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We present observations of the Sunyaev-Zel'dovich effect (SZE) in the Bulletcluster (1E 0657--56) using the APEX-SZ instrument at 150 GHz with a resolutionof 1 arcmin. The main results are maps of the SZE in this massive, merginggalaxy cluster. The cluster is detected with 23 sigma significance within thecentral 1 arcmin radius of the source position. The SZE map has a broadlysimilar morphology to that in existing X-ray maps of this system, and we findno evidence for significant contamination of the SZE emission by radio or IRsources. In order to make simple quantitative comparisons with cluster gasmodels derived from X-ray observations, we fit our data to an isothermalelliptical beta model, despite the inadequacy of such a model for this complexmerging system. With an X-ray derived prior on the power-law index, beta = 1.04+0.16 -0.10, we find a core radius r_c =142 +/- 18 arcsec, an axial ratio of0.889 +/- 0.072, and a central temperature decrement of -771 +/- 71micro-K_CMB, including a +/-5.5% flux calibration uncertainty. Combining theAPEX-SZ map with a map of projected electron surface density from Chandra X-rayobservations, we determine the mass-weighted temperature of the cluster gas tobe T_mg=10.8 +/- 0.9 keV, significantly lower than some previously reportedX-ray spectroscopic temperatures. Under the assumption of an isothermal clustergas distribution in hydrostatic equilibrium, we compute the gas mass fractionfor prolate and oblate spheroidal geometries and find it to be consistent withprevious results from X-ray and weak lensing observations. This work is thefirst result from the APEX-SZ experiment, and represents the first reportedscientific result from observations with a large array of multiplexedsuperconducting transition-edge sensor bolometers.

Sunyaev-Zel'dovich Effect Observations of the Bullet Cluster (1E 0657-56) with APEX-SZ