Proc. SPIE. 9143, Space Telescopes and Instrumentation 2014: Optical, Infrared, and Millimeter Wave
KEYWORDS: Point spread functions, Stars, Data modeling, Calibration, Satellites, Error analysis, Image analysis, Charge-coupled devices, Surface conduction electron emitter displays, Picture Archiving and Communication System
The Nano-JASMINE mission has been designed to perform absolute astrometric measurements with unprecedented accuracy; the end-of-mission parallax standard error is required to be of the order of 3 milli arc seconds for stars brighter than 7.5 mag in the zw-band(0.6μm-1.0μm) .These requirements set a stringent constraint on the accuracy of the estimation of the location of the stellar image on the CCD for each observation. However each stellar images have individual shape depend on the spectral energy distribution of the star, the CCD properties, and the optics and its associated wave front errors. So it is necessity that the centroiding algorithm performs a high accuracy in any observables. Referring to the study of Gaia, we use LSF fitting method for centroiding algorithm, and investigate systematic error of the algorithm for Nano-JASMINE. Furthermore, we found to improve the algorithm by restricting sample LSF when we use a Principle Component Analysis. We show that centroiding algorithm error decrease after adapted the method.
Small-JASMINE program (Japan Astrometry Satellite Mission for INfrared Exploration) is one of applicants for JAXA (Japan Aerospace Exploration Agency) space science missions launched by Epsilon Launch Vehicles, and now being reviewed in the Science Committee of ISAS (Institute of Space and Astronautical Science), JAXA. Telescope of 300 mm aperture diameter will focus to the central region of the Milky Way Galactic. The target of Small-JASMINE is to obtain reliable measurements of extremely small stellar motions with the highest accuracy of 10 μ arcseconds and to provide precise distances and velocities of multitudes of stars up to 30,000 light years. Preliminary Structure design of Small- JASMINE has been done and indicates to satisfy all of requirements from the mission requirement, the system requirement, Epsilon Launch conditions and interfaces of the small science satellite standard bus. High margin of weight for the mission allows using all super invar structure that may reduce unforeseen thermal distortion risk especially caused by connection of different materials. Thermal stability of the telescope is a key issue and should be verified in a real model at early stage of the development.
We describe the measurement of detailed and precise Pixel Response Functions (PRFs) of a fully depleted CCD. Measurements were performed under different physical conditions, such as different wavelength light sources or CCD operating temperatures. We determined the relations between these physical conditions and the forms of the PRF. We employ two types of PRFs: one is the model PRF (mPRF) that can represent the shape of a PRF with one characteristic parameter and the other is the simulated PRF (sPRF) that is the resultant PRF from simulating physical phenomena. By using measured, model, and simulated PRFs, we determined the relations between operational parameters and the PRFs. Using the obtained relations, we can now estimate a PRF under conditions that will be encountered during the course of Nano-JASMINE observations. These estimated PRFs will be utilized in the analysis of the Nano-JASMINE data.
Nano-JASMINE (NJ) is a very small astrometry satellite project led by the National Astronomical Observatory
of Japan. The satellite is ready for launch, and the launch is currently scheduled for late 2013 or early 2014.
The satellite is equipped with a fully depleted CCD and is expected to perform astrometry observations for stars
brighter than 9 mag in the zw-band (0.6 µm–1.0 µm). Distances of stars located within 100 pc of the Sun can
be determined by using annual parallax measurements. The targeted accuracy for the position determination of
stars brighter than 7.5 mag is 3 mas, which is equivalent to measuring the positions of stars with an accuracy
of less than one five-hundredth of the CCD pixel size. The position measurements of stars are performed by
centroiding the stellar images taken by the CCD that operates in the time and delay integration mode. The
degradation of charge transfer performance due to cosmic radiation damage in orbit is proved experimentally.
A method is then required to compensate for the effects of performance degradation. One of the most effective
ways of achieving this is to simulate observed stellar outputs, including the effect of CCD degradation, and then
formulate our centroiding algorithm and evaluate the accuracies of the measurements. We report here the planned
procedure to simulate the outputs of the NJ observations. We also developed a CCD performance-measuring
system and present preliminary results obtained using the system.
The current status of the Nano-JASMINE project is reported. Nano-JASMINE is a very small-sized (50 cm
cubic form) satellite that is expected to carry out astrometric observations of nearby bright stars. The satellite
will determine distances of more than 8000 stars by performing annual parallax measurements, which is the only
direct method to measure the distance of an astronomical object. The mission is required to continue for more
than two years to obtain reliable annual parallax measurements. In addition, Nano-JASMINE will serve as a
preliminary to the main JASMINE mission. We expect that Nano-JASMINE will be launched in August 2011
from the Alcantara Space Center in Brazil using the Cyclone-4 rocket.
Nano-JASMINE is a very small satellite mission for global space astrometry with milli-arcsecond accuracy, which
will be launched in 2011. In this mission, centroids of stars in CCD image frames are estimated with sub-pixel
accuracy. In order to realize such a high precision centroiding an algorithm utilizing a least square method is
employed. One of the advantages is that centroids can be calculated without explicit assumption of the point
spread functions of stars. CCD centroiding experiment has been performed to investigate whether this data
analysis is available, and centroids of artificial star images on a CCD are determined with a precision of less than
0.001 pixel. This result indicates parallaxes of stars within 300 pc from Sun can be observed in Nano-JASMINE.
The telescope geometry of JASMINE should be stabilized and monitored with the accuracy of about 10 to 100
picometer or 10 to 100 picoradian in root-mean-square over about 10 hours. For this purpose, a high-precision
interferometric laser metrology system is employed. One of useful techniques for measuring displacements in
extremely minute scales is the heterodyne interferometrical method. Experiment for verification of multi degree
of freedom measurement was performed and mirror motions were successfully monitored with three degree of
The JASMINE instrument uses a beam combiner to observe two different fields of view separated by 99.5
degrees simultaneously. This angle is so-called basic angle. The basic angle of JASMINE should be stabilized
and fluctuations of the basic angle should be monitored with the accuracy of 10 microarcsec in root-mean-square
over the satellite revolution period of 5 hours. For this purpose, a high-precision interferometric laser metrogy
system is employed. One of the available techniques for measuring the fluctuations of the basic angle is a method
known as the wave front sensing using a Fabry-Perot type laser interferometer. This technique is to detect
fluctuations of the basic angle as displacement of optical axis in the Fabry-Perot cavity. One of the advantages
of the technique is that the sensor is made to be sensitive only to the relative fluctuations of the basic angle
which the JASMINE wants to know and to be insensitive to the common one; in order to make the optical axis
displacement caused by relative motion enhanced the Fabry-Perot cavity is formed by two mirrors which have
long radius of curvature. To verify the principle of this idea, the experiment was performed using a 0.1m-length
Fabry-Perot cavity with the mirror curvature of 20m. The mirrors of the cavity were artificially actuated in
either relative way or common way and the resultant outputs from the sensor were compared.
JASMINE and ILOM are space missions which are in progress at the National Astronomical Observatory of Japan. These two projects need a common astrometric technique to obtain precise positions of star images on solid state detectors to accomplish the objectives. We have carried out measurements of centroid of artificial star images on a CCD to investigate the accuracy of the positions of the stars, using an algorithm for estimating them from photon weighted means of the stars. We find that the accuracy of the star positions reaches 1/300 pixel for one measurement. We also measure positions of stars, using an algorithm for correcting the distorted optical image. Finally, we find that the accuracy of the measurement for the positions of the stars from the strongly distorted image is under 1/150 pixel for one measurement.
We report an outline and a current status of developing a small, all-aluminum made telescope for Nano-JASMINE.
Nano-JASMINE is a nano-size astrometry satellite that will demonstrate some key technologies required for
JASMINE (Japan Astrometry Satellite Mission for Infrared Exploration) in a real space environment and will
measure absolute positions of bright stars (z ≤ 8 mag) with accuracies about 1 milli-arcsecond in a few years
mission. It has a Ritchey-Chretien type telescope with a 5-cm effective aperture, a 167-cm focal length and a field
of view of 0.5x0.5 degree. The telescope only occupies a volume about 15x12x12 cm, and weighs two kilograms
or less. Almost all of the structures and the optical elements of the telescope, including two aspherical mirrors
three flat mirrors and a dual-angled flat mirror that combines the beam from a relative angle of 99.5 degrees into
the primary mirror, are made out of aluminum alloy, being figured by diamond turning machines. The Bread
Board Model (BBM) of the telescope was now measured to be achieving a diffraction-limited performance at
We introduce a Japanese plan of infrared(z-band:0.9μm) space astrometry(JASMINE-project). JASMINE is
the satellite (Japan Astrometry Satellite Mission for INfrared Exploration) which will measure distances and
apparent motions of stars around the center of the Milky Way with yet unprecedented precision. It will measure
parallaxes, positions with the accuracy of 10 micro-arcsec and proper motions with the accuracy of ~ 4microarcsec/
year for stars brighter than z=14mag. JASMINE can observe about ten million stars belonging to the
bulge components of our Galaxy, which are hidden by the interstellar dust extinction in optical bands. Number of
stars with σ/π < 0.1 in the direction of the Galactic central bulge is about 1000 times larger than those observed
in optical bands, where π is a parallax and σ is an error of the parallax. With the completely new "map of the
bulge in the Milky Way", it is expected that many new exciting scientific results will be obtained in various fields
of astronomy. Presently, JASMINE is in a development phase, with a target launch date around 2015. We adopt
the following instrument design of JASMINE in order to get the accurate positions of many stars. A 3-mirrors
optical system(modified Korsch system)with a primary mirror of~
0.85m is one of the candidate for the optical
system. On the astro-focal plane, we put dozens of new type of CCDs for z-band to get a wide field of view. The
accurate measurements of the astrometric parameters requires the instrument line-of-sight highly stability and
the opto-mechanical highly stability of the payload in the JASMINE spacecraft. The consideration of overall
system(bus) design is now going on in cooperation with Japan Aerospace Exploration Agency(JAXA).
We explain simulation tools in JASMINE project (JASMINE simulator). The JASMINE project stands at the stage where its basic design will be determined in a few years. Then it is very important to simulate the data stream generated by astrometric fields at JASMINE in order to support investigations into error budgets, sampling strategy, data compression, data analysis, scientific performances, etc. Of course, component simulations are needed, but total simulations which include all components from observation target to satellite system are also very important. We find that new software technologies, such as Object Oriented(OO) methodologies are ideal tools for the simulation system of JASMINE(the JASMINE simulator).
In this article, we explain the framework of the JASMINE simulator.
The current status of the nano-JASMINE project is presented. Nano-JASMINE - a very small satellite weighing
less than 10 kg - aims to carry out astrometry measurements of nearby bright stars. This satellite adopts
the same observation technique that was used by the HIPPARCOS satellite. In this technique, simultaneous
measurements in two different fields of view separated by an angle that is greater than 90° are carried out; these
measurements are performed in the course of continuous scanning observations of the entire sky. This technique
enables us to distinguish between an irregularity in the spin velocity and the distribution of stellar positions.
There is a major technical difference between the nano-JASMINE and the HIPPARCOS satellites-the utilization
of a CCD sensor in nano-JASMINE that makes it possible to achieve an astrometry accuracy comparable to that
achieved by HIPPARCOS by using an extremely small telescope.
We developed a prototype of the observation system and evaluated its performance. The telescope (5cm)
including a beam combiner composed entirely of aluminum. The telescope is based on the standard Ritchey-
Chretien optical system and has a composite f-ratio of 33 that enables the matching of the Airy disk size to three
times the CCD pixel size of 15μm. A full depletion CCD will be used in the time delay integration (TDI) mode
in order to efficiently survey the whole sky in wavelengths including the near infrared.
The nano-JASMINE satellite is being developed as a piggyback system and is hoped for launch in 2008. We
expect the satellite to measure the position and proper motion of bright stars (m<sub>z</sub> < 8.3) with an accuracy of 1
mas, this is comparable to the accuracy achieved with the HIPPARCOS satellite.
We introduce a Japanese future plan of the IR space astrometry(JASMINE-project). JASMINE is an infrared(K-band) scanning astrometric satellite. JASMINE(I and/or II-project) is planned to be launched between 2013 and 2015 and will measure parallaxes, positions and proper motions with the precision of 10 microarcsec at K=12~14mag. JASMINE can observe about a few hundred million stars belonging to the disk and the bulge components of our Galaxy, which are hidden by the interstellar dust extinction in optical bands. Furthermore JASMINE will also measure the photometries of stars in K, J and H-bands. The main objective of JASMINE is to study the fundamental structure and evolution of the disk and the bulge components of the Milky Way Galaxy. Furthermore its important objective is to investigate stellar physics.
The optimum excitation conditions for pulsed CO<SUB>2</SUB> laser oscillation excited by microwaves are investigated to achieve oscillation with a short pulse width at a high repetition rate. The excitation conditions are optimized as follows; (1) by evaluating the decay time of excited N<SUB>2</SUB> molecule population density to optimize the gas mixture, and (2) by evaluating the discharge stability and the laser output waveform to optimize the magnetron drive conditions. We have developed a new coaxial fast gas flow pulsed CO<SUB>2</SUB> laser oscillator excited by microwaves, which produces pulses output with a rise time of less than 5 microsecond(s) ec rise-time and a 1/e- fall time of 30 microsecond(s) ec at a maximum repetition rate of 5 kHz. It is also possible to modulate the output power and the pulse waveform at high speed. The oscillator is currently being tested for application to a laser drilling system for printed wired boards.