During a scan of the archival BATSE daily records covering the entire 9.1 yr (TJD 8369È11690) of the BATSE operation, 3906 gamma-ray bursts (GRBs) have been detected. 2068 of these GRBs are previously known BATSE triggers, while 1838 of them are new nontriggered bursts. It is important that all events were detected in the same type of data and were processed with the same procedure. Therefore these 3906 GRBs constitute a uniform sample. We have created a publicly available electronic data base4 containing this sample. We describe the procedures of the data reduction, the selection of the GRB candidates, and the statistical tests for possible non-GRB contaminations. We also describe a novel test burst method used to measure the scan efficiency and the information obtained using the test bursts. Our scan decreases the BATSE detection threshold to D0.1 photon s~1 cm~2. As a Ðrst result, we show that the di †erential log NÈ log P distribution corrected for the detection efficiency extends to low brightnesses without any indication of a turnover. Any reasonable extrapolation of the new log NÈ log P to lower brightnesses imply a rate of several thousands of GRBs in the universe per year.

We present preliminary results of an off-line search for non-triggered gamma-ray bursts (GRBs) in the BATSE daily records for about 5.7 years of observations. We found more GRB-like events than the yield of the similar search of Kommers et al. (1998) and extended the Log N -log P distribution down to ∼ 0.1 ph cm −2 s −1 . The indication of a turnover of the log N -log P at a small P is not confirmed: the distribution is straight at 1.5 decades with the power law index -.6 and cannot be fitted with a standard candle cosmological model.

A population of X‐ray dominated gamma‐ray bursts (GRBs) observed by Ginga, BeppoSAX and the High Energy Transient Explorer (HETE‐2) should be represented in the Burst and Transient Source Experiment (BATSE) data as presumably soft bursts. We have performed a search for soft GRBs in the BATSE records in the 25–100 keV energy band. The softness of a burst spectrum could explain why it has been missed by the on‐board procedure and by the previous searches for untriggered GRBs tuned to the 50–300 keV range. We have found a surprisingly small number (∼ 20 yr−1 with fluxes down to 0.1 photon cm−2 s−1) of soft GRBs where the count rate is dominated by the 25–50 keV energy channel. This fact, as well as the analysis of HETE‐2 and common BeppoSAX/BATSE GRBs, indicates that the majority of GRBs with a low Epeak have a relatively hard tail with a high‐energy power‐law photon index β > −3. An exponential cutoff in GRB spectra below 10–15 keV may be a distinguishing feature of non‐GRB events.

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