A metrology system to measure the on-orbit movement of a ten meter mast has been built for the Nuclear Spectroscopic Telescope Array (NuSTAR) x-ray observatory. In this paper, the metrology system is described, and the performance is measured. The laser beam stability is discussed in detail. Pre-launch alignment and calibration are also described. The invisible infrared laser beams must be aligned to their corresponding detectors without deploying the telescope in Earth's gravity. Finally, a possible method for in-flight calibration of the metrology system is described.
The Faint Intergalactic Redshifted Emission Balloon (FIREBALL) had its first scientific flight in June 2009.
The instrument is a 1 meter class balloon-borne telescope equipped with a vacuum-ultraviolet integral field
spectrograph intended to detect emission from the inter-galactic medium at redshifts 0.3 < z < 1.0. The
scientific goals and the challenging environment place strict constraints on the pointing and tracking systems of
the gondola. In this manuscript we briefly review our pointing requirements, discuss the methods and solutions
used to meet those requirements, and present the aspect reconstruction results from the first successful scientific
FIREBALL (the Faint Intergalactic Redshifted Emission Balloon) is a balloon-borne 1m telescope coupled to an
ultraviolet fiber-fed spectrograph. FIREBALL is designed to study the faint and diffuse emission of the intergalactic
medium, until now detected primarily in absorption. FIREBALL is a path finding mission to test new technology
and make new constraints on the temperature and density of this gas. We report on the first successful science flight
of FIREBALL, in June 2009, which proved every aspect of the complex instrument performance, and provided the
strongest measurements and constraints on IGM emission available from any instrument.
In the context of the NASA CNES FIREBALL balloon borne experiment, we present the design of a semi-kinematic
mount to hold the 1 meter class mirrors of this mission. To maintain these large optics in a reasonable mass and price
budgets we choose thin ULE mirrors with a thickness over diameter ratio of 1/16. Such thin mirrors require a multi
support mount to reduce self weight deflection. Classical multi support mount used for ground based telescope would not
survive the level of shock observed in a balloon experiment either at parachute opening or landing. To firmly maintain
these mirrors in several points without noticeably deforming them we investigated the design of a two stages semi-kinematic
mount composed of 24 monopods. We present the detailed design of this innovative mirror mount, the finite
element modeling with the deduced optical wavefront deformation. During the FIREBALL integration and flight
campaign in July 2007 at CSBF, we confirmed the validity of the mechanical concept by obtaining an image quality well
within the required specifications. Variants of this approach are potentially applicable to large thin mirrors on ground-based
FIREBall (Faint Intergalactic Redshifted Emission Balloon) had a successful first engineering flight in July of 2007 from
Palestine, Texas. Here we detail the design and construction of the spectrograph. FIREBall consists of a 1m telescope
coupled to a fiber-fed ultraviolet spectrograph flown on a short duration balloon. The spectrograph is designed to map
hydrogen and metal line emission from the intergalactic medium at several redshifts below z=1, exploiting a small
window in atmospheric oxygen absorption at balloon altitudes. The instrument is a wide-field IFU fed by almost 400
fibers. The Offner mount spectrograph is designed to be sensitive in the 195-215nm window accessible at our altitudes
of 35-40km. We are able to observe Lyα, as well as OVI and CIV doublets, from 0.3 < z < 0.9. Observations of UV
bright B stars and background measurements allow characterization of throughput for the entire system and will inform
We are developing the Cosmic Web Imager (CWI) to detect and map emission from the intergalactic medium (IGM).
CWI will observe the strong, redshift UV resonance lines of Lyα 1216, CIV 1550, and OVI 1033 over 3600-9000 Å to
trace IGM at 1 < z < 7. CWI is an integral-field spectrograph designed for the Hale Telescope at Palomar Observatory.
CWI combines in a novel way three mature and extensively used instrumental techniques. The Integral Field Unit (IFU)
provides a wide 2D field of view of 60 × 40 arcsec2 for observing extended emission over a large region. The
spectrograph using Volume-Phase Holographic gratings have high peak diffraction efficiency and are tunable for
covering a large bandpass with a single grating. A low read noise CCD combined with source/background shiftand-nod
allowing control of systematics and Poisson-imited sky subtraction to observe the low surface brightness universe. With
a resolution of R=10,000 CWI is sensitive to limiting surface brightness ranging from 25 - 27.5 mag/arcsec2 (10 min - 8
hours integration). Recent high resolution simulations predict Lyα Fluorescence from IGM at 100 - 1000 LU1. CWI with
sensitivity of ~200 LU improves the current observational effort by an order of magnitude and enables us to explore
wide range of overdensity (δ ~ 30 - 104) testing the standard model of structure formation in the universe. CWI also
serves as the counter part to the balloon borne integral-field spectrograph Faint Intergalactic medium Redshifted
Emission Balloon (FIREBALL) currently being built and planned to be launched in Summer 2007. FIREBALL will
observe Lyα Fluorescence from IGM at z = 0.7. CWI combined with FIREBALL will enable us to observe the evolution
of IGM and the low surface brightness universe.
In the context of the NASA balloon borne experiment named Fireball (Faint Intergalactic Redshifted Emission BALLoon) dedicated to map the Intergalactic Medium, we designed a fiber-fed near ultraviolet spectrograph to work in the 200 nm atmospheric transmission window. We first describe the system level optimization leading to the atypical use in UV of a fiber Integral Field Unit at the focus of a one meter diameter parabolic mirror. For the qualification of the design we measured the absolute transmission of an UV polyimide 100 microns core fiber. The fiber bundle made of 400 fibers rearranged in a 50 mm slit feeds an F/2.5 spectrograph based on an Offner Littrow mount. We present the optical performances of this design with a high throughput and a well matched aperture ratio.
The High Energy Focusing Telescope (HEFT) is a balloon-borne, hard x-ray/gamma ray (20-70 keV) astronomical experiment. HEFT's 10 arcminute field of view and 1 arcminute angular resolution place challenging demands on its attitude control system (ACS). A microprocessor-based ACS has been developed to manage target acquisition and sidereal tracking. The ACS consists of a variety of sensors and actuators, with provisions for 2-way ground communication, all controlled by an on-board computer. Ground based pointing performance measurements indicate 1σ jitter of 7" and gyro drift rates of <1" s-1. Jitter is expected to worsen in the flight environment, but star tracker data are expected to reduce drift rates significantly, enabling a predicted 1σ absolute attitude determination of ≥4.7". HEFT is scheduled for flight in Spring 2004.
The Galaxy Evolution Explorer (GALEX), a NASA Small Explorer Mission planned for launch in Fall 2002, will perform the first Space Ultraviolet sky survey. Five imaging surveys in each of two bands (1350-1750Å and 1750-2800Å) will range from an all-sky survey (limit mAB~20-21) to an ultra-deep survey of 4 square degrees (limit mAB~26). Three spectroscopic grism surveys (R=100-300) will be performed with various depths (mAB~20-25) and sky coverage (100 to 2 square degrees) over the 1350-2800Å band. The instrument includes a 50 cm modified Ritchey-Chrétien telescope, a dichroic beam splitter and astigmatism corrector, two large sealed tube microchannel plate detectors to simultaneously cover the two bands and the 1.2 degree field of view. A rotating wheel provides either imaging or grism spectroscopy with transmitting optics. We will use the measured UV properties of local galaxies, along with corollary observations, to calibrate the UV-global star formation rate relationship in galaxies. We will apply this calibration to distant galaxies discovered in the deep imaging and spectroscopic surveys to map the history of star formation in the universe over the red shift range zero to two. The GALEX mission will include an Associate Investigator program for additional observations and supporting data analysis. This will support a wide variety of investigations made possible by the first UV sky survey.
We describe the design and performance of the pointing and aspect reconstruction system on the Gamma-Ray Arcminute Telescope Imaging System. The payload consists of a 4m long gamma-ray telescope, capable of producing images of the gamma-ray sky at an angular resolution of 2 arcminutes. The telescope is operated at an altitude of 40km in azimuth/elevation pointing mode. Using a variety of sensor, including attitude GPS, fiber optic gyroscopes, star and sun trackers, the system is capable of pointing the gamma-ray payload to within an arc-minute from the balloon borne platform. The system is designed for long-term autonomous operation and performed to specification throughout a recent 36 hour flight from Alice Springs, Australia. A star tracker and pattern recognition software developed for the mission permit aspect reconstruction to better than 10 arcseconds. The narrow field star tracker system is capable of acquiring and identifying a star field without external input. We present flight data form all sensors and the resultant gamma-ray source localizations.
We present the design, characterization, and flight performance of a sounding rocket instrument developed to address unanswered scientific questions regarding the extreme ultraviolet emissions of the star (epsilon) Canis Majoris (Adhara). The payload consists of an off axis parabolic telescope feeding a standard Rowland circle spectrograph and provides between 2 and 4 cm2 of effective area at the short and long wavelength ends of the bandpass, repectively. The spectrograph has a resolution of approximately 800 and covers the wavelength range 600 - 919 angstrom. In this paper we discuss specifics of the optical and mechanical design and present results from the initial calibration. The payload is presently scheduled for launch from Woomera, Australia, in the fall of 1995.