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

CHIRON - A Fiber Fed Spectrometer for Precise Radial Velocities

The CHIRON optical high-resolution echelle spectrometer was commissioned at the 1.5m telescope at CTIO in 2011. The instrument was designed for high throughput and stability, with the goal of monitoring radial velocities of bright stars with high precision and high cadence for the discovery of low-mass exoplanets. Spectral resolution of R=79,000 is attained when using a slicer with a total (including telescope and detector) efficiency of 6% or higher, while a resolution of R=136,000 is available for bright stars. A fixed spectral range of 415 to 880 nm is covered. The echelle grating is housed in a vacuum enclosure and the instrument temperature is stabilized to +-0.2deg. Stable illumination is provided by an octagonal multimode fiber with excellent light-scrambling properties. An iodine cell is used for wavelength calibration. We describe the main optics, fiber feed, detector, exposure-meter, and other aspects of the instrument, as well as the observing procedure and data reduction.Comment: 15 pages, 10 figures. Accepted by PAS

Fiber scrambling for high-resolution spectrographs. I. Lick Observatory

In this paper, we report all results obtained with a fiber scrambler on the Hamilton spectrograph at Lick Observatory. We demonstrate an improvement in the stability of the instrumental profile using this fiber scrambler. Additionally, we present data obtained with a double scrambler that further improves the stability of the instrument by a factor 2. These results show that errors related to the coupling between the telescope and the spectrograph are the dominant source of instrumental profile variability at Lick Observatory. In particular, we show a strong correlation between instrumental profile variations and hour angle, most likely due to pointing-dependent illumination of the spectrograph optics

Environmental variation drives continental-scale synchrony of European beech reproduction.

Spatial synchrony is the tendency of spatially separated populations to display similar temporal fluctuations. Synchrony affects regional ecosystem functioning, but it remains difficult to disentangle its underlying mechanisms. We leveraged regression on distance matrices and geography of synchrony to understand the processes driving synchrony of European beech masting over the European continent. Masting in beech shows distance-decay, but significant synchrony is maintained at spatial scales of up to 1,500 km. The spatial synchrony of the weather cues that drive interannual variation in reproduction also explains the regional spatial synchrony of masting. Proximity played no apparent role in influencing beech masting synchrony after controlling for synchrony in environmental variation. Synchrony of beech reproduction shows a clear biogeographical pattern, decreasing from the northwest to southeast Europe. Synchrony networks for weather cues resemble networks for beech masting, indicating that the geographical structure of weather synchrony underlies the biogeography of masting synchrony. Our results support the hypothesis that environmental factors, the Moran effect, are key drivers of spatial synchrony in beech seed production at regional scales. The geographical patterns of regional synchronization of masting have implications for regional forest production, gene flow, carbon cycling, disease dynamics, biodiversity, and conservation

Summer solstice orchestrates the subcontinental-scale synchrony of mast seeding

High interannual variation in seed production in perennial plants can be synchronized at subcontinental scales with wide consequences for ecosystem functioning, but how such synchrony is generated is unclear1-3. We investigated the factors contributing to masting synchrony in European beech (Fagus sylvatica), which extends to a geographic range of 2,000 km. Maximizing masting synchrony via spatial weather coordination, known as the Moran effect, requires a simultaneous response to weather conditions across distant populations. A celestial cue that occurs simultaneously across the entire hemisphere is the longest day (the summer solstice). We show that European beech abruptly opens its temperature-sensing window on the solstice, and hence widely separated populations all start responding to weather signals in the same week. This celestial 'starting gun' generates ecological events with high spatial synchrony across the continent

A High Spectral Resolution Study of the Soft X-ray Background with the X-ray Quantum Calorimeter

We present here a combined analysis of four high spectral resolution observations of the Diffuse X-ray Background (DXRB), made using the University of Wisconsin-Madison/Goddard Space Flight Center X-ray Quantum Calorimeter (XQC) sounding rocket payload. The observed spectra support the existence of a $\sim0.1~$keV Local Hot Bubble and a $\sim0.2~$keV Hot Halo, with discrepancies between repeated observations compatible with expected contributions of time-variable emission from Solar Wind Charge Exchange (SWCX). An additional component of $\sim0.9~$keV emission observed only at low galactic latitudes can be consistently explained by unresolved dM stars.Comment: 21 pages, 6 figures, accepted for publication in Ap