Syntax:
-SYSREM Ninput_color Ninput_airmass initial_airmass_file sigma_clip1 sigma_clip2 saturation correctlc omodel [model_outdir] otrends [trend_outfile] useweights Example 1.$ ./vartools -l EXAMPLES/trendlist_tfa -header \ -rms \ -SYSREM 2 1 EXAMPLES/3 5. 5. 8. 1 \ 1 EXAMPLES/OUTDIR1 1 EXAMPLES/OUTDIR1/sysrem.trends 1 \ -rms #Name Mean_Mag_0 RMS_0 Expected_RMS_0 Npoints_0 \ SYSREM_MeanMag_1 SYSREM_Trend_0_Coeff_1 SYSREM_Trend_1_Coeff_1 SYSREM_Trend_2_Coeff_1 SYSREM_RMS_1 \ Mean_Mag_2 RMS_2 Expected_RMS_2 Npoints_2 EXAMPLES/4 10.35142 0.00209 0.00114 3227 \ 10.35130 -0.83218 -0.86967 -0.03662 0.00087 \ 10.35137 0.00116 0.00114 3227 EXAMPLES/5 10.43962 0.00288 0.00114 3903 \ 10.43976 -0.03154 -0.05758 -0.02459 0.00177 \ 10.43962 0.00197 0.00114 3903 EXAMPLES/6 10.52762 0.00209 0.00121 3933 \ 10.52774 0.28190 0.30516 0.02490 0.00104 \ 10.52762 0.00115 0.00121 3933 EXAMPLES/7 10.56966 0.00349 0.00116 3626 \ 10.56988 0.14423 0.11560 -0.02852 0.00239 \ 10.56969 0.00254 0.00116 3626 EXAMPLES/8 10.61152 0.00225 0.00125 3957 \ 10.61160 0.01083 0.00955 0.00017 0.00178 \ 10.61152 0.00181 0.00125 3957 EXAMPLES/9 10.73139 0.00187 0.00133 3954 \ 10.73148 0.14601 0.13900 -0.00614 0.00124 \ 10.73139 0.00142 0.00133 3954 EXAMPLES/10 10.87781 0.00236 0.00143 3974 \ 10.87792 0.23422 0.25903 0.02672 0.00105 \ 10.87781 0.00120 0.00143 3974
Example illustrating the syntax of the -SYSREM command. We apply SYSREM to the light curves in the list EXAMPLES/trendlist_tfa, using 2 initial "color"-like terms (corresponding to the second and third columns in EXAMPLES/trendlist_tfa) and one initial "airmass"-like term. For the "airmass"-like term was use the file EXAMPLES/3. We apply 5 sigma-clipping for determining the mean magnitudes of the light curves and for determining whether or not points contribute to the iterative SYSREM fit. We set the saturation magnitude to 8.0 and we correct the light curves. We output the SYSREM model light curves to the directory EXAMPLES/OUTDIR1 and we output the trends to the file EXAMPLES/OUTDIR1/sysrem.trends. We caluclate the RMS before and after applying -SYSREM to illustrate the effect of SYSREM on the light curves. In practice one would apply SYSREM to a much larger set of light curves, and would use the airmass, seeing, temperature and other known image-dependent parameters (i.e. parameters which differ from image to image, but are fixed for all stars in a given image) for the initial "airmass"-like terms, and parameters such as the ra/dec, star colors, and other known star-dependent parameters (i.e. parameters which differ from star to star, but are fixed for a given star over all images) for the initial "color"-like terms.