NASA’s James Webb Space Telescope (JWST) is a 6.5m diameter, segmented, deployable telescope for cryogenic IR space astronomy. The JWST Observatory includes the Optical Telescope Element (OTE) and the Integrated Science Instrument Module (ISIM), that contains four science instruments (SI) and the Fine Guidance Sensor (FGS). The SIs are mounted to a composite metering structure. The SIs and FGS were integrated to the ISIM structure and optically tested at NASA's Goddard Space Flight Center using the Optical Telescope Element SIMulator (OSIM). OSIM is a full-field, cryogenic JWST telescope simulator. SI performance, including alignment and wavefront error, was evaluated using OSIM. We describe test and analysis methods for optical performance verification of the ISIM Element, with an emphasis on the processes used to plan and execute the test. The complexity of ISIM and OSIM drove us to develop a software tool for test planning that allows for configuration control of observations, implementation of associated scripts, and management of hardware and software limits and constraints, as well as tools for rapid data evaluation, and flexible re-planning in response to the unexpected. As examples of our test and analysis approach, we discuss how factors such as the ground test thermal environment are compensated in alignment. We describe how these innovative methods for test planning and execution and post-test analysis were instrumental in the verification program for the ISIM element, with enough information to allow the reader to consider these innovations and lessons learned in this successful effort in their future testing for other programs.

Castelaz , F. C. Bruhweiler, A.B. Schultz, M.B. Niedner, C. Miskey, and D.J. MacConnell , SSC/IPAC, MS 314-6, California Institute of Technology, Pasadena, CA 91125, mccollum@ipac.caltech.edu, Pisgah Astronomy Research Institute, 1 PARI Dr., Rosman, NC 28772-9614, mcastelaz@pari.edu, Catholic Univ. of America, Dept. of Physics, , IACS, Washington, DC 20064, Science Programs, Computer Sciences Corporation, Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, NASA GSFC Laboratory for Astronomy and Solar Physics, Code 681, Greenbelt, MD 20771, Catholic Univ. of America, Dept. of Physics, IACS, Washington, DC 20064.

We present optical simulations of a new approach to directly image terrestrial planets. Terrestrial planets typically are 10 orders of magnitude fainter than the central star, a difficult challenge for any optical system. Our studies show that the combination of an external occulter and an apodizer yields the required contrast, with significantly reduced requirements on stray light and diffraction. This mitigates the very high mirror tolerances required of other coronagraphic methods and makes exo-planet detection feasible with current technology.

We present preliminary analysis of new HST observations of the transiting extrasolar planet HD 209458b. Photometric observations were obtained with the Fine Guidance Sensor (FGS) on the Hubble Space Telescope (HST), providing milli-mag precision and high time resolution (40 Hz). The FGS photometry allows us to derive precise stellar/orbital parameters (ephemeris, inclination, limb darkening) and planetary radius, and also allows a search for the presence of planetary rings and satellites. We discuss preliminary results and two approaches to modelling the observations.

We present the discovery of two T dwarf binaries, 2MASS 1225-2739AB and 2MASS 1534-2952AB, identified in a sample of 10 T dwarfs imaged with the Hubble Space Telescope (HST) Wide Field Planetary Camera 2. Companionship is established by the uniquely red F814W-F1042M colors of the binary components, caused by heavily pressure-broadened K I absorption centered at 7665 and 7699 Å. The separations of the two binary systems are 0.″282 ± 0.″005 and 0.″065 ± 0.″007, implying projected separations of 3.17 ± 0.14 and 1.0 ± 0.3 AU, respectively. These close separations are similar to those found in previous brown dwarf binary searches and permit orbital mapping over the coming decade. 2MASS 1225-2739AB has a substantially fainter secondary, with ΔMF814W = 1.59 ± 0.04 and ΔMF1042M = 1.05 ± 0.03; this system is likely composed of a T6 primary and T8 secondary with mass ratio 0.7-0.8. The observed binary fraction of our HST sample, 20%, is consistent with results obtained for late-type M and L field dwarfs and implies a bias-corrected binary fraction of 9% for a ≳ 1 AU and q ≳ 0.4, significantly lower than the binary fractions of F-G and early-type M dwarf stars. Neither of the T binaries have separations a ≳ 10 AU, consistent with results from other brown dwarf binary searches. Using the statistical models of Weinberg, Shapiro, & Wasserman, we conclude that tidal disruption by passing stars or giant molecular clouds, which limits the extent of wide stellar binaries, plays no role in eliminating wide brown dwarf binaries, implying either disruption very early in the formation process (ages ≲1-10 Myr) or a formation mechanism that precludes such systems. We find that the maximum binary separation in the brown dwarf regime appears to scale as M, a possible clue to the physical mechanism that restricts wide substellar systems.

We describe a 1-meter space telescope plus free-flying occulter craft mission that would provide direct imaging and spectroscopic observations of Jovian and Uranus-sized planets about nearby stars not detectable by Doppler techniques. The Doppler technique is most sensitive for the detection of massive, close-in extrasolar planets while the use of a free-flying occulter would make it possible to image and study stellar systems with planets comparable to our own Solar System. Such a mission with a larger telescope has the potential to detect earth-like planets.Previous studies of free-flying occulters reported advantages in having the occulting spot outside the telescope compared to a classical coronagraph onboard a space telescope. Using an external occulter means light scatter within the telescope is reduced due to fewer internal obstructions and less light entering the telescope and the polishing tolerances of the primary mirror and the supporting optics can be less stringent, thereby providing higher contrast and fainter detection limits. In this concept, the occulting spot is positioned over the star by translating the occulter craft, at distances of 1,000 to 15,000 km from the telescope. Any source within the telescope field-of-view can be occulted without moving the telescope.In this paper, we present our current concept for a 1-m space telescope matched to a free-flying occulter, the Umbral Missions Blocking Radiating Astronomical Sources (UMBRAS) space mission. An UMBRAS space mission consists of a Solar Powered Ion Driven Eclipsing Rover (SPIDER) occulter craft and a matched (apodized) telescope. The occulter spacecraft would be semi-autonomous, with its own propulsion systems, internal power (solar cells), communications, and navigation capability. Spacecraft rendezvous and formation flying would be achieved with the aid of telescope imaging, RF or laser ranging, celestial navigation inputs, and formation control algorithms.

We have developed a data reduction procedure to extract multiple spectra from a single two-dimensional Space Telescope Imaging Spectrograph (STIS) image of a crowded stellar field. This paper provides a description of our new technique, utilizing a STIS ultraviolet spectral image, acquired with the G140L grating and the 52" x 2" aperture, sampling a concentration of O and B stars in the central region of the NGC 604 starburst in M33. The software routines can disentangle and produce reliable ultraviolet spectra of stars with angular separations as small as 0."055. Use of the extraction slit, based on our model of the spectral cross-dispersion profile, generates spectra with slightly higher resolution than the STScI standard processing. Our results clearly show that the spectral imaging capability of STIS represents a powerful tool for studying luminous stars in the star-forming regions of the Local Group.

We present results using 2-D spectral imagery and photometry obtained with the Hubble Space Telescope (HST) for the starburst H II region, NGC 604, in nearby galaxy M33. The spectral imagery was acquired with the Space Telescope Imaging Spectrograph (STIS) using the MAMA/G140L configuration, spanning 1170-1730 A. From a single 1720 sec STIS exposure, we extracted spectra for 49 stars and derived individual UV spectral types for 40 stars in the crowded 25"x2" stellar field. These stars represent a significant fraction of the young, luminous O and B stars. Three objects have pronounced He II 1640 emission, the signature of W-R or luminous Of stars. By combining UV fluxes with WFPC and WFPC2 visual photometry, we derive the extinction curve for NGC 604. We use this curve, the distance for M33, derived UV spectral types, and HST photometry, to determine positions of these stars in the upper H-R diagram. The revised O star effective temperature scale (Martins et al.) is essential in obtaining reliable positions in the log(L*)-log(T(eff)) plane. These stars are quite young with an age of ~3 Myr. The spectra and photometry indicate three exceedingly luminous objects. Their inferred locations in the H-R diagram indicate stellar masses > 120 solar masses. High spatial resolution HST imagery provides no evidence of multiple stars composing these objects. Still we cannot eliminate the possibility that they are unresolved multiple stars of lower mass, possibly W-R stars. Tests demonstrate that the ten most luminous stars predominantly determine the UV spectral features seen in the total light of NGC 604. We conclude that interpretation of spectral fitting of more distant starburst galaxies, where individual stars are not resolved, must be done with extreme care.

In this manuscript, we further develop our concepts for the free-flying occulter space-based mission, the Umbral Missions Blocking Radiating Astronomical Sources (UMBRAS). Our optical simulations clearly show that an UMBRAS-like mission designed around a 4-m telescope and 10-m occulter could directly image terrestrial planets. Such a mission utilizing existing technology could be built and flown by the end of the decade. Moreover, many of the other proposed concepts for Terrestrial Planet Finder (TPF) could significantly benefit by using an external occulter. We present simultations for an optical design comprising a square aperture telescope plus square external occulter. We show that the entire diffraction pattern, which is propagated from occulter to telescope and through telescope to focal plane, may be characterized by two parameters, the Fresnel number and the ratio of the telescope diameter to the occulter width. Combining the effects of a square occulter with apodization provides a much more rapid roll-off in the PSF intensity between the diffraction spikes than may be achieved with an unapodized telecope aperture and occulter. We parameterize our results with respect to wavefront quality and compare them against other competing methods for exo-planet imaging. The combination of external occulter and apodization yields the required contrast in the region of the PSF essential for exo-planet detection. An occulter external to the telescope (i.e., in a separate spacecraft, as opposed to a classical coronagraph with internal occulter) reduces light scatter within the telescope by approximately 2 orders of magnitude. This is due to less light actually entering the telescope. Reduced scattered light significantly relaxes the constraints on the mirror surface roughness, especially in the mid-spatial frequencies critical for planet detection. This study, plus our previous investigations of engineering as well as spacecraft rendezvous and formation flying clearly indicates that the UMBRAS concept is very competitive with, or superior to, other proposed concepts for TPF missions.

We present our analysis of Hubble Space Telescope/Planetary Camera narrow-bandpass and broadband imagery of the inner 3 kpc region of NGC 1068. Our analysis of F160BW and F547M broadband continuum imagery suggests that roughly 40% of the scattered active galactic nucleus (AGN) continuum emission originates from an unobscured single cloud complex largely free from dust with total number densities typical of diffuse clouds in our own Milky Way. The net emission-line fluxes are extracted from continuum-subtracted narrow-bandpass imagery for Ha + [N ], Hβ, S II λλ6717, 6731, and [O III] λ5007. Although the [O ]/(Hα + [N ]) flux ratio shows a sharp drop-off at distances beyond ~4'' northeast of the nucleus, the [O ]/Hb ratio indicates no such decrease. This implies that the ionization of these species is not strongly influenced by shocks associated with the expanding radio lobes as inferred from a previous study. The sharp drop-off seen in the [O ]/(Ha + [N ]) appears to be due to high interstellar reddening immediately beyond the scattering bright clouds near the nucleus, as further evidenced by the high Ha/Hb ratio in this region. The presence of a faint inner spiral arm interior to the sharply defined star formation ring, possibly driven by an outer-inner Linblad resonance, may provide a means of fueling the central AGN, as recently suggested by Yuan and Kuo. Because IR observations do not support the presence of a true AGN torus in NGC 1068, we present a qualitative model in which the radio ejecta has carved out an ionization cone in the high concentration of dense molecular clouds surrounding the nucleus. This picture also implies that the extended conical emission region to the northeast of the nucleus lies near the galactic plane and is surrounded by lower density ambient gas than that surrounding the highly ionized gas southwest of the nucleus.

In this paper we discuss operational considerations for the free-flying occulter. Operations consist of maneuvering the Solar-Powered Ion-Driven Eclipsing Rover (SPIDER) between targets, alignment with the space-based telescope line of sight to the target, and stationkeeping target-to-target maneuvers need to be optimized to conserve propellant. A reasonable balance needs to be determined between target observation rate and the number of targets that are observable during mission lifetime. Velocity matching of the SPIDER with the telescope is essential to mission performance. An appropriate combination of solar electric and cold-gas thrusters provides the ability to match velocities using positional information derived from comminution and ranging between telescope, occulter and any metrology stations. Desirable features of using an external coronagraphic vehicle include the ability to obtain coronagraphic data with any instrument on the telescope-- imaging, spectroscopic, or interferometric.