MMT Observatory Research Articles

GRB 021211 as a Faint Analog of GRB 990123: Exploring the Similarities and Differences in the Optical Afterglows

We present B, V, Rc, J, H, and Ks photometry of the optical afterglow of the gamma-ray burst GRB 021211 taken at the Magellan, MMT, and WIYN observatories between 0.7 and 50 days after the burst. We find an intrinsic spectral slope at optical and near-infrared wavelengths of 0.69 +/- 0.14 at 0.87 days. The optical decay during the first day is almost identical to that of GRB 990123 except that GRB 021211's optical afterglow was intrinsically approximately 38 times fainter, and the transition from the reverse shock to the forward shock may have occurred earlier than it did for GRB 990123. We find no evidence for a jet break or the cooling break passing through optical frequencies during the first day after the burst. There is weak evidence for a break in the J-band decay between 0.89 and 1.87 days which may be due to a jet. The optical and infrared data are consistent with a relativistic fireball where the shocked electrons are in the slow cooling regime and the electron index is 2.3 +/- 0.1. The forward shock appears to have been expanding in a homogeneous ambient medium during the first day after the burst. Our analysis suggests that the jet of GRB 021211 may have a small opening angle and that the total gamma-ray energy is likely to be much less than the canonical value of 1.33E+51 erg. If this is the case then it is possible that most of the energy of the burst is in another form such as a frozen magnetic field, supernova ejecta, or a second jet component. The host galaxy of GRB 021211 is subluminous and has a star formation rate of at least one Solar mass per year.

Richard Joseph Elston

Richard Joseph Elston, known for his development of innovative astronomical instrumentation, died on 26 January 2004 in Gainesville, Florida, after a four-year battle with Hodgkin’s lymphoma. A professor of astronomy at the University of Florida, Richard had an unusually broad range of interests and skills, and a willingness to share his passion for astronomy with others, which made him a highly valued member of the astronomical community.Born 1 July 1960, in Albuquerque, New Mexico, Richard was the son of a geologist father and a journalist mother. His childhood interest in astronomy and instrumentation matured as he majored in physics and astronomy at the University of New Mexico (BS, 1983) under the mentorship of Michael Zeilik. Richard pursued his PhD in astronomy at the University of Arizona and earned his degree in 1988. He pioneered the use of IR arrays for deep imaging surveys of the sky to study galaxy formation, and completed his thesis “Search for Rapidly Forming Galaxies at High Redshift” under the direction of George Rieke. Richard’s graduate work included the first detection of galaxies at intermediate redshifts with evolved populations too red to have been identifiable from optical imaging surveys alone. In the Astro-physical Journal Letters in 1988, he, George Rieke, and Marcia Rieke reported the discovery of this new class of galaxies, now known as EROs (Extremely Red Objects), important as the possible progenitors of present-day elliptical galaxies. Following postdoctoral positions at Kitt Peak National Observatory from 1988 to 1991 and at the Observatories of the Carnegie Institution of Washington from 1991 to 1992, Richard joined the scientific staff of Cerro Tololo Inter-American Observatory in Chile, part of NSF’s National Optical Astronomy Observatory. By 1994, he had become head of CTIO’s IR instrumentation program and was leading the development of new instruments for the US astronomical community.In 1996, Richard married astronomer Elizabeth Lada, and both joined the faculty of the University of Florida. They worked closely together and with their colleagues to develop the department into a leading center for astronomical research. Richard assembled a strong near-IR instrument team whose most recently completed instrument was FLAMINGOS, the Florida Multi-object Imaging Near-IR Grism Observational Spectrometer. FLAMINGOS serves as both a wide-field IR imager and multi-object spectrograph. Successfully used at the 6.5-meter MMT Observatory, 8-m Gemini South telescope, and KPNO 2.1-m and Mayall 4-m telescopes, FLAMINGOS allows scientists to complete observations in one night that would previously have required 100 nights. FLAMINGOS is the primary instrument for several major survey programs that are studying topics ranging from how individual stars and planets form to how the largest structures in the universe evolve. One of Richard’s innovations with FLAMINGOS was the use of a separate “pre-dewar” that maintains at cryogenic temperatures the multislit masks required to select the targets for observation, but can be thermally cycled more quickly than the entire instrument. This feature allows the changing of masks on a nightly basis. New instruments having the innovations pioneered with FLAMINGOS are under construction and are to be used at several of the world’s largest telescopes in the decades ahead.Richard was involved in getting both the University of Florida and the US astronomical community on the path toward larger telescope facilities. He played a crucial role in the University of Florida’s joining the team building the 10.4-m Grand Telescope of the Canary Islands. As a member of the panel that studied optical/near-IR astronomy from the ground for the most recent (2000) National Academies decadal review of astronomy, Richard was a passionate advocate for open access to the next large (30-m class) telescope to be built. The final report included a recommendation for a public role in such a telescope. Richard’s work as a researcher and educator was recognized in 2000, when he was named a recipient of the Presidential Early Career Awards for Scientists and Engineers. With the birth of his son, Joseph, in 1999, Richard’s life reached an important milestone. During his battle with cancer, Richard awed everyone with his ability to be productive professionally and still be so devoted to his family. He and his son shared a love for the outdoors and adventure. Richard was an expert SCUBA instructor, skier, hiker, wind surfer, airplane pilot, and sailor. Joseph is already a “proto-naturalist.” Richard will be best remembered as a wonderful father, beloved husband, loving brother, son, uncle, friend, and inspiration to all whose lives he touched.Richard Joseph ElstonPPT|High resolution© 2004 American Institute of Physics.

Emission‐Line Properties ofz > 4 Quasars

We present results of a program of high signal-to-noise spectroscopy for 44 QSOs at redshifts > 4 using the MMT and Keck observatories. The quasar spectra cover 1100 -- 1700 A in the rest frame for sources spanning a luminosity range of approximately 2 orders of magnitude. Comparisons between these data and spectra of lower redshift quasars reveal a high degree of similarity, although differences are present in the profiles and the strengths of some emission features. An examination of the luminosity dependence of the emission lines reveals evidence for a weak or absent Baldwin effect among z > 4 QSOs. We compare measurements for objects in our sample with results from other high redshift surveys characterized by different selection techniques. Distributions of equivalent widths for these different ensembles are consistent with a common parent population, suggesting that our sample is not strongly biased, or in any case, subject to selection effects that are not significantly different from other surveys, including the Sloan Digital Sky Survey. Based on this comparison, we tentatively conclude that the trends identified here are representative of high z QSOs. In particular, the data bolster indications of supersolar metallicities in these luminous, high-z sources, which support scenarios that assume substantial star formation at epochs preceding or concurrent with the QSO phenomena.

PISCES: A Wide‐Field, 1–2.5 μm Camera for Large‐Aperture Telescopes11Observations reported here were obtained at the MMT Observatory, a joint facility of the University of Arizona and the Smithsonian Institution.

ABSTRACTWide‐field‐of‐view infrared cameras, operating on the new generation of large telescopes, offer unprecedented gains in the detection of faint sources and in observing efficiency for both direct imaging and spectroscopy. With a 1024 × 1024 pixel, 1–2.5 μm detector, the PISCES camera provides 8.′5 and 3.′16 fields at the 2.3 m Bok telescope and 6.5 m Multiple Mirror Telescope, respectively. Its refractive optics utilize all spherical surfaces and standard glasses. A cold pupil stop suppresses the thermal background produced by the emissive surfaces normally present in Cassegrain optical configurations. The optical design is directly extendable to wider fields with larger detector formats. Future upgrades include low‐resolution (R = 200–500) multiobject spectroscopy.

The Spectrum of the Night Sky over Mount Hopkins and Kitt Peak: Changes after a Decade11The research described here is based on data obtained in part at the MMT Observatory, a joint facility of the Smithsonian Institution and the University of Arizona.

ABSTRACTRecent (1998–1999) absolute spectrophotometry of the night sky over two southern Arizona astronomical sites, Kitt Peak and Mount Hopkins, is compared to similar data obtained in 1988 at each site. The current zenith sky brightness in the range ∼3700–6700 Å is essentially identical at the two sites and is as dark now as Palomar Observatory was in the early 1970s, when it was generally considered a premier dark observing site. Converted to broadband measurements, our spectrophotometry is equivalent to B = 22.63, V = 21.45 mag arcsec−2, for the zenith night sky. The contribution of high‐pressure sodium street lights to broadband V is about 0.2 mag arcsec−2, comparable to the strong airglow O i λ5577 line. During the period from 1988 to 1998–1999, the zenith sky brightness increased only modestly, with the largest changes being seen for Kitt Peak, where the zenith sky has brightened by ≈0.1–0.2 mag arcsec−2 in the blue‐optical region. For Kitt Peak we also have both 1988 and 1999 observations at modestly large zenith distances ( ZD ≈ 60°). In the directions away from Tucson, the sky has brightened by ≈0.35 mag arcsec−2 over the intervening decade. Toward Tucson the change has been larger, approximately 0.5 mag arcsec−2. In most directions the increase in the sky brightness has lagged behind the fractional increase in population growth, which we attribute to good outdoor lighting ordinances, a fact which is further reflected in the decrease in Hg emission. However, our results emphasize the need for diligent attention as developments creep closer to our observing sites.

9.5. The “double nucleus” of M31 in J, H, and K

Hubble Space Telescope images of the nucleus of M31 show a double-peaked structure with the primary peak being offset from the center by approximately 0.5″. We observed the central 13″ of M31 in the J, H, and Ks passbands to determine the nuclear structure in the near-infrared. Observations were taken at the MMT Observatory, using a low-order adaptive optics system, FASTTRAC II (Gray et. al. 1995). The diffraction limit for the system is 0.25″ in K band. PSF images showed correction to 0.5″ FWHM. Uncorrected images showed the seeing to be about 1″. The images were deconvolved using several methods to check for consistency. We used Iterative-Blind Deconvolution, Richardson-Lucy, and Wiener filter algorithms, getting similar results for each. Measurements suggest the PSF in the deconvolved images is approximately 0.35″ FWHM.