Absolute Calibration of the Infrared Array Camera on the Spitzer Space Telescope
Absolute Calibration of the Infrared Array Camera on the Spitzer Space Telescope
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DOI：
10.1086/432670
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发表时间：
2005-07
影响因子：
3.5
通讯作者：
W. Reach;S. Megeath;M. Cohen;J. Hora;S. Carey;J. Surace;S. Willner;P. Barmby;G. Wilson;W. Glaccum;P. Lowrance;M. Marengo;G. Fazio
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作者：
W. Reach;S. Megeath;M. Cohen;J. Hora;S. Carey;J. Surace;S. Willner;P. Barmby;G. Wilson;W. Glaccum;P. Lowrance;M. Marengo;G. Fazio
斯皮策太空望远镜上的红外阵列相机（IRAC）是通过比较黄道北极附近的一组a星的光度测定结果，与基于地面观测和恒星大气模型的预测结果进行校准的。相对于A -恒星大气模型，点源的亮度被校准到3%的精度，以与校准恒星相同的方式进行观测和分析。这包括对恒星在阵列中的位置和质心在峰值像素内的位置的修正。IRAC测光的长期稳定性是通过监测每月观测几次的A矮星和K巨星（靠近黄道北极）的亮度来测量的；光度测量在一年内稳定在1.5% （rms）。IRAC在标称运行时，通过每12小时监测至少一个次级校准器（靠近黄道面）来测量IRAC光度法的中间时间尺度稳定性；中期光度测量稳定，色散（均方根）为1%。发现其中一个二次校准器具有显著的时间变量（5%）中红外发射，其周期（7.4天）与光学光曲线匹配；它可能是造父变星。
The Infrared Array Camera (IRAC) on the Spitzer Space Telescope is absolutely calibrated by comparing photometry of a set of A stars near the north ecliptic pole to predictions based on ground‐based observations and a stellar atmosphere model. The brightness of point sources is calibrated to an accuracy of 3%, relative to models for A‐star stellar atmospheres, for observations performed and analyzed in the same manner as for the calibration stars. This includes corrections for the location of the star in the array and the location of the centroid within the peak pixel. Long‐term stability of the IRAC photometry was measured by monitoring the brightness of A dwarfs and K giants (near the north ecliptic pole) observed several times per month; the photometry is stable to 1.5% (rms) over a year. Intermediate‐timescale stability of the IRAC photometry was measured by monitoring at least one secondary calibrator (near the ecliptic plane) every 12 hr while IRAC was in nominal operations; the intermediate‐term photometry is stable, with a 1% dispersion (rms). One of the secondary calibrators was found to have significantly time‐variable (5%) mid‐infrared emission, with a period (7.4 days) matching the optical light curve; it is possibly a Cepheid variable.