Fig. 2.2
Limits to the EGRET energy fluences as function of the assumed spectral index. The
limits are shown for GRB940217 (upper panel) and GRB910601 (lower panel).The
energy fluences were calculated for the energy range of 30MeV-30GeV, 90\% confidence
level and the corresponding T90. The arrow head and tail correspond to the upper and
lower limit of EGRET fluences, respectively. The upper limits change less than a factor
of 2 for spectral indices less than -2.0. Similar results are obtained for other burst.
Fig. 2.3
Limits to EGRET energy fluences in T90 for bursts given in Table \ref{tbl-allfov}. They
are calculated in the energy range of 30MeV-30GeV, for 90\% confidence level, spectral
index equal to -2.4 and the corresponding T90 for each burst. They are plotted as function
of the BATSE fluence for each burst. When the lower limit was equal to zero, only a
triangle has plotted for the upper limit. The arrow heads and tails correspond to the upper
and lower limits of EGRET fluences, respectively. When an arrow was plotted for a
burst, the number of observed events $n$, the expected value $b$ and the probability $P$
of observing those events in T90 as fluctuation of the background are given in the plot,
starting with bursts with higher to lower BATSE fluences. The dashed line corresponds to
equal fluences in BATSE and EGRET energy sensitivity. The arrows with highest
BATSE fluences correspond to the previous EGRET observations. The remaining two
arrows are detections with significance less than 3$\sigma$.
Fig. 2.4
Same as Fig. \ref{fluT90}, but for a 200s time interval starting at the BATSE trigger.
GRB910305 showed 8 and 9 photons in T90($\sim$50s) and 200s after the BATSE
trigger, respectively. Despite the arrow for GRB910305, there is not significant 200sduration high-energy emission since the expected background is above 1 photon and only
one photon was observed in the 150s following T90. GRB940301 is a similar case.
Fig 2.5
Limits to EGRET energy fluences for bursts given in Table \ref{tbl-allfov}. They are
calculated in the energy range of 30MeV-30GeV, for 90\% confidence level, spectral
index equal to -2.4 and time intervals of 10s (upper panel) and 20s (lower panel) both
starting at T90 seconds after the BATSE trigger. They are plotted as function of the
BATSE fluence for each burst. When the lower limit was equal to zero, only a triangle
has plotted for the upper limit. The arrow heads and tails correspond to the upper and
lower limits of EGRET fluences, respectively. When an arrow was plotted for a burst, the
probability $P$ of observing $n$ events as fluctuation of the expected background $b$
was calculated. Blue arrows correspond to detections at least 3$\sigma$ significant; $n$,
$b$ and $P$ were given in the plot for these cases starting with bursts with higher to
lower BATSE fluences. The dashed line corresponds to equal fluences in BATSE and
EGRET energy sensitivity.
Fig. 2.6
Same as Fig. \ref{fluT10T20} but for time intervals of 50 (upper panel) and 100 (lower
panel) seconds, both starting at T90 seconds after the BATSE trigger.
Fig 3.1
Typical BATSE spectra in HERB format. BATSE accumulated spectra for the first 7s
after the BATSE trigger for GRB910503 is shown. The crosses are BATSE data.
Depending on the data format, different channels were excluded from the analysis. In
general, for HERB format the lowest seven channels were excluded because they were
below the lower level discriminator energy threshold and, few of the highest channels
were also excluded because they were saturated. The energy channels between the solid
lines are the channels included in the analysis. The dotted line represents the background
model (see text for details).
Fig 3.2
Typical TASC solar spectra. TASC accumulated solar spectra for $\sim$1000s is shown.
Spectral features are observed at 1.46MeV, 2.61MeV, 7.64MeV, $\sim$10MeV and
beyond 100MeV corresponding to $\rm ^{40}K$, $\rm ^{232}Th$, neutron capture of
$\rm Fe$, an instrumental artifact and cosmic muons respectively. The potassium line is
used to calibrate TASC data.
Fig 3.3
Dead time estimate considering different count rates. Two different ways to estimate
TASC dead time are compared for different count rates and spectral indexes.
DeadTime$\rm _der$ refers to the derived dead time and DeadTime$_1$ refers to the
obtained using counts in channel one (see text). The discrepancy is at most 5\% for count
rates below 60,000 counts per second independently of the spectral index.
Fig. 3.4
Two different ways to estimate TASC live time are compared for different count rates
and burst durations in upper panel. The derive TASC live time is compared with the true
TASC live time from a Monte Carlo simulation in lower panel. “LiveTime Der”,
“LiveTime Ch1” and “LiveTime True” refers to derived live time, live time from using
counts in channel 1 and the true live time from a Monte Carlo simulation, respectively
(see text). \%C=10,50 and 100 correspond to burst count rates of 1,000, 5,000 and 10,000
counts per second. The disagreement between the true, derived and calculated with
channel 1 live times is worse for the brightest burst but it is in less than a 7\% for all
burst for which TASC is most sensitive (longer than a few seconds). The derived live
time showed a better agreement with the true live time than the calculated with channel 1.
Fig. 3.5
TASC sensitivity as function of the zenith and azimuth angles. TASC sensitivity is shown
for the energies of cobalt-60 lines as a function of zenith (upper panel) angle for fixed
azimuth angles of 168 (squares and solid line) and 180 (triangles and dotted line) degrees
and, as a function of azimuth (lower panel) angle for fixed zenith angles of 45 (squares
and solid line) and 90 (triangles and dotted line) degrees. Data and Monte Carlo predicted
trends are consistent. The discrepancies are attributed to the CGRO mass model because
of an underestimation of the intervening spacecraft material.
Fig. 3.9
BATSE energy fluence above 300keV as function of the Total BATSE energy fluence
for the brightest BATSE bursts. The BATSE energy fluence above 300keV is divided by
the total BATSE energy fluence to emphasize its contribution to the Total fluence. Black
triangles, blue squares and red squares correspond to bursts satisfying the selection
criteria with none, one or more than one TASC spectrum with significant detection.
Tbl 3.1
TASC spectral information for bursts included in the analysis. Third column indicates
how many TASC spectra with significant detection were analyzed for each burst. Fourth
column indicates the problems with TASC data when TASC spectra were not available.
If none problem is reported, TASC spectra were available but did not have significant
detection. Last column reports the existing references for each burst.
Fig. 3.11
Histogram of zenith and azimuth angles for the selected bursts. Red and blue lines
correspond to all burst passing the selection criteria and only the ones with more than one
TASC spectrum with significant detection, respectively. Same angle distribution is
observed in both cases.