The Hitomi (ASTRO-H) mission is the sixth Japanese x-ray astronomy satellite developed by a large international collaboration, including Japan, USA, Canada, and Europe. The mission aimed to provide the highest energy resolution ever achieved at E > 2 keV, using a microcalorimeter instrument, and to cover a wide energy range spanning four decades in energy from soft x-rays to gamma rays. After a successful launch on February 17, 2016, the spacecraft lost its function on March 26, 2016, but the commissioning phase for about a month provided valuable information on the onboard instruments and the spacecraft system, including astrophysical results obtained from first light observations. The paper describes the Hitomi (ASTRO-H) mission, its capabilities, the initial operation, and the instruments/spacecraft performances confirmed during the commissioning operations for about a month.
The Hitomi (ASTRO-H) mission is the sixth Japanese X-ray astronomy satellite developed by a large international collaboration, including Japan, USA, Canada, and Europe. The mission aimed to provide the highest energy resolution ever achieved at E > 2 keV, using a microcalorimeter instrument, and to cover a wide energy range spanning four decades in energy from soft X-rays to gamma-rays. After a successful launch on 2016 February 17, the spacecraft lost its function on 2016 March 26, but the commissioning phase for about a month provided valuable information on the on-board instruments and the spacecraft system, including astrophysical results obtained from first light observations. The paper describes the Hitomi (ASTRO-H) mission, its capabilities, the initial operation, and the instruments/spacecraft performances confirmed during the commissioning operations for about a month.
Wide Field Camera 3 (WFC3) is the most used instrument on board the Hubble Space Telescope. Providing a broad range of high quality imaging capabilities from 200 to 1700mn using Silicon CCD and HgCdTe IR detectors, WFC3 is fulfilling both our expectations and its formal requirements. With the re-establishment of the observatory level "spatial scan" capability, we have extended the scientific potential ofWFC3 in multiple directions. These controlled scans, often in combination with low resolution slit-less spectroscopy, enable extremely high precision differential photometric measurements of transiting exo-planets and direct measurement of sources considerably brighter than originally anticipated. In addition, long scans permit the measurement of the separation of star images to accuracies approaching 25 micro-arc seconds (a factor of 10 better than prior FGS or imaging measurements) enables direct parallax observations out to 4 kilo-parsecs. In addition, we have employed this spatial scan capability to both assess and improve the mid spatial frequency flat field calibrations.
WFC3 uses a Teledyne HgCdTe 1014xl014 pixel Hawaii-lR infrared detector array developed for this mission. One aspect of this detector with implications for many types of science observations is the localized trapping of charge. This manifests itself as both image persistence lasting several hours and as an apparent response variation with photon arrival rate over a large dynamic range. Beyond a generally adopted observing strategy of obtaining multiple observations with small spatial offsets, we have developed a multi-parameter model that accounts for source flux, accumulated signal level, and decay time to predict image persistence at the pixel level. Using a running window through the entirety of the acquired data, we now provide observers with predictions for each individual exposure within several days of its acquisition.
Ongoing characterization of the sources on infrared background and the causes of its temporal and spatial variation has led to the appreciation of the impact of He I 1.083 micron emission from the earth's atmosphere. This adds a significant and variable background to the two filters and two grisms which include this spectral feature when the HST spacecraft is outside of the earth's shadow.
After nearly five years in orbit, long term trending of the scientific and engineering behavior of WFC3 demonstrates excellent stability other than the expected decline in CCD charge transfer efficiency. Addition of post-flash signal to images is shown to markedly improve the transfer efficiency for low level signals. Combined with a pixel based correction algorithm developed at STScl, CCD performance is stabilized at levels only slightly degraded from its initial values.
The joint JAXA/NASA ASTRO-H mission is the sixth in a series of highly successful X-ray missions developed by the Institute of Space and Astronautical Science (ISAS), with a planned launch in 2015. The ASTRO-H mission is equipped with a suite of sensitive instruments with the highest energy resolution ever achieved at E > 3 keV and a wide energy range spanning four decades in energy from soft X-rays to gamma-rays. The simultaneous broad band pass, coupled with the high spectral resolution of ΔE ≤ 7 eV of the micro-calorimeter, will enable a wide variety of important science themes to be pursued. ASTRO-H is expected to provide breakthrough results in scientific areas as diverse as the large-scale structure of the Universe and its evolution, the behavior of matter in the gravitational strong field regime, the physical conditions in sites of cosmic-ray acceleration, and the distribution of dark matter in galaxy clusters at different redshifts.
Like essentially all IR arrays, the IR detector in the Wide Field Camera 3 (WFC3) instrument on-board Hubble Space
Telescope (HST) exhibits afterimages, known as persistence, following exposures to light levels that approach or
exceed saturation of individual pixels of the detector. The nature of the persistence in the HgCdTe WFC3/IR detector is
distinctly non-linear in that the amount of persistence is not simply proportional to the exposure level. Instead, the
amount of persistence is small until the exposure reaches about half saturation at which point it rises fairly rapidly until
the exposure reaches about twice saturation and then it increases gradually with increasing saturation. The persistence
shows typical power law decay with time over the periods of time that are relevant to HST observations. Given the
frequent usage of the WFC3/IR detector on HST, it is not possible to completely avoid the effects of persistence in
observations obtained with HST by introducing time gaps between IR observations. Therefore, we have developed a
parameterized persistence model that we are using to estimate the amount of persistence in all WRC3/IR images. These
estimates are available for all existing WFC3/IR images through the Mikulski Archive at STScI (MAST) to help HST
users remove persistence from their images. Here we discuss the characterization of persistence in the WFC3 detector in
orbit, the fraction of observations that are affected by persistence, and the effectiveness of the tools we have developed
to reduce the effects of persistence in WFC3 images.
The joint JAXA/NASA ASTRO-H mission is the sixth in a series of highly successful X-ray missions initiated
by the Institute of Space and Astronautical Science (ISAS). ASTRO-H will investigate the physics of the highenergy
universe via a suite of four instruments, covering a very wide energy range, from 0.3 keV to 600 keV.
These instruments include a high-resolution, high-throughput spectrometer sensitive over 0.3–12 keV with
high spectral resolution of ΔE ≦ 7 eV, enabled by a micro-calorimeter array located in the focal plane of
thin-foil X-ray optics; hard X-ray imaging spectrometers covering 5–80 keV, located in the focal plane of
multilayer-coated, focusing hard X-ray mirrors; a wide-field imaging spectrometer sensitive over 0.4–12 keV,
with an X-ray CCD camera in the focal plane of a soft X-ray telescope; and a non-focusing Compton-camera
type soft gamma-ray detector, sensitive in the 40–600 keV band. The simultaneous broad bandpass, coupled
with high spectral resolution, will enable the pursuit of a wide variety of important science themes.
We now know that the flux of a source measured with HgCdTe arrays is not a simple, linear function, but depends on the
count-rate as well as the total number of counts. In addition to the count-rate non-linearity (and probably related to the
same physical mechanism), HgCdTe detectors are also susceptible to image persistence. Most of the persistence image
fades in a few minutes, but there is a longer-term component that can result in faint afterimages in the next orbit,
approximately 45 minutes later. For sources saturated at ~100 times full-well, the afterimages can persist for hours
afterwards. This report describes results from ground and on-orbit tests to characterize the persistence and the count-rate
non-linearity in the WFC3 IR detector during its first year of operation.
Installed in the Hubble Space Telescope (HST) in May 2009, the Wide Field Camera 3 (WFC3) is performing extremely
well on-orbit. Designed to complement the other instruments on-board the Hubble Space Telescope (HST) and enhance
the overall science performance of the observatory, WFC3 is effectively two instruments in one. The UVIS channel,
with its pair of e2v 4Kx2K CCD chips provides coverage from 200 to 1000 nm while the IR channel, with a Teledyne
HgCdTe focal plane array (FPA) on a Hawaii-1R multiplexer, covers the 800-1700 nm range. This report summarizes
the performance of the WFC3 detectors, including primary characteristics such as quantum efficiency, read noise, dark
current levels, and cosmetics, as well as hysteresis prevention and the impact of radiation damage in the CCDs. In
addition, we discuss effects in the IR detector such as persistence, count rate non-linearity, 'snowballs', and 'negative'
The joint JAXA/NASA ASTRO-H mission is the sixth in a series of highly successful X-ray missions initiated
by the Institute of Space and Astronautical Science (ISAS). ASTRO-H will investigate the physics of the
high-energy universe by performing high-resolution, high-throughput spectroscopy with moderate angular
resolution. ASTRO-H covers very wide energy range from 0.3 keV to 600 keV. ASTRO-H allows a combination
of wide band X-ray spectroscopy (5-80 keV) provided by multilayer coating, focusing hard X-ray
mirrors and hard X-ray imaging detectors, and high energy-resolution soft X-ray spectroscopy (0.3-12 keV)
provided by thin-foil X-ray optics and a micro-calorimeter array. The mission will also carry an X-ray CCD
camera as a focal plane detector for a soft X-ray telescope (0.4-12 keV) and a non-focusing soft gamma-ray
detector (40-600 keV) . The micro-calorimeter system is developed by an international collaboration led
by ISAS/JAXA and NASA. The simultaneous broad bandpass, coupled with high spectral resolution of
ΔE ~7 eV provided by the micro-calorimeter will enable a wide variety of important science themes to be
The scientific capabilities of the James Webb Space Telescope (JWST) fall into four themes. The End of the Dark Ages:
First Light and Reionization theme seeks to identify the first luminous sources to form and to determine the ionization
history of the universe. The Assembly of Galaxies theme seeks to determine how galaxies and the dark matter, gas,
stars, metals, morphological structures, and active nuclei within them evolved from the epoch of reionization to the
present. The Birth of Stars and Protoplanetary Systems theme seeks to unravel the birth and early evolution of stars,
from infall onto dust-enshrouded protostars, to the genesis of planetary systems. Planetary Systems and the Origins of
Life theme seeks to determine the physical and chemical properties of planetary systems around nearby stars and of our
own, and investigate the potential for life in those systems. To enable these for science themes, JWST will be a large
(6.5m) cold (50K) telescope with four instruments, capable of imaging and spectroscopy from 0.6 to 29 microns wavelength.
This paper summarizes the findings of the Next Generation Space Telescope (NGST) Detector Requirements Review Panel. This panel was comprised of NGST Integrated Science Instrument Module study representatives, detector specialists, and members of the NGST project science team. It has produced a report that recommends detector performance levels, and has provided rationale for deriving these levels from basic, anticipated NGST science goals and programs. Key parameters such as detector array format, quantum efficiency, and noise are discussed and prioritized.
A brief overview of the Next Generation Space Telescope science instrument module is given, development plans for engineering design, enabling technologies, and science instruments are discussed. Up-coming schedule milestones of community interest are also presented.