We have developed a near infrared camera called ANIR (Atacama Near InfraRed camera) for the University of
Tokyo Atacama 1.0m telescope installed at the summit of Co. Chajnantor (5640m altitude) in northern Chile.
The camera is based on a PACE HAWAII-2 array with an Offner relay optics for re-imaging, and field of view
3 × 5.
3 with pixel scale of 0.
31/pix. It is also capable of optical/infrared simultaneous imaging by inserting
a dichroic mirror before the focal plane. The high altitude and extremely low water vapor (PWV=0.5mm) of
the site enables us to perform observation of hydrogen Paschenα (Paα) emission line at 1.8751 μm. The first
light observation was carried out in July 2009, and we have successfully obtained Paα images of the Galactic
center using the N1875 narrow-band filter. This is the first success of Paα imaging of a Galactic object from a
ground based telescope. System efficiencies for the broad-band filters are measured to be 15% at the J-band and
30% at Ks, while that of the N1875 narrow-band filter, corresponding to Paα; wavelength, varies from 8 to 15%,
which may be caused by fluctuation of the atmospheric transmittance. ATRAN simulation suggests that this
corresponds to PWV of 0.3 - 1.5mm, consistent with previous results of the site testing. Measured seeing size
is median ~0.
8, corresponding to the real seeing value of 0.
6 - 0.
8. These results demonstrates the excellent
capability of the site for infrared observations.
Proc. SPIE. 7021, High Energy, Optical, and Infrared Detectors for Astronomy III
KEYWORDS: Digital signal processing, Clocks, Cameras, Field programmable gate arrays, Control systems, Data processing, Signal processing, Fiber reinforced polymers, Infrared radiation, Operating systems
Real-time capabilities are required for a controller of a large format array to reduce a dead-time attributed by readout and
data transfer. The real-time processing has been achieved by dedicated processors including DSP, CPLD, and FPGA
devices. However, the dedicated processors have problems with memory resources, inflexibility, and high cost.
Meanwhile, a recent PC has sufficient resources of CPUs and memories to control the infrared array and to process a
large amount of frame data in real-time. In this study, we have developed an infrared array controller with a software
real-time operating system (RTOS) instead of the dedicated processors. A Linux PC equipped with a RTAI extension
and a dual-core CPU is used as a main computer, and one of the CPU cores is allocated to the real-time processing. A
digital I/O board with DMA functions is used for an I/O interface. The signal-processing cores are integrated in the OS
kernel as a real-time driver module, which is composed of two virtual devices of the clock processor and the frame
processor tasks. The array controller with the RTOS realizes complicated operations easily, flexibly, and at a low cost.
We present the development and first astronomical applications of VPH grisms which are now operated at
cryogenic temperature in MOIRCS, a Cassegrain near-infrared instrument of the Subaru Telescope. We designed
and fabricated the VPH grisms with a resolving power ~3000 for the use in near-infrared bands. The VPH
grating, encapsulated in BK7 glass, is glued between two ZnSe prisms with vertex angle of 20 deg. After
repeating several thermal cycles down to ~100 K carefully enough not to cause irreparable damage on the
grism during cooling, we evaluated the performance at cryogenic temperature in the laboratory and found no
deterioration and no large difference in the performance from that measured in room temperature. Based on
commissioning observations with MOIRCS, we have confirmed the high efficiency (~0.8) and the resolving power
of the original design. Common use of the grisms is due to start in the second semester of 2008.
We have been developing a near infrared camera called ANIR (Atacama Near InfraRed camera), for the University
of Tokyo Atacama 1.0m telescope installed at the summit of Co. Chajnantor (5640m altitude) in Northern Chile.
The major aim of this camera is to carry out an imaging survey in Paschen α emission line (1.8751μm) from
the ground for the first time. The camera is based on a PACE-HAWAII2 array with an Offner relay optics for
re-imaging, and field of view is 5.'3 × 5.'3 with pixel scale of 0."308/pix. It is scheduled to see first light in the
end of 2008, and start the Paschen α/β survey of the Galactic plane in 2009.
MOIRCS is a new Cassegrain instrument of Subaru telescope, dedicated for wide field imaging and multi-object spectroscopy in near-infrared. MOIRCS has been constructed jointly by Tohoku University and the Subaru Telescope and saw the first light in Sept., 2004. The commissioning observations to study both imaging and spectroscopic performance were conducted for about one year. MOIRCS mounts two 2048 × 2048 HAWAII2 arrays and provides a field of view of 4' x 7' with a pixel scale of 0."117. All-lens optical design is optimized for 0.8 to 2.5 μm with no practical chromatic aberration. Observations confirm the high image quality over the field of view without any perceptible degradation even at the field edge. The best seeing we have obtained so far is FWHM=0."18. A novel design of MOIRCS enables us to perform multi-object spectroscopy with aluminum slit masks, which are housed in a carrousel dewar and cooled to ~ 110 K. When choosing MOS mode, a manipulator pulls out a slit mask from the carrousel into the MOIRCS main dewar and sets it properly at the Cassegrain focus. The carrousel is shuttered by a gate valve, so that it can be warmed and cooled independently to exchange slit-mask sets during daytime. We have tested various configurations of 30 or more multi-slit positions in various sky fields and found that targets are dropped at the centers of slits or guide holes within a dispersion of about 0.3 pixels (0."03). MOIRCS has been open to common use specifically for imaging observations since Feb. 2006. The MOS function will be available in next August.
MOIRCS (Multi-Object Infrared Camera and Spectrograph) is a new instrument for the Subaru telescope. In order to perform observations of near-infrared imaging and spectroscopy with cold slit mask, MOIRCS contains many device components, which are distributed on an Ethernet LAN. Two PCs wired to the focal plane array electronics operate two HAWAII2 detectors, respectively, and other two PCs are used for integrated control and quick data reduction, respectively. Though most of the devices (e.g., filter and grism turrets, slit exchange mechanism for spectroscopy) are controlled via RS232C interface, they are accessible from TCP/IP connection using TCP/IP to RS232C converters. Moreover, other devices are also connected to the Ethernet LAN. This network distributed structure provides flexibility of hardware configuration. We have constructed an integrated control system for such network distributed hardwares, named T-LECS (Tohoku University - Layered Electronic Control System). T-LECS has also network distributed software design, applying TCP/IP socket communication to interprocess communication. In order to help the communication between the device interfaces and the user interfaces, we defined three layers in T-LECS; an external layer for user interface applications, an internal layer for device interface applications, and a communication layer, which connects two layers above. In the communication layer, we store the data of the system to an SQL database server; they are status data, FITS header data, and also meta data such as device configuration data and FITS configuration data. We present our software system design and the database schema to manage observations of MOIRCS with Subaru.
TUFPAC (Tohoku University Focal Plane Array Controller) is an array control system originally designed for flexible control and efficient data acquisition of 2048 x 2048 HgCdTe (HAWAII-2) array. A personal computer operated by Linux OS controls mosaic HAWAII-2s with commercially available DSP boards installed on the PCI bus. Triggered by PC, DSP sends clock data to front-end electronics, which is isolated from the DSP board by photo-couplers. Front-end electronics supply powers, biases and clock signals to HAWAII2. Pixel data are read from four outputs of each HAWAII2 simultaneously by way of four channel preamps and ADCs. Pixel data converted to 16 bit digital data are stored in the frame memory on the DSP board.
Data are processed in the memory when necessary. PC receives the frame data and stores it in the hard disk of PC in FITS format. A set of the DSP board and front-end electronics is responsible for controlling each HAWAII-2. One PC can operate eight mosaic arrays at most. TUFPAC is applicable to the control of CCDs with minor changes of front-end electronics.
We report on the results of the performance tests of the HAWAII-2 FPAs for Multi-Object Infra-Red Camera and Spectrograph (MOIRCS). MOIRCS provides wide-field imaging mode (4'x7' F.O.V.) and multi-object spectroscopy mode for the wavelength range from 0.85 to 2.5 μm. To achieve the wide field-of-view with the high angular resolution, we use two 2048 x 2048 HgCdTe FPAs, HAWAII-2. We have made performance tests of both the engineering-grade and the science-grade HAWAII-2 arrays. Array performances such as stability of bias frames, read noise and dark current are evaluated at the operating temperature of 78K. In addition, we search for the optimum well depth, readout speed by changing bias voltages. We have finished tests of the engineering-grade array and the performance of our science-grade arrays is under investigation.
MOIRCS (Multi-Object InfraRed Camera and Spectrograph) is one of the second generation instruments for the Subaru Telescope. This instrument is under construction by the National Astronomical Observatory of Japan and Tohoku University. It has imaging and multi-object spectroscopy (MOS) capabilities in the wavelength range from 0.85 μm to 2.5 μm with 4' x 7' F.O.V. The focal plane is imaged onto two 2048 x 2048 pixel HAWAII-2 HgCdTe arrays with a pixel scale of 0."12 pixel-1 through two independent optical trains. The optical design is optimized to maximize K band performance. Unique design of MOIRCS allows multi-object spectroscopy out to K band with cooled multi-slit masks. Twenty-four masks are stored in a mask dewar and are exchanged in the cryogenic environment. The mask dewar has its own vacuum pump and cryogenic cooler, and the masks can be assessed without breaking the vacuum of the main dewar. The two-channel optics and arrays are mounted back-to-back of a single optical bench plate. A PC-Linux based infrared array control system has been prepared to operate HAWAII-2. The first light of MOIRCS is planned in the spring of 2003.
We use the HAWAII-2 (2048 × 2048 HgCdTe) FPAs in MOIRCS (Multi-Object Infra-Red Camera and Spectrograph) for the astronomical use on the Subaru telescope. MOIRCS, which is currently being constructed by Tohoku University and the National Astronomical Observatory of Japan, is one of the second generation instruments for Subaru. It will provide the wide-field imaging mode (4 × 7 arcmin2) and the multi-object spectroscopy mode with the wavelength range of 0.8 to 2.5 μm.
To achieve the large field of view with the high spatial resolution, we use two large-format near-infrared arrays, HAWAII-2. We have developed an infrared array control system specially designed for flexible control and efficient data acquisition of the HAWAII-2 arrays. The array control system, TUFPAC, consists of a personal computer operated by LINUX OS and commercially available DSP boards. By using TUFPAC and the cryostat for array tests, we have made tests of the HAWAII-2 array. In this paper, we report on our array control system and the results of various performance tests for the HAWAII-2 array.