record CatalogHeader() {
  STAR0: Int32LE,   # Subtract from star number to get sequence number
  STAR1: Int32LE,   # First star number in file
  STARN: Int32LE,   # Number of stars; <0 → coordinates J2000
  STNUM: Int32LE,   # ID scheme / name flag
  MPROP: Int32LE,   # Motion info: 0=none, 1=proper, 2=radial
  NMAG:  Int32LE,   # Number of magnitudes (0–10)
  NBENT: Int32LE    # Bytes per star entry
}

record StarEntry(STNUM, MPROP, NMAG) {
  when STNUM > 0 { XNO: Float32LE },               # Catalog number
  SRA0:  Float64LE,                                # Right Ascension
  SDEC0: Float64LE,                                # Declination
  ISP:   Bytes(2),                                 # Spectral type
  when abs(NMAG) > 0 { MAG: Int16LE[abs(NMAG)] },  # Magnitudes
  when MPROP >= 1 {
    XRPM: Float32LE,                               # R.A. proper motion
    XDPM: Float32LE                                # Dec. proper motion
  },
  when MPROP == 2 { SVEL: Float64LE },             # Radial velocity
  when STNUM < 0 { NAME: Bytes(-STNUM) }           # Object name
}

# File structure
header: CatalogHeader

# Parse the header to get the number of stars and entry parameters
STNUM = header.STNUM
MPROP = header.MPROP
NMAG  = header.NMAG
NBENT = header.NBENT
record_count = abs(header.STARN)

expect sizeof(StarEntry(STNUM, MPROP, NMAG)) == NBENT

stars: StarEntry(STNUM, MPROP, NMAG)[record_count]