. E. Woosley. (New York: Springer, 1991) 515-526. WEILER, K. W. and SRAMEK, R. A. "The Observation and Interpretation of Radio Supernova in Nearby Galaxies." In: Interpretation of Modem Synthesis Observations of Spiral Galaxies. Ed. N. Duric and P. C. Crane. (San Francisco: Astronomical Society of the Pacific, 1991) 91-101.

52 WEILER, K. W.; VAN DYK, S. D.; PANAGIA, N.; SRAMEK, R. A.; and DISCENNA, J. L "The 10 Year Radio Light Curves for SN 1979C" Astrophys. J.. 28a 161-166, 1991.

WEINBERG, D. H.; SZOMORU, A.; GUHATHAKURTA, P.; and VAN GORKOM, J. H. "On the Population of H I Dwarf Galaxies." Astrophys. J.. 222, L13-L16, 1991.

WELLS, D. C "Archiving at NRAO's VLA and VLBA Telescopes." In: Databases and On-line Data in Astronomy. Ed. M. A Albrecht and D. Egret (Dordrecht: Kluwer, 1991) 125-126.

WHITE, S. M.; KUNDU, M. R.; and GOPALSWAMY, N. "Strong Magnetic Fields and Inhomogeneity in the Solar Corona." Astrophys. J.. 266, L43-L46,1991.

WIETFELDT, R. D. and D'ADDARIO, L "Compatibfflty Issues in VLBI." IAU CoUoq.. 12L 98-101, 1991.

WIETFELDT, R. D. and FRAIL, D. A. "Burst Mode VLBI and Pulsar Applications." IAU Colloq.. 12L 76-79, 1991.

WILKINSON, P. N.; AKUJOR, C. E.; CORNWELL, T. J.; and SAIKIA, D. J. "3C380: A Powerful Radio Source Seen End-On?" Mon. Not Rov. Astron. Soc- 248, 86-90, 1991.

WILKINSON, P. N.; TZOUMIS, A. K.; BENSON, J. M.; WALKER, R. C; SIMON, R. S.; and KAHN, F. D. "A Disrupted Radio Jet Inside the Host Galaxy of the Quasar 3C48." NalUIk 222, 313-315, 1991.

WILLIAMS, B. A.; MCMAHON, P. M.; and VAN GORKOM, J. H. "VLA Neutral Hydrogen Imaging of Compact Groups of Galaxies. II. HCG 31, 44, and 79." AslDBlL-L, 1QL 1957-1968,1991.

WILLSON, R. F.; SCHMELZ, J. T; GONZALEZ, R. D.; LANG, K. R.; and SMITH, K. L "Multi-Wave Band SMM- VLA Observations of an M2 Flare and an Associated Coronal Mass Ejection." Astrophys. J^ 228, 360-371, 1991.

WILSON, A. S.; HELPER, T. T.; HANIFF, C. A.; and WARD, M. J. "The Starburst Ring Around the Seyfert Nucleus in NGC 7469." Astrophvs. J.. 381. 79-84, 1991.

WILSON, T. L; GAUME, R.; and JOHNSTON, K. J. "High Resolution Observations of the (9,8) Ammonia Maser Line in W51-IRS2." Astron. Astrophvs.. 251. L7-L10, 1991.

53 WILSON, T. L; JOHNSTON, K. J.; and MAUERSBERGER, R. "The Internal Structure of Molecular Oouds. II. The W3(OH)/W3(H20) Region." Astron. Astrophys., 25L 220-230,1991.

WINDHORST, R. A.; BURSTEIN, D.; MATHIS, D. F.; NEUSCHAEFER, L W.; BERTOLA, F.; BUSON, L M.; KOO, D. C; MATTHEWS, K.; PARTHEL, P. D.; and CHAMBERS, K. C "The Discovery of a Young Radio Galaxy at z«2390: Probing Initial Star Formation at z^3.0." Astrophys. J.. 280, 362-383, 1991.

WOMACK, M.; ZIURYS, LM.; and WYCKOFF, S. "NjH^ in Orion: Chemical Oues to the Dynamics of the Quiescent Gas." Astrophys. J.. 220, L99-L102, 1991.

WOOD, C A.; MUFSON, S. L; and DICKEL, J. R. "The Magnetic Structure of the Filaments in the Supernova Remnant IC 443." Ast£QIkI» M2,224-233, 1991.

WOOD, D. O. S. and CHURCHWELL, E. "The Dynamics and Physical Properties of the Cometary Nebula G29.96-0.02." Astrophys. J.. 222, 199-207, 1991.

WOOTTEN, A. "Dense Core Structures and Fragmentation in the Rho Ophiuchi Molecular Ooud." IAU Svmp.. 147. 229-233,1991.

WOOTTEN, A.; MANGUM, J. G.; TURNER, B. E.; BOGEY, M.; BOULANGER, F.; COMBES, F.; ENCRBNAZ, P. J.; and GERIN, M. "Detection of Interstellar H3O*: A Confirming Line." Astrophvs. J.. 380. L79-L83,1991.

WROBEL, J. M. "Active Nuclei and Star Formation in E/S0 Galaxies." In: Interpretation of Modem Synthesis Observations of Spiral Galaxies. Ed. N. Duric and P. C. Crane. (San Francisco: Astronomical Society of the Pacific, 1991) 197-207.

WROBEL, J. M. "Radio Continuum Sources in Nearby and Bright E/S0 Galaxies: Sample Selection and Well-Studied Cases." Aslmikl* Ml, 127-147, 1991.

WROBEL, J. M. and HEESCHEN, D. S. "Radio Continuum Sources in Nearby and Bright E/S0 Galaxies: Active Nuclei versus Star Formation." Astron. J.. 101. 148-169, 1991.

YIN, Q. F. and HEESCHEN, D. S. "NGC 6052." IAU Ore- 5276. 25 May 1991.

54 YIN, Q. F. and HEESCHEN, D. S. "Two Radio Supernovae in the Unusual Galaxy Markarian 297." HatUIfe, 224, 130-132, 1991.

YIN, Q.; HEESCHEN, D. S.; SASLAW, W. C; and HUANG, Z. "VLA Observations of the Peculiar Interacting Galaxies NGC 7463-7464." In: Interpretation of Modem Synthesis Observations of Spiral Galaxies. Ed. N. Duric and P. C Crane. (San Francisco: Astronomical Society of the Pacific, 1991) 263-266.

YUN, M. S.; HO, P. T. P.; and LO, K. Y. "Disrupted HI Environment Around M82." In: Slolinss. Ed. A. D. Haschick and P. T. P. Ho. (San Francisco: Astronomical Society of the Pacific, 1991) 35-42.

YUSEF-ZADEH, F. and MORRIS, M. "A Windswept Cometary Tail on the Galactic Center Supergiant IRS 7." Astrophys. J., 22L L59-L62,1991.

ZENSUS, J. A. "43-GHz VLBI Imaging of the Quasar 3C 345." In: Variability of Active Galactic Nuclei. Ed. H. R. Miller and P. J. Wiita. (Cambridge: Cambridge University Press, 1991) 151-152.

ZHANG, F. J. and BAATH, L B. "The Submilliarcsecond Radio Structure of the Two BL Lac Objects Mkn421 and 0735+178." Mon. Not Roy. Astron. Soc. 248, 566-571, 1991.

ZHAO, J.-H.; GOSS, W. M.; LO, K. Y.; and EKERS, R. D. "High Resolution VLA Images of the Galactic Centre at 2- cm Wavelength With Large Dynamic Range." Katme, 224, 46-48,1991.

ZHOU, S.; EVANS, N. J. II; GUSTEN, R.; MUNDY, L G.; and KUTNER, M. L "CS Multitransitional Studies of Density Distribution in Star-Forming Regions. I. The NGC 2071 Region." Astrophys. J.. 222,518-530,1991.

ZIURYS, LM. "SiS in Outflow Regions: More High-Temperature Silicon Chemistry." Astrophys. J.. 379. 260-266. 1991.

55 ADDITIONS TO THE 1990 PUBLICATIONS LIST

COTTON, W. "AIPS Project, National Radio Astronomy Observatory." Bull. Am. Astron. Soc. 22, 913-1990. DEY, A; VAN BREUGEL, W. J. M.; and SHIELDS, J. C "Radio Loud Far-Infrared Galaxies." IAU Colloq.. 124, 309- 314, 1990. FINDLAY, J. W. "The CaUbration Horn Antenna." IEEE Ant Prop. Soc Mag.. 22, 6-15, 1990. GREISEN, E. W. "The Astronomical Image Processing System." In: Acquisition. Processing and Archiving of Astronomical Images. Ed. G. Longo and G. Sedmak. (Naples: Osservatorio Astronomico di Capodimonte, 1990) 125- 142. GREISEN, E. W. "Image Formation by Radio Interferometers." In: Acquisition. Processing, and Archiving of Astronomical Images. Ed. G. Longo and G. Sedmak. (Naples: Osservatorio Astronomico di Capodimonte, 1990) 51-81. GREISEN, E.W. "Introduction to FITS." In: Acquisition. Processing, and Archiving of Astronomical Images. Ed. G. Longo and G. Sedmak. (Naples: Osservatorio Astronomico di Capodimonte, 1990) 347-363. HAN, X. and HJELLMING, R. M. "Radio Observations of V404 Cta (=GS2023+338)." In: Accretion-Powered Compact Binaries. Ed. C. W. Mauche. (Cambridge: Cambridge University Press, 1990) 25-28. HJELLMING, R. M. "Imaging or Resolving the Radio Shells of Novae." In: Accretion-Powered Compact Binaries. Ed. C W. Mauche. (Cambridge: Cambridge University Press, 1990) 363-366. KAPAHI, V. K. "Misaligned Radio Quasars." Current ScL 52, 561-564,1990. MORRIS, S. L; LIEBERT, J.; GIOIA, I.; MACCACARO, T; SCHILD, R.; and STOCKE, J. "MS 1603.6+2600: An Unusual X-ray Selected Binary System at High Galactic Latitude." In: Accretion-Powered Compact Binaries. Ed. C W. Mauche. (Cambridge: Cambridge University Press, 1990) 39-42. ZLOBEC, P.; MESSEROTTI, M.; DULK, G. A.; and KUCERA, T. "Pulsations During a Type IV Burst Observed at Trieste and the VIA." In: The Dynamic Sun. Ed. L Dezso. (Debrecen, Hungary: Debrecen Heliophysical Observatory, 1990) 200-201.

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