NXS Observing at KPNO March/April 2009 [4m 05B-0045 run Mar 25-Apr 1, 2009]

测量XCS星团巡天中约50个X射线星团候选者的光度红移。这是NOAO 4米望远镜（CTIO和KPNO）上NXS项目（总共40个夜晚）的最终时间分配（8个夜晚）。XCS是由萨塞克斯大学的Kathy Romer博士领导的国际合作项目。XCS的目标是找到XMM卫星在其10年寿命期间偶然发现的所有X射线星团，然后用它们来解决银河系外天文学和宇宙学中的各种科学问题。NXS数据正在由苏塞克斯大学的一名STFC支持的博士生Nicola Mehrtens处理。她发现红移可以用图像以一种稳健的方式测量，而不是更传统和耗时的光谱方法。通过将NXS成像与XMM提供的X射线数据相结合，我们能够得出各种科学结论。这些结论的范围从星系在大质量星系团中的演化方式到基本宇宙学参数（包括暗能量的能量密度）的测量。NXS项目是一项重大的国际奋进，跨越了3年和8次望远镜活动。最后一次活动由NOAO授予NXS，以补偿前一次运行中的仪器问题。它给了我们一个独特的机会来完成我们的星系团样本的红移覆盖，在一个特别丰富的天空区域（北银河帽在这次运行中是可见的）。

To measure photometric redshifts for about 50 X-ray cluster candidates from the XCS cluster survey. This is the final allocation of time (8 nights) for the NXS project (40 nights total) on NOAO 4m telescopes (CTIO and KPNO). XCS is a international collaboration led by Dr Kathy Romer at the University of Sussex. XCS aims to find all the X-ray clusters detected by accident by the XMM satellite during its 10 year lifespan, and then to use them to attack a variety of science questions in extra galactic astronomy and cosmology. The NXS data are being processed by an STFC supported PhD student at the University of Sussex, Nicola Mehrtens. She has found that redshifts can be measured in a robust way using images, rather than the more traditional - and time consuming - spectroscopy method. Through the combination of the NXS imaging with X-ray data available from the XMM, we are able to make a variety of scientific conclusions. These conclusions range from the way galaxies evolve in massive clusters to measurements of fundamental cosmological parameters (including the energy density of dark energy). The NXS project has been a major international endeavor, spanning 3 years and 8 telescope campaigns. The final campaign was awarded to NXS by NOAO to compensate for instrument problems during a previous run. It gives us a unique opportunity to complete the redshift coverage for our cluster sample in a particularly rich region of the sky (the North Galactic cap is visible during this run).