If entered with good status this routine calculates the variance between a SKYDIP dataset and the theoretical curve generated by the the sky and telescope parameters in FIT. Additionally, the residual of the fit is also returned (absolute value of measured data mins fitted values). Data points with bad quality will be ignored. If no valid data points are found then an error will be reported and bad status returned. The data are passed in via common.

The FIT vector is composed as follows:-

• x(1) = ETA_TEL

• x(2) = B

• x(3) = TAU

For a given airmass:-

$$J_{}$$ theory = (1-${\eta }_{}$ tel) J_tel + ${\eta }_{}$ telJ_atm (1-B $exp\left(-\tau Airmass\right))\text{(65)}$$$ $$J_{}$$ atm = J_amb X_G (66) $$$$ $$X_G=1+\frac{h1\times h2}{J_{}}$$ amb $exp\left(-\tau \times Airmass\left(i\right)/X\text{\_}Gconst\right)\text{(67)}$$$ Invocation CALL SCULIB_SKYDIP_VAR (RESIDUAL, VAR, N, FIT, NDEG, STATUS) Arguments RESIDUAL = DOUBLE PRECISION (Returned) residual of the fit (absolute difference between the model and the data) VAR = DOUBLE PRECISION (Returned) the chi-squared value of the current fit N = INTEGER (Given) the number of parameters being fit, should be 3 FIT (N) = DOUBLE PRECISION (Given) the fit parameters:- FIT (1) = ETA_TEL FIT (2) = B FIT (3) = TAUZ NDEG = INTEGER (Given) the number of degrees of freedom STATUS = INTEGER (Given and returned) global status Copyright Copyright ©1995-2000 Particle Physics and Astronomy Research Council. All Rights Reserved. ←Prev  SURF Programming Interface Next→  TOC ↑