Photometric follow-up of transiting planet candidates Marton Hidas UNSW

Transit searches ● Periodic drop in flux as planet transits host star ● Low probability of observing transit ➔ need many stars (~10000) ● Prefer bright stars (V<~13) ➔ wide-field (few degrees)

Wide-field transit searches ● Wide-field searches target “hot Jupiters” around F-M dwarfs – about 1 in 1000 stars has one in edge-on orbit – period: a few days – transit depth: ~0.01 mag – transit duration: ~3 hours

Wide-field transit searches One drawback: ● most have ~10” pixels AND ● look at crowded fields ➢ Blending ➢ Deeper eclipses become “planet-like” 1'

Photometric follow-up ● Resolve blended stars ● Identify star with transits & measure actual depth ● Two colours ➢ Remove eclipsing binaries ● Obtain higher precision lightcurve ➢ Can be fitted with model to obtain parameters of system

Photometric follow-up with PILOT Advantages: ● High spatial resolution ● Continuous time coverage ● Low scintillation & small variation in airmass ➢ high-precision photometry ● Targets are bright ➢ can be used as AO reference stars

Photometric follow-up with PILOT ● Follow-up in V & R, or V & I ● At shortest wavenengths, isoplanatic angle is ~10” ➢ PSF will vary significantly within region of interest (~60”), and with time! ➢ difficult to obtain high photometric precision ● Possible solutions ➢ Use only tip-tilt correction ➢ Use V for highest resolution, photometry in R, I (J?) ● PSF must be well sampled

Three-transit phase coverage D. Caldwell

South Pole Extrasolar Planet Search D. Caldwell