fastness! and delivery!

The hypothesis-combination trick mentioned yesterday did indeed work, speeding up Foreman-Mackey's exoplanet search code by a factor of about 30 and keeping the same result, which is that we can detect Earth-like exoplanets on year-ish orbits around at least some Sun-like stars in the Kepler data. Now are there any? This speed-up, combined with the four orders of magnitude Foreman-Mackey got this weekend makes for a total speed up of 105.5, all in one crazy week. And then at lunch, Mike O'Neil (NYU) told us that given the form of our Gaussian Process kernel, he could probably get us another substantial speed-up using something called a "fast Gaussian transform". If this turns out to be true (we have to do some math to check), our exoplanet search could get down to less than a minute per star (which would be dandy).

In other overwhelming-force news, Fadely delivered psf-model fits to thousands of stars in HST WFC3 IR-channel data, showing that we can do a very good job of modeling the pixel-level data in preparation for flat-field determination. And Hou delivered a complete manuscript draft on his diffusive nested ensemble sampler. So it was a great day of hard work by my team paying off handsomely.


  1. Hi David, I'm currently analyzing WFC3 images, can you tell me where are your PSF models from? Besides IR-channel, do you have any idea of UVIS-channel PSF? Thanks!

  2. We are using the TinyTim PSF right now. We think there might be better options, but we don't know what they are yet.

    1. Maybe there are some better choice, e.g. hybrid PSFs build from tinytim and stars, see Fig 1 and Fig 2 of http://adsabs.harvard.edu/abs/2012ApJS..203...24V . The problem is the UVIS psf, I have found a significant mismatch for Tinytim PSFs...