The 85-cm telescope at Xinglong station is a prime focus system that operates well with high science outputs. The telescope has been upgraded since 2014 with a new corrector, and new filters and camera, which are prov...The 85-cm telescope at Xinglong station is a prime focus system that operates well with high science outputs. The telescope has been upgraded since 2014 with a new corrector, and new filters and camera, which are provided by Beijing Normal University. The filter set is the Johnson-Cousins UBV RI system. We report the test results of the new system including bias, dark current, linearity, gain and readout noise of the CCD camera. Then we derive accurate instrumental calibration coefficients in UBV RI bands with Landolt standard stars during photometric nights. Finally, we give the limiting magnitudes with various exposure times and signal-to-noise ratios for observers as references.展开更多
A large ground-based optical/infrared telescope is being planned for a world-class astronomical site in China.The cloud-free night percentage is the primary meteorological consideration for evaluating candidate sites....A large ground-based optical/infrared telescope is being planned for a world-class astronomical site in China.The cloud-free night percentage is the primary meteorological consideration for evaluating candidate sites.The data from GMS and NOAA satellites and the MODIS instrument were utilized in this research,covering the period from 1996 to 2015.Our data analysis benefits from overlapping results from different independent teams as well as a uniform analysis of selected sites using GMS+NOAA data.Although significant ground-based monitoring is needed to validate these findings,we identify three different geographical regions with a high percentage of cloud-free conditions(~83%on average),which is slightly lower than at Mauna Kea and Cerro Armazones(~85%on average)and were chosen for the large international projects TMT and ELT respectively.Our study finds evidence that cloud distributions and the seasonal changes affected by the prevailing westerly winds and summer monsoons reduce the cloud cover in areas influenced by the westerlies.This is consistent with the expectations from climate change models and is suggestive that most of the identified sites will have reduced cloud cover in the future.展开更多
The Large Optical/infrared Telescope(LOT)is a ground-based 12 m diameter optical/infrared telescope,which is proposed to be built in the western part of China in the next decade.To select the best site which satisfies...The Large Optical/infrared Telescope(LOT)is a ground-based 12 m diameter optical/infrared telescope,which is proposed to be built in the western part of China in the next decade.To select the best site which satisfies the construction and future operation of LOT,data monitoring and comparing are required for all the candidate sites.The comparison of most of the instruments was done at Xinglong Observatory.These instruments include weather station,all sky camera,sky background meter and differential image motion monitor(DIMM).This paper introduces the instruments used in LOT site monitoring and the instruments comparisons.The results show that the instrument is stable and the data uniformity of the identical instruments is good.This paper provides a fundamental description of LOT site monitoring.展开更多
Based on previous site testing and satellite cloud data,Ali,Daocheng and Muztagh-ata have been selected as candidate sites for the Large Optical/Infrared Telescope(LOT) in China.We present the data collection,processi...Based on previous site testing and satellite cloud data,Ali,Daocheng and Muztagh-ata have been selected as candidate sites for the Large Optical/Infrared Telescope(LOT) in China.We present the data collection,processing,management and quality analysis for our site testing based on using similar hardware.We analyze meteorological data,seeing,background light,cloud and precipitable water vapor data from 2017 March 10 to 2019 March 10.We also investigated the relative usefulness of our all-sky camera data in comparison to that from the meteorological TERRA satellite data based on a night-by-night comparison of the correlation and consistency between them.We find a 6% discrepancy arising from a wide range of factors.展开更多
基金support from the staff at the Xinglong 85-cm telescopesupport from the National Natural Science Foundation of China(NSFC)through grant 11673003+3 种基金the National Basic Research Program of China(973 program,2014CB845700)partially supported by the Open Project Program of the Key Laboratory of Optical Astronomy(National Astronomical Observatories)NSFC under Grant Nos.11403088 and 11273051(Xinjiang Astronomical Observatory)Chinese Academy of Sciences and Department of Astronomy,Beijing Normal University
文摘The 85-cm telescope at Xinglong station is a prime focus system that operates well with high science outputs. The telescope has been upgraded since 2014 with a new corrector, and new filters and camera, which are provided by Beijing Normal University. The filter set is the Johnson-Cousins UBV RI system. We report the test results of the new system including bias, dark current, linearity, gain and readout noise of the CCD camera. Then we derive accurate instrumental calibration coefficients in UBV RI bands with Landolt standard stars during photometric nights. Finally, we give the limiting magnitudes with various exposure times and signal-to-noise ratios for observers as references.
基金partly supported by the Operation,Maintenance and Upgrading Fund for Astronomical Telescopes and Facility Instruments,budgeted from the Ministry of Finance of China(MOF)and administered by the Chinese Academy of Sciences(CAS)supported by the National Natural Science Foundation of China(Grant Nos.11573054,11703065,11603044 and 11873081)+1 种基金support from a CAS PIFIUK STFC grant ST/R006598/1。
文摘A large ground-based optical/infrared telescope is being planned for a world-class astronomical site in China.The cloud-free night percentage is the primary meteorological consideration for evaluating candidate sites.The data from GMS and NOAA satellites and the MODIS instrument were utilized in this research,covering the period from 1996 to 2015.Our data analysis benefits from overlapping results from different independent teams as well as a uniform analysis of selected sites using GMS+NOAA data.Although significant ground-based monitoring is needed to validate these findings,we identify three different geographical regions with a high percentage of cloud-free conditions(~83%on average),which is slightly lower than at Mauna Kea and Cerro Armazones(~85%on average)and were chosen for the large international projects TMT and ELT respectively.Our study finds evidence that cloud distributions and the seasonal changes affected by the prevailing westerly winds and summer monsoons reduce the cloud cover in areas influenced by the westerlies.This is consistent with the expectations from climate change models and is suggestive that most of the identified sites will have reduced cloud cover in the future.
基金partly supported bythe Operation Maintenance and Upgrading Fund for Astronomical Telescopes and Facility Instruments,budgeted from the Ministry of Finance of China(MOF)and administrated by the Chinese Academy of Sciences(CAS)the grants from Joint Research Fund in Astronomy from the National Natural Science Foundation of China(Nos.U1831209 and U1731131)Youth Innovation Promotion Association CAS(No.2017077)。
文摘The Large Optical/infrared Telescope(LOT)is a ground-based 12 m diameter optical/infrared telescope,which is proposed to be built in the western part of China in the next decade.To select the best site which satisfies the construction and future operation of LOT,data monitoring and comparing are required for all the candidate sites.The comparison of most of the instruments was done at Xinglong Observatory.These instruments include weather station,all sky camera,sky background meter and differential image motion monitor(DIMM).This paper introduces the instruments used in LOT site monitoring and the instruments comparisons.The results show that the instrument is stable and the data uniformity of the identical instruments is good.This paper provides a fundamental description of LOT site monitoring.
基金partly supported by the Operation,Maintenance and Upgrading Fund for Astronomical Telescopes and Facility Instruments,budgeted from the Ministry of Finance of China (MOF) and administered by the Chinese Academy of Sciences (CAS)supported by the National NaturalScience Foundation of China (Grant Nos.11573054,11703065,11603044 and 11873081)HRAJ acknowledges support from a CAS PIFI and UK STFC grant ST/R006598/1。
文摘Based on previous site testing and satellite cloud data,Ali,Daocheng and Muztagh-ata have been selected as candidate sites for the Large Optical/Infrared Telescope(LOT) in China.We present the data collection,processing,management and quality analysis for our site testing based on using similar hardware.We analyze meteorological data,seeing,background light,cloud and precipitable water vapor data from 2017 March 10 to 2019 March 10.We also investigated the relative usefulness of our all-sky camera data in comparison to that from the meteorological TERRA satellite data based on a night-by-night comparison of the correlation and consistency between them.We find a 6% discrepancy arising from a wide range of factors.