影像来源与版权:NASA, NICER

说明:中子星内部组成探测器(NICER)是国际太空站的酬载之一。当国际太空站每93分钟绕地球一圈之时,NICER也在转向回旋以追踪宇宙的X射线源。在轨道的夜面时,它的X射线侦测器一直开启。所以当NICER从一个标的转到另一个标的时,就划出了这幅由22个月数据建构出的NICER全天图,里头的亮弧和循环。在这张X射线全天图里,这些光弧通常会聚在NICER例行观测和追踪的波霎(脉冲星)上,因而形成了图上醒目的亮斑。波霎是在自转的中子星,并会发出精准如钟的规律X射线脉冲。这些脉冲的时间极为精确,可用来作为导航和推算太空船的速率及位置之用。在这幅NICER的X射线全天图所使用之座标里,天球赤道贯过图的中央。(NICER – Neutron star Interior Composition Explorer 中子星内部组成探测器)

NICER at Night
Image Credit & Copyright: NASA, NICER

Explanation: A payload on board the International Space Station, the Neutron star Interior Composition Explorer (NICER) twists and turns to track cosmic sources of X-rays as the station orbits planet Earth every 93 minutes. During orbit nighttime, its X-ray detectors remain on. So as NICER slews from target to target bright arcs and loops are traced across this all-sky map made from 22 months of NICER data. The arcs tend to converge on prominent bright spots, pulsars in the X-ray sky that NICER regularly targets and monitors. The pulsars are spinning neutron stars that emit clock-like pulses of X-rays. Their timing is so precise it can be used for navigation, determining spacecraft speed and position. This NICER X-ray, all-sky, map is composed in coordinates with the celestial equator horizontally across the center.
Astronomy Picture of the Day 06/01/2019