List of Figures

1. GRBM light curves of bursts.
2. Duration ($T_{90}$) Distribution of 2704 BATSE bursts (from http://www.batse.msfc.nasa.gov/batse/grb/duration/).
3. HR-Duration ($T_{90}$) Correlation of GRBs. The squares spot the WFC/BeppoSAX bursts: to date, it has been possible to detect afterglows only from long bursts (from http://www.batse.msfc.nasa.gov/batse/grb/4bcatalog/.)
4. Direction distribution of 2704 bursts detected by BATSE (from http://www.batse.msfc.nasa.gov/batse/grb/skymap/).
5. LogN-LogS Distribution for 799 BATSE bursts (from [Kouveliotou, 1992]).
6. Redshift Distribution (Nov 2001).
7. Isotropic energy, fluence and host magnitude ($R$ and $V$ filters) as a function of redshift (Nov 2001; from [Ghisellini, 2001]).
8. Rebrightening of the GRB980326 optical afterglow: it might be connected with an underlying SN. Here the R-band light curve has been fitted with an initial power law decay plus a SN Ic light curve for the redshift range $0.5-1.6$. The best-fit redshift occurs at $z \sim 0.95$ and seems consistent with the observed spectrum (from [Bloom et al., 1999]).
9. Energy Distribution of GRBs with known redshift in two cases: isotropic emissions (top panel), and geometry-corrected for jet-like emissions (bottom panel). The non-isotropic case tightly clusters the distribution around $5\times 10^{50}$ erg. (From [Frail et al., 2001]).
10. The two different cases of spherical and jet-like emission: the visibility cone, defined by the time-evolving bulk Lorentz factor, should distinguish at late times between the two cases. (From [Ghisellini, 2001]).
11. Cartoon for the Fireball Model.
12. Broad Band Synchrotron Spectrum of a GRB afterglow, according to the Fireball Model. (From [Sari, Piran & Narayan, 1998])
13. GRB-Host Galaxy Offset Distribution. It seems to favour a progenitor population associated with star forming regions. (From [Djorgovski et al., 2001]).
14. The IPN triangulation method.
15. Ulysses-Earth distance as a function of time.
16. Schematic view of the Rossi-XTE payload.
17. Schematic view of HETE-II.
18. Sketch of the BeppoSAX satellite structure (From Piro 1995).
19. The BeppoSAX Scientific Payload
20. The PDS and GRBM experiments.
21. A Sketch of the PDS and of its electronics (from [Frontera et al. 1997a]).
22. The Ground Support Facilities and Data Flow (from [Bruca L. et al., 1998a]).
23. Linear fit of the OBT-UT relationship in the case of the OP 11729 (July, 31 - August, 1, 2001). In the upper panel, the conversion couples concerning the overall OP, the best linear fit and the temporal residuals are plotted : in the case of FOT data, a unique linear fit is performed on data taken from several contiguous orbits. In the lower panel, the zoom on a single orbit data from the same OP is shown: in this figure, the fit is the same as before, but when dealing with RAW data, the OBT-UT conversion is performed one orbit at a time.
24. Top panel: schematic top view of the payload model: the two couples of NFIs, the HPGSPC (right) and the WFC box (left) are clearly visible around the PDS/GRBM square box. Bottom panel: side view of the model: the orange box represents the electronics, while the pedestal (used during the on-ground calibration sessions) is violet (from [Calura et al., 2000]).
25. GRBM Localization of GRB980109: the different $\chi^2$ levels are shown; The triangle denotes the burst position as determined by the WFC, while the asterisk spots the GRBM centroid.
26. GRBM Localization of GRB000516: the different $\chi^2$ levels are shown; The triangle denotes the burst position as determined by the IPN, while the asterisk spots the GRBM centroid.
27. GRBM Localization of GRB990627: the different $\chi^2$ levels are shown; this localization shows different relative minima.
28. GRBM 1 s light curves, one for each energy band and for each unit (OP 11729, from July 31 to August 1, 2001). From top to bottom, the GRBM 1-4 and AC 1-4 bands are plotted. The duration is $10^5$ s. The count rates are measured in counts/s: actually, for clarity, these rates are the averages of 20 s bins; however, in the GRBM band, softer than the AC band, it is apparent that there are more spikes. The repetitive structures have the same periodicity of the BeppoSAX orbital period; the periodic data gaps correpond to the SAGA passages.
29. GRBM 1 s light curves, one for each energy band and for each unit (orbit n. 26855, August 2, 2001). The duration is $\sim$6000 s. These are the typical time profiles of the GRBM ratemeters during a single orbit. At $t\sim$30921 SOD, corresponding to 08:35:21 UT, the GRB010802 was detected by the automatic on-line quest (automatic mail n. lkGRB[268]): in this case, the GRB was bright enough to be detected in all units, in both energy bands.
30. Example of moving parabolic fit applied to estimate the expected background counts for each bin. For a detailed description, see the section about the late SWTCs. In this case, both the energy bands of unit 1 are shown (OP 04421, May 1998). The +2$\sigma$ level over the expected background is plotted.
31. Distributions of the counts (unit 1, GRBM band in the left and AC band in the right panel, respectively) taken from the OP 04421 (May 9-10, 1998), lasted $10^5$ s. A moving parabolic fit estimates the background counts expected for each time bin: here the deviations of the measured counts from the corresponding values are expressed in $\sigma$, calculated as the square root of the expected counts. The $\sigma$s of the best fitting normal distributions are consistent with the poissonian $\sigma$s.
32. Distributions of the counts (unit 1, GRBM band in the left and AC band in the right panel, respectively) taken from the OP 00915 (September 13, 1996), lasted 9500 s. This is a rare OP, because it shows a non-poissonian noise, since the standard deviation of its distribution is $\sim 1.5$ times the poissonian $\sigma$.
33. Example of a strong spike occurred in unit 1, GRBM band, at 11:25:43.06 UT, on August 26, 2001. Left panel: 1 s bin profile; right panel: same profile with a 7.8125 ms resolution. The typical exponential decay is clearly visible: in this case, a least square fit estimates the exponential decay constant $\tau = 81 \pm 1$ ms, $\chi^2_r = 1.38$. The dip, visible in the middle of the HTR pulse, is fake and it is due to the 6 bit counters' recycling.
34. Example of solar X-ray flare detected by the GRBM, units 2+3, on April 15, 2001, at 13:44 UT (upper panel: GRBM band; lower panel: AC band). This flare shows a ``curious'' profile: the fast drop has been caused by the occultation of the Sun behind the Earth, as seen from the BeppoSAX point of view.
35. Example of a pre-SAGA event, occurred on July 30, 1999.
36. Two single occultation steps in the GRBM band, unit 1: left panel: Crab ($\phi=273$$^\circ$, $\theta=7$$^\circ$, OP 03991); right panel: CygX-1 ($\phi=287$$^\circ$, $\theta=7$$^\circ$, OP 04421).
37. Summed occultation steps of Crab in the GRBM band, unit 1: left panel: occ. beginning; right panel: occ. end (OP 03991).
38. Summed occultation steps of CygX-1 in the GRBM band, unit 1: left panel: occ. beginning; right panel: occ. end (OP 04421, May 1998).
39. Time history of NTB 960723, UT 04:46:03, (also BATSE trigger 5551) in all the GRBM units, both energy bands. Only unit 2 detected it. This NTB was caught trough SWTC 2: actually, its BATSE direction was $\sim$70$^\circ$above the Earth limb and $\sim$11$^\circ$off-axis with respect to unit 2.
40. Time history of NTB 960802 (also BATSE trigger 5559) in all the GRBM units, both energy bands. Only unit 1 detected it. Like NTB 960723, also this NTB was caught trough SWTC 2: its BATSE direction was $\sim$20$^\circ$above the Earth limb and $\sim$18$^\circ$off-axis with respect to unit 1.
41. Time history of NTB 980421 (also BATSE trigger 6698) in all the GRBM units, both energy bands. The burst can be seen in all the profiles, but it matched the OBTC only in unit 1, because too faint in the other units. It triggered both SWTC 2 and SWTC 3. Its BATSE direction was $\sim$73$^\circ$above the Earth limb and $\sim$55$^\circ$off-axis with respect to unit 1, the one with the best SNR.
42. Time history of NTB 960913 (also BATSE trigger 5604) in all the GRBM units, both energy bands. The burst was bright enough in the units 2 and 3 to match the OBTCs, but, since it occurred during the dead time of a previous fake event that triggered the GRBM, there are no HTR counts of it. It triggered all the SWTCs. Its BATSE direction was $\phi\simeq 23$$^\circ$and $\theta\simeq -23$$^\circ$ in the BeppoSAX frame of reference, i.e. bewteen the axes of units 2 and 3: this fully agrees with the GRBM units that indeed detected it.
43. The OTB 970315 (left: 40-700 keV, right: $>$100 keV) occurred just before the SAGA transit (unit 1, 40-700 keV energy band). The parabolic background fit is overplotted: this was estimated after visual inspection, by using a proper interval preceding the burst.
44. Time profiles of NTB 010518 in both energy bands of unit 3, that detected it: this burst did not trigger the on-board logic, because too faint; nevertheless, it triggered the SWTC 4, making it possible to discover the faint X-ray counterpart in the WFC 2 (GCN 1062).
45. Time profiles of NTB 980511, also detected by BATSE (# 6753); this GRB triggered SWTC 3, thanks to the counts in the units nn. 2 and 3, the two brightest ones (this agrees with the BATSE direction, $\phi=44$$^\circ$, $\theta=-15$$^\circ$). A small data gap is visible $\sim 30$ s before the GRB. The background fits and the +2$\sigma$ levels are overplotted, as well. The two intervals around the burst, used for fitting, are highlighted.
46. Time profiles of the short NTB 961116; this GRB triggered SWTC 2 in the units nn. 1 and 2. The background fits and the +2$\sigma$ levels are overplotted, as well. The two intervals around the burst, used for fitting, are highlighted. The presence of a spike at $t=-100$ s little biases the fit in the cases of GRBM1 and GRBM4; this spike triggered the on-board logic ``just too early'', preventing the GRBM from acquiring HTR data of the NTB.
47. Scheme of the on-line quest.
48. GRBM unit # 3 light curves of GRB010317: the automatic background fit is shown.
49. Example of a 31.25 ms GRBM light curve used for the IPN: GRB010412.
50. The Ulysses-BeppoSAX annulus intersects the WFC error circle of GRB010412 (courtesy of K. Hurley).
51. GRB010923: the triangle spots the IPN position ( $\phi=223.7\rm ^{\circ}=-136.3\rm ^{\circ}$, $\theta=+9.3\rm ^{\circ}$) while the asterisk denotes the GRBM position centroid ( $\phi=213\rm ^{\circ}=-147\rm ^{\circ}$, $\theta=-5.0\rm ^{\circ}$) and the cross corresponds to the 2nd, wrong IPN solution ( $\phi=203.7\rm ^{\circ}=-156.3\rm ^{\circ}$, $\theta=-29.3\rm ^{\circ}$) : the GRBM position allowed to resolve the IPN ambiguity.
52. GRB010923: the IPN triangulation redundancy is resolved by means of the GRBM error circle, as it includes only one of the two possible intersection regions (courtesy of K. Hurley).
53. Examples of localization of two IPN bursts: both GRB000630 (left panel) and GRB001204 (right panel) were detected by Ulysses, BeppoSAX/GRBM, Konus/WIND and NEAR. In both cases, the two IPN annuli, crossing each other, are shown. Only for the first an afterglow was found (optical band); GRB001204 was a short duration burst (courtesy of K. Hurley).
54. GRB010304. Top panel: 40-700 keV GRBM3 light curve; bottom panel: 2-28 keV WFC2 light curve (courtesy of J.J.M. in 't Zand). Example of WFC burst that did not trigger the GRBM on-board logic, but did the automatic GRB on-line quest (lkGRB[171]). The zero time corresponds to the S/W trigger time.
55. GRB010501, UT 06:37:27 Top panel: 40-700 keV GRBM1 light curve; bottom panel: 2-28 keV WFC1 light curve (courtesy of J.J.M. in 't Zand). This faint burst did trigger the on-line quest, and was missed by the GRBM on-board logic, (lkGRB[206]). The zero time corresponds to the S/W trigger time.
56. GRB010518, UT 06:43:09 Top panel: 40-700 keV GRBM3 light curve; bottom panel: 2-28 keV WFC2 light curve (courtesy of J.J.M. in 't Zand). Another example of faint burst that did trigger the on-line quest, and was missed by the GRBM on-board logic, (lkGRB[218], GCN 1062).
57. GRB010213, UT 02:57:23 Top panel: 40-700 keV GRBM3 light curve; bottom panel: 2-28 keV WFC2 light curve (courtesy of J.J.M. in 't Zand). This bright burst did not trigger the GRBM on-board logic, because it occurred during the GRBM dead time; since the on-line quest was off, it was missed at the epoch and finally discovered during an off-line search.
58. GRB961228, UT 00:29:58, is an example of a GRBM-BATSE common burst. Upper panel: GRBM 40-700 keV light curve (summed counts of all units); lower panel: BATSE $> 55$ keV light curve.
59. GRB980923, UT 08:22:58, is an example of a GRBM-Stern's BATSE common burst. Upper panel: GRBM 40-700 keV light curve (unit 3); lower panel: BATSE $55-300$ keV light curve as taken from Stern's catalog (event identificator: 11079d).
60. GRBM off-line efficiency as a function of the local direction (aitoff projection); these values have been obtained by splitting the local sky according to two regular grids: cube- and dodecahedron-shaped; then, the results have been merged into a unique figure.
61. Background Fit for GRB000830, UT 11:39:08. From top to bottom: GRBM1, ..., GRBM4, AC1, ..., AC4.
62. Background subtracted light curves of GRB000830, UT 11:39:08. From top to bottom: GRBM1, ..., GRBM4, AC1, ..., AC4.
63. $T_{90}$ Estimation for GRB000830, UT 11:39:08. Top panel: $7.8125$ ms light curve for the GRBM 3+2 energy bands. Bottom panel: integrated light curve, with the 0%, 5%, 95% and 100% fluence levels shown.
64. Sky Exposure (equatorial coordinates).
65. Sky Exposure (galactic coordinates).
66. Sky Exposure as a function of Declination.
67. BeppoSAX Local Sky Exposure (GRBM units 1, 2, 3, 4 axes point to $\phi=270\rm ^{\circ}, 0\rm ^{\circ}, 90\rm ^{\circ}, 180\rm ^{\circ}$, respectively, with $\theta=0\rm ^{\circ}$ for all).
68. BeppoSAX Local Sky Exposure as a function of the local elevation angle $\theta$ for four different $\phi=270\rm ^{\circ}, 0\rm ^{\circ}, 90\rm ^{\circ}, 180\rm ^{\circ}$, corresponding to the normal directions of GRBM units 1, 2, 3, 4, respectively.
69. $T_{90}$ and $T_{50}$ Distributions of 891 GRBs detected by the GRBM (40-700 keV).
70. $T_{90}$ Distribution of 777 GRBs and $T_{50}$ Distribution of 689 GRBs (40-700 keV). Only durations known with at least 3$\sigma$ significance have been taken.
71. HR-Duration Correlation of 891 GRBM bursts. In the upper panel, duration is expressed in terms of $T_{90}$, while $T_{50}$ has been used in the lower panel.
72. HR-Duration Correlation of 501 ($T_{90}$) and 497 ($T_{50}$) GRBM bursts. In the upper panel, duration is expressed in terms of $T_{90}$, while $T_{50}$ has been used in the lower panel.
73. HR Distribution of 891 GRBs from the GRBM catalog.
74. HR Distribution of 790 GRBs from the GRBM catalog, with at least 3$\sigma$ significant HRs.
75. Direction Distribution of 362 GRBs from the GRBM catalog, in common with BATSE 4B, Kommers' and Stern's catalogs. The directions are taken from these catalogs (galactic coordinates, aitoff projection).
76. Direction Distribution of 639 GRBs from the GRBM catalog; 79 well localized GRB positions, 283 from BATSE 4B, 18 from Kommers', 61 from Stern's,and 198 GRBM positioned GRBs (galactic coordinates, aitoff projection).
77. Direction Distribution of 362 GRBs from the GRBM catalog, in common with BATSE 4B, Kommers' and Stern's catalogs. The directions are taken from these catalogs (aitoff projection). Upper panel: BeppoSAX local coordinates; bottom panel: equatorial coordinates (in this case, only the 283 common BATSE 4B bursts are shown.
78. GRBM-true Position Angular Distance Distribution. The sample only includes 45 well localized GRBs (WFC, IPN, etc...).
79. GRBM-BATSE Position Angular Distance Distribution. The sample only includes 152 BATSE 4B GRBs, that have been localized also with the GRBM localization technique.
80. GRBM-BATSE Position Angular Distance Distribution. The sample only includes 203 BATSE (4B+Kommers'+Stern's) GRBs, that have been localized also with the GRBM localization technique.
81. GRBM-BATSE Position Discrepancy Distribution. The sample only includes 152 BATSE 4B GRBs, that have been localized also with the GRBM localization technique. The discrepancy takes into account both the total error (90% CL) owing to the GRBM localization and the total BATSE error, with $1.6\rm ^{\circ}$ systematic for the latter.
82. GRBM-BATSE Position Discrepancy Integral Distributions. The sample only includes 152 BATSE 4B (top panel) and 203 BATSE 4B+Kommers'+Stern's (bottom panel) GRBs, that have been localized also with the GRBM localization technique. The discrepancy takes into account both the total error (90% CL) owing to the GRBM localization and the total BATSE error, with $1.6\rm ^{\circ}$ systematic for the latter.
83. GRBM Direction Distribution of a sample of 446 GRBs localized with the GRBM localization technique. The frame of reference is local to BeppoSAX. The clustering tendency in the nearby of the BeppoSAX equatorial plane is apparent.
84. Direction Distribution of the GRBM-BATSE (4B) common sample of 152 GRBs localized with the GRBM localization technique. The frame of reference is local to BeppoSAX. Both GRBM and BATSE positions are spotted. The clustering tendency in the nearby of the BeppoSAX equatorial plane is apparent, when compared with the BATSE distribution.
85. Direction Distribution of a sample of 45 GRBs, that have been localized with the GRBM localization technique, and whose position was already known thanks to other experiments, mainly WFC and IPN. The frame of reference is local to BeppoSAX. Both GRBM and true positions are shown. The clustering tendency in the nearby of the BeppoSAX equatorial plane is apparent.
86. Top panel: cumulative fluence distribution (40-700 keV). The solid line shows the best powerlaw fit $N(>S) \propto S^{-\alpha}$, with $\alpha = 1.01 \pm 0.01 (1\sigma)$; the dashed line shows the case $\alpha = -3/2$. Bottom panel: cumulative peak countrate distribution (40-700 keV); the best fit gives $\alpha = 1.05 \pm 0.01 (1\sigma)$.
87. Top panel: cumulative fluence distribution ($>$ 100 keV). The solid line shows the best powerlaw fit $N(>S) \propto S^{-\alpha}$, with $\alpha = 0.98 \pm 0.01 (1\sigma)$; the dashed line shows the case $\alpha = -3/2$. Bottom panel: cumulative peak countrate distribution ($>$ 100 keV); the best fit gives $\alpha = 1.08 \pm 0.01 (1\sigma)$.
88. GRBM Light Curves of some SGR1900+14 bursts (40-700 keV).
89. GRBM Light Curves of other SGR1900+14 bursts (40-700 keV).
90. GRBM Light Curves of some SGR1627-41 bursts (40-700 keV).
91. GRBM Light Curves of other SGR1627-41 bursts (40-700 keV).
92. GRBM Light Curves of two bursts from SGR1806-20 (40-700 keV).
93. GRBM3 Time Profiles of 980901, UT 17:06:27.06, from SGR1900+14: the overall profile (3) is split into three slices: (3a), (3b), (3c).
94. GRBM average spectrum of 980901, 17:06:27.06 UT, from SGR1900+14. The best fit with a black body law yields $kT = 16.8 \pm 1.3$ keV, $\chi^2 = 0.81$.
95. Background subtracted light curves of two giant flares from SGR1900+14: August 27, 1998 (top), April 18, 2001 (bottom). The $5.16$ s modulation is apparent in both cases. In the 1998 case, the initial spike is affected by the GRBM counters' recycling.
96. GRBM Spectra of the two Giant Flares: August 1998 (slice B) (top) and April 2001 (slice A) (bottom). Both have been fitted with black body plus broken power law; $\chi^2 = 1.2$ for both cases. (From Guidorzi et al., 2002, in preparation)
97. The light curves of both giant flares (first 40 s) are compared, according to two different offsets: by making the two steepest rises (top panel), and the two onsets (bottom panel) coincide, respectively; (August 98 is grey; April 01 is black). The slices have the $5.16$ s periodicity.
98. The huge April 02, 2001, solar flare as seen by the GRBM (UT 21:36:40): no dead time correction. The 1 s ratemeters recycled in several 1 s bins. (GRBM unit 2, 40-700 keV).
99. May 4, 1998, solar flare (UT 09:29:17), as seen by the GRBM (40-700 keV and $>$ 100 keV time profiles are shown in the top and bottom panels, resp.): this flare lasted $\sim$ 24 min (GRBM units 1+3).
100. GRBM light curves of GRB980516 (from top to bottom: GRBM1, ... GRBM4, AC1,..., AC4.
101. Zoomed background subtracted light curves of the GRBM 1+2 units; in both energy bands (top: 40-700 keV; bottom: $>$100 keV) the onset is clearly visible at $t\sim 0$ s.
102. GRBM average spectra of GRB980516. Top panel: fit with the Band Law ($\chi^2 = 1.02$); middle panel: fit with a broken power law (unfolded spectrum, $\chi^2 = 1.03$); bottom panel: fit with a single power law (unfolded spectrum, $\chi^2 = 1.25$).