The bit-error-rate (BER) performance of an optically preamplified peak detecting burst mode (BM) receiver is analyzed. The analysis takes into account amplified spontaneous emission (ASE) noise and, for the first time with this receiver architecture, interchannel crosstalk. Furthermore, the ASE beat noises are more appropriately included through the use of a noncentral chi-square (NCCS) distribution in contrast to earlier attempts, which used a Gaussian approximation (GA), though a GA is also developed here for the interchannel crosstalk case, for comparative purposes. Results are presented in terms of BER and penalty curves. The peak detector-based BM receiver shows larger threshold acquisition (TA) penalty than an integrator-based BM receiver in the presence of ASE. Also ASE beat noise modeling using the NCCS distribution shows greater power penalty for interchannel crosstalk than does the GA. The sum of separate crosstalk and TA penalties is found to be less than the combined TA penalty obtained in the presence of interchannel crosstalk.