photcal fitparams fitting problems
sochuwing wrote on Sep 27, 2009
Hi all,
I have a question on fitparams task in photcal package.
I am doing BVR CCD photometry on Landolt standard fields. I carried out aperture photometry using phot task successfully. I created standard stars observation file, configuration file without any problem. However, when I tried to fit the color transformation parameters using fitparams task, I got unexpected values of fitted parameters with large errors. Below is a example:
Notice that the reduce chi values are closed to 1.0. And the residuals plots looked good although I manually deleted some data points. I expected that values of b2, v2, r2 should close to local atmospheric extinction.
I tried different sets of data and even different computer system but no improvement. Please help!
C. W. So
Hong Kong
I have a question on fitparams task in photcal package.
I am doing BVR CCD photometry on Landolt standard fields. I carried out aperture photometry using phot task successfully. I created standard stars observation file, configuration file without any problem. However, when I tried to fit the color transformation parameters using fitparams task, I got unexpected values of fitted parameters with large errors. Below is a example:
#EQUATION: BFIT
low_reject 3.
high_reject 3.
nreject 2
grow 0.
tol 0.001
maxiter 15
niterations 7
total_points 15
rejected 0
deleted 5
standard deviation 0.04107045
reduced chi 0.9571341
average error 0.04290982
average scatter 0.03426239
RMS 0.034362
parameter value error
b1 -22.4677525 14.0451870 (fit)
b2 0.9810821 11.9270010 (fit)
b3 -0.2237727 0.0381375 (fit)
b4 0.0000000 0.0000000 (constant)
#RESULTS: BFIT
# objectid function fit residuals sigma
109_537 INDEF INDEF INDEF INDEF
109_231 -10.894 -10.84491 -0.0490942 0.03500673
109_949 INDEF INDEF INDEF INDEF
109_954 INDEF INDEF INDEF INDEF
109_71 -9.607 -9.569576 -0.03742409 0.03919797
109_381 -8.973 -9.035948 0.06294823 0.04492829
109_199 -8.937 -8.974043 0.03704262 0.04646451
109_959 INDEF INDEF INDEF INDEF
109_375 -9.324 -9.339437 0.01543617 0.03830028
109_396 -9.301 -9.332361 0.03136158 0.06941117
109_84 -10.411 -10.39605 -0.01495171 0.03630304
109_197 -9.827 -9.839395 0.01239491 0.04130268
109_243 -8.858 -8.889539 0.03153896 0.06121202
109_255 -9.45 -9.441734 -0.008265495 0.03936891
109_956 INDEF INDEF INDEF INDEF
#EQUATION: VFIT
low_reject 3.
high_reject 3.
nreject 2
grow 0.
tol 0.001
maxiter 15
niterations 11
total_points 15
rejected 0
deleted 0
standard deviation 0.08987222
reduced chi 1.000351
average error 0.08984072
average scatter 0.07798248
RMS 0.08038416
parameter value error
v1 -20.4153061 11.1404839 (fit)
v2 -0.8760154 9.9203043 (fit)
v3 0.0217483 0.0581047 (fit)
v4 0.0000000 0.0000000 (constant)
#RESULTS: VFIT
# objectid function fit residuals sigma
109_537 -11.115 -11.03292 -0.08208466 0.07843537
109_231 -12.042 -12.03526 -0.006738663 0.07830828
109_949 -8.4 -8.553191 0.1531916 0.09232663
109_954 -8.818 -8.934447 0.1164474 0.08599858
109_71 -9.917 -9.904435 -0.01256466 0.07923684
109_381 -9.646 -9.6546 0.008600235 0.07942862
109_199 -10.458 -10.37309 -0.08490849 0.07970763
109_959 -8.401 -8.588625 0.1876249 0.1001911
109_375 -10.079 -10.0526 -0.02640343 0.07924813
109_396 -10.06 -10.05194 -0.008058548 0.09224026
109_84 -11.078 -10.99881 -0.07919121 0.07862103
109_197 -10.814 -10.78577 -0.02823257 0.08010784
109_243 -9.408 -9.426986 0.01898575 0.08845488
109_255 -10.261 -10.21959 -0.04141045 0.07917238
109_956 -6.708 -6.73173 0.02373028 0.0940321
#EQUATION: RFIT
low_reject 3.
high_reject 3.
nreject 2
grow 0.
tol 0.001
maxiter 15
niterations 10
total_points 15
rejected 0
deleted 7
standard deviation 0.07011595
reduced chi 1.000283
average error 0.07009614
average scatter 0.06854982
RMS 0.05543153
parameter value error
r1 0.6648800 25.5249767 (fit)
r2 -20.3206730 23.2387848 (fit)
r3 0.1417382 0.0997740 (fit)
r4 0.0000000 0.0000000 (constant)
#RESULTS: RFIT
# objectid function fit residuals sigma
109_537 -11.693 -11.6088 -0.08420181 0.068861
109_231 -12.904 -12.99983 0.09583092 0.06882004
109_949 -9.184 -9.217869 0.03386879 0.08076235
109_954 -9.861 -9.834419 -0.02658081 0.07265148
109_71 -10.339 -10.34616 0.007164955 0.07018296
109_381 -10.272 -10.29895 0.02695179 0.07017975
109_199 -11.614 -11.54502 -0.06898308 0.07022725
109_959 INDEF INDEF INDEF INDEF
109_375 INDEF INDEF INDEF INDEF
109_396 INDEF INDEF INDEF INDEF
109_84 INDEF INDEF INDEF INDEF
109_197 INDEF INDEF INDEF INDEF
109_243 INDEF INDEF INDEF INDEF
109_255 INDEF INDEF INDEF INDEF
109_956 -7.614 -7.644293 0.03029346 0.08211241
Notice that the reduce chi values are closed to 1.0. And the residuals plots looked good although I manually deleted some data points. I expected that values of b2, v2, r2 should close to local atmospheric extinction.
I tried different sets of data and even different computer system but no improvement. Please help!
C. W. So
Hong Kong
Last post on Sep 27, 2009