# The following file is from Jim Gunn, from June 2001. It should be # self-explanatory; for most purposes, you will want to use the second # column. Consider this file preliminary. # # These filter curves have been used to calculate the effective # wavelengths and the qtdl/l (see Chapter 8 of the Black Book) of the # filters; the values are: # # u 3551 0.0171 # g 4686 0.0893 # r 6166 0.0886 # i 7480 0.0591 # z 8932 0.0099 # # Table Caption For Response Functions # # The first column is the wavelength in \AAngstroms. The second column # (respt) is the quantum efficiency on the sky looking through 1.3 # airmasses at APO for a point source. The third column (resbig) is the # QE under these conditions for very large sources (size greater than # about 80 pixels) for which the infrared scattering is negligible. The # only filters for which the infrared scattering has any effect are r and # i; the scattering in the bluer chips is negligible, and the z chips are # not thinned and the phenomenon does not exist. The fourth column # (resnoa) is the response of the third column with {\it no} atmosphere, # and the fifth column is the assumed atmospheric transparency at {\it # one} airmass at APO. The tables were constructed using monochromator # illumination of the camera with a bandpass of about 100 \AA, sampled for # the u filter at 50 \AA intervals and for the others at 100 \AA # intervals. These measurements were compared with measured responses of # the component filters and detectors and three additional points were # interpolated using these data, two at the extreme toes and one # additional (in g, r, and i) at the point of the beginning of the sharp # cutoff of the shortpass interference filter. These points are necessary # in order to make spline interpolation of the response data well-behaved. # These spline-interpolated response data were then multiplied by measured # aluminum reflectivities and scaled atmospheric transmission to produce # the tables below. The overall normalization is somewhat uncertain, # but this uncertainty does not affect the shapes. Note, however, that # there has been no attempt to remove the finite resolution of the # monochromator measurements. These tables are the {\it averages} of the # responses for all six of the camera chips with a given filter. The # responses are in general very similar except in the z band, where the # nonuniformity of the infrared rolloff, presumably associated with # varying thickness of the epitaxial layer or perhaps the gate structures # in these thick devices, introduces variations in the effective wavelengths # of the filters of order 100 \AA. We are currently working on better # response functions and will present them when they become available, but # these will suffice for most applications. In all cases the first point # is a measured point, so the grid of wavelengths at which measurements # exist is a subset of the wavelength lists here. # # SDSS Camera u Response Function 47 Points # # lam respt resbig resnoa xatm 2980 0.0000 0.0000 0.0000 0.0727 3005 0.0001 0.0001 0.0014 0.0992 3030 0.0005 0.0005 0.0071 0.1308 3055 0.0013 0.0013 0.0127 0.1673 3080 0.0026 0.0026 0.0198 0.2075 3105 0.0052 0.0052 0.0314 0.2470 3130 0.0093 0.0093 0.0464 0.2862 3155 0.0161 0.0161 0.0629 0.3444 3180 0.0240 0.0240 0.0794 0.3920 3205 0.0323 0.0323 0.0949 0.4300 3230 0.0405 0.0405 0.1093 0.4585 3255 0.0485 0.0485 0.1229 0.4817 3280 0.0561 0.0561 0.1352 0.5007 3305 0.0634 0.0634 0.1458 0.5189 3330 0.0700 0.0700 0.1545 0.5351 3355 0.0756 0.0756 0.1617 0.5486 3380 0.0803 0.0803 0.1679 0.5581 3405 0.0848 0.0848 0.1737 0.5669 3430 0.0883 0.0883 0.1786 0.5727 3455 0.0917 0.0917 0.1819 0.5812 3480 0.0959 0.0959 0.1842 0.5959 3505 0.1001 0.1001 0.1860 0.6112 3530 0.1029 0.1029 0.1870 0.6221 3555 0.1044 0.1044 0.1868 0.6294 3580 0.1053 0.1053 0.1862 0.6350 3605 0.1063 0.1063 0.1858 0.6406 3630 0.1075 0.1075 0.1853 0.6476 3655 0.1085 0.1085 0.1841 0.6553 3680 0.1084 0.1084 0.1812 0.6631 3705 0.1064 0.1064 0.1754 0.6702 3730 0.1024 0.1024 0.1669 0.6763 3755 0.0966 0.0966 0.1558 0.6815 3780 0.0887 0.0887 0.1419 0.6863 3805 0.0787 0.0787 0.1247 0.6912 3830 0.0672 0.0672 0.1054 0.6965 3855 0.0549 0.0549 0.0851 0.7023 3880 0.0413 0.0413 0.0634 0.7088 3905 0.0268 0.0268 0.0405 0.7158 3930 0.0145 0.0145 0.0216 0.7235 3955 0.0075 0.0075 0.0110 0.7315 3980 0.0042 0.0042 0.0062 0.7393 4005 0.0022 0.0022 0.0032 0.7464 4030 0.0010 0.0010 0.0015 0.7526 4055 0.0006 0.0006 0.0008 0.7581 4080 0.0004 0.0004 0.0006 0.7631 4105 0.0002 0.0002 0.0003 0.7680 4130 0.0000 0.0000 0.0000 0.7727