A cross check between BATSE and GRBM detections of GRB has been made. A deep study carried out over about one year has given the results listed in Tab. 4.11.2, from Preger et al. 1999, where with "Hardware OFF" we indicate that the instrument is switched off, and this can occur for example during the passage of the satellite over the South Atlantic Geomagnetic Anomaly, or in case of satellite maintenance. With "Software OFF", instead, we indicate that the instrument is on, but the software is not enabled: data are stored and can be analyzed, but the trigger function is inactive. A particular care was devoted to the study of possible selection effects on the GRBM trigger efficiency, showing a clear selection on duration (only 2 events shorter than 1 s), a partial correlation between intensity and incoming direction (weaker events are preferably triggered at directions close to the satellite's equatorial plane). The angular distribution of these GRBs in the satellite rest frame reveals the pair of detectors GRBM2 and GRBM3 as the most efficient in triggering GRBs (we remind here that a valid GRB is recognized when at least 2 detectors trigger on the same event).
| Number of days | 374 |
| BATSE triggers | 322 |
| GRBM simultaneous triggers | 61 |
| GRBM hardware OFF | 119 |
| GRBM software OFF | 3 |
| Detected but not triggered | 24 |
| Data not available | 11 |
| Common triggers | 32% |
| Common detections | 46% |