ImageHDU:
  BDARK:
    Description: height of downside dark reference region
    Flag: ""
    Format: I4
    Remark: 2(EMCCD)/0(NIR)
  BITPIX:
    Description: bits per data value
    Flag: ""
    Format: I2
    Remark: always 16 for raw data
  BSCALE:
    Description: ""
    Flag: ""
    Format: R8
    Remark: always 32768.0
  BUNIT:
    Description: physical unit of array values
    Flag: ""
    Format: C08
    Remark: always ‘ADU’
  BZERO:
    Description: ""
    Flag: ""
    Format: R8
    Remark: always 1.0
  CHIPLAB:
    Description: chip label
    Flag: ""
    Format: C08
    Remark: EMCCD/NIR
  CD1_1:
    Description: partial of first axis coordinate w.r.t. x
    Flag: ""
    Format: R8
    Remark: ""
  CD1_2:
    Description: partial of first axis coordinate w.r.t. y
    Flag: ""
    Format: R8
    Remark: ""
  CD2_1:
    Description: partial of second axis coordinate w.r.t. x
    Flag: ""
    Format: R8
    Remark: ""
  CD2_2:
    Description: partial of second axis coordinate w.r.t. y
    Flag: ""
    Format: R8
    Remark: ""
  CHIPTEMP:
    Description: chip temperature (in K)
    Flag: ""
    Format: R4
    Remark: ""
  CRPIX1:
    Description: x-coordinate of reference pixel
    Flag: ""
    Format: R8
    Remark: 小数点后1位有效数字
  CRPIX2:
    Description: y-coordinate of reference pixel
    Flag: ""
    Format: R8
    Remark: 小数点后1位有效数字
  CRVAL1:
    Description: first axis value at reference pixel
    Flag: ""
    Format: R8
    Remark: ""
  CRVAL2:
    Description: second axis value at reference pixel
    Flag: ""
    Format: R8
    Remark: ""
  CTYPE1:
    Description: the coordinate type for the first axis
    Flag: ""
    Format: C08
    Remark: always ‘RA---TAN’
  CTYPE2:
    Description: the coordinate type for the second axis
    Flag: ""
    Format: C08
    Remark: always ‘DEC--TAN’
  DATASEC:
    Description: data section
    Flag: ""
    Format: C20
    Remark: 1024*1024(EMCCD)/640*512(NIR)有效图像大小
  DETSIZE:
    Description: detector size
    Flag: ""
    Format: C20
    Remark: 1080*1050(EMCCD)/640*512(NIR)图像总大小
  DET_BIAS:
    Description: CCD bias voltage
    Flag: ""
    Format: R4
    Remark: ""
  DEWTEMP:
    Description: dewer temperature (in K)
    Flag: ""
    Format: R4
    Remark: ""
  EXPINDEX:
    Description: index of exploration
    Flag: ""
    Format: R4
    Remark: ""
  IMGINDEX:
    Description: index of image
    Flag: ""
    Format: R4
    Remark: ""
  IMG_DUR:
    Description: image frame exposure duration
    Flag: ""
    Format: R4
    Remark: ""
  IMG_CAB:
    Description: ""
    Flag: ""
    Format: R4
    Remark: ""
  IMG_PA:
    Description: position angle at IMG_CABT
    Flag: ""
    Format: R4
    Remark: ""
  IMG_RA:
    Description: RA of pointing (degree) at IMG_CABT
    Flag: ""
    Format: R4
    Remark: ""
  IMG_DEC:
    Description: DEC of pointing (degree) at IMG_CABT
    Flag: ""
    Format: R4
    Remark: ""
  EXPNUM:
    Description: number of exploration in this file
    Flag: ""
    Format: R4
    Remark: ""
  EMGAIN:
    Description: EMgain for EMCCD
    Flag: ""
    Format: R4
    Remark: ""
  IMG_EXPT:
    Description: exposure start time of this frame
    Flag: ""
    Format: R8
    Remark: 各模块给出的曝光开始时刻
  EXTNAME:
    Description: ""
    Flag: ""
    Format: C08
    Remark: ""
  EXTVER:
    Description: ""
    Flag: ""
    Format: I2
    Remark: always 1
  FILTER:
    Description: filter band
    Flag: ""
    Format: C08
    Remark: ""
  GAIN:
    Description: CCD gain
    Flag: ""
    Format: R4
    Remark: ""
  IWA:
    Description: inner working angle of CPIC
    Flag: ""
    Format: R4
    Remark: ""
  LDARK:
    Description: width of leftside dark reference region
    Flag: ""
    Format: I4
    Remark: 16(EMCCD)/0(NIR)
  LS_STAT:
    Description: laser status
    Flag: ""
    Format: C04
    Remark: on/off
  NAXIS:
    Description: number of data axes
    Flag: ""
    Format: I2
    Remark: always 2
  NAXIS1:
    Description: length of first data axis
    Flag: ""
    Format: I4
    Remark: ""
  NAXIS2:
    Description: length of second data axis
    Flag: ""
    Format: I4
    Remark: ""
  NCHAN:
    Description: number of readout channels
    Flag: ""
    Format: I2
    Remark: always 1
  OSCAN1:
    Description: horizontal overscan width
    Flag: ""
    Format: I4
    Remark: 16(EMCCD)/0(NIR)
  OSCAN2:
    Description: vertical overscan width
    Flag: ""
    Format: I4
    Remark: 18(EMCCD)/0(NIR)
  OWA:
    Description: outer working angle of CPIC
    Flag: ""
    Format: R4
    Remark: ""
  PIXSCAL:
    Description: pixel scale
    Flag: ""
    Format: R4
    Remark: ""
  PIXSIZE:
    Description: pixel size
    Flag: ""
    Format: R4
    Remark: ""
  PSCAN1:
    Description: horizontal prescan width
    Flag: ""
    Format: I4
    Remark: 8(EMCCD)/0(NIR)
  PSCAN2:
    Description: vertical prescan height
    Flag: ""
    Format: I4
    Remark: always 0
  RDARK:
    Description: width of rightside dark reference region
    Flag: ""
    Format: I4
    Remark: 16(EMCCD)/0(NIR)
  READTIME:
    Description: readout time
    Flag: ""
    Format: R4
    Remark: ""
  RON:
    Description: readout noise
    Flag: ""
    Format: R4
    Remark: ""
  ROSPEED:
    Description: readout speed (in MHz)
    Flag: ""
    Format: R4
    Remark: ""
  UDARK:
    Description: height of upside dark reference region
    Flag: ""
    Format: I4
    Remark: 6(EMCCD)/0(NIR)
  WCSAXES:
    Description: number of World Coordinate System axes
    Flag: ""
    Format: I2
    Remark: always 2
  WFSINFO1:
    Description: x-direction residuals of WFS of CPIC
    Flag: ""
    Format: R4
    Remark: ""
  WFSINFO2:
    Description: y-direction residuals of WFS of CPIC
    Flag: ""
    Format: R4
    Remark: ""
  XTENSION:
    Description: extension type
    Flag: ""
    Format: C08
    Remark: ""
  OTHERS:
    Description: ""
    Flag: ""
    Format: ""
    Remark: other specific parameters
  DETNAME:
    Description: detector serial number
    Flag: ""
    Format: C08
    Remark: ""
PrimaryHDU:
  BITPIX:
    Description: ""
    Flag: ""
    Format: I2
    Remark: ""
  CABEND:
    Description: ""
    Flag: ""
    Format: R8
    Remark: 曝光结束后，最近一次广播的绝对定位时间
  CABSTART:
    Description: ""
    Flag: ""
    Format: R8
    Remark: 曝光开始后，最近一次广播的绝对定位时间
  CHECKSUM:
    Description: SHA256 checksum of global headers
    Flag: ""
    Format: C65
    Remark: hdu-checksum
  DATE:
    Description: date this file was written
    Flag: ""
    Format: C20
    Remark: "(yyyy-mm-ddThh:mm:ss)"
  DATE-OBS:
    Description: date of the observation
    Flag: ""
    Format: C20
    Remark: 地面指令设置的曝光开始时刻 (yyyy-mm-ddThh:mm:ss)
  DEC_PNT0:
    Description: DEC of the pointing (degrees) at CABSTART
    Flag: ""
    Format: R8
    Remark: 太赫兹模块由星敏提供，其余模块由导星提供
  DEC_PNT1:
    Description: DEC of the pointing (degrees) at CABEND
    Flag: ""
    Format: R8
    Remark: 太赫兹模块由星敏提供，其余模块由导星提供
  EPOCH:
    Description: coordinate epoch
    Flag: ""
    Format: "R4 "
    Remark: 当前历元
  EQUINOX:
    Description: ""
    Flag: ""
    Format: R4
    Remark: always 2000.0
  EULER0_1:
    Description: Euler angle 1 at CABSTART
    Flag: ""
    Format: R8
    Remark: 姿态误差不大于0.05角秒
  EULER0_2:
    Description: Euler angle 2 at CABSTART
    Flag: ""
    Format: R8
    Remark: ""
  EULER0_3:
    Description: Euler angle 3 at CABSTART
    Flag: ""
    Format: R8
    Remark: ""
  EULER1_1:
    Description: Euler angle 1 at CABEND
    Flag: ""
    Format: R8
    Remark: 姿态误差不大于0.05角秒
  EULER1_2:
    Description: Euler angle 2 at CABEND
    Flag: ""
    Format: R8
    Remark: ""
  EULER1_3:
    Description: Euler angle 3 at CABEND
    Flag: ""
    Format: R8
    Remark: ""
  EXPEND:
    Description: exposure end time (MJD)
    Flag: ""
    Format: R8
    Remark: 各模块给出的曝光结束时刻
  EXPSTART:
    Description: exposure start time (MJD)
    Flag: ""
    Format: R8
    Remark: 各模块给出的曝光开始时刻
  EXPTIME:
    Description: exposure duration
    Flag: ""
    Format: R4
    Remark: EXPEND-EXPSTART
  EXTEND:
    Description: ""
    Flag: ""
    Format: L1
    Remark: always T
  FILENAME:
    Description: ""
    Flag: ""
    Format: C80
    Remark: CSST_PREFIX_TYPE_YYYYMMDDhhmmss_YYYYMMDDhhmmss_OBSID_MM_L0_VER
  FILETYPE:
    Description: type of data found in data file
    Flag: ""
    Format: C12
    Remark: ‘BIAS’, ‘DARK’, ‘FLAT’, ‘SCI’, etc
  FITSCREA:
    Description: FITS create software version
    Flag: ""
    Format: ""
    Remark: ""
  GROUPS:
    Description: ""
    Flag: ""
    Format: L1
    Remark: always F
  INSTRUME:
    Description: instrument used to acquire data
    Flag: ""
    Format: C06
    Remark: ‘MSC’, ‘MCI’, etc
  MOONANG0:
    Description: angle between moon and optical axis at CABSTART
    Flag: ""
    Format: R4
    Remark: CABSTART时刻，月亮与光轴的夹角
  MOONANG1:
    Description: angle between moon and optical axis at CABEND
    Flag: ""
    Format: R4
    Remark: CABEND时刻，月亮与视轴的夹角
  NAXIS:
    Description: ""
    Flag: ""
    Format: I2
    Remark: always 0
  NEXTEND:
    Description: number of array dimensions
    Flag: ""
    Format: I2
    Remark: always 1
  OBJECT:
    Description: object name
    Flag: ""
    Format: C30
    Remark: 主巡天可以使用天区编号
  OBJ_DEC:
    Description: DEC of the object (degrees)
    Flag: ""
    Format: R8
    Remark: ""
  OBJ_RA:
    Description: RA of the object (degrees)
    Flag: ""
    Format: R8
    Remark: ""
  OBSID:
    Description: observation ID
    Flag: ""
    Format: C11
    Remark: 观测编号，X+OBSTYPE+8位数字，X是设备编号
  POSI0_X:
    Description: orbital position in X direction at CABSTART
    Flag: ""
    Format: R8
    Remark: R=Sqrt(X^2+Y^2+Z^2)绝对误差不大于16.8公里（单倍中误差）
  POSI0_Y:
    Description: orbital position in Y direction at CABSTART
    Flag: ""
    Format: R8
    Remark: ""
  POSI0_Z:
    Description: orbital position in Z direction at CABSTART
    Flag: ""
    Format: R8
    Remark: ""
  POSI1_X:
    Description: orbital position in X direction at CABEND
    Flag: ""
    Format: R8
    Remark: R=Sqrt(X^2+Y^2+Z^2)绝对误差不大于16.8公里（单倍中误差）
  POSI1_Y:
    Description: orbital position in Y direction at CABEND
    Flag: ""
    Format: R8
    Remark: ""
  POSI1_Z:
    Description: orbital position in Z direction at CABEND
    Flag: ""
    Format: R8
    Remark: ""
  POS_ANG0:
    Description: position angle at CABSTART
    Flag: ""
    Format: R8
    Remark: CABSTART时刻，CSST发射坐标系下y轴与北天极的夹角精确到角秒
  POS_ANG1:
    Description: position angle at CABSTART at CABEND
    Flag: ""
    Format: R8
    Remark: CABEND时刻，CSST坐标框架下y轴与北天极的夹角精确到角秒
  RADECSYS:
    Description: reference coordinate system
    Flag: ""
    Format: C08
    Remark: always ‘ICRS’
  RA_PNT0:
    Description: RA of the pointing (degrees) at CABSTART
    Flag: ""
    Format: R8
    Remark: 太赫兹模块由星敏提供，其余模块由导星提供
  RA_PNT1:
    Description: RA of the pointing (degrees) at CABEND
    Flag: ""
    Format: R8
    Remark: 太赫兹模块由星敏提供，其余模块由导星提供
  REFFRAME:
    Description: guide star catalog version
    Flag: ""
    Format: C16
    Remark: e.g., CSSTGSC-1.0
  SATESWV:
    Description: software version in the satellite
    Flag: ""
    Format: C16
    Remark: ""
  SIMPLE:
    Description: ""
    Flag: ""
    Format: L1
    Remark: ""
  SUNANGL0:
    Description: angle between sun and optical axis at CABSTART
    Flag: ""
    Format: R4
    Remark: CABSTART 时刻，太阳与光轴的夹角
  SUNANGL1:
    Description: angle between sun and optical axis at CABEND
    Flag: ""
    Format: R4
    Remark: CABEND时刻，太阳与光轴的夹角
  TARGET:
    Description: target name (hhmmss+ddmmss)
    Flag: ""
    Format: C13
    Remark: hhmmss+ddmmss, 作为目标标识记录到秒，比RA和DEC精度低
  TELESCOP:
    Description: telescope used to acquire data
    Flag: ""
    Format: C06
    Remark: always ‘CSST’
  TEL_ALT0:
    Description: altitude refer to Earth limb at CABSTART
    Flag: ""
    Format: R8
    Remark: CABSTART时刻，地平面与光轴的夹角精确到0.1度
  TEL_ALT1:
    Description: altitude refer to Earth limb at CABEND
    Flag: ""
    Format: R8
    Remark: CABEND时刻，地平面与光轴的夹角精确到0.1度
  VELO0_X:
    Description: the orbital velocity in X direction at CABSTART
    Flag: ""
    Format: R8
    Remark: V=Sqrt(Vx^2+Vy^2+Vz^2) 误差不大于0.025米/秒（单倍中误差）
  VELO0_Y:
    Description: the orbital velocity in Y direction at CABSTART
    Flag: ""
    Format: R8
    Remark: ""
  VELO0_Z:
    Description: the orbital velocity in Z direction at CABSTART
    Flag: ""
    Format: R8
    Remark: ""
  VELO1_X:
    Description: the orbital velocity in X direction at CABEND
    Flag: ""
    Format: R8
    Remark: V=Sqrt(Vx^2+Vy^2+Vz^2) 误差不大于0.025米/秒（单倍中误差）
  VELO1_Y:
    Description: the orbital velocity in Y direction at CABEND
    Flag: ""
    Format: R8
    Remark: ""
  VELO1_Z:
    Description: the orbital velocity in Z direction at CABEND
    Flag: ""
    Format: R8
    Remark: ""
