Re: Fit Mode selected but no fit line appears

Posted by karenacollins on Dec 03, 2016; 7:07pm
URL: http://astroimagej.170.s1.nabble.com/Fit-Mode-selected-but-no-fit-line-appears-tp553p556.html

Hi Ed,

Thanks for the data files. Indeed, the constant value of -1.0 in the
airmass column will cause the fit to ignore that detrend column and not
draw a line, because there is no best fit of a constant value to another
dataset (all fits are equal). If you have another valid detrend
parameter set in addition to airmass, you would have seen a fit line
regardless. In the case of your top light curve, airmass is constant,
and BJD_TDB is all NaNs, so neither column gives AIJ a valid detrend
dataset to fit.

If you calculated airmass and BJD_TDB using DP, make sure you set up the
target and observatory coordinates correctly in the DPCC panel, and
re-run DP. Also, there is a bug in the default value of the BJD_TDB fits
header name in the DP program. Follow these directions to correct the
BJD_TDB default setting:

http://astroimagej.1065399.n5.nabble.com/Calculate-BJD-TDB-in-Data-Processor-and-load-it-into-the-Multi-Aperture-measurements-table-td286.html

If you want to recalculate the airmass and BJD_TDB values without
re-running DP, follows these instructions:

http://astroimagej.1065399.n5.nabble.com/Add-new-astronomical-values-such-as-BJD-TDB-AIRMASS-etc-to-an-exisiting-measurements-table-td91.html

After you have valid airmass and BJD_TDB data columns, your fits should
work correctly.

Karen