UV And Red-IR Radiation Flashes EnergyCharacteristics Measured by UV&IR

Detector On-Board“Universitetsky-Tatiana-2” Satellite.

G.K. Garipov1, B.A. Khrenov1, P.A. Klimov1, V.S. Morozenko1, M.I. Panasyuk1, V.I. Tulupov1, V.M.

Shahparonov1, S.A. Sharakin1, S.I. Svertilov1, N.N. Vedenkin1, I.V. Yashin1, H.I Salazar2, O.B. Martinez2,

E.L. Ponce2, J.P. Cotsomi2, I.H. Park3.  

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

-180 -150 -120 -90 -60 -30 0 30 60 90 120 150 1800

20

40

60

80

100

Nu

mb

er o

f fla

sh

es

Longitude, degree

Unmodified by triggerModified by trigger

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.