Polarimeter for Inner Coronal Studies (PICS)

The Polarimeter for Inner Coronal Studies (PICS) at the Mauna Loa Solar Observatory (MLSO) records the full solar disk and limb in the neutral emission line of Hydrogen at 656.3 nm known as H-alpha (H) at a 3 minute cadence. Solar limb images are 1534 x 1030 pixels and solar disk images are 1024 x 1024 pixels. All images have a platescale of 2.9 arcseconds per pixel. The limb image field-of-view (FOV) extends out to 2.3 solar radii (4.6 solar radii across) in the low latitude regions and out to 1.5 solar radii (3 solar radii across) over the solar poles. It operated from September 25, 1997 until February 23, 2010. PICS was an upgrade to the older H instrument known as the Digital Prominence Monitor (DPM). PICS has a narrower H bandpass filter than the DPM. This provides significantly sharper disk imaging. PICS also includes improved optics for acquiring solar limb observations. PICS data products consist of fits and gif formatted images: 1) full disk H images (‘asc’ in the filename), 2) full disk Hwith limb darkening correction applied (‘asl’ in the filename) and 3) H limb images (‘alr’ in the filename). The limb-darkened corrected full disk (asl) images are oriented with solar north up. The uncorrected fits disk images (asc) and limb images (alr) are in the geo-coordinate system. These data can be oriented to solar north up by rotating by [-1*pangle] (see PICS fits header keywords: CROTA1, CROTA2, and SOLAR_P0). Gif images contain annotation indicating the direction of solar north. All PICs data are available on the MLSO web page and can be used to identify and track solar prominences, filaments and their eruptions, chromospheric waves produced by flares and CMEs, sunspots, active regions and variations in chromospheric structure over the solar cycle.

莫纳罗亚太阳天文台（Mauna Loa Solar Observatory, MLSO）的日冕内部研究偏振计（Polarimeter for Inner Coronal Studies, PICS）以3分钟的采样间隔，记录氢原子656.3 nm处的中性发射谱线（即Hα（H-alpha）波段）下的完整太阳日面与临边图像。其中太阳临边图像分辨率为1534×1030像素，日面图像分辨率为1024×1024像素，所有图像的像素比例尺均为2.9角秒每像素。临边图像的视场（field-of-view, FOV）在低纬度区域可延伸至2.3倍太阳半径（跨径达4.6倍太阳半径），在太阳极区则延伸至1.5倍太阳半径（跨径达3倍太阳半径）。该设备于1997年9月25日至2010年2月23日期间运行。PICS是对老旧的Hα波段观测设备——数字日珥监测仪（Digital Prominence Monitor, DPM）的升级型号：其搭载的Hα波段带通滤波器比DPM更窄，可获得分辨率更高的日面成像效果；同时配备了经过优化的光学系统，用于获取太阳临边观测数据。PICS的数据产品包含fits与gif两种格式的图像，具体分为三类：1）完整日面Hα图像（文件名含“asc”标识）；2）已完成临边暗化校正的完整日面Hα图像（文件名含“asl”标识）；3）Hα波段太阳临边图像（文件名含“alr”标识）。已完成临边暗化校正的日面图像（asl格式）默认以太阳北方向为图像上方；未校正的fits格式日面图像（asc）与临边图像（alr）则采用地理坐标系，可通过旋转[-1×pangle]角度将此类数据调整为太阳北向上的方位（具体可参考PICS的fits文件头关键字：CROTA1、CROTA2与SOLAR_P0）。gif格式图像会附带标注以指示太阳北方向。所有PICS数据均可在MLSO官方网站获取，可用于识别并追踪太阳日珥、暗条及其爆发事件，以及耀斑与日冕物质抛射（Coronal Mass Ejection, CME）产生的色球波动、太阳黑子、活动区，还有太阳活动周内色球层结构的演化特征。