• Journal of Astronomy and Space Sciences
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• 제18권2호
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• pp.145-152
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• 2001

태양의 극자외선 복사를 연구하기 위한 인공위성 탑재용 소형 극자외선 태양망원경의 공학 모형을 설계하였다. 극자외선 태양망원경은 $584.3AA$(He I)과 $629.7AA$(OV)의 두 파장대역에서 태양을 관측하기 위한 목적으로 설계되었다. 광학계는 Ritchey-Chr 샤두 방식이고, 망원경의 유효구경과 유효 초점 거리는 각각 80mm, 640mm이다. 회전 필터 휠을 사용하여 He I과 OV 방출선을 관측할 수 있도록 하였다. 검출기의 MCP (Microchannel Plate)는 채널 길이 대 직경의 비가 40:1인 Z-stack 타입이고, photocathode로서 KBr이 MCP 초점면에 코팅되며, MCP와 CCD는 fiber optic taper로 연결되도록 디자인하였다. 광학계 설계에 대한 분석은 광학계산용 상용 소프트웨어를 이용하였다.

• 천문학회보
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• 제42권2호
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• pp.78.1-78.1
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• 2017

We present a noble method to determine BH mass of many AGNs directly through reverberation mapping using a small telescope with wide-field of view. In 2017 August we installed five medium-band filters to a 0.25m diameter $5deg^2$ FOV telescope at the McDonald observatory. The width of these filters (FWHM ~ 50nm) are matched to the broad line width of type-1 AGNs at various redshifts. From recently obtained data, about r ~ 19 magnitude AGNs can be detected in line component with 150s exposure. With this magnitude limit, about 20~30 AGNs can be studied in one field. We plan to carry out at one day cadence observation over 20~30 fields, enabling us to monitor up to ~1000 AGNs over a wide range of variability. This poster presents out plan and early results from test observation.

• Journal of the Optical Society of Korea
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• 제13권2호
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• pp.178-183
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• 2009

At the time that the Keck-I 10m telescope was constructed in 1993, the era of Very Large Telescopes (VLTs) was opened. Now thirteen VLTs are in operation, and the largest of the monolithic mirrors is 8.4 m in diameter. Such monolithic mirrors are mostly aspheric and require high accuracies on the surface figures, reaching up to the diffraction limit. At present, next generation telescopes, Giant telescopes, are being developed. One is the GMT (Giant Magellan Telescope) whose size is 25.4 m in diameter. The primary mirror consists of seven segments figuring elliptical shapes on the surface. The surrounding six segments are off-axis and the edges are steep, as the fast focal ratio is adopted. It means that testing of the mirrors is a challenging task. In this paper, testing methods for the GMT primary mirror are reviewed, and accuracy of measuring devices is assessed. Results and discussions follow.

• 천문학회보
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• 제42권1호
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• pp.57.2-57.2
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• 2017

Remote and robotic telescopes are the most effective instrument for astronomical survey projects. The system is based on the dynamic operation of all astronomical instruments such as dome and telescope control system (TCS), focuser, filter wheel and data taking camera. We adopt the ASCOM driver platform to control the instruments through the integrated software. It can convert different interface libraries from various manufacturers into a uniform standard library. This allows us to effectively control astronomical instruments without modifying codes. We suggest a conceptual design of software for automation of a small telescope such as the new wide-field 0.25m telescope at McDonald Observatory. It can also be applied to operation of multi-telescopes in future projects.

• Journal of Astronomy and Space Sciences
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• 제27권2호
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• pp.153-160
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• 2010

We modified the optical system of 500 mm wide-field telescope of which point spread function showed an irregularity. The telescope has been operated for Near Earth Space Survey (NESS) located at Siding Spring Observatory (SSO) in Australia, and the optical system was brought back to Korea in January 2008. After performing a numerical simulation with the tested value of surface figure error of the primary mirror using optical design program, we found that the surface figure error of the mirror should be fabricated less than root mean square (RMS) $\lambda$/10 in order to obtain a stellar full width at half maximum (FWHM) below $28\;{\mu}m$. However, we started to figure the mirror for the target value of RMS $\lambda$/20, because system surface figure error would be increased by the error induced by the optical axis adjustment, mirror cell installation, and others. The radius of curvature of the primary mirror was 1,946 mm after the correction. Its measured surface figure error was less than RMS $\lambda$/20 on the table of polishing machine, and RMS $\lambda$/15 after installation in the primary mirror cell. A test observation performed at Daeduk Observatory at Korea Astronomy and Space Science Institute by utilizing the exiting mount, and resulted in $39.8\;{\mu}m$ of stellar FWHM. It was larger than the value from numerical simulation, and showed wing-shaped stellar image. It turned out that the measured-curvature of the secondary mirror, 1,820 mm, was not the same as the designed one, 1,795.977 mm. We fabricated the secondary mirror to the designed value, and finally obtained a stellar FWHM of $27\;{\mu}m$ after re-installation of the optical system into SSO NESS Observatory in Australia.

• 천문학회보
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• 제32권1호
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• pp.24.1-24.1
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• 2007

• 천문학회보
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• 제34권1호
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• pp.120.2-120.2
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• 2009

• Journal of the Optical Society of Korea
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• 제16권3호
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• pp.243-246
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• 2012

An off-axis four-mirror-anastigmatic telescope is presented here which is composed of two aspheric surfaces and two spherical surfaces. The entrance pupil diameter is 290 mm and the stop is located at the primary mirror. The effective focal length is 900 mm. The strip field of view for the telescope is $15^{\circ}{\times}0.2^{\circ}$ and if the telescope is launched into an orbit about 400 km altitude, the observed range width will be more than 105 km within a scene without any other auxiliary scanning instrument. The spectral range can be as wide as from visual wave band to infrared wave band in the mirror system. This telescope can be used for environmental monitoring with different detectors whose pixel is adapted to the optical resolution. In this paper, the spectral range is chosen as 3.0 -5.0 ${\mu}m$, and center distance of the pixel is 30 ${\mu}m$. And the image quality is near the diffraction limit.

• 천문학논총
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• 제32권1호
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• pp.331-335
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• 2017

We present project updates of the next-generation infrared space mission SPICA (Space Infrared Telescope for Cosmology and Astrophysics) as of November 2015. SPICA is optimized for mid- and far-infrared astronomy with unprecedented sensitivity, which will be achieved with a cryogenically cooled (below 8 K), large (2.5 m) telescope. SPICA is expected to address a number of key questions in various fields of astrophysics, ranging from studies of the star-formation history in the universe to the formation and evolution of planetary systems. The international collaboration framework of SPICA has been revisited. SPICA under the new framework passed the Mission Definition Review by JAXA in 2015. A proposal under the new framework to ESA is being prepared. The target launch year in the new framework is 2027/28.

• 천문학회보
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• 제36권2호
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• pp.93.2-93.2
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• 2011

Japan Aerospace Exploration Agency (JAXA) has measured space environment and its effects on spacecraft and astronaut since 1987. At present, we have operated space environment monitors onboard one GEO spacecraft, one QZO spacecraft, and two LEO spacecrafts. The obtained space environment data has been gathered into the Space Environment and Effects System database (SEES, http://sees.tksc.jaxa.jp/). In this presentation, measurement result of space environment in low earth orbit obtained by the Daichi satellite from 2006 through 2011 is reported as well as recent activities in space environment engineerings in JAXA. The Technical Data Acquisition Equipment (TEDA) on board the Daichi satellite (Advanced Land Observing Satellite: ALOS) had been operated in low earth orbit at 700 km altitude with 98 degree inclination from February 2006 until April 2011. The TEDA consists of the Light Particle Telescope and the Heavy Ion Telescope. The operation period of the Daichi satellite was through the solar-activity minimum period. The space radiation environment around the Daichi satellite had been almost stable. However, large solar flares followed by CMEs sometimes disturbed the space radiation environment in the orbit of the Daichi satellite. In addition, high speed solar wind often flowed and modulated the electron flux in the horn region. On the other hand, a little variation was seen in the SAA region.