exposure

Slide1: 

Sky coverage with LOBSTER-ISS N.P.Bannister

Slide2: 

CODE DETAILS ISS orbital model based on NORAD SGP4 algorithm & two-line element sets Based on historical orbit data All modules inactive while ISS passes over SAA Individual modules inactive when Sun < 25° of module centre Static & time dependent obscuration by ISS structure not yet implemented Current maps based on 30 second time steps, 0.5 degree angular resolution

Slide3: 

INSTANTANEOUS FIELD OF VIEW Equatorial (,) Galactic (lII,bII) +90 +90 -90 -90 0 h 24 h -180 -180 Instantaneous field of view of 6 Lobster-ISS modules in the baseline configuration 1 x module field: 22.5° x 27° Module orientation: units 1- 4 tilted 30° forward (RAM direction) of zenith unit 5 tilted 35° forward of zenith unit 6 tilted 40° forward of zenith

Slide4: 

SINGLE ORBIT COVERAGE Solar avoidance Module overlap Orbit poles -90 -180 +180 +90 Coverage in ~1 orbit (90 minutes) September 25th 07:30 h – 09:00 h (Exposure times in seconds) Marginal overlap of adjacent fields Exact field size subject to revision For a target in one orbit: max obs ~ 1800 secs (near-pole) min non-zero ~ 400 secs (centre) Galactic Coordinates Map 4294

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AVOIDANCE ZONES -90 Time lost to SAA passages 1 year of observation. Time in seconds. -180 -90 -180 Time lost to solar avoidance 1 year of observation. Time in seconds. +180 +180 +90 +180 +90 Lost exposure time (Sun + SAA) 1 year of observation. Time in seconds. -180 -90 +90 Galactic Coordinates Galactic Coordinates Galactic Coordinates

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OBSERVATION FREQUENCY (1 year) (% of orbits) -90 -180 +180 +90 Lowest coverage ~ 73% of orbits Significant area (~15%) with 100% coverage Galactic Coordinates

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SENSITIVITY ESTIMATES Approximate 3 detection limits (ergs cm-2 sec-1) Crab-like spectrum: N(E)=AE-2.1 photons cm-2 sec-1 No H absorbing column March 2000, 30 second time resolution.

Slide8: 

Approximate 3 detection limits (ergs cm-2 sec-1) Spectrum: N(E)=AE-1.7 photons cm-2 sec-1 Absorbing H column: 3x1020 atoms cm-2 March 2000, 30 second time resolution. SENSITIVITY ESTIMATES

Slide9: 

LOBSTER COVERAGE OF SPECIFIC TARGETS TARGET α2000 δ2000 NGC 4051 12 03 09.6 +44 31 53 (1) NGC 4151 12 10 32.6 +39 24 21 (2) NGC 5548 14 17 59.5 +25 08 12 (3) NGC 3783 11 39 01.8 - 37 44 19 (4) NGC 3516 11 06 47.5 +72 34 07 (5) 3C273 12 29 06.7 +02 03 09 (6) PKS2155-304 21 58 52.0 - 30 13 32 (7) Mrk421 11 04 27.3 +38 12 32 (8) PKS0558-504 05 59 47.4 - 50 26 52 (9) (1 year of observations)

Slide10: 

Galactic coordinates Target locations (frequency plot superposed) 1 2 3 4 5 6 7 8 9 Galactic Coordinates 4 5 6

Slide11: 

Galactic coordinates Target locations (frequency plot superposed) 1 2 3 4 5 6 7 8 9 Galactic Coordinates 7 8 9

Slide12: 

Observing frequency at general locations General locations (frequency plot superposed) Galactic Coordinates 1 2 3 4 5 6 1 2 3 4 5 6

Slide13: 

Detailed coverage example: Galactic centre. 1 year