An orientable, stabilized balloon-borne gondola for around-the-world flights

A system capable of pointing a balloon-borne telescope at selected celestial objects to an accuracy of approximately 10 arc minutes for an extended period (weeks to months) without reliance on telemetry is described. A unique combination of a sun/star tracker, an on-board computer, and a gyrocompass is utilized for navigation, source acquisition and tracking, and data compression and recording. The possibilities for intelligent activities by the computer are also discussed

A mercuric detector system for X-ray astronomy. 2. Results from flight tests of a balloon borne instrument

To establish the expected sensitivity of a new hard X-ray telescope design, an experiment was conducted to measure the background counting rate at balloon altitudes (40 km) of mercuric iodide, a room temperature solid state X-ray detector. The prototype detector consisted of two thin mercuric iodide (HgI2) detectors surrounded by a large bismuth germanate (Bi4Ge3O12) scintillator operated in anticoincidence. The bismuth germanate shield vetoed most of the background counting rate induced by atmospheric gamma-rays, neutrons and cosmic rays. A balloon-borne gondola containing a prototype detector assembly was designed, constructed and flown twice in the spring of 1982 from Palestine, Texas. The second flight of this instrument established a differential background counting rate of 4.2 O.7 x 10-5 counts/sec cm keV over the energy range of 40 to 80 keV. This measurement was within 50% of the predicted value. The measured rate is approx 5 times lower than previously achieved in shielded NaI/CsI or Ge systems operating in the same energy range. The prediction was based on a Monte Carlo simulation of the detector assembly in the radiation environment at float altitude

Rapid fluctuations in the high-energy X-ray flux from a source in Crux

Balloonborne X ray telescopic observations of two point sources in Cru

Report of the x ray and gamma ray sensors panel

Overall five major areas of technology are recommended for development in order to meet the science requirements of the Astrotech 21 mission set. These are: detectors for high resolution gamma ray spectroscopy, cryogenic detectors for improved x ray spectral and spatial resolution, advanced x ray charge coupled devices (CCDs) for higher energy resolution and larger format, extension to higher energies, liquid and solid position sensitive detectors for improving stopping power in the energy range 5 to 500 keV and 0.2 to 2 MeV. Development plans designed to achieve the desired capabilities on the time scales required by the technology freeze dates have been recommended in each of these areas

Previously Claimed(/Unclaimed) X-ray Emission Lines in High Resolution Afterglow Spectra

We review the significance determination for emission lines in the Chandra HETGS spectrum for GRB020813, and we report on a search for additional lines in high resolution Chandra spectra. No previously unclaimed features are found. We also discuss the significance of lines sets reportedly discovered using XMM data for GRB011211 and GRB030227. We find that these features are likely of modest, though not negligible, significance.Comment: 4 pages, 1 figures, to appear in Santa Fe GRB Conference Proceedings, 200

Chandra Observations of the Optically Dark GRB030528

The X-ray-rich GRB030528 was detected by the HETE satellite and its localization was rapidly disseminated. However, early optical observations failed to detect a counterpart source. In a 2-epoch ToO observation with Chandra, we discovered a fading X-ray source likely counterpart to GRB030528. The source brightness was typical of X-ray afterglows observed at similar epochs. Other observers detected an IR source at a location consistent with the X-ray source. The X-ray spectrum is not consistent with a large absorbing column.Comment: 4 pages, 1 figures, to appear in Santa Fe GRB Conference Proceedings, 200

Optical and X-ray Observations of the Afterglow to XRF030723

The X-ray-flash XRF030723 was detected by the HETE satellite and rapidly disseminated, allowing for an optical transient to be detected ~1 day after the burst. We discuss observations in the optical with Magellan, which confirmed the fade of the optical transient. In a 2-epoch ToO observation with Chandra, we discovered a fading X-ray source spatially coincident with the optical transient. We present spectral fits to the X-ray data. We also discuss the possibility that the source underwent a rebrightening in the X-rays, as was observed in the optical. We find that the significance of a possible rebrightening is very low (~1 sigma).Comment: 4 pages, 2 figures, to appear in Santa Fe GRB Conference Proceedings, 200

Extension and Integral Representation of the finite Hilbert Transform In Rearrangement Invariant Spaces

The finite Hilbert transform $T$ is a classical (singular) kernel operator which is continuous in every rearrangement invariant space $X$ over $(-1,1)$ having non-trivial Boyd indices. For $X=L^p$, $1<p<\infty$, this operator has been intensively investigated since the 1940's (also under the guise of the ``airfoil equation''). Recently, the extension and inversion of $T\colon X\to X$ for more general $X$ has been studied in G. P. Curbera, S. Okada, W. J. Ricker, Inversion and extension of the finite Hilbert transform on $(-1,1)$, Ann. Mat. Pura Appl. 198 (2019), 1835-1860, where it is shown that there exists a larger space $[T,X]$, optimal in a well defined sense, which contains $X$ continuously and such that $T$ can be extended to a continuous linear operator $T\colon[T,X]\to X$. The purpose of this paper is to continue this investigation of $T$ via a consideration of the $X$-valued vector measure $m_X\colon A\mapsto T(\chi_A)$ induced by $T$ and its associated integration operator $f\mapsto \int_{-1}^1f\,dm_X$. In particular, we present integral representations of $T\colon X\to X$ based on the $L^1$-space of $m_X$ and other related spaces of integrable functions

Discovery and Characterization of Transiting SuperEarths Using an All-Sky Transit Survey and Follow-up by the James Webb Space Telescope

Doppler and transit surveys are finding extrasolar planets of ever smaller mass and radius, and are now sampling the domain of superEarths (1-3 Earth radii). Recent results from the Doppler surveys suggest that discovery of a transiting superEarth in the habitable zone of a lower main sequence star may be possible. We evaluate the prospects for an all-sky transit survey targeted to the brightest stars, that would find the most favorable cases for photometric and spectroscopic characterization using the James Webb Space Telescope (JWST). We use the proposed Transiting Exoplanet Survey Satellite (TESS) as representative of an all-sky survey. We couple the simulated TESS yield to a sensitivity model for the MIRI and NIRSpec instruments on JWST. We focus on the TESS planets with radii between Earth and Neptune. Our simulations consider secondary eclipse filter photometry using JWST/MIRI, comparing the 11- and 15-micron bands to measure CO2 absorption in superEarths, as well as JWST/NIRSpec spectroscopy of water absorption from 1.7-3.0 microns, and CO2 absorption at 4.3-microns. We project that TESS will discover about eight nearby habitable transiting superEarths. The principal sources of uncertainty in the prospects for JWST characterization of habitable superEarths are superEarth frequency and the nature of superEarth atmospheres. Based on our estimates of these uncertainties, we project that JWST will be able to measure the temperature, and identify molecular absorptions (water, CO2) in one to four nearby habitable TESS superEarths.Comment: accepted for PASP; added discussion and figure for habitable planets; abridged Abstrac

Earliest detection of the optical afterglow of GRB 030329 and its variability

We report the earliest detection of an extremely bright optical afterglow of the gamma-ray burst (GRB) 030329 using a 30cm-telescope at Tokyo Institute of Technology (Tokyo, JAPAN). Our observation started 67 minutes after the burst, and continued for succeeding two nights until the afterglow faded below the sensitivity limit of the telescope (approximately 18 mag). Combining our data with those reported in GCN Circulars, we find that the early afterglow light curve of the first half day is described by a broken power-law (t^{- alpha}) function with indices alpha_{1} = 0.88 +/- 0.01 (0.047 < t < t_{b1} days), alpha_{2} = 1.18 +/- 0.01 (t_{b1} < t < t_{b2} days), and alpha_{3} = 1.81 +/- 0.04 (t_{b2} < t < 1.2 days), where t_{b1} ~ 0.26 days and t_{b2} ~ 0.54 days, respectively. The change of the power-law index at the first break at t ~ 0.26 days is consistent with that expected from a ``cooling-break'' when the cooling frequency crossed the optical band. If the interpretation is correct, the decay index before the cooling-break implies a uniform ISM environment.Comment: 13 pages, 1 table and 2 figures. Accepted to the Astrophysical Journal Letter