Four Oke-Gunn (OG) standards, HD 19445, HD 84937, BD+26 2606 and BD+17 4708 are used as standard stars for flux calibration in the BATC project. They are also widely used in the visual wavelength region in many other ...Four Oke-Gunn (OG) standards, HD 19445, HD 84937, BD+26 2606 and BD+17 4708 are used as standard stars for flux calibration in the BATC project. They are also widely used in the visual wavelength region in many other photometric projects. Over the years we have observed on 58 good photometric nights, and the data obtained are used for flux calibration. Normally two or three OG standards are observed in every photometric night. The data are used for getting the atmospheric extinction coefficients and instrumental magnitude zero point. We also use these data to make inter-comparisons among the magnitudes of these standard stars. As a result, we found the magnitudes of HD 19445, HD 84937 and BD+17 4708 to agree well with those estimated in previous work to within 0.03 magnitude. However, BD+26 2606 shows a larger deviation especially at short wavebands. Possible reasons are analyzed and the revised magnitudes are obtained for these standards. It is shown that the quality of flux calibration of the BATC fields is significantly approved by applying the new magnitudes.展开更多
SimWall is a user-friendly, stereo tiled display wall system composed of 18 commodity projectors operated by a Linux graphics cluster. Collaborating together, these projectors work as a single logical display capable ...SimWall is a user-friendly, stereo tiled display wall system composed of 18 commodity projectors operated by a Linux graphics cluster. Collaborating together, these projectors work as a single logical display capable of giving a high-resolution show, large-scale, and passive stereo scene. In order to avoid tedious system setup and maintenance, software-based automatic geometry and photometric calibration are used. The software calibration is integrated to the system seamlessly by an on-card transform method and is transparent to users. To end-users, SimWall works just as a common PC, but provides super computing, rendering and displaying ability. In addition, SimWall has stereoscopic function that gives users a semi-immersive experience in polarized passive way. This paper presents system architecture, implementation, and other technical issues such as hardware constraints, projectors alignment, geometry and photometric calibration, implementation of passive stereo, and development of overall soft- ware environment.展开更多
文摘Four Oke-Gunn (OG) standards, HD 19445, HD 84937, BD+26 2606 and BD+17 4708 are used as standard stars for flux calibration in the BATC project. They are also widely used in the visual wavelength region in many other photometric projects. Over the years we have observed on 58 good photometric nights, and the data obtained are used for flux calibration. Normally two or three OG standards are observed in every photometric night. The data are used for getting the atmospheric extinction coefficients and instrumental magnitude zero point. We also use these data to make inter-comparisons among the magnitudes of these standard stars. As a result, we found the magnitudes of HD 19445, HD 84937 and BD+17 4708 to agree well with those estimated in previous work to within 0.03 magnitude. However, BD+26 2606 shows a larger deviation especially at short wavebands. Possible reasons are analyzed and the revised magnitudes are obtained for these standards. It is shown that the quality of flux calibration of the BATC fields is significantly approved by applying the new magnitudes.
基金Project supported by the National Natural Science Foundation of China for Distinguished Young Scholars (No. 60225009)the Major Research Plan of China (No. 90405003)
文摘SimWall is a user-friendly, stereo tiled display wall system composed of 18 commodity projectors operated by a Linux graphics cluster. Collaborating together, these projectors work as a single logical display capable of giving a high-resolution show, large-scale, and passive stereo scene. In order to avoid tedious system setup and maintenance, software-based automatic geometry and photometric calibration are used. The software calibration is integrated to the system seamlessly by an on-card transform method and is transparent to users. To end-users, SimWall works just as a common PC, but provides super computing, rendering and displaying ability. In addition, SimWall has stereoscopic function that gives users a semi-immersive experience in polarized passive way. This paper presents system architecture, implementation, and other technical issues such as hardware constraints, projectors alignment, geometry and photometric calibration, implementation of passive stereo, and development of overall soft- ware environment.
