All-sky images taken from Dome A, Dome Fuji and Ridge A

This dataset contains images of the sky taken with the HRCAM (High Resolution CAMera) instrument. HRCAM is a digital SLR camera (Canon EOS 50D; 15 megapixels) equipped with a fish-eye lens (Sigma 4.5-mm f/2.8) for all-sky coverage on a 1.6 crop sensor.HRCAM was primarily designed by Daniel Luong-Van. Nick Tothill helped with construction. Michael Ashley helped with design, construction, software, and operation.The directories here are:/documentation PDFs of papers and a PhD thesis describing the instrument and results/raw Canon RAW image files - these are the original images /jpg JPG images extracted from some of the raw files/thumbs Thumbnail images extracted from some of the raw filesSeveral versions of HRCAM have been built. You can tell which one is used from the serial numbers of the Canon EOS 50D camera, as stored in the RAW image files. Camera serial number 0330104673 was sent to Dome A, 2110703496 to Ridge A, and 2210700089 to Dome Fuji.The image filenames in the various directories contain the UNIX epoch in seconds at which the exposure started. To convert the UNIX epoch to a date/time, you can use the Linux date command, as per the following example:data -u -d @1282890600Images from Dome A:The original HRCAM was first installed in PLATO at Dome A during January 2010. The camera was refurbished and reinstalled in PLATO-A for 2015.There are 12703 images, with cadences of 240 and 660 seconds (with different exposure times), taken from Dome A. The images are in raw/h1*.raw, and start with h1282890600.raw at Fri 27 Aug 2010 06:30:00 UTC, and end with h1295604000.raw at Fri 21 Jan 2011 10:00:00 UTC. In addition, there are 709 images, with cadences of 900 seconds in jpg/h12*.jpg, starting with h1282915324.jpg at Fri 27 Aug 2010 13:22:04 UTC, and ending with h1284925919.jpg at Sun 19 Sep 2010 19:51:59 UTC. In addition, there are 10339 images, with cadences from 120 to 1800 seconds, taken from Dome A. The images are in raw/h1-*.raw and jpg/h1-*.jpg, with thumbnails in thumbs/*jpg, and start with h1-1421930703.jpg at Thu 22 Jan 2015 12:45:03 UTC, and end with h1-1434252625.jpg at Sun 14 Jun 2015 03:30:25 UTC.Images from Dome Fuji:HRCAM2 was taken to Dome Fuji and installed in PLATO-F by the Japanese 52nd JARE expedition during the 2010/2011 season. In the images, green Engine Module is at the top of the image, two small iridium aerials are at left and bottom, the Iridium Openport antenna is in the insulated white box at lower left, the meteorological tower is also visible. The "egg of vision" is on the right, just above the Iridium aerial. The image reaches to the horizon in all directions.There are 21336 images, with cadences of 240 and 660 seconds (with different exposure times), taken from Dome Fuji. The images are in raw/h1*.raw, and start with h1296361840.raw at Sun 30 Jan 2011 04:30:40 UTC, and end with h1310294940.raw at Sun 10 Jul 2011 10:49:00 UTC. In addition, there are 8487 images, with cadences of 900 seconds in jpg/h1*.jpg, starting with h1299704642.jpg at Wed 09 Mar 2011 21:04:02 UTC, and ending with h1310295070.jpg at Sun 10 Jul 2011 10:51:10 UTC.Images from Ridge A:HRCAM3 was taken to Ridge A and installed in PLATO-R during the 2011/2012 season by a team led by Craig Kuleas of the University of Arizona. In the images, the solar panels are at the top of the image, the Ubob cameras are at 40 degrees CW, the HEAT telescope is at 60 degrees, the SCAR flag is at 110 degrees, and the meteorological tower at 200 degrees. North is at approximately 20 degrees. The image reaches very close to the horizon in all directions.There are 12730 images, with cadences of 300 seconds, taken from Ridge A. The images are in raw/h3-*.raw, and start with h3-1331181001.raw at Thu 08 Mar 2012 04:30:01 UTC, and end with h3-1335099900.raw at Sun 22 Apr 2012 13:05:00 UTC.Processing the RAW images:exiftool is a convenient piece of free software for processing Canon RAW images. dcraw can be used to extract images.On a Linux computer you can use commands such as these:To list all the metadata in a RAW file:exiftool -all h1282890600.rawTo extract the PreviewImage and ThumbnailImage from a RAW file:exiftool -b -PreviewImage h1282890600.raw - h1282890600.jpgexiftool -b -ThumbnailImage h1282890600.raw - h1282890600-thumb.jpgTo copy metadata to a JPG file:exiftool -tagsFromFile h1282890600.raw -exif:all -overwrite_original h1282890600.jpg

本数据集包含使用HRCAM（High Resolution CAMera，高分辨率相机）设备拍摄的天空图像。HRCAM为一款数码单反相机（佳能EOS 50D，1500万像素），搭载适马（Sigma）4.5mm f/2.8鱼眼镜头，适配1.6倍裁切传感器以实现全天空覆盖拍摄。HRCAM主要由Daniel Luong-Van设计，Nick Tothill协助完成组装，Michael Ashley则在设计、组装、软件及设备运维方面提供了支持。

本数据集包含以下目录：
1. /documentation：收录描述该设备与相关研究成果的论文PDF及博士学位论文；
2. /raw：佳能RAW格式原始图像文件，即采集的原始图像；
3. /jpg：从部分原始文件中提取的JPG格式图像；
4. /thumbs：从部分原始文件中提取的缩略图。

HRCAM已推出多个版本，可通过佳能EOS 50D相机的序列号（存储于RAW图像文件中）区分具体版本。其中序列号为0330104673的设备部署于冰穹A（Dome A），2110703496部署于脊岭A（Ridge A），2210700089部署于富士冰穹（Dome Fuji）。

各目录下的图像文件名均包含曝光开始时的UNIX纪元时间（秒级）。若需将UNIX纪元时间转换为标准日期时间，可使用Linux系统的date命令，示例如下：`date -u -d @1282890600`

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### 冰穹A（Dome A）采集的图像
HRCAM初代设备于2010年1月首次安装于冰穹A的PLATO观测站。该相机经翻新后，于2015年重新部署至PLATO-A观测站。
本次采集的图像共12703张，采样间隔为240秒与660秒（对应不同曝光时长），存储路径为raw/h1*.raw，图像时间范围从2010年8月27日周五06:30:00 UTC对应的h1282890600.raw，至2011年1月21日周五10:00:00 UTC对应的h1295604000.raw。
此外，该目录下还有709张采样间隔为900秒的JPG格式图像，存储路径为jpg/h12*.jpg，时间范围从2010年8月27日周五13:22:04 UTC对应的h1282915324.jpg，至2010年9月19日周日19:51:59 UTC对应的h1284925919.jpg。
另有10339张采样间隔为120秒至1800秒的图像，存储路径为raw/h1-*.raw与jpg/h1-*.jpg，缩略图存储于thumbs/*jpg，时间范围从2015年1月22日周四12:45:03 UTC对应的h1-1421930703.jpg，至2015年6月14日周日03:30:25 UTC对应的h1-1434252625.jpg。

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### 富士冰穹（Dome Fuji）采集的图像
HRCAM2由日本第52次南极科考队于2010/2011赛季携带至富士冰穹，并安装于PLATO-F观测站。
该图像中，绿色发动机模块位于画面顶部，左右两侧及底部各有一个小型铱星天线，左下角的隔热白色箱体中安装有铱星Openport天线，同时还可拍到气象塔。“视觉之卵”位于画面右侧，略高于铱星天线位置。该图像可覆盖全地平线范围。
本次采集的图像共21336张，采样间隔为240秒与660秒（对应不同曝光时长），存储路径为raw/h1*.raw，时间范围从2011年1月30日周日04:30:40 UTC对应的h1296361840.raw，至2011年7月10日周日10:49:00 UTC对应的h1310294940.raw。
此外，该目录下还有8487张采样间隔为900秒的JPG格式图像，存储路径为jpg/h1*.jpg，时间范围从2011年3月9日周三21:04:02 UTC对应的h1299704642.jpg，至2011年7月10日周日10:51:10 UTC对应的h1310295070.jpg。

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### 脊岭A（Ridge A）采集的图像
HRCAM3由亚利桑那大学Craig Kuleas带领的团队于2011/2012赛季携带至脊岭A，并安装于PLATO-R观测站。
该图像中，太阳能板位于画面顶部，Ubob相机位于顺时针40度方向，HEAT望远镜位于60度方向，SCAR旗帜位于110度方向，气象塔位于200度方向。正北方向约为20度。该图像可覆盖至接近地平线的全范围。
本次采集的图像共12730张，采样间隔为300秒，存储路径为raw/h3-*.raw，时间范围从2012年3月8日周四04:30:01 UTC对应的h3-1331181001.raw，至2012年4月22日周日13:05:00 UTC对应的h3-1335099900.raw。

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### RAW图像处理
exiftool是一款便捷的免费开源软件，可用于处理佳能RAW格式图像；dcraw可用于提取图像文件。
在Linux系统中可使用如下命令：
1. 查看RAW文件的全部元数据：`exiftool -all h1282890600.raw`
2. 从RAW文件中提取预览图与缩略图：
`exiftool -b -PreviewImage h1282890600.raw - > h1282890600.jpg`
`exiftool -b -ThumbnailImage h1282890600.raw - > h1282890600-thumb.jpg`
3. 将RAW文件的元数据复制至JPG文件：`exiftool -tagsFromFile h1282890600.raw -exif:all -overwrite_original h1282890600.jpg`