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WFPC2 SYNPHOT photflam and Zeropoints

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) + PHOTZPT
and 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