We aim to provide a quasar sample that is more complete than any previous surveys by using a combined selection technique to reduce the selection effects. Here we present the observational results for the X-ray candid...We aim to provide a quasar sample that is more complete than any previous surveys by using a combined selection technique to reduce the selection effects. Here we present the observational results for the X-ray candidates in the field of the Leo Cluster. We found 33 X-ray AGNs in this field of which 10 are new discoveries. The X-ray data and optical spectra of these AGNs are given. We also study the near-IR properties of the X-ray-selected AGNs by using the data from 2MASS. Most of the AGNs in our sample span the color range 0.0〈B-J〈2.5,1.0〈 J-Ks 〈2.0 and 0.5〈H-Ks〈1.2.展开更多
探索如何利用低成本的低轨卫星(low Earth orbit,LEO)星群的精密轨道资料探测地球重力场,并以COSMIC(constellation observing system for meteorology ionosphere & climate)为研究实例初步分析了其覆盖性和方法的可行性。
新一代重力卫星计划主要依靠高精度星载加速度计(ACC)、星间测距系统(KBR)或星载梯度计(SGG)进行地球重力场探测。搭载高精度星载GPS接收机的低轨卫星(low earth orbit,LEO)可以相对较低成本获取LEO卫星的精密轨道。卫星精密轨道一方面...新一代重力卫星计划主要依靠高精度星载加速度计(ACC)、星间测距系统(KBR)或星载梯度计(SGG)进行地球重力场探测。搭载高精度星载GPS接收机的低轨卫星(low earth orbit,LEO)可以相对较低成本获取LEO卫星的精密轨道。卫星精密轨道一方面服务于LEO的主任务(如遥感、气象等);另一方面可以将这类LEO卫星和星座综合起来,构成LEO星群LEO星群精密轨道数据包含的丰富地球重力场信息为获取地球重力场的时变信息提供可能。本文给出一种利用LEO星群精密轨道数据反演地球重力场低阶带谐系数时变信息的实用方法——交叠点法,该方法可有效消弱非保守力等因素对重力场反演的影响。然后,以COSMIC(constellation observing system for meteorology ionosphere&climate)为实例分析LEO星群交叠点的覆盖特性,径向轨道精度对交叠点法的影响。最后进行低阶带谐系数(C02和C03)时变信号的模拟计算,并对结果进行分析。展开更多
基金the National Natural Science Foundation of China.
文摘We aim to provide a quasar sample that is more complete than any previous surveys by using a combined selection technique to reduce the selection effects. Here we present the observational results for the X-ray candidates in the field of the Leo Cluster. We found 33 X-ray AGNs in this field of which 10 are new discoveries. The X-ray data and optical spectra of these AGNs are given. We also study the near-IR properties of the X-ray-selected AGNs by using the data from 2MASS. Most of the AGNs in our sample span the color range 0.0〈B-J〈2.5,1.0〈 J-Ks 〈2.0 and 0.5〈H-Ks〈1.2.
文摘探索如何利用低成本的低轨卫星(low Earth orbit,LEO)星群的精密轨道资料探测地球重力场,并以COSMIC(constellation observing system for meteorology ionosphere & climate)为研究实例初步分析了其覆盖性和方法的可行性。
文摘新一代重力卫星计划主要依靠高精度星载加速度计(ACC)、星间测距系统(KBR)或星载梯度计(SGG)进行地球重力场探测。搭载高精度星载GPS接收机的低轨卫星(low earth orbit,LEO)可以相对较低成本获取LEO卫星的精密轨道。卫星精密轨道一方面服务于LEO的主任务(如遥感、气象等);另一方面可以将这类LEO卫星和星座综合起来,构成LEO星群LEO星群精密轨道数据包含的丰富地球重力场信息为获取地球重力场的时变信息提供可能。本文给出一种利用LEO星群精密轨道数据反演地球重力场低阶带谐系数时变信息的实用方法——交叠点法,该方法可有效消弱非保守力等因素对重力场反演的影响。然后,以COSMIC(constellation observing system for meteorology ionosphere&climate)为实例分析LEO星群交叠点的覆盖特性,径向轨道精度对交叠点法的影响。最后进行低阶带谐系数(C02和C03)时变信号的模拟计算,并对结果进行分析。
