Spitzer Cosmic Dawn Survey

Cosmic Dawn is a new infrared survey covering the three Euclid deep fields and four other Euclid calibration fields using Spitzer's Infrared Array Camera (IRAC). These new observations are combined with all relevant IRAC archival data of these fields in order to produce the deepest possible mosaics of these regions. In total, these observations represent nearly 11% of the total Spitzer mission time. The resulting mosaics cover a total of approximately 71.5 deg^2 in the 3.6 and 4.5 micron bands, and approximately 21.8 deg^2 in the 5.8 and 8 micron bands. They reach at least 24 AB magnitude in the 3.6 micron band and up to ~5 mag deeper in the deepest regions. The astrometry is tied to the Gaia astrometric reference system, and the typical astrometric uncertainty for sources with 16 < [3.6] < 19 is 0.15". The photometric calibration is in excellent agreement with previous WISE measurements. Given that the Spitzer Space Telescope has now been decommissioned these mosaics are likely to be the definitive reduction of these IRAC data. This survey therefore represents an essential first step in assembling multi-wavelength data on the Euclid deep fields which are set to become some of the premier fields for extragalactic astronomy in the 2020s.

This dataset or service is made available by the Infrared Science Archive (IRSA) at IPAC, which is operated by the California Institute of Technology under contract with the National Aeronautics and Space Administration.

Cosmic Dawn（宇宙黎明）是一项全新红外巡天项目，利用斯皮策太空望远镜（Spitzer Space Telescope）的红外阵列相机（Infrared Array Camera, IRAC），覆盖3个欧几里得（Euclid）深场与另外4个欧几里得校准场。本项目将这批新观测数据与上述天区的全部相关IRAC存档数据整合，以生成这些区域迄今最深的拼接天图。总体而言，这批观测耗时约占斯皮策太空望远镜总任务时长的11%。

最终生成的拼接天图在3.6微米与4.5微米波段的覆盖总面积约为71.5平方度，在5.8微米与8微米波段的覆盖总面积约为21.8平方度。其在3.6微米波段的极限星等至少可达24 AB星等，在最深天区甚至可再深约5个星等。该天图的天体测量绑定至盖亚（Gaia）天体测量参考系统，对于[3.6]星等介于16至19之间的源，其典型天体测量不确定度为0.15角秒。其光度校准与此前广域红外巡天探测器（Wide-field Infrared Survey Explorer, WISE）的测量结果高度吻合。鉴于斯皮策太空望远镜现已退役，这批拼接天图或将成为这些IRAC数据的权威归算成果。因此，该巡天项目为欧几里得深场的多波长数据整合迈出了关键第一步——这些天区将成为21世纪20年代河外天文学领域的核心观测场之一。

本数据集或服务由IPAC下属的红外科学档案馆（Infrared Science Archive, IRSA）提供，该机构由加州理工学院受美国国家航空航天局合同委托运营。