Congratulations to KELT-South on KELT-10b

KELT-South is a competitor to WASP-South, and indeed sits near WASP-South on the same plateau at SAAO’s Sutherland observatory site, performing a similar transit search.

KELT-South have just announced their first discovery, KELT-10b, a highly inflated planet that is larger than Jupiter (at 1.4 Jupiter radii) but less massive than Saturn (at 0.68 Jupiter masses). With WASP-South, HATSouth, KELT-South and the imminent NGTS, there are now four ground-based transit searches discovering planets in the Southern skies.

One advantage of the competition is that we can “reverse engineer” other teams’ planets to improve our own procedures. Indeed, trying to work out why we missed HAT and KELT planets has previously revealed bugs in our software.

Since we cover millions of stars the only way to look for transits is by automated search routines, but these throw up so many “false positive” detections that in the end we have to select candidates by eye. Humans are fallible, and it seems we simply overlooked KELT-10b. We have only relatively sparse data on it, fewer than 5000 photometric points, but, still, the presence of a transit dip at the correct period seems obvious enough once one knows that it is there. Here are the WASP-South data folded on the transit period, and the periodogram analysis revealing the periodic dip:

WASP data on KELT-10b

Congratulations to the KELT-South team on getting there first and on a fine discovery!