We have monitored the Neptune-mass, exoplanet-hosting M dwarf GJ 581 with the 1 m Swope Telescope at Las Campanas Observatory over two predicted transit epochs. A neutral density filter centered at 550 nm was used during the first epoch, yielding 6.33 hr of continuous light-curve coverage with an average photometric precision of 1.6 mmag and a cadence of 2.85 minutes. The second epoch was monitored in the B band over 5.85 hr, with an average photometric precision of 1.2 mmag and a 4.28 minute cadence. No transits are apparent on either night, indicating that the orbital inclination is less than 88.1d for all planets with radii larger than 0.38RNep (=1.48 R⊕). Because planets with the most likely interior compositions will have radii larger than 1.55 R⊕, we place an inclination limit of 88.1d for the system. The corresponding minimum mass of the exoplanet GJ 581b remains 0.97MNep (=16.6 R⊕). Based on observations obtained with the 1 m Swope Telescope at Las Campanas Observatory, which is operated by the Carnegie Institution of Washington.
- Publications of the Astronomical Society of the Pacific
- Pub Date:
- November 2006
- Stars: Planetary Systems;
- stars: individual (GJ 581);
- 7 pages, 2 figures, 1 table, to appear in PASP