Hyper Suprime-Cam: Camera dewar design Komiyama, Yutaka; Obuchi, Yoshiyuki; Nakaya, Hidehiko ...
Publications of the Astronomical Society of Japan,
01/2018, Letnik:
70, Številka:
SP1
Journal Article
Recenzirano
Abstract
This paper describes the detailed design of the CCD dewar and the camera system which is a part of the wide-field imager Hyper Suprime-Cam (HSC) on the 8.2 m Subaru Telescope. On the 1.°5 ...diameter focal plane (497 mm in physical size), 116 four-side buttable 2 k × 4 k fully depleted CCDs are tiled with 0.3 mm gaps between adjacent chips, which are cooled down to −100°C by two pulse tube coolers with a capability to exhaust 100 W heat at −100°C. The design of the dewar is basically a natural extension of Suprime-Cam, incorporating some improvements such as (1) a detailed CCD positioning strategy to avoid any collision between CCDs while maximizing the filling factor of the focal plane, (2) a spherical washers mechanism adopted for the interface points to avoid any deformation caused by the tilt of the interface surface to be transferred to the focal plane, (3) the employment of a truncated-cone-shaped window, made of synthetic silica, to save the back focal space, and (4) a passive heat transfer mechanism to exhaust efficiently the heat generated from the CCD readout electronics which are accommodated inside the dewar. Extensive simulations using a finite-element analysis (FEA) method are carried out to verify that the design of the dewar is sufficient to satisfy the assigned errors. We also perform verification tests using the actually assembled CCD dewar to supplement the FEA and demonstrate that the design is adequate to ensure an excellent image quality which is key to the HSC. The details of the camera system, including the control computer system, are described as well as the assembling process of the dewar and the process of installation on the telescope.
Polarimetry is a crucial method to investigate solar magnetic fields. From the viewpoint of space weather, the magnetic field in solar filaments, which occasionally erupt and develop into ...interplanetary flux ropes, is of particular interest. To measure the magnetic field in filaments, high-performance polarimetry in the near-infrared wavelengths employing a high-speed, large-format detector is required; however, so far, this has been difficult to be realized. Thus, the development of a new infrared camera for advanced solar polarimetry has been started, employing a HAWAII-2RG (H2RG) array by Teledyne, which has
2048
×
2048
pixels, focusing on the wavelengths in the range of
1.0
-
1.6
μ
m
. We solved the problem of the difficult operation of the H2RGs under “fast readout mode” synchronizing with high-speed polarization modulation by introducing a “MACIE” (Markury ASIC Control and Interface Electronics) interface card and new assembly codes provided by Markury Scientific. This enables polarization measurements with high frame-rates, such as 29–117 frames per seconds, using a H2RG. We conducted experimental observations of the Sun and confirmed the high polarimetric performance of the camera.
ABSTRACT
We describe a weak lensing view of the downsizing of star-forming galaxies based on cross-correlating a weak lensing (
κ
) map with a predicted map constructed from a redshift survey. ...Moderately deep and high-resolution images with Subaru/Hyper Suprime-Cam covering the
DLS F2 field provide a
κ
map with 1 arcmin resolution. A dense complete redshift survey of the F2 field including 12,705 galaxies with
is the basis for construction of the predicted map. The zero-lag cross-correlation between the
κ
and predicted maps is significant at the 30
σ
level. The width of the cross-correlation peak is comparable to the angular scale of rich clusters at
, the median depth of the redshift survey. Slices of the predicted map in
redshift bins enable exploration of the impact of structure as a function of redshift. The zero-lag normalized cross-correlation has significant local maxima at redshifts coinciding with known massive X-ray clusters. Even in slices where there are no known massive clusters, there is a significant signal in the cross-correlation originating from lower mass groups that trace the large-scale of the universe. Spectroscopic
measurements enable division of the sample into star-forming and quiescent populations. In regions surrounding massive clusters of galaxies, the significance of the cross-correlation with maps based on star-forming galaxies increases with redshift from 5
σ
at
z
= 0.3 to 7
σ
at
the fractional contribution of the star-forming population to the total cross-correlation signal also increases with redshift. This weak lensing view is consistent with the downsizing picture of galaxy evolution established from other independent studies.
We present new results of Fe II l1.644 km spectroscopy toward the jets from HL Tau and RW Aur carried out with the Subaru Telescope combined with the adaptive optics system. We observed the regions ...within 2"-3" from the stars with the subarcsecond resolutions of 0".5 and 0".2 for HL Tau and RW Aur, respectively. In addition to the strong high-velocity component (HVC) extended along each jet, we detected a blueshifted low-velocity component (LVC) seen as a wing or shoulder of the HVC at each stellar position. The position velocity diagrams of the two objects show a characteristic similar to those of the cold disk wind and X-wind models in that the Fe II line width is broad close to the stellar position and narrower at the extended jet. A closer comparison suggests, however, that the disk wind model tends to have too large a line width at the HVC, while the X-wind model has excess redshifted emission at the stellar position. The narrow velocity width with symmetric line profiles of the observed HVC supports an X-wind-type model, while the LVC, located away from the star, favors the presence of a disk wind. The Fe II emission shows a gap of 0".8 for HL Tau and a marked drop of Y6-0".2 for RW Aur between the redshifted jet and the star, which indicate optically thick disks of 6160 and <40 AU in radius, respectively. Part of the Br12 emission of HL Tau originates from the jet itself because its normalized line profile shows a signigicantly large deviation from the normalized continuum in spatial profile.
The design and performance of the Cassegrain Adaptive Optics (AO) system for the 8.2 m Subaru Telescope are reported. The system is based on a curvature wavefront sensor with 36 photon-counting ...avalanche photodiode modules and a bimorph wavefront correcting deformable mirror with 36 driving electrodes. The engineering first light of the AO system took place in 2000 December. The AO system has been in service since 2002 April for two open-use instruments, an infrared camera and spectrograph and a coronagraph imager with adaptive optics. The Strehl ratio in the
$K$
-band is around 0.3 for bright guide stars under
${0\rlap {.}{}^{\mathrm {\prime \prime }}4} K$
-band seeing condition. The control loop performs with 2060 corrections per second. High sensitivity of the wavefront sensor allows significant improvement in the image quality, even for faint guide stars down to
$R = 18 \,\mathrm{mag}$
. The FWHM of stellar images in a globular cluster was measured to derive an estimation of the isoplanatic angle and was found nearly constant out to
$30''$
from the guide star, indicating that the height of the effective turbulent layer of that particular night was less than 1.8 km. The on-going upgrade plans for a fivefold increase in the number of control elements and for the installation of a laser guide AO system are described.
Performance of back supportless CCDs for the NeXT mission Takagi, Shin-ichiro; Go Tsuru, Takeshi; Matsumoto, Hironori ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
04/2005, Letnik:
541, Številka:
1
Journal Article
Recenzirano
New X-ray Telescope (NeXT) will be the next Japanese X-ray astronomical satellite, which will be launched around 2010. A multilayer super mirror will give NeXT a large effective area across the ...0.1–80
keV band. This wide bandpass requires a focal plane detector that is also sensitive along the entire energy band. As the focal plane detector for NeXT, we have been developing a Wideband hybrid X-ray Imager (WXI) consisting of X-ray CCDs and pixelized CdTe detector. The X-ray CCD of the WXI is required to maintain high quantum efficiency up to the high-energy band while allowing hard X-rays to pass undetected through the depletion (sensitive) layer. In order to meet these requirements, we have been developing a back supportless CCD (BS-CCD) which has a thick depletion layer, a thinned Si wafer and a back supportless structure. As the first step, we manufactured a test model of BS-CCD in order to (1) learn the handling and thinning process and (2) confirm that there is no change of the performance. For the mechanical strength and the safe handling of the wafer, we decided to thin the wafer to
∼
200
μ
m
. We verified the thickness of the depletion layer and wafer of the BS-CCD to be about 70 and
190
μ
m
, respectively. The energy resolution at 5.9
keV of 144
eV and the read-out noise of 7 electrons (rms) are equal to those of an un-thinned CCD, hence, we confirmed that our thinning process has no effect on the performance.
ABSTRACT We describe a weak lensing view of the downsizing of star-forming galaxies based on cross-correlating a weak lensing (κ) map with a predicted map constructed from a redshift survey. ...Moderately deep and high-resolution images with Subaru/Hyper Suprime-Cam covering the DLS F2 field provide a κ map with 1 arcmin resolution. A dense complete redshift survey of the F2 field including 12,705 galaxies with is the basis for construction of the predicted map. The zero-lag cross-correlation between the κ and predicted maps is significant at the 30 level. The width of the cross-correlation peak is comparable to the angular scale of rich clusters at , the median depth of the redshift survey. Slices of the predicted map in redshift bins enable exploration of the impact of structure as a function of redshift. The zero-lag normalized cross-correlation has significant local maxima at redshifts coinciding with known massive X-ray clusters. Even in slices where there are no known massive clusters, there is a significant signal in the cross-correlation originating from lower mass groups that trace the large-scale of the universe. Spectroscopic measurements enable division of the sample into star-forming and quiescent populations. In regions surrounding massive clusters of galaxies, the significance of the cross-correlation with maps based on star-forming galaxies increases with redshift from 5 at z = 0.3 to 7 at the fractional contribution of the star-forming population to the total cross-correlation signal also increases with redshift. This weak lensing view is consistent with the downsizing picture of galaxy evolution established from other independent studies.
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