A procedure for fitting point sources in SMEI white-light full-sky maps
A procedure for fitting point sources in SMEI white-light full-sky maps
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SMEI白光全天图中点源的拟合过程
DOI：
10.1117/12.734808
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发表时间：
2007
期刊：
影响因子：
--
通讯作者：
B. Jackson
中科院分区：
文献类型：
--
作者：
P. Hick;A. Buffington;B. Jackson
太阳质量抛射成像仪（SMEI）由三个CCD相机组成，每个相机的视场为60° × 3°，组合扫描160°弧的天空。SMEI在102分钟的航天器轨道上覆盖整个天空。每个轨道的单独4秒曝光被组装成全天空地图。SMEI数据简化的主要目标是将天空中的汤姆逊散射信号与太阳风中的自由电子隔离开来。要达到所需的光度精度，其中一个步骤是从全天空图中单独拟合和删除亮度超过6等的恒星。SMEI光学器件的点扩散函数有几个不寻常的性质。它具有大约一度的全宽，是不对称的，并且宽度取决于在视场中形成图像的位置而变化。此外，PSF在恒星天空上的方向在一年中旋转超过360度。我们描述的程序，用于适应和减去个别恒星的SMEI全天空地图。该过程的副产品是亮于6等星的恒星的轨道时间分辨率的时间序列。Buffington等人（2007年）使用这些结果来校准SMEI仪器与LASCO C3日冕物质抛射。
The Solar Mass Ejection Imager (SMEI) instrument consists of three CCD cameras with individual fields of view of 60° × 3° degrees that combined sweep a 160° arc of sky. SMEI covers the entire sky in one spacecraft orbit of 102 minutes. Individual 4-s exposures from each orbit are assembled into full-sky maps. The primary objective in the SMEI data reduction is to isolate the Thomson-scattering signal across the sky from free electrons in the solar wind. One of the steps needed to achieve the required photometric precision is the individual fitting and removal of stars brighter than 6th magnitude from the full-sky maps. The point-spread function of the SMEI optics has several unusual properties. It has a full width of about one degree, is asymmetric, and varies in width depending on where in the field of view the image is formed. Moreover, the orientation of the PSF on the sidereal sky rotates over 360 degree over the course of a year. We describe the procedure used to fit and subtract individual stars from the SMEI full-sky maps. A by-product of this procedure are time series at the orbital time resolution for stars brighter than 6th magnitude. These results are used by Buffington et al. (2007) to calibrate the SMEI instrument against the LASCO C3 coronagraph.