Table of new SYNPHOT photflams and zeropoints (updated May, 1997).
This table presents the new photflams and zeropoints based on the May 1997 WFPC2 SYNPHOT update. The older photflams from the previous version of the SYNPHOT tables are included as well.
The zeropoints in ST mags are derived from
m = -2.5log10(photflam) + PHOTZPTand are based on constant flux density per unit wavelength (and thus result in constant magnitudes for spectra having constant flux per unit wavelength). PHOTZPT is always -21.1.
Vega mags provide a good approximation to the more conventional photometric systems (where Vega is zero in any passband). The difference required to convert ST mags to Vega mags was obtained by running the STSDAS task 'calcphot' using a Bruzual model spectrum (the correction is independent of spectrum, but calcphot requires an input spectrum). For more details on SYNPHOT, please see the STSDAS SYNPHOT guide at: stsdas.stsci.edu/Files/SynphotManual.pdf
About the May 1997 SYNPHOT Table Update:
The STSDAS tables used by SYNPHOT to provide the photometric calibration information in the image headers (photflam, pivwav, etc.) have been updated based on new calibration data. Details concerning the changes will be documented in an Instrument Science Report to be issued later in early July. All UV filters shortward of F439W were updated, as well as some of the more frequently-used broadband filters redward of F439W (F450W, F555W, F606W, F675W, F702W, F785LP, F791W, F814W, F850LP, and F1042M). Changes were installed in the OPUS pipeline May 16, 1997.
With a few exceptions, changes to non-UV filter modes were relatively minor: generally ~1-2% or less. F785LP, F850LP, and F1042M were more: ~1-4%, ~1-6$, and ~2-15% for them, respectively, depending on the chip. The UV filters required somewhat larger changes to bring SYNPHOT into agreement with the observations, ranging from ~2% (e.g., F255W and F300W) to ~5% (F170W, F218W) to 10% or more (F160BW, F375N).
The new tables, along with a README file (containing history of all WFPC2 SYNPHOT updates), are available via anonymous ftp to stsci.edu, in the directory cdbs/comp/wfpc2. Note that the tables are in binary STSDAS format, readable with tasks in the IRAF/STSDAS 'ttools' and SYNPHOT packages. A table summarizing the photflam changes and new zero-points, as well as the README file (guide to WFPC2 SYNPHOT tables) and ASCII versions of the tables, and Photometry Cookbook, can all be found on the WFPC2 Photometry Webpage.obsmode photflam(old) photflam(new) ZP(STmag) ZP(vegamag) wfpc2,1,f122m,a2d7 7.919e-15 8.088e-15 14.130 13.768 wfpc2,1,f160bw,a2d7 4.681e-15 5.212e-15 14.607 14.985 wfpc2,1,f170w,a2d7 1.486e-15 1.551e-15 15.923 16.335 wfpc2,1,f185w,a2d7 1.921e-15 2.063e-15 15.614 16.025 wfpc2,1,f218w,a2d7 1.019e-15 1.071e-15 16.325 16.557 wfpc2,1,f255w,a2d7 5.354e-16 5.736e-16 17.004 17.019 wfpc2,1,f300w,a2d7 5.927e-17 6.137e-17 19.430 19.406 wfpc2,1,f336w,a2d7 5.730e-17 5.613e-17 19.527 19.429 wfpc2,1,f343n,a2d7 3.885e-15 8.285e-15 14.104 13.990 wfpc2,1,f375n,a2d7 3.234e-15 2.860e-15 15.259 15.204 wfpc2,1,f380w,a2d7 2.537e-17 2.558e-17 20.380 20.939 wfpc2,1,f390n,a2d7 6.538e-16 6.764e-16 16.824 17.503 wfpc2,1,f410m,a2d7 1.032e-16 1.031e-16 18.867 19.635 wfpc2,1,f437n,a2d7 7.419e-16 7.400e-16 16.727 17.266 wfpc2,1,f439w,a2d7 2.993e-17 2.945e-17 20.227 20.884 wfpc2,1,f450w,a2d7 8.948e-18 9.022e-18 21.512 21.987 wfpc2,1,f467m,a2d7 5.783e-17 5.763e-17 19.498 19.985 wfpc2,1,f469n,a2d7 5.359e-16 5.340e-16 17.081 17.547 wfpc2,1,f487n,a2d7 3.960e-16 3.945e-16 17.410 17.356 wfpc2,1,f502n,a2d7 3.018e-16 3.005e-16 17.705 17.965 wfpc2,1,f547m,a2d7 7.724e-18 7.691e-18 21.685 21.662 wfpc2,1,f555w,a2d7 3.491e-18 3.483e-18 22.545 22.545 wfpc2,1,f569w,a2d7 4.169e-18 4.150e-18 22.355 22.241 wfpc2,1,f588n,a2d7 6.152e-17 6.125e-17 19.432 19.172 wfpc2,1,f606w,a2d7 1.881e-18 1.900e-18 23.203 22.887 wfpc2,1,f622w,a2d7 2.805e-18 2.789e-18 22.787 22.363 wfpc2,1,f631n,a2d7 9.199e-17 9.148e-17 18.997 18.514 wfpc2,1,f656n,a2d7 1.471e-16 1.461e-16 18.488 17.564 wfpc2,1,f658n,a2d7 1.043e-16 1.036e-16 18.862 18.115 wfpc2,1,f673n,a2d7 6.047e-17 5.999e-17 19.455 18.753 wfpc2,1,f675w,a2d7 2.906e-18 2.899e-18 22.744 22.042 wfpc2,1,f702w,a2d7 1.870e-18 1.872e-18 23.219 22.428 wfpc2,1,f785lp,a2d7 4.785e-18 4.727e-18 22.213 20.688 wfpc2,1,f791w,a2d7 2.933e-18 2.960e-18 22.722 21.498 wfpc2,1,f814w,a2d7 2.504e-18 2.508e-18 22.902 21.639 wfpc2,1,f850lp,a2d7 8.422e-18 8.357e-18 21.595 19.943 wfpc2,1,f953n,a2d7 2.571e-16 2.333e-16 17.980 16.076 wfpc2,1,f1042m,a2d7 1.956e-16 1.985e-16 18.156 16.148 wfpc2,1,fquvn,a2d15 1.392e-15 1.344e-15 16.079 16.319 wfpc2,1,fqch4n15,a2d15 1.885e-16 1.800e-16 18.262 17.829 wfpc2,1,fqch4p15,a2d15 3.808e-16 3.518e-16 17.534 16.028 wfpc2,2,f122m,a2d7 7.856e-15 7.381e-15 14.230 13.868 wfpc2,2,f160bw,a2d7 4.644e-15 4.563e-15 14.752 15.126 wfpc2,2,f170w,a2d7 1.474e-15 1.398e-15 16.036 16.454 wfpc2,2,f185w,a2d7 1.905e-15 1.872e-15 15.719 16.132 wfpc2,2,f218w,a2d7 1.011e-15 9.887e-16 16.412 16.646 wfpc2,2,f255w,a2d7 5.312e-16 5.414e-16 17.066 17.082 wfpc2,2,f300w,a2d7 5.880e-17 5.891e-17 19.475 19.451 wfpc2,2,f336w,a2d7 5.684e-17 5.445e-17 19.560 19.462 wfpc2,2,f343n,a2d7 3.854e-15 8.052e-15 14.135 14.021 wfpc2,2,f375n,a2d7 3.208e-15 2.796e-15 15.284 15.229 wfpc2,2,f380w,a2d7 2.517e-17 2.508e-17 20.401 20.959 wfpc2,2,f390n,a2d7 6.486e-16 6.630e-16 16.846 17.524 wfpc2,2,f410m,a2d7 1.024e-16 1.013e-16 18.886 19.654 wfpc2,2,f437n,a2d7 7.360e-16 7.276e-16 16.745 17.284 wfpc2,2,f439w,a2d7 2.969e-17 2.895e-17 20.246 20.903 wfpc2,2,f450w,a2d7 8.877e-18 8.856e-18 21.532 22.007 wfpc2,2,f467m,a2d7 5.737e-17 5.660e-17 19.518 20.004 wfpc2,2,f469n,a2d7 5.316e-16 5.244e-16 17.101 17.566 wfpc2,2,f487n,a2d7 3.928e-16 3.871e-16 17.430 17.377 wfpc2,2,f502n,a2d7 2.993e-16 2.947e-16 17.727 17.987 wfpc2,2,f547m,a2d7 7.662e-18 7.502e-18 21.712 21.689 wfpc2,2,f555w,a2d7 3.464e-18 3.396e-18 22.573 22.571 wfpc2,2,f569w,a2d7 4.136e-18 4.040e-18 22.384 22.269 wfpc2,2,f588n,a2d7 6.103e-17 5.949e-17 19.464 19.204 wfpc2,2,f606w,a2d7 1.865e-18 1.842e-18 23.236 22.919 wfpc2,2,f622w,a2d7 2.782e-18 2.700e-18 22.821 22.397 wfpc2,2,f631n,a2d7 9.126e-17 8.848e-17 19.033 18.550 wfpc2,2,f656n,a2d7 1.459e-16 1.410e-16 18.527 17.603 wfpc2,2,f658n,a2d7 1.034e-16 9.992e-17 18.901 18.154 wfpc2,2,f673n,a2d7 5.999e-17 5.785e-17 19.494 18.793 wfpc2,2,f675w,a2d7 2.882e-18 2.797e-18 22.783 22.080 wfpc2,2,f702w,a2d7 1.855e-18 1.809e-18 23.256 22.466 wfpc2,2,f785lp,a2d7 4.747e-18 4.737e-18 22.211 20.692 wfpc2,2,f791w,a2d7 2.910e-18 2.883e-18 22.750 21.529 wfpc2,2,f814w,a2d7 2.484e-18 2.458e-18 22.924 21.665 wfpc2,2,f850lp,a2d7 8.355e-18 8.533e-18 21.572 19.924 wfpc2,2,f953n,a2d7 2.551e-16 2.448e-16 17.928 16.024 wfpc2,2,f1042m,a2d7 1.941e-16 2.228e-16 18.030 16.024 wfpc2,2,fquvn,a2d15 8.631e-16 8.251e-16 16.609 17.369 wfpc2,2,fquvn33,a2d15 1.392e-15 1.325e-15 16.094 16.334 wfpc2,2,fqch4n,a2d15 2.548e-16 2.719e-16 17.814 17.812 wfpc2,2,fqch4n33,a2d15 1.885e-16 1.758e-16 18.288 17.855 wfpc2,3,f122m,a2d7 7.844e-15 8.204e-15 14.115 13.752 wfpc2,3,f160bw,a2d7 4.637e-15 5.418e-15 14.565 14.946 wfpc2,3,f170w,a2d7 1.472e-15 1.578e-15 15.905 16.313 wfpc2,3,f185w,a2d7 1.902e-15 2.083e-15 15.603 16.014 wfpc2,3,f218w,a2d7 1.010e-15 1.069e-15 16.327 16.558 wfpc2,3,f255w,a2d7 5.304e-16 5.640e-16 17.022 17.037 wfpc2,3,f300w,a2d7 5.871e-17 5.985e-17 19.457 19.433 wfpc2,3,f336w,a2d7 5.675e-17 5.451e-17 19.559 19.460 wfpc2,3,f343n,a2d7 3.848e-15 8.040e-15 14.137 14.023 wfpc2,3,f375n,a2d7 3.203e-15 2.772e-15 15.293 15.238 wfpc2,3,f380w,a2d7 2.513e-17 2.481e-17 20.414 20.972 wfpc2,3,f390n,a2d7 6.476e-16 6.553e-16 16.859 17.537 wfpc2,3,f410m,a2d7 1.022e-16 9.990e-17 18.901 19.669 wfpc2,3,f437n,a2d7 7.348e-16 7.188e-16 16.758 17.297 wfpc2,3,f439w,a2d7 2.964e-17 2.860e-17 20.259 20.916 wfpc2,3,f450w,a2d7 8.864e-18 8.797e-18 21.539 22.016 wfpc2,3,f467m,a2d7 5.728e-17 5.621e-17 19.525 20.012 wfpc2,3,f469n,a2d7 5.308e-16 5.211e-16 17.108 17.573 wfpc2,3,f487n,a2d7 3.922e-16 3.858e-16 17.434 17.380 wfpc2,3,f502n,a2d7 2.989e-16 2.944e-16 17.728 17.988 wfpc2,3,f547m,a2d7 7.650e-18 7.595e-18 21.699 21.676 wfpc2,3,f555w,a2d7 3.458e-18 3.439e-18 22.559 22.561 wfpc2,3,f569w,a2d7 4.129e-18 4.108e-18 22.366 22.253 wfpc2,3,f588n,a2d7 6.094e-17 6.083e-17 19.440 19.179 wfpc2,3,f606w,a2d7 1.863e-18 1.888e-18 23.210 22.896 wfpc2,3,f622w,a2d7 2.778e-18 2.778e-18 22.791 22.368 wfpc2,3,f631n,a2d7 9.112e-17 9.129e-17 18.999 18.516 wfpc2,3,f656n,a2d7 1.457e-16 1.461e-16 18.488 17.564 wfpc2,3,f658n,a2d7 1.033e-16 1.036e-16 18.862 18.115 wfpc2,3,f673n,a2d7 5.990e-17 6.003e-17 19.454 18.753 wfpc2,3,f675w,a2d7 2.878e-18 2.898e-18 22.745 22.042 wfpc2,3,f702w,a2d7 1.852e-18 1.867e-18 23.222 22.431 wfpc2,3,f785lp,a2d7 4.739e-18 4.492e-18 22.269 20.738 wfpc2,3,f791w,a2d7 2.905e-18 2.913e-18 22.739 21.512 wfpc2,3,f814w,a2d7 2.480e-18 2.449e-18 22.927 21.659 wfpc2,3,f850lp,a2d7 8.342e-18 7.771e-18 21.674 20.018 wfpc2,3,f953n,a2d7 2.547e-16 2.107e-16 18.091 16.186 wfpc2,3,f1042m,a2d7 1.938e-16 1.683e-16 18.334 16.326 wfpc2,3,fquvn,a2d15 1.135e-15 1.084e-15 16.312 17.042 wfpc2,3,fqch4n,a2d15 3.808e-16 3.366e-16 17.582 16.076 wfpc2,4,f122m,a2d7 8.049e-15 8.003e-15 14.142 13.778 wfpc2,4,f160bw,a2d7 4.758e-15 5.133e-15 14.624 15.002 wfpc2,4,f170w,a2d7 1.510e-15 1.531e-15 15.938 16.350 wfpc2,4,f185w,a2d7 1.952e-15 2.036e-15 15.628 16.040 wfpc2,4,f218w,a2d7 1.036e-15 1.059e-15 16.338 16.570 wfpc2,4,f255w,a2d7 5.442e-16 5.681e-16 17.014 17.029 wfpc2,4,f300w,a2d7 6.024e-17 6.097e-17 19.437 19.413 wfpc2,4,f336w,a2d7 5.824e-17 5.590e-17 19.531 19.433 wfpc2,4,f343n,a2d7 3.949e-15 8.255e-15 14.108 13.994 wfpc2,4,f375n,a2d7 3.287e-15 2.855e-15 15.261 15.206 wfpc2,4,f380w,a2d7 2.579e-17 2.558e-17 20.380 20.938 wfpc2,4,f390n,a2d7 6.645e-16 6.759e-16 16.825 17.504 wfpc2,4,f410m,a2d7 1.049e-16 1.031e-16 18.866 19.634 wfpc2,4,f437n,a2d7 7.540e-16 7.416e-16 16.725 17.263 wfpc2,4,f439w,a2d7 3.042e-17 2.951e-17 20.225 20.882 wfpc2,4,f450w,a2d7 9.095e-18 9.053e-18 21.508 21.984 wfpc2,4,f467m,a2d7 5.878e-17 5.786e-17 19.494 19.980 wfpc2,4,f469n,a2d7 5.447e-16 5.362e-16 17.077 17.542 wfpc2,4,f487n,a2d7 4.025e-16 3.964e-16 17.405 17.351 wfpc2,4,f502n,a2d7 3.067e-16 3.022e-16 17.699 17.959 wfpc2,4,f547m,a2d7 7.850e-18 7.747e-18 21.677 21.654 wfpc2,4,f555w,a2d7 3.549e-18 3.507e-18 22.538 22.538 wfpc2,4,f569w,a2d7 4.237e-18 4.181e-18 22.347 22.233 wfpc2,4,f588n,a2d7 6.253e-17 6.175e-17 19.424 19.163 wfpc2,4,f606w,a2d7 1.911e-18 1.914e-18 23.195 22.880 wfpc2,4,f622w,a2d7 2.851e-18 2.811e-18 22.778 22.354 wfpc2,4,f631n,a2d7 9.350e-17 9.223e-17 18.988 18.505 wfpc2,4,f656n,a2d7 1.495e-16 1.473e-16 18.480 17.556 wfpc2,4,f658n,a2d7 1.060e-16 1.044e-16 18.854 18.107 wfpc2,4,f673n,a2d7 6.147e-17 6.043e-17 19.447 18.745 wfpc2,4,f675w,a2d7 2.953e-18 2.919e-18 22.737 22.034 wfpc2,4,f702w,a2d7 1.901e-18 1.883e-18 23.213 22.422 wfpc2,4,f785lp,a2d7 4.863e-18 4.666e-18 22.227 20.701 wfpc2,4,f791w,a2d7 2.981e-18 2.956e-18 22.723 21.498 wfpc2,4,f814w,a2d7 2.545e-18 2.498e-18 22.906 21.641 wfpc2,4,f850lp,a2d7 8.560e-18 8.194e-18 21.616 19.964 wfpc2,4,f953n,a2d7 2.613e-16 2.268e-16 18.011 16.107 wfpc2,4,f1042m,a2d7 1.988e-16 1.897e-16 18.205 16.197 wfpc2,4,fquvn,a2d15 1.468e-15 1.403e-15 16.032 16.624 wfpc2,4,fqch4n,a2d15 1.716e-16 1.651e-16 18.356 17.387