#- DESI basic parameters
#- 18 Mar 2020  (unchanged from v15)
#- Parameters for calculating effective area, from DESI-0347v6
#-   trussarea = 0.5*(M1_diameter-obscuration_diameter) * M2_support_width
#-   geomarea = PI*(M1_diameter/2)^2 - PI*(obscuration_diameter/2)^2 - 4*trussarea
area:
    M1_diameter: 3.797          # meters
    obscuration_diameter: 1.8   # meters
    M2_support_width: 0.03      # meters
    geometric_area: 8.658739421 # m^2, derived

#- Fiber parameters, from DESI-0347v5
fibers:
    diameter_um: 107.0          # microns (canonical)
    diameter_arcsec: 1.52       # arcsec (average; derived quantity)

#- Fiber positioners, from DESI-0455v1
positioners:
    #- Patrol radius has maximum reach, and inner minimum unreachable
    radius_max: 6.0     # max patrol radius [mm]
    radius_min: 0.1     # best estimate min patrol radius [mm]
    
#- From DESI-0334v3 spectrograph design
spectro:
    fiber_spacing: 0.230        # center-to-center spacing on slit [mm]
    fiber_group_spacing: 0.556  # cen-to-cen gap between groups on slit [mm]
    fibers_per_group: 25        #
    groups_per_ccd: 20          #
    nfibers: 500                # should = fibers_per_group * groups_per_ccd

#- CCD parameters from DESI-0334v3 and DESI-0336v4; readnoise from CDR spec
#- read noise and darkcurrent updated from DESI-0347 v14
#- NOTE: wavelengths run in the Y direction
#- NOTE: npix_x does *not* include the prescanpixels
ccd:
    b:
        pixsize: 15.0       # pixel size [microns]
        npix_x: 4096        # number of pixels in x direction (# columns)
        npix_y: 4096        # number of pixels in y direction (# rows)
        prescanpixels: 4    # number of pre-scan pixels
        keepoutpixels: 5    # number of pixels at detector edge with large distortion
        readnoise: 3.29     # electrons/pixel RMS
        darkcurrent: 1.89   # electrons/hour/pixel
        gain: 1.0           # electrons per ADU
    r:
        pixsize: 15.0       # pixel size [microns]
        npix_x: 4114        # number of pixels in x direction (# columns)
        npix_y: 4128        # number of pixels in y direction (# rows)
        prescanpixels: 7    # number of pre-scan pixels
        keepoutpixels: 20   # number of pixels at detector edge with large distortion
        thickness: 250      # CCD thickness [microns]
        readnoise: 2.69     # electrons/pixel RMS
        darkcurrent: 1.14   # electrons/hour/pixel
        gain: 1.0           # electrons per ADU
    z:
        pixsize: 15.0       # pixel size [microns]
        npix_x: 4114        # number of pixels in x direction (# columns)
        npix_y: 4128        # number of pixels in y direction (# rows)
        prescanpixels: 7    # number of pre-scan pixels
        keepoutpixels: 20   # number of pixels at detector edge with large distortion
        thickness: 250      # CCD thickness [microns]
        readnoise: 2.69     # electrons/pixel RMS
        darkcurrent: 1.14   # electrons/hour/pixel
        gain: 1.0           # electrons per ADU
        
#- Exposure times
exptime_dark: 1000.0              # airmass=1 dust=0 reference exp time *TBC* [sec]
exptime_bright: 300.0        # default exp time for bright time
t_interexp_normal: 120       # time between exposures [seconds]
t_interexp_same_field: 60    # sec between exposures if repeating same field

#- Jacoby seeing (subtract in quadrature from Dey and Valdes seeing values)

jacoby_seeing: 0.219         # arcsec FWHM