OPERA Pipeline Calibrated Wavelength

Wavelength is corrected for:
  • Heliocentric velocity correction (middle of the exposure)
  • Spectrograph drift (using telluric lines)


    • The modified julian date from "MJDATE" fits keyword can be off by 2 to 7 seconds comparing to the open shutter time.
    Therefore the modified julian date is recomputed using time keyword in the fits file.

    The heliocentric velocity is computed using:
    1) the "SHUTOPEN" keyword to derive the modified julian date OR
    2) the "DATE-OBS" and "TIME-OBS" keywords to derive the modified julian date OR
    3) the "MJDATE" keyword, when the two previous options are not available.

    The heliocentric julian date at TT (taking care of the leap second) is used to calculate the final Heliocentric correction, which incluses the lunar, orbital and diurnal components.

    FITS KEYWORDS

    HRV = 17.2635 / heliocentric RV correction (km/s)
    HRVLUNAR= 0.00589814 / lunar component of HRV correction (km/s)
    HRVORBIT= 17.0642 / orbital component of HRV correction (km/s)
    HRVDIURN= 0.193403 / diurnal component of HRV correction (km/s)

    HJDUTC = 2457406.256036 / heliocentric Julian date (UTC)
    HJDTT = 2457406.256825 / heliocentric Julian date (TT)

    TELLRV = -0.0338706 / telluric RV correction (km/s)
    TELLERR = 0.298638 / telluric RV correction error (km/s)