1-D.V. Skobeltsyn Institute of Nuclear Physics, Moscow State University, Russia.2-University of Puebla (BUAP), Puebla, Mexico.3-Research Center of MEMS Space Telescope, Ewha Womans University, Seoul, Korea.
September 6-11, 2010 Nor Amberd, Armenia
1) FOV: 15°2) Each PMT area: 0.4 cm2
UV wavelengths 240-400 nmRed-IR wavelengths 600-800 nm3) Oscillogramm length: 128 ms4) Time sample and trigger integration time: 1 ms.5) Trigger selected one event per minute (Tatiana-1 selected one event per circle)6) High voltage control system
Orbit:height 800 – 850 km Orbit type solar synchronous Mass ~100 kgActive operation time of about 4 monthsEarth orientation accuracy (1 – 3) degreePower consumption 20 – 25 WattVoltage 24-34 V
“Universitetsky-Tatiana-2”
UV and Red-IR radiation detector.
Block-diagram of UV/IR/CPD detectors at the MSU “Tatiana 2” satellite
Examples of measured events•Simultaneous UV and IR enhancements•Classified in 4 types due to temporal profiles features
Flash UV energy calculation
1. Total event energy 2. Peak event energy
UV detector data:M – high voltage codeN – ADC code
tpMGe
CNN
)(
)103( 3
det
S
RNNatm
2
det
4
atm
totUV NEE
5.86 )255(103)( MMG
max, atm
peakUV NEE
Total UV energy release distribution of measured events
• The combined distribution of all types flashes
• It is modified by– Geometry of event and
detector FOV
– Triggering system of detector
Does the flashes “spectrum” depends on flash location (ocean, land or coast)?
Distribution of energy release in UV (flash brightness) , for various locations (land, ocean, coast)
0,01 0,1 1 10 100 1000 100001E-4
1E-3
0,01
0,1
1
10
100
ocean
dN/d
E
E, kJ
0,01 0,1 1 10 100 1000 100001E-4
1E-3
0,01
0,1
1
10
100
land
dN/d
E
E, kJ
0,01 0,1 1 10 100 1000 100001E-4
1E-3
0,01
0,1
1
10
100
coast
dN
/dE
E, kJ
Rate of measured events
Satellite exposition
Above land 37 % 30 %
Above ocean 35 % 65 %
Coast 28 % 5 %
Tatiana-2 ISUAL
Nl/No (Nl&Nc)/No (Nl&Nc)/No
2.3 3.5 ELVES ~1
Sprites ~4
Lightning ~10
Global geographical distribution of measured flashes
UV flashes energy distributionTotal energy of event (128 ms)Peak energy of event (1 ms)
Modeling of spectrum and “trigger effect”
Spectrum of TLE
0,01 0,1 1 10 100 1000 100001E-4
1E-3
0,01
0,1
1
10
100
1000
10000
100000
dN
/dE
Energy, kJ
E-2
γ = -2
The spectrum modification depends on number of flashes occurred during 1 min (time of event selection).Trigger decrease number of low energy events.This modeling doesn’t take into account concrete geometry of events and detectors FOV.
Original flash energy distribution
0,01 0,1 1 10 100 1000 100001E-4
1E-3
0,01
0,1
1
10
100
1000
10000
1ms
dN/d
E
E, kJ
E-2 Excess of low energy events
Change of spectrum exponent
The original spectrum consists of two parts with exponents -2 and -1. Those exponents are obtained in analysis of the experimental spectrum modified by trigger. The “bright” flashes (peak energy in 1 msec E>3 kJ) are considered as TLE. They were detected in the Tatiana-1 experiment.Additional peak at energies below 1 kJ is considered as flashes of another phenomenon (their world map differs from TLE map).
Difference of low and high energy events geographical distribution
Geographical distribution of flashes with 1 ms energy less 1 kJ.
Geographical distribution of flashes with 1 ms energy more
then 3 kJ.
Red-IR/UV number of photons ratio in measured flashes.
0 5 10 15 20 25 30 35 400
20
40
60
80
100
120
140
160N
um
be
r o
f fla
she
s
IR/UV
0,01 0,1 1 10 100 1000 10000
1
10
100
Peak energy, kJ
IR/U
V
Maximum in Red-IR/UV ratio distribution for all flashes is ~ 6.
For low energy flashes the mean Red-IR/UV ratio is higher than for energetic ones, but for all events there is no evident correlation between flash energy and Red-IR/UV ratio.
Conclusions
1. Tatiana-2 has measured more than 1000 flashes during 3 months of its operation.
2. The total and peak UV energy flashes distribution were obtained from satellite data and the “trigger effect” was analyzed. Energy spectrum consists of three components: high energy with γ ~ -2, middle energy with γ ~ -1 (both components considered to be signals of TLE) and low energy peak, which origin is under analysis.
3. The geographical distribution of flashes was found different for “high” and “low” energy flashes. Events of high energy are concentrated near equator and thunderstorm regions, low energy events distributed more even.
4. Red-IR/UV ratio varies in large range for all flashes. Low energy events (E<1 kJ) have larger Red-IR/UV ratio.
