M.D. Roberts, S.A. Dazeley, P.G. Edwards, T. Hara, Y. Hayami, J. Holder, F. Kakimoto, S. Kamei, A. Kawachi, T. Kifune, R. Kita, T. Konishi, A. Masaike, Y. Matsubara, T. Matsuoka, Y. Mizumoto, M. Mori, H. Muraishi, Y. Muraki, K. Nishijima, S. Oda, S. Ogio, J.R. Patterson, G.P. Rowell, T. Sako, K. Sakurazawa, R. Susukita, A. Suzuki, R. Suzuki, T. Tamura, T. Tanimori, G.J. Thornton, S. Yanagita, T. Yoshida and T. Yoshikoshi
Observational and theoretical results indicate that low-redshift BL~Lacertae objects are the most likely extragalactic sources to be detectable at TeV energies. In this paper we present the results of observations of 4 BL~Lacertae objects (PKS0521$-$365, EXO\,0423.4$-$0840, PKS2005$-$489 and PKS2316$-$423) made between 1993 and 1996 with the CANGAROO 3.8\,m imaging \v Cerenkov telescope. During the period of these observations the gamma-ray energy threshold of the 3.8m\,telescope was $\sim$2\,TeV. Searches for steady long-term emission have been made, and, inspired by the TeV flares detected from Mkn~421 and Mkn~501, a search on a night-by-night timescale has also been performed for each source. Comprehensive Monte Carlo simulations are used to estimate upper limits for both steady and short timescale emission.