Revised fluxes for Gliese 229B

We have used the coronagraphic instrument CoCo with the Infrared Telescope Facility's camera, NSFCAM, to obtain improved photometry at JHKL' of the giant planet/brown dwarf Gliese 229B. We have recalibrated the published spectra for this object and recalculated its luminosity. Our L' value and our flux calibration of the spectra at JHK are significantly different from those previously published. Our results show good agreement at all bands except H with evolutionary models by Burrows et al. which include grain condensation. The model comparison implies that Gliese 229B is likely to be a 0.5 Gyr old 25M(J) object with T-eff similar to 900 K.