The u'g'r'i'z' Standard Star System:

USNO40 Filters

USNO40 Filter Transmission Curves

The u'g'r'i'z' filters used on the USNO 40-in telescope at Flagstaff Station, Arizona, were manufactured by Asahi Spectra Co. Ltd. in Japan according to the specifications given at this URL.

Here, we present the tabulated transmission curves for each filter, which were measured in 1995 by the SDSS Japan Participation Group (JPG):

  • 3-inch filters for USNO
    u'
    g'
    r'
    i'
    z'

    USNO40 Response Functions

    These files were created by Jim Gunn and are response (QE) functions for the USNO 40-inch/SITe 1024^2 UV-coated CCD as best as is understood at this point (011218). The z' functions are quite uncertain, as we have no measurements of the USNO CCD at all; though the response through the visible and even into the uv is quite constant from device to device, the far IR response is quite variable. The QEs have been corrected for IR scattering and are the appropriate responses for point sources, NOT extended objects. These corrections are probably as uncertain as the underlying response is.

    For more details, consult this README file.

    As better measurements of the USNO40 response functions are determined, they will be placed on this website.

  • USNO40 Response Curves
    u'
    g'
    r'
    i'
    z'
    Return to Main Page