1. Observational Prospect of NIREBL
ISAS/JAXA
T. MATSUMOTO, S. MATSUURA, and T. WADA

2. Issues to be observed Spectral shape
Confirmation of the spectral gap at ~1mm real?
Other spectral features?
Fluctuation
Spatial correlation over the wide range of angular scale
Search for the large scale structure at high redshift
Absolute measurements
Avoid ambiguity of the model ZL
Rocket experiment
ASTRO-F
SPICA
Out of zodiacal cloud mission

3. ASTRO-F Formation and evolution of galaxies, stars, and planets
First dedicated infrared mission of ISAS
70cm cooled infrared telescope
Advanced Infrared Survey
50 times higher sensitivity,
10 times better spatial resolution,
has longer wavelength band,
than IRAS
Instruments
IRC(Infrared Camera)
512x412 InSb array camera, 1.5”/pixel
band imaging: K, L, and M bands
low resolution spectroscopy: R-30 slit 2x50 pixel, R-15 4x50 pixel
256x256 SiAs array
FIS(Far Infrared Surveyor)
Launch target : August, 2005
Orbit : sun synchronous orbit, 750km altitude
Mission life: ~1.5 year (liq. He holding time)
+ 2 years (dedicated to NIR Observations)
ISAS/ESA collaboration: 10% of the pointing observations are opened to ESA scientists

4. Observation of NIREBL with ASTRO-F
Advantages of IRC/ASTRO-F observation
Point-source rejection by high-resolution imaging observation
Limiting magnitude at the K band is ~20 mag. for one pointing obseravation (~10 min.)
　 This corresponds to ~30 nW m-2 sr-1 for 1 pixel (5s)
Almost all galactic stars and faint galaxies can be identified
Discrimination of the fluctuation of the zodiacal light
Observation of the same field at the different time epoch
Observation plans
1. Detection of the NIREBLfluctuation over the wide range of angular scale
Wide area survey towards north ecliptic pole (NEP) is being proposed.
Coordination with galaxy deep survey group
2. Detailed study of the spectrum of IREBL
Low resolution spectroscopy at different ecliptic latitudes (2~5mm)
Spectrum without contamination of stars and galaxies can be obtained
We welcome participation of theoreticians even in planning stage!

5. IRC SURVEY STRATEGIES Depth and Area Number of Pointings1
0.02 10
100
1000 ?
100
Number of Pointings 10 1
Area (sq. deg.)

6. Expected fluctuation and detection capability of IRC/ASTRO-F (Cooray et al., submitted to Ap.J.)

7. IRC background measurements around NEP
1. Wide-band deep imaging in K, L and M bands
Spectral resolution
l/Dl
Survey area [sq.degree]
Exposure time per frame
[# of pointings]
Single pixel detection limit (5s) *
[nW/cm2/sr]
Number of galaxies per camera frame**
Number of dark pixels per frame ***
Wide-field Shallow（phase-3) 3
100
1 (500 s) 30
2x10^3
>1.5x10^5
Shallow (Phase-1,2) 10
Deep (Phase1,-2) 1
10 (1.4 hrs)
(3-4)x10^3
>1.3x10^5
Ultra Deep
(Phase-1, 2)
0.02
100 (14 hrs)
(0.5-1)x10^4
>8x10^4
* in unit of surface brightness (lIl)
** FOV of the IRC camera frame is 10’x10’
*** number of pixels available for the background analysis = total number of pixels – (confusion factor) x (number of galaxies)
= 1.7x10^5 – (3pics x 3pics) x (number of galaxies)
2. Spectroscopy
Spectral resolution l/Dl
Survey area
Exposure time
Detection limit (5s)
[nW/cm2/sr]
Number of galaxies
Number of dark pixels
Spectroscopy 30
(l = 2.0 – 5 mm)
3” x 73”
x 100 directions
(various b and b)
1 pointing (500 s)
30 (pixel binning)
~10 (10 sky average) 2 90

8. Out of zodiacal cloud mission
Infrared observation without the zodiacal light provides decisive result for the NIREBL!

9. Possible mission concept of out of zodiacal cloud mission!
Scientific objectives
Accurate measurement of
spectrum and fluctuation of IREBL
Instrumentation
Telescope 5cm dia. lens system
Wavelength range mm
Pixel FOV ~10’
Detector HgCdTe
Cooling system radiation cooling
Weight 3 kg