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Tue, 11/02/2021 - 23:48
I am a new member to the group. I have an On-Axis guider and I use PHD2 for guiding. I am reading Dennis Conti's guide to Exoplanet best practices, but I have two questions. My filter wheel contains the following filters from Astrodon: Luminance, Red, Green, Blue, CBB, NIR, i', z', V.
Q1: Which is the best filter to use for general AstroImajeJ measurements (or is it a filter I do not yet have)?
Q2: Which is the best filter to use along with AstroImageJ to detect false positives (i.e. eclipsing binaries, vs. exoplanets)? Or would it be a filter I do not yet have?
Thanks,
Ed
Hi Ed,
The choice of filter - whether with AstroImageJ or any other exoplanet analysis program - depends on the objective of the observation. For example, if you are trying refine the period of a confirmed exoplanet by trying to get an accurate estimate of the transit midpoint, then the filter that provides the highest SNR would be best. On the other hand, if you are part of an exoplanet follow-up team, such as with TESS, you may be asked to use a particular filter to help determine if there is a chromaticity difference in the transit depth from one filter (e.g., blue) to another (e.g., red). If there is such a difference then this indicates that the transit is most likely due to an eclipsing binary vs. an exoplanet.
So, for "casual" exoplanet observing, your CBB or V filter should work fine.
Hope this helps.
Dennis
Dennis, The V filter transmits light between 500nm and 700nm. My CCD can pick up light all the way to 1000 nm. Why not just no filter at all for general exoplanet observing if you want to gather as much light as possible and maximize SNR?
Dennis, The V filter transmits light between 500nm and 700nm. My CCD can pick up light all the way to 1000 nm. Why not just no filter at all for general exoplanet observing if you want to gather as much light as possible and maximize SNR?
Hi Ed,
One advantage of using a standard filter is that you can then compute limb darkening coefficients (see https://astroutils.astronomy.osu.edu/exofast/limbdark.shtml) that are used in the model fitting.
Dennis
That makes sense. Thanks.
Dennis, I worked with Dr. Antonio Claret to determine the LDCs for the CBB filter. They are now available at: cbbldc.com Our work led to a paper in "Research Notes of the American Astronomical Society (RNAAS)"
Ed