Search

A systematic calibration approach is presented to correlate the digital output of an infrared camera and the scene temperature. Aided by the optoelectronic properties of the camera, as few as two experimental data points are needed to establish this correlation. This approach can readily include the effects of atmospheric transmission, scene emissivity, and different background subtractions. Hence, the temperature conversion in flight can be reliably obtained from laboratory calibration. The conversion function can also be used to identify the camera’s thermal sensitivity and temperature resolution, which are important information in different space missions. In applying this calibration procedure to a laboratory camera and the compact thermal imager onboard the International Space Station, its validity is confirmed.

We present time series photometry of the M dwarf transiting exoplanet system GJ 436 obtained with the Extrasolar Planet Observation and Characterization (EPOCh) component of the NASA EPOXI mission. We conduct a search of the high-precision time series for additional planets around GJ 436, which could be revealed either directly through their photometric transits or indirectly through the variations these second planets induce on the transits of the previously known planet. In the case of GJ 436, the presence of a second planet is perhaps indicated by the residual orbital eccentricity of the known hot Neptune companion. We find no candidate transits with significance higher than our detection limit. From Monte Carlo tests of the time series, we rule out transiting planets larger than 1.5 R [?] interior to GJ 436b with 95% confidence and larger than 1.25 R [?] with 80% confidence. Assuming coplanarity of additional planets with the orbit of GJ 436b, we cannot expect that putative planets with orbital periods longer than about 3.4 days will transit. However, if such a planet were to transit, we would rule out planets larger than 2.0 R [?] with orbital periods less than 8.5 days with 95% confidence. We also place dynamical constraints on additional bodies in the GJ 436 system, independent of radial velocity measurements. Our analysis should serve as a useful guide for similar analyses of transiting exoplanets for which radial velocity measurements are not available, such as those discovered by the Kepler mission. From the lack of observed secular perturbations, we set upper limits on the mass of a second planet as small as 10 M [?] in coplanar orbits and 1 M [?] in non-coplanar orbits close to GJ 436b. We present refined estimates of the system parameters for GJ 436. We find P = 2.64389579 +- 0.00000080 d, R [?] = 0.437 +- 0.016 R , and Rp = 3.880 +- 0.147 R [?]. We also report a sinusoidal modulation in the GJ 436 light curve that we attribute to star spots. This signal is best fit by a period of 9.01 days, although the duration of the EPOCh observations may not have been long enough to resolve the full rotation period of the star.

We present time series photometry and constraints on additional planets in five of the exoplanetary systems studied by the EPOCh (Extrasolar Planet Observation and Characterization) component of the NASA EPOXI mission: HAT-P-4, TrES-3, TrES-2, WASP-3, and HAT-P-7. We conduct a search of the high-precision time series for photometric transits of additional planets. We find no candidate transits with significance higher than our detection limit. From Monte Carlo tests of the time series using putative periods from 0.5 days to 7 days, we demonstrate the sensitivity to detect Neptune-sized companions around TrES-2, sub-Saturn-sized companions in the HAT-P-4, TrES-3, and WASP-3 systems, and Saturn-sized companions around HAT-P-7. We investigate in particular our sensitivity to additional transits in the dynamically favorable 3:2 and 2:1 exterior resonances with the known exoplanets: if we assume coplanar orbits with the known planets, then companions in these resonances with HAT-P-4b, WASP-3b, and HAT-P-7b would be expected to transit, and we can set lower limits on the radii of companions in these systems. In the nearly grazing exoplanetary systems TrES-3 and TrES-2, additional coplanar planets in these resonances are not expected to transit. However, we place lower limits on the radii of companions that would transit if the orbits were misaligned by 2.deg0 and 1.deg4 for TrES-3 and TrES-2, respectively.

As part of the NASA EPOXI Mission of Opportunity, we observed seven known transiting extrasolar planet systems in order to construct time series photometry of extremely high phase coverage and precision. Here we present the results for four "hot-Jupiter systems" with near-solar stars--HAT-P-4, TrES-3, TrES-2, and WASP-3. We observe 10 transits of HAT-P-4, estimating the planet radius Rp = 1.332 +- 0.052 R Jup, the stellar radius R [?] = 1.602 +- 0.061 R , the inclination i = 89.67 +- 0.30 deg, and the transit duration from first to fourth contact t = 255.6 +- 1.9 minutes. For TrES-3, we observe seven transits and find Rp = 1.320 +- 0.057 R Jup, R [?] = 0.817 +- 0.022 R , i = 81.99 +- 0.30 deg, and t = 81.9 +- 1.1 minutes. We also note a long-term variability in the TrES-3 light curve, which may be due to star spots. We observe nine transits of TrES-2 and find Rp = 1.169 +- 0.034 R Jup, R [?] = 0.940 +- 0.026 R , i = 84.15 +- 0.16 deg, and t = 107.3 +- 1.1 minutes. Finally, we observe eight transits of WASP-3, finding Rp = 1.385 +- 0.060 R Jup, R [?] = 1.354 +- 0.056 R , i = 84.22 +- 0.81 deg, and t = 167.3 +- 1.3 minutes. We present refined orbital periods and times of transit for each target. We state 95% confidence upper limits on the secondary eclipse depths in our broadband visible bandpass centered on 650 nm. These limits are 0.073% for HAT-P-4, 0.062% for TrES-3, 0.16% for TrES-2, and 0.11% for WASP-3. We combine the TrES-3 secondary eclipse information with the existing published data and confirm that the atmosphere likely does not have a temperature inversion.