Detrending

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Detrending

BPVietje
Hi All,

I'm new to exoplanet observations, but have analyzed 5 transits to date in AIJ.  I would like to learn more about the detrending process, and what is actually happening when I select airmass or another parameter.  Is there a relevant article or book chapter that describes the process -- maybe "Detrending for Idiots"?

I've read the threads in which the number and appropriate use of detrend parameters were discussed, but I have yet to find information on how the process works, statistically.

Thank you kindly,

Brad Vietje
Newbury, VT
www.nkaf.org
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Re: Detrending

karenacollins
Administrator
Hi Brad,

Detrending is explained mathematically in Section 4.4 and equation 5 of the AIJ paper available here on arXiv:

http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2017arXiv170104817C&link_type=PREPRINT&db_key=PRE

At a high level, first the best linear fit of a "trend" data set (such as airmass) to the light curve is found. That
results in a coefficient that is used to produce a scaled version of the trend dataset that is then subtracted from (or
divided into - if that option is selected) the light curve to remove the trend from the light curve dataset. The region
of the light curve used to find the best fit coefficient is defined by the "fit mode" selected on the "Multi-plot
Y-data" panel and the "left" and "right" markers on the "Multi-plot Main" panel. If the exoplanet transit light curve
fitting mode is selected, the full light curve is used, but the linear fit of the trend data set(s) is found
simultaneously with the best fitting transit model.

Karen