National Optical Astronomy Observatories National Optical Astronomy Observatories Quarterly Report October - December 1990 TABLE OF CONTENTS I. INTRODUCTION 1 II. SCIENTIFIC HIGHLIGHTS 1 A. Cosmis Voids 1 B. Chiron 2 C. Surface Dynamics 2 D. South Pole Observations 3 E. Effect of Active Regions on Intermediate-Degree Solar Oscillations 3 F. Resolved Images of High Redshift QSOs: A First Look 4 G. Astrophysical Jets: More Robust than Previously Thought? 4 H. Sub-Arcsecond Structure of R Aquarii: An Accretion Disk Revealed 5 III. PERSONNEL 6 A. Visiting Scientists 6 B. New Hires 6 C. Terminations 6 D. Change in Status 6 IV. INSTRUMENTATION, NEW PROJECTS, AND OBSERVATORY ACTIVITIES . 7 A. 8-M Project 7 B. Advanced Optical Telescope Technology Program (AOTT) 8 C. Global Oscillation Network Group (GONG) 9 D. WIYN Project 10 E. Instrumentation Projects 11 F. Observatory Activities 16 V. PROGRAM SUPPORT 17 A. Director's Office 17 B. Central Administrative Services 19 C. Central Computer Services 19 D. Central Facilities Operations 20 E. Engineering and Technical Services 21 F. Publications and Information Resources 21 Appendices Appendix A Telescope Usage Statistics Appendix B Observational Programs Appendix C NOAO Annual Safety Report I. INTRODUCTION This quarterly report covers scientific highlights for the period of October through December 1990, as well as personnel changes for the period. The report also discusses progress on the 8-m telescopes, GONG, WIYN, and instrumentation projects. The appendices list telescope usage statistics and observational programs. II. SCIENTIFIC HIGHLIGHTS A. Cosmic Voids The observed smoothness of the cosmic background radiation leads one to expect that at a sufficiently large scale the universe should be homogenous. To test this expectation the space distribution of galaxies must be determined over the largest possible sky areas and, if redshifts are used as distance indicators, they must be determined for the faintest possible galaxies. However, properly done, this is such an enormous task that available surveys have been necessarily limited to finite sky areas and to galaxies brighter than convenient limits. A prime example is the on-going survey being carried out by Harvard Smithsonian Center for Astrophysics (CfA) astronomers J.P. Huchra, M. Geller, and collaborators. In this survey, galaxies brighter than about magnitude 15.5 are surveyed in sky areas consisting of strips a few degrees wide in declination but extending over a wide range of right ascension. This survey has shown extensive sheet-like concentrations of galaxies including the so- called "Great Wall." Since the sky strips are not necessarily contiguous and only relatively bright galaxies are observed, the CfA survey is not ideal for the study of what appears to be extensive voids surrounded by concentrations of galaxies. A survey adapted to the study of possible voids was undertaken by R.P. Kirshner (Harvard U.), A. Oemler (Yale U.), P.L. Schechter (Massachusetts Inst, of Tech.), and S.A. Shectman (Carnegie Obs.). Galaxies brighter than about magnitude 17 located within a set of small sample regions near the galactic north pole were included. The extremely large number of galaxies in the extensive sky area that had to be surveyed in order to delineate a possible void, made it necessary to limit the study to such sample regions. Observations obtained in 1987 with the Palomar 5-m telescope and with the KPNO 4-m telescope resulted in the finding of an apparent void toward the constellation of Bootes. With a 106 Mpc3 volume, the so-called Bootes void is a statistically significant low density region for normal galaxies. A similar survey has now been completed in the southern hemisphere. With spectroscopic observations obtained with the Las Campanas 2.5-m telescope and photometric observations obtained with the CTIO 1.5-m telescope, Kirshner, Oemler, Schechter, and Shectman have found evidence of a possible void toward the constellation of Phoenix. This survey included 150 galaxies brighter than magnitude 17.6. Again, numerous sample regions were selected. These spread over a 25 degree diameter area. The observed galaxies show a significant low density region between redshifts 11,600 and 15,400 km/sec. The apparent Phoenix void is, however, not as clearly defined as the one in Bo5tes. A search for the galaxies that might have been missed in the 25 degree area covered by the sample region shows, at a redshift of 14,500 km/sec, a clustering of galaxies. Also, three compact bright galaxies within the region have radial velocities that place them within the suspected void. Independent surveys by other investigators show that additional galaxies, near the periphery of the apparent low-density region, have radial velocities within the range mentioned earlier. Prudently, Kirshner, Oemler, Schechter, and Shectman consider the possibility that the Phoenix "void" may be spurious, but conclude that it probably is an underdense region. So far, existing surveys of distant galaxies show no evidence of homogeneity in the universe. The smoothness of the cosmic background radiation remains a challenging fact for observational cosmologists. B. Chiron In February 1988, when observing at Mauna Kea, astronomers D.J. Tholen, W.K. Hartmann, and D.P. Cruikshank (U. of Hawaii) found that asteroid No. 2060 (Chiron) was 0.7 magnitudes brighter than expected from predictions based on its position in space and its well-known rotational brightness variations. Chiron's bright outburst was found to persist past 31 October when Lowell Observatory astronomers S.J. Bus and E. Boswell, in collaboration with L. French (Massachusetts Inst, of Tech.), observed it with the CTIO 0.9-m telescope. On this occasion, Chiron's rotational light variations showed an unexpected decrease in amplitude. As it turned out, this was the first indication that Chiron was surrounded by a coma. Chiron's orbit with a semi-major axis of 13.7 A.U. places it, even at perihelion, well beyond Jupiter: far away from the asteroid belt. This unique orbit for an asteroid caused numerous speculations about Chiron's origin. Was it perhaps an escaped satellite from one of the outer major planets, or possibly a comet captured by the gravitational attraction of those planets? At first, Chiron's brightness outburst resembled frequently observed episodic cometary activity at large heliocentric distances. This led astronomer K. Meech (U. of Hawaii) to include Chiron in a program of comet observations to be carried out at CTIO in collaboration with KPNO astronomer M. Belton. An aim of the program was to search for a coma surrounding Chiron. Formation of a comet-like coma as Chiron approaches its perihelion could explain its unusual brightness outburst. Observations were made in January 1989 with the CTIO 0.9-m telescope and continued in April 1989 with the KPNO 4-m telescope. On 10 April a 5 arcsec coma surrounding Chiron was detected in KPNO direct CCD images. By its reflectivity, the coma could explain the brightness outburst and why its rotational light variations had been partly masked during the earlier CTIO observations. Further analysis of the observations suggests that the coma is caused by dust particles gravitationally bound to Chiron rather than ejected into space, as in comets. This would explain why its brightness outburst has lasted much longer than those typical of comets. Drs. Meech and Belton suggest that the dust particles may be thrown outward by gas escaping from regions of activity on Chiron's surface. Although its origin remains unknown, Chiron certainly will be carefully monitored as it approaches its 1996 perihelion. C. Surface Dynamics G. Simon, A. Title (Lockheed), and N. Weiss (U. of Cambridge), have been working on the modeling of mesogranules and exploders on the solar surface. Correlation tracking of high-resolution observations reveals a horizontal flow field containing both the supergranulation pattern and a much smaller pattern corresponding to mesogranulation. Exploding granules (exploders) occur preferentially near the centers of mesogranules. This raises the question, Are mesogranules just collections of exploders? Radial outflow in exploders and mesogranules can be modeled by superposing gaussian source functions. Simon, Title, and Weiss use this model to explore the relationship between mesogranules and exploders. Although they demonstrate that there is mathematical equivalence between mesogranules and exploders distributed normally about the mesogranules center, their results indicate that the observed mesogranular velocity pattern is not consistent with a flow pattern generated by exploders dropped randomly on the solar surface. Detailed comparison with observations suggests that the averaged mesogranular velocity is produced by a combination of a persistent outflow from a source together with exploders distributed randomly about its center. Similar analysis shows that supergranules are not the result of random occurrences of mesogranules. D. South Pole Observations The high-degree helioseismometer was shipped to the South Pole in mid-September with the goal of obtaining observations of solar oscillations uninterrupted by the day-night cycle. A field party consisting of T. Duvall (NASA), J. Harvey, S. Jefferies (Bartol), D. Neff, and M. Pomerantz (Bartol) departed from the United States on 22 October and arrived at the South Pole on 31 October. Since the camera system has 2 arcsec pixels, they were particularly interested in getting observations of high-degree oscillations at a time of high solar activity. The polar solar observatory site was activated in early November and, after the equipment arrived, the instrument was set up. An initial problem with the high speed guider was located and fixed. First observations were made on 9 November. After a few days of observing, the weather became cloudy and unusually windy. Two storms produced massive snow drifts around the instrument. However, starting on 23 November relatively good weather prevailed for two weeks and a large amount of data was obtained. Measurements of seeing quality were also obtained during this period.