We describe a new BVRI multicolor CCD photometric system situated at the prime focus of the 85-cm telescope at the Xinglong Station of NAOC. Atmospheric extinction effects, photometric accuracy and color calibration d...We describe a new BVRI multicolor CCD photometric system situated at the prime focus of the 85-cm telescope at the Xinglong Station of NAOC. Atmospheric extinction effects, photometric accuracy and color calibration dependence of the system are investigated. Additional attention was paid to giving observers guidance in estimating throughput, detection limit, signal-to-noise ratio and exposure time.展开更多
Aerosol plays a key role in determining radiative balance, regional climate and human health.Severe air pollution over Northeast China in recent years urges more comprehensive studies to figure out the adverse effects...Aerosol plays a key role in determining radiative balance, regional climate and human health.Severe air pollution over Northeast China in recent years urges more comprehensive studies to figure out the adverse effects caused by excessive aerosols. In this study, column aerosol measurements over urban Harbin, a metropolis located at the highest latitude in Northeast China, during May 2016 to March 2017 were conducted using a CIMEL sun-photometer to analyze local aerosol properties and its variation from different aspects. According to the observations, aerosol optical depth at 440 nm（AOD_（440）） ranges from 0.07 up to 1.54, and the large variability in both AOD_（440） and Angstrom Exponent（AE_（440–870）） indicates the frequent change of aerosol types due of different emission sources. Coarse mode particles dominated Harbin during the studying period because of the long-range transported dust and probably the suspended snow crystals in winter. As the wavelength increases, relatively consistent decrease trends of single scattering albedo（SSA） and asymmetry factor（ASY） were observed in spring, autumn, and winter, indicating the presence of absorbing polluted aerosols. Mixed type（MIX） aerosol dominated the study region with a total percentage of 34%, and biomass burning and urban industry（BB/UI）, clean continental（CC）, and desert dust（DD） aerosols were found to be 31%, 27%, and 8%, respectively. The current work fills up the optical characteristics of aerosols in Harbin, and will contribute to the in-depth understanding of local aerosol variation and regional climate change over Northeast China.展开更多
Nitro MAC(French acronym for continuous atmospheric measurements of nitrogenous compounds)is an instrument which has been developed for the semi-continuous measurement of atmospheric nitrous acid(HONO).This instrument...Nitro MAC(French acronym for continuous atmospheric measurements of nitrogenous compounds)is an instrument which has been developed for the semi-continuous measurement of atmospheric nitrous acid(HONO).This instrument relies on wet chemical sampling and detection using high performance liquid chromatography(HPLC)-visible absorption at540 nm.Sampling proceeds by dissolution of gaseous HONO in a phosphate buffer solution followed by derivatization with sulfanilamide/N-(1-naphthyl)-ethylenediamine.The performance of this instrument was found to be as follows:a detection limit of around 3 ppt with measurement uncertainty of 10%over an analysis time of 10 min.Intercomparison was made between the instrument and a long-path absorption photometer(LOPAP)during two experiments in different environments.First,air was sampled in a smog chamber with concentrations up to 18 ppb of nitrous acid.Nitro MAC and LOPAP measurements showed very good agreement.Then,in a second experiment,ambient air with HONO concentrations below250 ppt was sampled.While Nitro MAC showed its capability of measuring HONO in moderate and highly polluted environments,the intercomparison results in ambient air highlighted that corrections must be made for minor interferences when low concentrations are measured.展开更多
We describe the design and construction of a new rapid 3-channel CCD photometer, dedicated to simultaneous multicolor photometric observations of rapidly variable objects. This photometer is equipped on the 1-meter te...We describe the design and construction of a new rapid 3-channel CCD photometer, dedicated to simultaneous multicolor photometric observations of rapidly variable objects. This photometer is equipped on the 1-meter telescope at the Xinglong Observatory. It allows simultaneous imaging within fields of view of 18.81′×18.8′, 18.2′×17.6′ and 9.2′×9.2′ in the Sloan Digital Sky Survey＇s g′, r′ and i′ bands, respectively. The results of its calibration and performance are reported.展开更多
Durable press finishing of cotton fabrics with polycarboxylic acid increases fabric wrinkle-resistance at the expense of its mechanical strength. Severe tensile strength loss is the major disadvantage for wrinkle resi...Durable press finishing of cotton fabrics with polycarboxylic acid increases fabric wrinkle-resistance at the expense of its mechanical strength. Severe tensile strength loss is the major disadvantage for wrinkle resistant cotton fabrics.Tensile strength loss of cotton fabric crosslinked by a polycarboxylic acid can be attributed to depolymerization and crosslink of cellulose molecules. Measurement of the molecular weight of cotton fabric before and after crosslinked by polycarboxylic acids can offer a possibility of direct understanding of the depolymerization. In this research, amultiple angle laser light scattering photometer was used todetermine the absolute molecular weight of cotton fabric treated with BTCA at different pH and then hydrolyzed with 0. 5 M NaOH solution at 50℃ for 144 h. The results indicate that average molecular weights of cotton fabric treated with polycarboxylic acids at different pH are almost the same.展开更多
The Si Tian project,designed to utilize 60 telescopes distributed across multiple sites in China,is a next-generation timedomain survey initiative.As a pathfinder for the Si Tian project,the Mini-Si Tian(MST)has been ...The Si Tian project,designed to utilize 60 telescopes distributed across multiple sites in China,is a next-generation timedomain survey initiative.As a pathfinder for the Si Tian project,the Mini-Si Tian(MST)has been proposed and implemented to test the Si Tian’s brain and data pipeline,and to evaluate the feasibility of its technology and science cases.Mounted at the Xinglong Observatory,the MST project comprises three 30 cm telescopes and has been operated since 2022 November.Each telescope of the MST possesses a large field of view,covering 2°.29×1°.53 FOV,and is equipped withg',r'andi'filters,respectively.Acting as the pioneer of the forthcoming Si Tian project,the MST is dedicated to the discovery of variable stars,transients,and outburst events,and has already obtained some interesting scientific results.In this paper,we will summarize the first-two-year operation of the MST project.展开更多
The SiTian project,with its vast field of view,will become an ideal platform for scientific research on asteroids.In this study,we develop a pipeline to analyze the photometry of asteroids and derive their periods fro...The SiTian project,with its vast field of view,will become an ideal platform for scientific research on asteroids.In this study,we develop a pipeline to analyze the photometry of asteroids and derive their periods from the data collected by the SiTian pathfinder project Mini-SiTian(MST).The pipeline is applied to the MST f02 region,an MST test region with a sky area of 2°.29×1°.53.Rotation periods of 22 asteroids are derived by the obtained light curve analysis.Among them,there are eight asteroids available in the Asteroid Lightcurve Photometry Database(ALCDEF),and six of them with more photometric points(>200)that have similar period parameters as the ones in ALCDEF.Additionally,the periods for 14 of these asteroids are newly obtained and are not listed in ALCDEF.This study demonstrates the feasibility of asteroid photometric research by the SiTian project.It shows that future observations from the SiTian project will provide even more photometry of asteroids,significantly increasing the number of available light curves.The potential vast photometric data on asteroids will help us to further understand the physics of asteroids,their material composition,and the formation and evolution of the solar system.展开更多
In this article,we have modeled the astroclimatic parameters using data from the fifth reanalysis series(ERA5)from the European Centre for Medium-Range Weather Forecasts over the period 2010-2020.These data have been ...In this article,we have modeled the astroclimatic parameters using data from the fifth reanalysis series(ERA5)from the European Centre for Medium-Range Weather Forecasts over the period 2010-2020.These data have been projected onto the site of the Roque de los Muchachos Observatory(ORM).The analysis covers the main parameters influencing the quality of astronomical observation,notably the vertical profiles of temperature,potential temperature,and optical turbulence(C_(n)~2),as well as the vertical wind distributions and seasonal behaviors of atmospheric turbulence,which are treated in detail by specifying the wind speed at the 200 hPa level(V200).Around this level,the wind at high altitude presents moderate speeds and a generally stable direction,conditions favorable for adaptive optics.The thermal profiles show good agreement with standard atmospheric models,with a well-defined tropopause and a stable stratosphere,as well as the integrated parameters such as seeing(free and total),isoplanatic angle,and coherence time.The results reveal a stratified and stable atmosphere,with turbulence predominantly concentrated in the lower troposphere.The thermal profiles show a good agreement with standard atmospheric models,with a well-defined tropopause and a stable stratosphere.The seasonality of the astroclimatic parameters indicates conditions particularly favorable for observation during the winter months,with the median of free seeing,total seeing,isoplanatic angle and a coherence time as respectively 0″.48,0″.72,2″,and 6 ms.These results confirm the strong potential of ORM as a reference astronomical site,capable of hosting high-precision observation instruments.The methodological approach employed also provides a replicable basis for the characterization of other candidate sites for the installation of ground-based telescopes.As a preliminary study,this work establishes a scientific basis for further on-site monitoring and detailed characterization of the ORM site.展开更多
The solar corona is the primary driver of the solar storms and space weather.In order to routinely monitor the coronal activities,a dedicated solar telescope is essential,a coronagraph.However,the site conditions suit...The solar corona is the primary driver of the solar storms and space weather.In order to routinely monitor the coronal activities,a dedicated solar telescope is essential,a coronagraph.However,the site conditions suitable for a ground-based coronagraph are rather critical and necessitate stringent site selection criteria.Among the numerous astronomical observatory site parameters,the sky background brightness of the day is recognized as a key parameter in evaluating the quality of a solar observatory for coronal observation before considering to install a coronagraph.To achieve optimal sky brightness observing condition,coronagraphs are usually installed on high mountains where the atmosphere is thin and the background scattered light effects from the sky are significantly reduced.Given the unique characteristics of the Tibetan Plateau,often referred to as the"Third Pole"of the Earth,a scientific assessment is crucial to evaluate its suitability as a potential location for the next-generation Chinese Giant Solar Telescope and large coronagraphs.Here,we report the first results of our measurements of the sky brightness at the Namco Lake location(30°45.0′N,90°40.0′E,4730 m above sea level,the highest large lake in the world),using a new Sky Brightness Monitor during the period 2013 August to December.The results show that the average value of the normalized(per airmass)sky brightness is as low as 13.84μI_(☉)for 530 nm.The excellent sky brightness conditions at the Namco Lake location demonstrate its high suitability for routine coronal observations.Therefore,the Namco site deserves attention for solar observations and we should continue to carry out in-depth monitoring and systematic study of multiple parameters in the future.展开更多
基金Supported by the National Natural Science Foundation of China.
文摘We describe a new BVRI multicolor CCD photometric system situated at the prime focus of the 85-cm telescope at the Xinglong Station of NAOC. Atmospheric extinction effects, photometric accuracy and color calibration dependence of the system are investigated. Additional attention was paid to giving observers guidance in estimating throughput, detection limit, signal-to-noise ratio and exposure time.
基金supported by the National Natural Science Foundation of China (Nos. 51776051 and 51406041)
文摘Aerosol plays a key role in determining radiative balance, regional climate and human health.Severe air pollution over Northeast China in recent years urges more comprehensive studies to figure out the adverse effects caused by excessive aerosols. In this study, column aerosol measurements over urban Harbin, a metropolis located at the highest latitude in Northeast China, during May 2016 to March 2017 were conducted using a CIMEL sun-photometer to analyze local aerosol properties and its variation from different aspects. According to the observations, aerosol optical depth at 440 nm（AOD_（440）） ranges from 0.07 up to 1.54, and the large variability in both AOD_（440） and Angstrom Exponent（AE_（440–870）） indicates the frequent change of aerosol types due of different emission sources. Coarse mode particles dominated Harbin during the studying period because of the long-range transported dust and probably the suspended snow crystals in winter. As the wavelength increases, relatively consistent decrease trends of single scattering albedo（SSA） and asymmetry factor（ASY） were observed in spring, autumn, and winter, indicating the presence of absorbing polluted aerosols. Mixed type（MIX） aerosol dominated the study region with a total percentage of 34%, and biomass burning and urban industry（BB/UI）, clean continental（CC）, and desert dust（DD） aerosols were found to be 31%, 27%, and 8%, respectively. The current work fills up the optical characteristics of aerosols in Harbin, and will contribute to the in-depth understanding of local aerosol variation and regional climate change over Northeast China.
基金supported by EU Sixth Framework Programme(FP6)Eurochamp program(grant number 505968)EU Seventh Framework Programme(FP7)Eurochamp-2 program(grant number 228335)+2 种基金the NeoRad program from the French National Agency for Research(ANR-07-2/21-8908)the PhotoBat project from the Primequal program of the French Ministry of Environment(Primequal-project number 19599)the PhotoPaq LIFE+program(LIFE 08/ENV/F/000487 PHOTOPAQ)
文摘Nitro MAC(French acronym for continuous atmospheric measurements of nitrogenous compounds)is an instrument which has been developed for the semi-continuous measurement of atmospheric nitrous acid(HONO).This instrument relies on wet chemical sampling and detection using high performance liquid chromatography(HPLC)-visible absorption at540 nm.Sampling proceeds by dissolution of gaseous HONO in a phosphate buffer solution followed by derivatization with sulfanilamide/N-(1-naphthyl)-ethylenediamine.The performance of this instrument was found to be as follows:a detection limit of around 3 ppt with measurement uncertainty of 10%over an analysis time of 10 min.Intercomparison was made between the instrument and a long-path absorption photometer(LOPAP)during two experiments in different environments.First,air was sampled in a smog chamber with concentrations up to 18 ppb of nitrous acid.Nitro MAC and LOPAP measurements showed very good agreement.Then,in a second experiment,ambient air with HONO concentrations below250 ppt was sampled.While Nitro MAC showed its capability of measuring HONO in moderate and highly polluted environments,the intercomparison results in ambient air highlighted that corrections must be made for minor interferences when low concentrations are measured.
文摘We describe the design and construction of a new rapid 3-channel CCD photometer, dedicated to simultaneous multicolor photometric observations of rapidly variable objects. This photometer is equipped on the 1-meter telescope at the Xinglong Observatory. It allows simultaneous imaging within fields of view of 18.81′×18.8′, 18.2′×17.6′ and 9.2′×9.2′ in the Sloan Digital Sky Survey＇s g′, r′ and i′ bands, respectively. The results of its calibration and performance are reported.
基金The Project-sponsored by SRF for ROCS, SEM and EYTP of MOE
文摘Durable press finishing of cotton fabrics with polycarboxylic acid increases fabric wrinkle-resistance at the expense of its mechanical strength. Severe tensile strength loss is the major disadvantage for wrinkle resistant cotton fabrics.Tensile strength loss of cotton fabric crosslinked by a polycarboxylic acid can be attributed to depolymerization and crosslink of cellulose molecules. Measurement of the molecular weight of cotton fabric before and after crosslinked by polycarboxylic acids can offer a possibility of direct understanding of the depolymerization. In this research, amultiple angle laser light scattering photometer was used todetermine the absolute molecular weight of cotton fabric treated with BTCA at different pH and then hydrolyzed with 0. 5 M NaOH solution at 50℃ for 144 h. The results indicate that average molecular weights of cotton fabric treated with polycarboxylic acids at different pH are almost the same.
基金supported by the National Key R&D Program of China(grant No.2023YFA1608304 and No.2023YFA1608300)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB0550100 and XDB0550000)the National Natural Science Foundation of China(NSFC,grant Nos.12090041,12090040,11903054,12422303,and 12261141690)。
文摘The Si Tian project,designed to utilize 60 telescopes distributed across multiple sites in China,is a next-generation timedomain survey initiative.As a pathfinder for the Si Tian project,the Mini-Si Tian(MST)has been proposed and implemented to test the Si Tian’s brain and data pipeline,and to evaluate the feasibility of its technology and science cases.Mounted at the Xinglong Observatory,the MST project comprises three 30 cm telescopes and has been operated since 2022 November.Each telescope of the MST possesses a large field of view,covering 2°.29×1°.53 FOV,and is equipped withg',r'andi'filters,respectively.Acting as the pioneer of the forthcoming Si Tian project,the MST is dedicated to the discovery of variable stars,transients,and outburst events,and has already obtained some interesting scientific results.In this paper,we will summarize the first-two-year operation of the MST project.
基金supports from the National Natural Science Foundation of China(NSFC,grant Nos.12203002 and 11973015)supports from the National Key Basic R&D Program of China via 2023YFA1608303 and the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB0550103)+6 种基金supports from the National Natural Science Foundation of China(NSFCgrant No.12373015)supports from the National Natural Science Foundation of China(NSFCgrant Nos.12120101003 and 12373010)National Key R&D Program of China(grant Nos.2023YFA1607800,2023YFA1607804,2022YFA1602902)Beijing Municipal Natural Science Foundation(grant No.1222028)Strategic Priority Research Program of the Chinese Academy of Science(grant Nos.XDB0550100 and XDB0550000).
文摘The SiTian project,with its vast field of view,will become an ideal platform for scientific research on asteroids.In this study,we develop a pipeline to analyze the photometry of asteroids and derive their periods from the data collected by the SiTian pathfinder project Mini-SiTian(MST).The pipeline is applied to the MST f02 region,an MST test region with a sky area of 2°.29×1°.53.Rotation periods of 22 asteroids are derived by the obtained light curve analysis.Among them,there are eight asteroids available in the Asteroid Lightcurve Photometry Database(ALCDEF),and six of them with more photometric points(>200)that have similar period parameters as the ones in ALCDEF.Additionally,the periods for 14 of these asteroids are newly obtained and are not listed in ALCDEF.This study demonstrates the feasibility of asteroid photometric research by the SiTian project.It shows that future observations from the SiTian project will provide even more photometry of asteroids,significantly increasing the number of available light curves.The potential vast photometric data on asteroids will help us to further understand the physics of asteroids,their material composition,and the formation and evolution of the solar system.
文摘In this article,we have modeled the astroclimatic parameters using data from the fifth reanalysis series(ERA5)from the European Centre for Medium-Range Weather Forecasts over the period 2010-2020.These data have been projected onto the site of the Roque de los Muchachos Observatory(ORM).The analysis covers the main parameters influencing the quality of astronomical observation,notably the vertical profiles of temperature,potential temperature,and optical turbulence(C_(n)~2),as well as the vertical wind distributions and seasonal behaviors of atmospheric turbulence,which are treated in detail by specifying the wind speed at the 200 hPa level(V200).Around this level,the wind at high altitude presents moderate speeds and a generally stable direction,conditions favorable for adaptive optics.The thermal profiles show good agreement with standard atmospheric models,with a well-defined tropopause and a stable stratosphere,as well as the integrated parameters such as seeing(free and total),isoplanatic angle,and coherence time.The results reveal a stratified and stable atmosphere,with turbulence predominantly concentrated in the lower troposphere.The thermal profiles show a good agreement with standard atmospheric models,with a well-defined tropopause and a stable stratosphere.The seasonality of the astroclimatic parameters indicates conditions particularly favorable for observation during the winter months,with the median of free seeing,total seeing,isoplanatic angle and a coherence time as respectively 0″.48,0″.72,2″,and 6 ms.These results confirm the strong potential of ORM as a reference astronomical site,capable of hosting high-precision observation instruments.The methodological approach employed also provides a replicable basis for the characterization of other candidate sites for the installation of ground-based telescopes.As a preliminary study,this work establishes a scientific basis for further on-site monitoring and detailed characterization of the ORM site.
基金supported by the National Natural Science Foundation of China(NSFC,grant Nos.12373063 and 11533009)the Deanship of Scientific Research at King Saud University for funding this work through research group No.(RG-1440-092)。
文摘The solar corona is the primary driver of the solar storms and space weather.In order to routinely monitor the coronal activities,a dedicated solar telescope is essential,a coronagraph.However,the site conditions suitable for a ground-based coronagraph are rather critical and necessitate stringent site selection criteria.Among the numerous astronomical observatory site parameters,the sky background brightness of the day is recognized as a key parameter in evaluating the quality of a solar observatory for coronal observation before considering to install a coronagraph.To achieve optimal sky brightness observing condition,coronagraphs are usually installed on high mountains where the atmosphere is thin and the background scattered light effects from the sky are significantly reduced.Given the unique characteristics of the Tibetan Plateau,often referred to as the"Third Pole"of the Earth,a scientific assessment is crucial to evaluate its suitability as a potential location for the next-generation Chinese Giant Solar Telescope and large coronagraphs.Here,we report the first results of our measurements of the sky brightness at the Namco Lake location(30°45.0′N,90°40.0′E,4730 m above sea level,the highest large lake in the world),using a new Sky Brightness Monitor during the period 2013 August to December.The results show that the average value of the normalized(per airmass)sky brightness is as low as 13.84μI_(☉)for 530 nm.The excellent sky brightness conditions at the Namco Lake location demonstrate its high suitability for routine coronal observations.Therefore,the Namco site deserves attention for solar observations and we should continue to carry out in-depth monitoring and systematic study of multiple parameters in the future.
