Astronomical polarimetric observation is one of the important methods in modern astrophysics research field. In the infrared bands, polarimetric observation is one effective tool to study the evolution and formation of star, and reveal multiband radiation characteristics of high-energy celestial bodies and other aspects. This paper will introduce the system composition, operating principle, calibration and data analysis method of polarimetric observation using HONIR camera on Kanata telescope. We also present part of the analysis results of AA Tau with polarimetric observation, which is one young classical T Tauri star.
The HiZ-GUNDAM (high-z Gamma-ray bursts for UNraveling the Dark Ages Mission) is a time-domain and multi-messenger astronomy mission by monitoring high-energy astronomical transient events such as gamma-ray bursts (GRBs). The HiZ-GUNDAM is designed to provide alerts of high-redshift GRBs with an ultra-wide field X-ray monitor and a co-onboard 30-cm telescope for immediate photometric follow-up observations in the visible and near-infrared. The HiZ-GUNDAM satellite automatically changes its attitude toward the discovered transient object, starts the follow-up observations with the telescope, and sends alert information including the detailed position, the apparent magnitude and photometric redshift of the transient object within one hour. This mission was selected as one of the mission concept candidates of the competitively-chosen medium-class mission of ISAS/JAXA in the mid-2020s. The basic design of the breadboard model of the telescope is undergoing, and the verification plan of it is studied. The optics are cooled down to 200 K by radiation cooling, and infrared detectors are additionally cooled down to 120 K by a mechanical cooler. All mirrors in the telescope are made of the same aluminum-alloy to reduce the alignment errors during cooling. The four-band simultaneous observation is realized by three beam splitters. The HgCdTe and HyViSi detectors are installed in this telescope. Basic technologies for these specifications are demonstrated by our other missions. In addition, the onboard detection algorithm of high-redshift GRBs by distinguishing them from nearby dusty galaxies in the orbit is also studied. In this paper, we introduce the current status of the development of the telescope onboard HiZ-GUNDAM.
We describe a development and performance evaluations for Mulit-wavelength SimultaneouS High throughput Imager and polarimeter called as ”MuSaSHI”. The science drivers are high-precision muticolor photometric stud- ies of time-variable astronomical phenomena such as variable stars, transiting planets and asteroids. MuSaSHI is designed to be mounted on the SaCRA telescope at Saitama University, dedicated for relatively wide ﬁeld imaging and polarimetry in the three optical bands (r: 550 to 680 nm, i: 700 to 810 nm, z: 820 to 1000 nm) . The instrument is equipped with three Back-Illuminated thinned e2v CCDs which provide simultaneous r, i, z images having a ﬁeld of view of 12.8 x 12.4 arcmin with a pixel scale of 0.73 arcsec. The optical system of MuSaSHI is composed of only two dichroic mirrors and three bandpass ﬁlters without lens, so that the total throughput is high especially at z band (~ 50%). In addition, the optics of MuSaSHI is designed for fast telescopes (F ~ 6.5) and with portability in mind so that it is able to be mounted on a larger aperture telescope with slower beam. The limiting magnitudes with 60 sec integration (10σ) are rlim = 16.8, ilim = 17.1, and zlim = 17.2 mag. We demonstrate relative photometric precisions of < 0.1 % in the all bands for a K0 V star WASP-84 which hosts a transiting planet with 30s exposure observations.
We have developed a photo-sensor for an optical photon counting imager for astronomy with high timing resolution. We customize a Multi Pixel Photon Counter as a monolithic Geiger avalanche photodiode array with a pixel size of 100 micro-meter. The prototype model consists of 4x4 pixels. Excellent timing response is achieved as fast as an order of nanosecond. We evaluate the basic performance of the sensor and confirm the gain linearity, uniformity and low dark count rates. We observe the Crab pulsar using this system with a 35-cm telescope, and successfully detected periodic pulses with a frequency consistent with that reported by radio observatory.
HiZ-GUNDAM is a future satellite mission which will lead the time-domain astronomy and the multi-messenger astronomy through observations of high-energy transient phenomena. A mission concept of HiZ-GUNDAM was approved by ISAS/JAXA, and it is one of the future satellite candidates of JAXA’s medium-class mission. We are in pre-phase A (before pre-project) and elaborating the mission concept, mission/system requirements for the launch in the late 2020s. The main themes of HiZ-GUNDAM mission are (1) exploration of the early universe with high-redshift gamma-ray bursts, and (2) contribution to the multi-messenger astronomy. HiZ-GUNDAM has two kinds of mission payload. The wide field X-ray monitors consist of Lobster Eye optics array and focal imaging sensor, and monitor ~1 steradian field of view in 0.5 – 4 keV energy range. The near infrared telescope has an aperture size 30 cm in diameter, and simultaneously observes four wavelength bands between 0.5 – 2.5 μm. In this paper, we introduce the mission overview of HiZ-GUNDAM.
We describe the Kottamia Faint Imaging Spectro-Polarimeter (KFISP) that has been recently developed and designed to be mounted to the Cassegrain focus of the 1.88m telescope at Kottamia Astronomical Observatory (KAO), Egypt. The optical design of KFISP is developed such that it can be used in various modes of operation. These are: direct imaging, spectroscopic (low and medium resolution), polarimetric imaging, and spectro-polarimetric. The KFISP is an all-refractive design to meet the polarimetric requirements and includes a focal reducer with a corrector section, collimator section, parallel beam section (containing various imaging components), and camera section. The corrector section gives an unvignetted Field-of-View (FoV) of 8ʹ × 8ʹ and the collimator section has a focal length of 305 mm and matches the focal ratio of the input beam. The parallel beam section is 200 mm long and near the middle of it there is an image of the telescope pupil. The camera section includes 5 elements and has a focal length of 154.51 mm which gives an instrument effective final focal ratio of f/6.14 (acting as a telescope focal reducer of 1:2 ratio). The KFISP contains an internal calibration system which hosts the calibration light injection system, an integrating sphere equipped with the required calibration light sources. The opto-mechanical parts of KFISP contain double-layered carbon fiber strut structure and comprises its subsystems of slit and guider assemblies, filter wheel drawer, grism wheel drawer, polarimetric components cubical box, and CCD camera which is integrated with camera optics. The KFISP has been fully commissioned, mounted and is being tested in all modes of operation. In this paper we introduce the ambitious scientific goals, the optical setups of KFISP, its opto-mechanical implementation and the performance analysis of the instrument. In addition, we will present sample of the first light observations obtained from the instrument.
We have developed an optical and near-infrared instrument HONIR (Hiroshima Optical and Near-InfraRed
camera) with imaging, spectroscopy, and polarimetry capabilities in two (one optical and one near-infrared)
bands simultaneously. Imaging capability with a field of view of 10 arcmin by 10 arcmin has been available
since 2011, as reported in the previous SPIE conference. In addition, spectroscopic and polarimetric optical
components (grisms, an Wollaston prism, a half-wave plate, and focal masks) were installed in the instrument,
which enabled us to perform spectroscopy and linear polarization measurement by imaging polarimetry and
spectro-polarimetry. Spectral resolution of R = λ/(triangle)λ ~ 440 - 800 is achieved in spectroscopy using a slit
mask with an 1".3 width. In polarimetry, instrumental polarization is less than ~0.05 % with stability of
better than ~0.05 %, which is sufficiently small to achieve an aimed accuracy of polarization measurement
of ~0.1 % at primal observing wavelengths.
We developed a new readout system for the near-infrared detector VIRGO-2K (2kx2k HgCdTe array) installed in the optical-infrared simultaneous camera, HONIR, for the 1.5 m Kanata telescope at Higashi-Hiroshima observatory. The main goal of this development is to read out one frame within ~ 1 second through 16 output readout mode of the detector, in order to reduce the overhead time per exposure. The system is based on a CCD controller, Kiso Array Controller (KAC). We redesigned the analog part of KAC to ﬁt VIRGO-2K. We employed a fully diﬀerential input circuit and a third order Bessel low-pass ﬁlter for noise reduction and a constant current system to improve the linearity of the detector. We set the cutoﬀ frequency of the Bessel low-pass ﬁlter at the readout clock rate (120 kHz). We also set the constant current at 200 μA according to the data sheet of VIRGO-2K. We tested the new readout system at room temperature and conﬁrmed that the low-pass ﬁlter works well as designed. The ﬂuctuation of the current level of the constant current system is less than 2% for the typical output voltage range of VIRGO-2K (3.2-4.4 V). We measured the readout noise caused by the new readout system (connected to cooled multiplexer) and found that it is 30-40 μV rms, being comparable to or slightly higher than the typical readout noise of VIRGO-2K, ∼ 37 μV rms.
We have developed an optical-infrared instrument HONIR (Hiroshima Optical and Near-InfraRed camera) to be attached to the 1.5-m Kanata telescope at Higashi-Hiroshima Observatory, Hiroshima University. HONIR is a three color (one optical and two near-infrared bands among 0.5–2.4 µm) simultaneous imager and spectrograph with a polarimetry function. The field of view of the imaging mode is 10 arcmin square with a spatial sampling of 0".29. Among the planned multipurpose functions, a two color (0.5–1.0 µm and 1.15–2.40 µm) simultaneous imaging function has been installed and operated so far. The remaining functions, spectroscopy and polarimetry, and the second near-infrared band arm, are under development and will be installed in the near future.
The Thirty Meter Telescope (TMT) is a next-generation optical/infrared telescope to be constructed on Mauna Kea,
Hawaii toward the end of this decade, as an international project. Its 30 m primary mirror consists of 492 off-axis
aspheric segmented mirrors. This paper describes the progress of the test fabrication of an outermost mirror segment for
the TMT as a joint R&D program between National Astronomical Observatory and Canon. A zero-expansion glass
CLEARCERAM™ blank was polished by a computer-controlled small-tool polishing machine (CSSP, Canon) and its
surface shape was measured by a touch-probe measuring machine(A-Ruler, Canon). Residuals of lower Zernike terms of
the surface shape were 11 nmRMS, clearing the original specifications based on the structure function. There remains,
however, a need to fulfill latest revised specifications. Possible solutions to improve and achieve the new specifications
and a plan for revising the process for mass production are also described.
We evaluated depth of subsurface damage on a ground surface of the ultra low expansion glass-ceramics
CLEARCERAMR®-Z HS (CC-Z HS) by Ohara Inc., which is one of the candidates for material for segmented
mirrors of the Thirty Meter Telescope. We made polishing spots of Magnetorheological Finishing on the
ground surface of CC-Z HS and measured exposed subsurface damage features on the spot surface. We also
studied on hydrofluoric acid etching of the CC-Z HS ground surface, which is expected to be an effective
method to remove a subsurface damage layer compared with time-consuming polishing. We etched small
ground surfaces of CC-Z HS and evaluated its uniformity.
We developed an aspheric convex 33-cm diameter secondary mirror of the Hiroshima University 1.5-m Ritchy-Chretien telescope using Zero-expansion Pore-free ceramics, which has physical properties (thermal expansion,
stiffness, thermal conductance, etc.) comparable with or better than existing zero-expansion glasses. After
high-precision grinding, polishing, and coating aluminum and silicon monoxide, we obtained the sufficient
optical reflecting surface with a figure error within λ/10 and a roughness of about 3 nm rms. The mirror has
been attached on the telescope and we confirmed its sufficient performance through a Hartmann test. To date
it has shown a good performance in our application and we suggest that this ceramic material has a potential
to be used for astronomical telescopes and related area.
We are developing a Cassegrain optical spectropolarimeter, LIPS.
LIPS employs an echelle-type spectrograph to get a high spectral
resolution of R > 7,000. LIPS consists of three instrumental units, a polarimeter, a spectrometer, and a detector. One serious problem was the appearance of 'spectral ripple' generated in the Pancharatnam type super-achromatic half-wave plate (PWP). We found out through laboratory works and numerical simulations that the ripple is caused by the interference among layers in the half-wave plate. In stead of PWP, we adopted a new type of super-achromatic half-wave plate composed of five polymethyl-methacrylate layers, which was manufactured by Astropribor Company in Ukraine. This wave plate greatly reduces reflection at the boundaries among layers, which results in significant reduction of ripple. Since the spring of 2001, we have carried out engineering observations with LIPS at IRS and UH88. We conclude from these observations that LIPS have achieved the accuracy of ΔP < 0.1 %.