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For balloon-borne telescopes, the primary mirror is the most important optical element, but designing a primary mirror with an excellent overall performance is a challenge. To comprehensively consider the contradictory objectives of the root mean square (RMS) surface error under gravity in the X and Z directions, the mass and fundamental frequency of the primary mirror, a parametric primary mirror design using the compromise programming method based on topology optimization is proposed. The parametric design of the compromise programming method based on topology optimization is used to find the optimal solution for X-direction RMS (RMSx), Z-direction RMS (RMSz), mass, and fundamental frequency. Compared with the initial primary mirror structure designed according to traditional experience, the overall performance is improved. Results show that the respective mass of the primary mirror, the RMSx and the RMSz decreased by 8.5%, 14.3% and 10.5% compared to those before optimization. Comprehensive consideration can prove the effectiveness of parametric design based on the topology optimization of the primary mirror. This method provides a reference for the design of other primary mirrors for balloon-borne telescope and space cameras.

The EXperiment for Cryogenic Large-Aperture Intensity Mapping (EXCLAIM) is a balloon-borne far-infrared telescope that will survey star formation history over cosmological time scales to improve our understanding of why the star formation rate declined at redshift z < 2, despite continued clustering of dark matter. Specifically,EXCLAIM will map the emission of redshifted carbon monoxide and singly-ionized carbon lines in windows over a redshift range 0 < z < 3.5, following an innovative approach known as intensity mapping. Intensity mapping measures the statistics of brightness fluctuations of cumulative line emissions instead of detecting individual galaxies, thus enabling a blind, complete census of the emitting gas. To detect this emission unambiguously, EXCLAIM will cross-correlate with a spectroscopic galaxy catalog. The EXCLAIM mission uses a cryogenic design to cool the telescope optics to approximately 1.7 K. The telescope features a 90-cm primary mirror to probe spatial scales on the sky from the linear regime up to shot noise-dominated scales. The telescope optical elements couple to six ��-Spec spectrometer modules, operating over a 420-540 GHz frequency band with a spectral resolution of 512 and featuring microwave kinetic inductance detectors. A Radio Frequency System-on-Chip (RFSoC) reads out the detectors in the baseline design. The cryogenic telescope and the sensitive detectors allow EXCLAIM to reach high sensitivity in spectral windows of low emission in the upper atmosphere. Here, an overview of the mission design and development status since the start of the EXCLAIM project in early 2019 is presented., SPIE Astronomical Telescopes + Instrumentation. arXiv admin note: substantial text overlap with arXiv:1912.07118

We present the data reduction software and the distribution of Level 1 and Level 2 products of the Stratospheric Terahertz Observatory 2 (STO2). STO2, a balloon-borne Terahertz telescope, surveyed star-forming regions and the Galactic plane and produced approximately 300,000 spectra. The data are largely similar to spectra typically produced by single-dish radio telescopes. However, a fraction of the data contained rapidly varying fringe/baseline features and drift noise, which could not be adequately corrected using conventional data reduction software. To process the entire science data of the STO2 mission, we have adopted a new method to find proper off-source spectra to reduce large-amplitude fringes and new algorithms including Asymmetric Least Square (ALS), Independent Component Analysis (ICA), and Density-based spatial clustering of applications with noise (DBSCAN). The STO2 data reduction software efficiently reduced the amplitude of fringes from a few hundred to 10 K and resulted in baselines of amplitude down to a few K. The Level 1 products typically have the noise of a few K in [CII] spectra and ~1 K in [NII] spectra. Using a regridding algorithm, we made spectral maps of star-forming regions and the Galactic plane survey using an algorithm employing a Bessel-Gaussian kernel. Level 1 and 2 products are available to the astronomical community through the STO2 data server and the DataVerse. The software is also accessible to the public through Github. The detailed addresses are given in Section 4 of the paper on data distribution., Accepted to Journal of Astronomical Instrumentation

Several classes of planetary science observations require high spatial resolution in UV and visible wavelengths. Key examples include (a) the detection of satellites and characterization of their orbits, (b) the discovery of faint and small objects among the NEO, asteroid, Kuiper belt or Sedna-like populations and (c) cloud or trace gas observations in planetary atmospheres. Hubble Space Telescope (HST) observations have been very productive in these areas: consider the recent discovery of Makemake's satellite (Parker et al., 2016), the discovery of 2014 MU69 (now the flyby target of the New Horizons spacecraft) or the OPAL (Outer Planet Atmospheres Legacy) program. Like HST, large-aperture ground-based telescopes with adaptive optics can also achieve spatial resolutions of 50 mas, but normally at wavelengths longer than ~1 μm. Projects like MagAO-2K are working on improving image quality at visible wavelengths, but while the core PSF (Point Spread Function) width might be narrow (projected to be 15 mas at the Magellan telescope), the Strehl ratio drops steeply with wavelength (Males et al., 2016). Not all science goals suffer equally from low Strehl ratios, however: cloud tracking on Venus is more tolerant of a low Strehl ratio than searching for a close satellite of Makemake. A telescope on a NASA super-pressure balloon would float above 99.3% of the atmosphere, where the inner Fried parameter is thought to be two meters or more. While atmospheric turbulence is not expected to impact image quality, there are other sources of wavefront error (WFE), such as mirror figuring, misalignment of the OTA (Optical Telescope Assembly) or asymmetric heating from the Sun or Earth. We reference recent work that estimates balloon telescope WFEs from different sources to generate a suite of plausible PSFs. We apply these PSFs to the UV and visible wavelength science cases outlined in the GHAPS/SIDT report (Gondola for High Altitude Planetary Science/Science Instrument Definition Team). We quantify the impact that WFE has on achieving the planetary observations outlined in the SIDT report.

We describe here a focal plane array of Cold-Electron Bolometer (CEB) detectors integrated in a frequency selective surface (FSS) for the 350 GHz detection band of the OLIMPO balloon-borne telescope. In our architecture, the two-terminal CEB has been integrated in the periodic unit cell of the FSS structure and is impedance matched to the embedding impedance seen by it and provides a resonant interaction with the incident submillimeter radiation. The detector array has been designed to operate in background noise limited condition for incident powers of 20 pW to 80 pW, making it possible to use the same pixel in both photometric and spectrometric configurations. We present high-frequency and dc simulations of our system, together with fabrication details. The frequency response of the FSS array, optical response measurements with hot/cold load in front of optical window, and with variable-temperature blackbody source inside cryostat are presented. A comparison of the optical response to the CEB model and estimations of noise equivalent power (NEP) is also presented.

The Nuclear Compton Telescope (NCT) is a balloon-borne telescope based on the 3D-positioning germanium detectors. It is designed to study astrophysical sources of gamma-ray emission in the energy range of 0.2 MeV to 10 MeV. The data readout system of NCT is designed to amplify, digitize and collect signals from a germanium detector according to a certain trigger scheme. It also has an interface to the NCT flight computer to receive commands and transfer data. This paper contains the design and the scientific test result of the readout system.

The Nuclear Compton Telescope (NCT) is a balloon-borne telescope designed to study astrophysical sources of nuclear line emission and polarization at soft gamma-ray (0.2-10 MeV) energies. NCT uses high-purity germanium strip detectors for 3D tracking of photon interactions. Compton imaging enables effective background rejection, resulting in a compact but highly efficient instrument. The NCT prototype completed a successful flight from Fort Sumner, New Mexico in 2005. We have since integrated additional detectors, updated the readout electronics, and improved other flight systems. Two flights of the full instrument are upcoming: a conventional flight in New Mexico and a long duration flight from Australia. We give an overview of the instrument and its status prior to the planned balloon flights.

資料番号: AA0045439018

日本とインドとの協力による気球搭載望遠鏡／遠赤外線分光観測による結果のうち、オリオン領域の化学進化について報告する。観測は、日本が開発したファブリ・ペロー分光器を、インドが開発した1m気球望遠鏡に搭載して行なわれた。大口径を活かした高分解能の観測に特徴がある。気球放球は1999年11月25日に、インド・デカン高原・Hyderabad気球基地から行われ、オリオン星雲の広い領域にわたって、遠赤外[CII]スペクトル線と連続波の観測に成功した。観測結果は、連続波と[CII]スペクトル線とが異なる空間分布を持っていることを示している。これは、両者の励起源の違いによるものと思われる。さらに、[CII]スペクトル線の分布を、CO、[CI]スペクトル線の分布と比べると、それらの分布は、単純な光解離領域モデル(一様密度、化学平衡を仮定)では説明できないことがわかった。密度依存性や、時間変化を考慮する必要があると思われる。, 資料番号: AA0045439020

PRONAOS 3 is a French balloon borne 2 meter sub-millimeter telescope for astronomy. Developed and operated from 1986 to 1999, it has been a precursor for the two European space missions to be launched in 2007: FIRST and Planck-Surveyor. PRONAOS has been built as a light and autonomous space platform able to resist the very hostile environment at the altitude of 40 kilometers. It has thus driven many technological developments such as a light carbon-fiber active optics, a daylight star-tracker, high sensitivity 300 mK bolometers and a pointing system with a 5 arc-seconds accuracy. With three successful stratospheric flights the major scientific contributions of PRONAOS have been : 1) The first measurement of the positive part of the spectral distortion of the Cosmic Microwave Background toward a cluster of galaxies. 2) The discovery of a cold dust phase in the Galactic interstellar medium, with temperatures ranging from 12 to 15 K, and evidence for new dust emissivity properties.

We report results obtained during the characterization of a commercial front-illuminated progressive scan interline transfer CCD camera. We demonstrate that the unmodified camera operates successfully in temperature and pressure conditions (-40C, 4mBar) representative of a high altitude balloon mission. We further demonstrate that the centroid of a well-sampled star can be determined to better than 2% of a pixel, even though the CCD is equipped with a microlens array. This device has been selected for use in a closed-loop star-guiding and tip-tilt correction system in the BIT-STABLE balloon mission., 14 pages, 16 figures. Accepted in Journal of Astronomical Instrumentation, special issue on Scientific Ballooning

We report on the performance of a high sensitivity 4.7 THz heterodyne receiver based on a NbN hot electron bolometer mixer and a quantum cascade laser (QCL) as local oscillator. The receiver is developed to observe the astronomically important neutral atomic oxygen [OI] line at 4.7448 THz on a balloon based telescope. The single-line frequency control and improved beam pattern of QCL have taken advantage of a third-order distributed feedback structure. We measured a double sideband receiver noise temperature (Trec(DSB)) of 815 K, which is ~ 7 times the quantum noise limit (hν/2kB). An Allan time of 15 s at an effective noise fluctuation bandwidth of 18 MHz is demonstrated. Heterodyne performance was further supported by a measured methanol line spectrum around 4.7 THz.

We present the thermal model of the Balloon-borne Large-Aperture Submillimeter Telescope for Polarimetry (BLASTPol). This instrument was successfully flown in two circumpolar flights from McMurdo, Antarctica in 2010 and 2012. During these two flights, BLASTPol obtained unprecedented information about the magnetic field in molecular clouds through the measurement of the polarized thermal emission of interstellar dust grains. The thermal design of the experiment addresses the stability and control of the payload necessary for this kind of measurement. We describe the thermal modeling of the payload including the sun-shielding strategy. We present the in-flight thermal performance of the instrument and compare the predictions of the model with the temperatures registered during the flight. We describe the difficulties of modeling the thermal behavior of the balloon-borne platform and establish landmarks that can be used in the design of future balloon-borne instruments., Comment: 18 pages, 11 figures. Presented at SPIE Ground-based and Airborne Telescopes V, June 23, 2014. To be published in Proceedings of SPIE Volume 9145

T. Sawano1, T. Tanimori1, H. Kubo1, A. Takada2, J. D. Parker1, T. Mizumoto1, S. Sonoda3, Y. Mizumura4, D. Tomono1, K. Nakamura1, Y. Matsuoka1, S. Komura1, Y. Sato1, S. Nakamura1, K. Miuchi5, S. Kabuki6, Y. Kishimoto7, S. Kurosawa8, S. Iwaki1, M. Tanaka9, M. Ikeno9, and T. Uchida9 1Department of Physics, Kyoto University, Kyoto 606-8502, Japan 2Research Institute for Sustainable Humanosphere, Kyoto University, Kyoto 611-0011, Japan 3Advanced Biomedical Engineering Research Unit, Kyoto University, Kyoto 606-8501, Japan 4Unit of Synergetic Studies for Space, Kyoto University, Kyoto 606-8502, Japan 5Department of Physics, Kobe University, Hyogo 657-8501, Japan 6Department of Radiation Oncology, Tokai University, Kanagawa 259-1193, Japan 7Radiation Science Center, KEK, Ibaraki 305-8501, Japan 8Institute for Materials Research, Tohoku University, Miyagi 980-8577, Japan 9Institute of Particle and Nuclear Studies, KEK, Ibaraki 319-1211, Japan

We present the results of integration and characterization of the SPIDER instrument after the 2013 pre-flight campaign. SPIDER is a balloon-borne polarimeter designed to probe the primordial gravitational wave signal in the degree-scale $B$-mode polarization of the cosmic microwave background. With six independent telescopes housing over 2000 detectors in the 94 GHz and 150 GHz frequency bands, SPIDER will map 7.5% of the sky with a depth of 11 to 14 $\mu$K$\cdot$arcmin at each frequency, which is a factor of $\sim$5 improvement over Planck. We discuss the integration of the pointing, cryogenic, electronics, and power sub-systems, as well as pre-flight characterization of the detectors and optical systems. SPIDER is well prepared for a December 2014 flight from Antarctica, and is expected to be limited by astrophysical foreground emission, and not instrumental sensitivity, over the survey region., Comment: 25 pages, 14 figures. Presented at SPIE Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy VII, June 26, 2014. To be published in Proceedings of SPIE Volume 9153

We introduce the light-weight carbon fiber and aluminum gondola designed for the SPIDER balloon-borne telescope. SPIDER is designed to measure the polarization of the Cosmic Microwave Background radiation with unprecedented sensitivity and control of systematics in search of the imprint of inflation: a period of exponential expansion in the early Universe. The requirements of this balloon-borne instrument put tight constrains on the mass budget of the payload. The SPIDER gondola is designed to house the experiment and guarantee its operational and structural integrity during its balloon-borne flight, while using less than 10% of the total mass of the payload. We present a construction method for the gondola based on carbon fiber reinforced polymer tubes with aluminum inserts and aluminum multi-tube joints. We describe the validation of the model through Finite Element Analysis and mechanical tests., Comment: 16 pages, 11 figures. Presented at SPIE Ground-based and Airborne Telescopes V, June 23, 2014. To be published in Proceedings of SPIE Volume 9145

We present the technology and control methods developed for the pointing system of the SPIDER experiment. SPIDER is a balloon-borne polarimeter designed to detect the imprint of primordial gravitational waves in the polarization of the Cosmic Microwave Background radiation. We describe the two main components of the telescope's azimuth drive: the reaction wheel and the motorized pivot. A 13 kHz PI control loop runs on a digital signal processor, with feedback from fibre optic rate gyroscopes. This system can control azimuthal speed with < 0.02 deg/s RMS error. To control elevation, SPIDER uses stepper-motor-driven linear actuators to rotate the cryostat, which houses the optical instruments, relative to the outer frame. With the velocity in each axis controlled in this way, higher-level control loops on the onboard flight computers can implement the pointing and scanning observation modes required for the experiment. We have accomplished the non-trivial task of scanning a 5000 lb payload sinusoidally in azimuth at a peak acceleration of 0.8 deg/s$^2$, and a peak speed of 6 deg/s. We can do so while reliably achieving sub-arcminute pointing control accuracy., 20 pages, 12 figures, Presented at SPIE Ground-based and Airborne Telescopes V, June 23, 2014. To be published in Proceedings of SPIE Volume 9145

We present the second generation BLASTbus electronics. The primary purposes of this system are detector readout, attitude control, and cryogenic housekeeping, for balloon-borne telescopes. Readout of neutron transmutation doped germanium (NTD-Ge) bolometers requires low noise and parallel acquisition of hundreds of analog signals. Controlling a telescope's attitude requires the capability to interface to a wide variety of sensors and motors, and to use them together in a fast, closed loop. To achieve these different goals, the BLASTbus system employs a flexible motherboard-daughterboard architecture. The programmable motherboard features a digital signal processor (DSP) and field-programmable gate array (FPGA), as well as slots for three daughterboards. The daughterboards provide the interface to the outside world, with versions for analog to digital conversion, and optoisolated digital input/output. With the versatility afforded by this design, the BLASTbus also finds uses in cryogenic, thermometry, and power systems. For accurate timing control to tie everything together, the system operates in a fully synchronous manner. BLASTbus electronics have been successfully deployed to the South Pole, and flown on stratospheric balloons., Presented at SPIE Ground-based and Airborne Telescopes V, June 23, 2014. To be published in Proceedings of SPIE Volume 9145

In this paper, we have discussed the development of a large Control Moment Gyroscope (51 N.M.S. CMG) and use CMG as the driving component to realize precise attitude control of a large balloon borne gondola (total weight 1.5 ton) on which the solar telescope, 80 cm in diameter, is equatorially mounted. On ground test, the pointing accuracy of the gondola of better than 1 arc-minute (R.M.S.) at its plumb line have finally been achieved. In addition, we have established a control model of the large balloon borne telescope pointing control system. By computer simulation and actual test on ground, we have achieved the pointing accuracy of better than 10 arc-seconds (R.M.S.) for the solar telescope.

Their distribution of redshifts manifests the falling cosmic rate of star formation since its heyday some two billion years after the Big Bang.

Set to fly in the Fall of 2013 from Ft. Sumner, NM, the High Energy Replicated Optics to Explore the Sun (HEROES) mission is a collaborative effort between the NASA Marshall Space Flight Center and the Goddard Space Flight Center to upgrade an existing payload, the High Energy Replicated Optics (HERO) balloon-borne telescope, to make unique scientific measurements of the Sun and astrophysical targets during the same flight. The HEROES science payload consists of 8 mirror modules, housing a total of 109 grazing-incidence optics. These modules are mounted on a carbon-fiber and Aluminum optical bench 6 m from a matching array of high pressure xenon gas scintillation proportional counters, which serve as the focal-plane detectors. The HEROES gondola utilizes a differential GPS system (backed by a magnetometer) for coarse pointing in the azimuth and a shaft angle encoder plus inclinometer provides the coarse elevation. The HEROES payload will incorporate a new solar aspect system to supplement the existing star camera, for fine pointing during both the day and night. The overall payload will be discussed as well as the new solar aspect system. This mission is funded by the NASA HOPE (Hands On Project Experience) Training Opportunity awarded by the NASA Academy of Program/Project and Engineering Leadership, in partnership with NASA's Science Mission Directorate, Office of the Chief Engineer and Office of the Chief Technologist.

A balloon-borne telescope is a efficient planetary observation method by a telescope mounted on a balloon gondola in the stratosphere. In order to observe planets in high accuracy, the pointing control system to catch and keep the target star in the field of view of the mission camera is important technology. This research aims to develop the high accuracy pointing control system of the balloon -borne telescope. In case of conducting the pointing control divided into the gondola attitude control and the telescope pointing control, vibration of the gondola attitude caused by disturbance influences the accuracy of the telescope pointing control. It is expected that the performance of the telescope pointing control is able to be improved by a compensation controller to cancel the influence of the gondola attitude disturbance. In this paper, the pointing control system equipping with the attitude disturbance compensator is proposed, and verification by some simulation studies are described.

The Balloon Experimental Twin Telescope for Infrared Interferometry (BETTII) is an 8-meter baseline far-infrared interferometer to fly on a high altitude balloon. Operating at wavelengths of 30-90 microns, BETTII will obtain spatial and spectral information on science targets at angular resolutions down to less than half an arcsecond, a capability unmatched by other far-infrared facilities. This requires attitude control at a level ofless than a tenth of an arcsecond, a great challenge for a lightweight balloon-borne system. We have designed a precision attitude determination system to provide gondola attitude knowledge at a level of 2 milliarcseconds at rates up to 100Hz, with accurate absolute attitude determination at the half arcsecond level at rates of up to 10Hz. A mUlti-stage control system involving rigid body motion and tip-tilt-piston correction provides precision pointing stability to the level required for the far-infrared instrument to perform its spatial/spectral interferometry in an open-loop control. We present key aspects of the design of the attitude determination and control and its development status.

1. Abstract Esrange Space Center located in northern Sweden has during 45 years been a leading launch site for both sounding rockets and stratospheric balloons. We have a unique combination of maintaining both stratospheric balloons and sounding rockets launch operations. Most balloon flights are normally handled inside Scandinavia but since 2005 semicircular flights are performed with recovery in northern Canada. The Swedish and Russian Governments have signed an agreement for peaceful exploration of space on 9 March 2010, which will permit circumpolar balloon flights. Within this agreement we are able to offer the science community long duration balloon flights in the Northern Hemisphere with durations for several weeks. The balloon operations at Esrange Space Center are yearly expanding. Both NASA and CNES have long term plans for balloon flights from northern Sweden. We have also received requests from Japanese Universities and JAXA for future balloon missions. To handle balloon campaigns with large numbers of payloads or build up for two different campaigns a new big assembly hall was ready for use in April 2011. In total 10 payloads have been flying for 4 to 5 days from Esrange westwards with landing in northern Canada since 2005. The SUNRISE balloon borne solar telescope is one example which made in June 2009 a more than 4 days semicircular balloon flight from Esrange. The Sunrise project is a collaborative project between the Max Planck Institute for Solar System Research in Katlenburg-Lindau and partners in Germany, Spain and the USA. The first circumpolar flight will take place in the second half of June 2012 with the PoGOLite balloon borne telescope studying the polarisation of gamma-rays from pulsars and will be recovered in Scandinavia after 12-15 days. The PoGoLite project is a collaborative project between Swedish, French, Japanese and US scientific teams.

We have developed a new liquid-helium cooled far-infrared Fabry-Perot interferometer (SFP) with high spectral resolution which will be incorporated and flown with our balloon-borne far-infrared 60 cm φ telescope FIT-FIT. This telescope has been built and already flown with other radiometric equipment in collaboration with the Geneva Observatory. The new spectrometer is designed to measure astronomical emission lines between 140 and 220 μm wavelength. Of special interest are the [NII]-line at 205 μm as well as the [CII]-line at 158 μm. In order to achieve high sensitivity we had to minimize the thermal radiation from the interferometer and its optics. For this reason all optics, including the scanning Fabry-Perot interferometer SFP, are liquid-helium cooled. This paper describes special new features of the design, operation, and test of its performance at liquid-helium temperature with optically pumped far-infrared gas lasers.

By using a balloon borne telescope, an extensive survey of the [CII] line emission of the Galaxy has been undertaken. To minimize the instrumental emission, an off-axis telescope with a Newtonian-Nasmyth focus was used in conjunction with a liquid helium cooled Fabry-Perot spectrometer. The beam size of the telescope was 12' in diameter and the spectral resolution of the spectrometer was 175 km/s in velocity scale. The balloon flights were made from Palestine, TX in 1991 and from Alice Springs, Australia in 1992. By both observations, the major part of the galactic plane in the northern sky and the southern sky has been scanned. As a result, a complete map of the [CII] line intensity distribution has been constructed for the region from—100° to 80° in galactic longitude and within ±4° in galactic latitude. In addition to the general scan of the galactic plane, the observations were extended to some individual sources, such as Cyg-X region, p-Oph dark cloud and Large Magellanic Cloud. The observed maps reveal strong [CII] line emission extensively distributed in the galactic plane, as well as many discrete sources associated with HII regions and/or molecular clouds. The distribution is more or less correlated with far infrared continuum and CO line intensity distributions. However, detailed comparisons show interesting differences between the three components.

We present a new γ-ray telescope based on the Limited Streamer Tube technology, used as tracking chambers to detect photons above 100 MeV. This technique allows to obtain very large sensitive areas (16 m2 in our experiment), together with a good angular resolution for payloads embarcable in high-altitude balloon flights. The capability to collect a large signal in a short exposure time makes the telescope particularly suitable and competitive with respect to satellite-based detectors for studying both periodic and random time variabilities on galactic and extragalactic γ-ray sources.

Our team is carrying out the project of Planet observation with high precision using balloon-borne telescope. The first model, BBT-1 was equipped with a three stage pointing system and an optical system to observe the detailed structure of the atmospheric motion of Venus. The first flight test was conducted in 2009, and the performance of the system was verified. However, because of a trouble of onboard computer, the flight operation could not been finished as planned. The second model “BBT-2” is now being developed and the next flight test is planned in 2011. The BBT-2 has a bus system including FPGAs and CPU, and it is expected to be more stable than the BBT-1.

We describe the development of the image‐stabilized telescope for project “Tera‐GATE.” This telescope can move the secondary mirror and cancel the image motion that arises from the gondola attitude error. We also report on the feedback system for the image stabilization and give an image quality estimation for the telescope.

We have introduced secondary-mirror chopping in our balloon-borne far-infrared 60 cm O telescope equipped with He-cooled filters and a composite silicon bolometer with an NEP of 1.3 10−14 W/Hz1/2 for imaging, radiometry and spectroscopy of the Cygnus region at the wavelengths 80 μm, 130 μm and 310 μm. The modified system was flown on September 26/27, 1990 with a 380'000m3 hydrogen balloon at the CNES station at Aire/Adour, France. Observations were performed at a platform height of 39 km during 5 hrs. We made successful measurements on the complexes DR21 and S106 of the Cygnus region as well as on Mars at the wavelengths mentioned.

The present status of the development of an extrinsic photoconductor based on a high-purity GaAs is reported. This photoconductor utilizing the shallow donor levels in GaAs and is highly sensitive for incident terahertz photons in the wavelength range 150 to 300 micron. The n-type GaAs crystal has been growth by liquid phase epitaxial (LPE) method, which is suitable to obtain thick and high-purity GaAs. The impurity concentration in GaAs layer has been decreased to the order of 10 13 atoms/cm -3 . By doping the donors lightly in the LPE growth process, C/Si, (background doped) Se and Te doped GaAs layers has been fabricated. The GaAs photoconductors using these crystals are sensitive in longer wavelength region than Ge:Ga photoconductors used in the past far-infrared astronomical observations. The most sensitive detector is obtained with C or Si background doped GaAs, of which NEP is reached to 3×10 -16 W/Hz 0.5 at the temperature of 1.5 K, at 290 micron, the peak of its responsivity spectrum. A balloon-borne telescope utilizing our GaAs photoconductors, Tera-GATE (THz observation with GaAs photoconductors and a balloon-borne Telescope) is now under development. The Tera-GATE is a 69 cm diameter telescope. On its focal plane, a photoconductor array with Winston cone has 2-mm entrance aperture and leads the incident photons to a cavity where 0.5-mm size photoconductor is installed. Measured optical efficiency of the cone/cavity system is in an acceptable range ~40 percent.

We describe the balloon-borne telescope (69cm aperture) for the project Tera-GATE (THz observation with GaAs photoconductors and a balloon-borne TElescope) aiming at the THz astronomical observations. THz region is the last frontier left not well explored and we are planning to have multiband photometric observations covering the wavelength from 50 to 300 microns and get completed SED data for some Young Stellar Objects in this band. The telescope, we are constructing, has image stabilizing system which cancels out pointing error (up to about 0.3 degrees) of the balloon gondola, and enables us to take a long exposure needed for highly sensitive observations. We will show the structure of the telescope, cold stop design, and characteristics of the image stabilizing system.

SUNRISE is an international project for the development, construction, and operation of a balloon-borne solar telescope with an aperture of 1 m, working in the UV/VIS spectral domain. The main scientific goal of SUNRISE is to understand the structure and dynamics of the magnetic field in the atmosphere of the Sun. SUNRISE will provide near diffraction-limited images of the photosphere and chromosphere with an unpredecented resolution down to 35 km on the solar surface at wavelengths around 220 nm. The focal-plane instrumentation consists of a polarization sensitive spectrograph, a Fabry-Perot filter magnetograph, and a phase-diverse filter imager working in the near UV. The first stratospheric long-duration balloon flight of SUNRISE is planned in Summer 2009 from the swedish ESRANGE station. SUNRISE is a joint project of the german Max-Planck-Institut fur Sonnensystemforschung (MPS), Katlenburg-Lindau, with the Kiepenheuer-Institut fur Sonnenphysik (KIS), Freiburg, Germany, the High-Altitude Observatory (HAO), Boulder, USA, the Lockheed-Martin Solar and Astrophysics Lab. (LMSAL), Palo Alto, USA, and the spanish IMaX consortium. In this paper we will present an actual update on the mission and give a brief description of its scientific and technological aspects.

4th International Workshop on Astronomy with Radioactivities - Filling and Sensitivity Gap in MeV Astronomy -- MAY 26-30, 2003 -- Kloster Seeon, GERMANY WOS: 000189181600051 A prototype balloon-borne telescope is being constructed for gamma-ray observations in the MeV energy range. The Tracking and Imaging Gamma-Ray Experiment (TIGRE) uses multi-layers of thin silicon detectors to track and measure the energy losses of Compton recoil electrons. When combined with the direction and energy of the Compton scattered gamma-ray a unique incident direction for each photon event is determined. This facilitates background rejection, improved sensitivity and image reconstruction. The converter/tracker also serves as an electron-positron pair detector for gamma-rays up to 100 MeV. The initial continental US flight will be used to determine the sub-orbital atmospheric backgrounds and search for polarized gamma-emission for the Crab pulsar. Longer southern hemisphere flights with an enhanced instrument will map out the Al-26 emissions from the galactic center region. (C) 2003 Elsevier B.V. All rights reserved.

Sunrise is a light-weight solar telescope with a 1 m aperture for spectro-polarimetric observations of the solar atmosphere. The telescope is planned to be operated during a series of long-duration balloon flights in order to obtain time series of spectra and images at the diffraction-limit and to study the UV spectral region down to ~200 nm, which is not accessible from the ground. The central aim of Sunrise is to understand the structure and dynamics of the magnetic field in the solar atmosphere. Through its interaction with the convective flow field, the magnetic field in the solar photosphere develops intense field concentrations on scales below 100 km, which are crucial for the dynamics and energetics of the whole solar atmosphere. In addition, Sunrise aims to provide information on the structure and dynamics of the solar chromosphere and on the physics of solar irradiance changes. Sunrise is a joint project of the Max-Planck-Institut fuer Aeronomie (MPAe), Katlenburg-Lindau, with the Kiepenheuer-Institut fuer Sonnenphysik (KIS), Freiburg, the High-Altitude Observatory (HAO), Boulder, the Lockheed-Martin Solar and Astrophysics Lab. (LMSAL), Palo Alto, and the Instituto de Astrofi sica de Canarias, La Laguna, Tenerife. In addition, there are close contacts with associated scientists from a variety of institutes.

This paper introduces our control software design for a tracing system of precise pointing on a balloon-borne telescope to observe the active details on the solar surface. The telescope is an equatorial one with 80 cm in diameter. Borne by balloon, it works at 30 km above the sea level so as to get rid of the image disturbance due to atmosphere. The system contains three parts: basket control, telescope control and tip-tilt control. For telescope control, the crude sensors for pointing detection are two rotating transformers, while the fine sensors two linear CCDs which produce the error signals of pointing. An inserted-type industry-control computer PC104 completes the position close-loop and then drives the servo amplifiers to carry out pointing, searching and tracing automatically. Due to the fact that the position control loop is closed with an improved digital PID arithmetic, the adjustment of the telescope may respond rapidly, therefore the telescope can precisely follow the Sun on the balloon. Simulation test shows that the tracing accuracy may reach as high as 4" (RMS).

Balloon borne instruments offer opportunities for astronomical observation in an environment that is superior to manyground observatories and less expensive than space borne observatories. BLAST is an infrared astronomical telescopethat will use a high altitude balloon as an observation platform. The BLAST telescope has a unique set of requirements:lightweight, low cost, zenith to horizon pointing, 10 arc-second pointing accuracy, high Strehl ratio far infrared/sub-milllimeter observation. The design of the BLAST telescope takes advantage of a pre-existing 2-m experimentallightweight carbon fiber mirror. Using this spherical primary, an aspheric secondary was designed to produce adiffraction limited telescope at 250 microns. The telescope metering structure was designed and fabricated using highstiffness, low mass, thermally stable carbon fiber. The secondary mirror was aggressively lightweighted and fabricatedusing state of the art diamond turning technology. Design was verified prior to manufacturing using finite elementstructural analyses in order to demonstrate compliance with the deflection requirements of the secondary mirror whenpointing zenith and near horizon. This paper will review the optical and opto-mechanical design, fabrication, integrationand alignment of the BLAST telescope.Keywords: infrared astronomy, carbon fiber composite, balloon borne telescope, lightweight mirror

We describe the Santa Barbara BEAST experiment, a balloon borne telescope to image the Cosmic Microwave Background (CMB) radiation anisotropy pattern. Some aspects of the map making pipeline are also discussed.