CBB filter LDCs now available for use with AstroImageJ

American Association of Variable Star Observers (AAVSO)
Fri, 07/01/2022 - 18:37

Dr. Antonio Claret from the Institute of Astrophysics of Andalusia and the Department of Theoretical Physics and the Cosmos, University of Granada, and I are publishing a Research Note in "Research Notes of the American Astronomical Society (RNAAS)" describing the advantages of the CBB filter for exoplanet differential astronomy (where transit depth chromaticity information is not needed).  Limb Darkening Coefficients (LDCs) are required for accurate exoplanetary modeling using AstroImageJ and similar tools.  Dr. Karen Collins posted a note on this work to the AstroImageJ forum this morning, AstroImageJ - Limb darkening coefficients for CBB filter (nabble.com) . 

The CBB was one of the primary filters used by Dr. Joshua Pepper in the KELT project.  The flux throughput of the CBB filter is 92% compared to 36% for the R filter, yet it reduces effective atmospheric extinction values for red and blue stars to just 8 mmag/airmass compared to 59 mmag/airmass for a clear filter.  Dr. Bruce Gary published an empirical analysis of the CBB filter which is summarized here: CBB Filter Advantages.pdf (cbbldc.com) .  In order to facilitate the use of the CBB filter I created a web interface providing the appropriate LDC values here: cbbldc.com .  This interface utilizes the latest LDC calculations by Dr. Claret and the LDC Power-2 law as well as the traditional Quadratic law based on the Atlas stellar atmospheric models.  Separately, Dr. Claret is publishing his latest research on the Power-2 law in the same journal.

Those wishing to use the CBB for their exoplanet transit differential photometry work may purchase the filter here: Astrodon ExoPlanet Light Curve Filters – FarpointAstro .

Ed Mullen