SOHO LASCO C2 Level 1.0 FITS Data

The LASCO C2 Calibrated FITS Data.

LASCO (Large Angle Spectroscopic Coronagraph) is comprised of three nested coronagraphs (C1, C2, and C3) that image the solar corona from 1.1--30 solar radii (C1: 1.1--3; C2: 1.5--6; and C3: 3--30). The inner coronagraph (C1) is a newly developed mirror version of the classic Lyot coronagraph without an external occulter, while the middle coronagraph (C2) and the outer one (C3) are externally occulted. C1 is equipped with a Fabry-Perot interferometer that can take monochromatic images over the whole field of view with a spectral resolution of 0.07 nm. By stepping the bandpass across a spectral line, line profiles and Doppler shifts can be derived from all 1024 x 1024 pixels simultaneously. With an equivalent pixel size of 5.6 arcsec, the spatial resolution of C1 is ~11 arcsec. The resolution is ~23 arcsec for C2, and 112 arcsec for C3. The calculated expected precision of the emission line measurements, for example, of the 637.4 nm Fe X line is 0.05 Km/s at 1.1 solar radii, 1.0 km/s at 2 solar radii, and 8.0 km/s at 3 solar radii, all for a 60 s exposure. All three devices use a 1024 x 1024 pixel CCD. The CCDs are passively cooled to 193 K, but can be heated above ambient temperatures to drive off condensed material. The readout rate is ~21 s for a full image, but any line on the CCD can be accessed within about 60 ms, the unwanted lines being dumped. The electronics box provides overall control, including observation programs and scheduling. An observation program can be scheduled to be run at an absolute time or just next in sequence. It can run for a certain number of iterations, an interval of time, or stop at an absolute time. The observation program tasks included, e.g., taking single images from one of the telescopes, a series of images through the three linear polarizers, and a sequence of images at a series of Fabry-Perot wavelength steps. The image processing tasks are primarily image compression, with seven different techniques being available. On average, the readout time should be ~6 minutes or about 200 images/day. This information is from the paper ``The Large Angle Spectroscopic Coronagraph (LASCO): Visible Light Coronal Imaging and Spectroscopy,'' by G. E. Brueckner et al. (Proceedings of the First SOHO Workshop, ESA SP-348, pp. 27-34, November 1992).

LASCO C2校准FITS数据。LASCO（大角径光谱日冕仪）由三个嵌套式日冕仪（C1、C2和C3）组成，其能够从1.1至30倍太阳半径（C1：1.1--3；C2：1.5--6；C3：3--30）对太阳日冕进行成像。内层日冕仪（C1）是一种新型设计的无外部遮掩器的经典Lyot日冕仪的反射镜版本，而中层日冕仪（C2）和外层日冕仪（C3）则采用了外部遮掩器。C1配备有能够覆盖整个视场并以0.07纳米的谱分辨率进行单色成像的Fabry-Perot干涉仪。通过在谱线上步进通带，可以同时从所有1024 x 1024像素中推导出线谱和多普勒频移。C1的等效像素大小为5.6角秒，其空间分辨率约为11角秒。C2的分辨率约为23角秒，而C3的分辨率为112角秒。以637.4纳米Fe X线的发射线测量为例，计算得到的预期精度在1.1倍太阳半径处为0.05千米/秒，在2倍太阳半径处为1.0千米/秒，在3倍太阳半径处为8.0千米/秒，所有这些均针对60秒曝光。所有三个设备均使用1024 x 1024像素的CCD。CCD通过被动冷却至193开尔文，但可加热至高于环境温度，以驱散凝结物质。全图读取速率约为21秒，但任何CCD上的线条均可在约60毫秒内访问，不想要的线条将被丢弃。电子箱提供整体控制，包括观测程序和调度。观测程序可以安排在绝对时间或序列中的下一个时间运行。它可以运行一定次数的迭代、一定时间间隔或停止在绝对时间。观测程序任务包括，例如，从望远镜中获取单张图像、通过三个线性偏振器的图像系列以及一系列在一系列Fabry-Perot波长步进下的图像序列。图像处理任务主要是图像压缩，提供了七种不同的技术。平均而言，读取时间应约为6分钟或大约200张图像/天。此信息来自G. E. Brueckner等人撰写的论文《大角径光谱日冕仪（LASCO）：可见光日冕成像和光谱学》，载于《第一次SOHO研讨会论文集》（ESA SP-348，第27-34页，1992年11月）。

搜集汇总

背景与挑战

背景概述

该数据集是SOHO卫星LASCO仪器的C2日冕仪校准FITS数据，用于观测太阳日冕在1.5至6个太阳半径范围内的亮度图像，时间分辨率为12分钟，起始于1995年12月8日。数据具有高空间分辨率（约23角秒）和开放访问权限（CC0-1.0许可），适用于太阳物理学研究，如日冕结构和活动分析。