Sensitivity Estimate for SPICA/SMI/LRS

version 2016.03.29 (I.Sakon)

1. Assumptions

【detectors】
-array size; 1K×1K Si:Sb BIB detector
-dark current; 0.8 electron/pix
-read noise; 25.0 electrons per readout
-saturation full well; 1.0E+5 (electrons)
-pixel pitch; 18 (µm/pix)
-exposure time; 600 (sec)
-shortest exposure time; 2 (sec)
-detector qunatum efficiency; "DETQE_SISB.DAT" (electron/photon)

【optics】
-diameter of the primary mirror; 2.5m
-secondary mirror shielding rate; 0.2
-plate scale; 0.7 (arcsec/pix)
-slit width; 3.7 (arcsec)
-energy fraction within 1st null radius; 0.9
-system efficiency (incl. mirror ref., short cut filter trans., etc); 0.3

【others】
-high background case;
・zodiacal light emission at ecliptic plane (β=0.0deg and ε=60deg)
・black body of T=268.5 K normalizzed to 80 MJy/sr at 25µm
-low background case;
・zodiacal light emission at ecliptic pole (β=90.0deg)
・black body of T=274.0 K normalizzed to 15 MJy/sr at 25µm
(Reach et al. 2003; Ootsubo et al. 2000)
- safety factor; 0.8
- number of pixels used to extract spectrum along cross dispersion direction;
first null diameter of the airy disk


2. Properties of LRS Spectra

2.1. Spectral Format

2.2. Point Spread Function

POS#01, POS#02, POS#03, POS#04, POS#05, POS#06, POS#07, POS#08, POS#09, POS#10, POS#11, POS#12, POS#13, POS#14, POS#15, POS#16, POS#17, POS#18, POS#19, POS#20
Data Format:
1st column; wavelength (µm)
2nd column; X (pix)
3rd column; Y (pix)
4th column; PSF FWHM size on detector plate along X direction (µm)
5th column; PSF FWHM size on detector plate along Y direction (µm)
note: pixel pitch is 18 (µm/pix)

2.3. Pixel-to-Wavelength Relation

Assumption for the pixel-to-wavelength relation;
Y [pix] =α [pix/µm2] λ2+β [pix/µm]λ+γ [pix]
Position α [pix/µm2] β [pix/µm] γ [pix]
#01 0.240696438 0.676020941 -57.9230292
#02 0.243494511 -0.673452477 234.710571
#03 0.24834328 -1.32077233 485.654367
#04 0.260506713 -1.88249491 729.398494
#05 0.238720342 0.597561451 -53.4697027
#06 0.241149793 -0.692105992 234.906887
#07 0.247442758 -1.37947451 485.157883
#08 0.261523424 -1.98558812 730.423354
#09 0.237277501 0.597883458 -52.9137145
#10 0.239761575 -0.705247811 235.865217
#11 0.248143493 -1.46752562 487.117763
#12 0.26507781 -2.13872102 732.430512
#13 0.237157147 0.599133466 -53.3687538
#14 0.239736729 -0.7220649 237.488176
#15 0.250140293 -1.56183455 489.830096
#16 0.269407705 -2.26839115 732.644914
#17 0.239364277 0.549181414 -53.1989736
#18 0.241294687 -0.730782039 239.32452
#19 0.252937404 -1.62142552 491.873823
#20 0.274005934 -2.32706008 728.741443


3. Estimated Sensitivity

3.1. 1-hour 5-sigma continuum sensitivity for a point source

(calculated for the adopted spectral resolution of R=λ/Δλairy)


ASKII Data:
POS#01, POS#02, POS#03, POS#04, POS#05, POS#06, POS#07, POS#08, POS#09, POS#10, POS#11, POS#12, POS#13, POS#14, POS#15, POS#16, POS#17, POS#18, POS#19, POS#20

Data Format:
1st column; wavelength (µm)
2nd column; 1-hour 5-sigma continuum sensitivity for a point source (µJy) [low background case]
3rd column; 1-hour 5-sigma continuum sensitivity for a point source (µJy) [high background case]


3.2. 1-hour 5-sigma line sensitivity for a point source


ASKII Data:
POS#01, POS#02, POS#03, POS#04, POS#05, POS#06, POS#07, POS#08, POS#09, POS#10, POS#11, POS#12, POS#13, POS#14, POS#15, POS#16, POS#17, POS#18, POS#19, POS#20

Data Format:
1st column; wavelength (µm)
2nd column; 1-hour 5-sigma line sensitivity for a point source (W/m2) [low background case]
3rd column; 1-hour 5-sigma line sensitivity for a point source (W/m2) [high background case]


3.3. 1-hour 5-sigma continuum sensitivity for extended sources

(calculated for the adopted spectral resolution of R=λ/Δλslit)


ASKII Data:
POS#01, POS#02, POS#03, POS#04, POS#05, POS#06, POS#07, POS#08, POS#09, POS#10, POS#11, POS#12, POS#13, POS#14, POS#15, POS#16, POS#17, POS#18, POS#19, POS#20

Data Format:
1st column; wavelength (µm)
2nd column; 1-hour 5-sigma continuum sensitivity for extended sources (MJy/sr) [low background case]
3rd column; 1-hour 5-sigma continuum sensitivity for extended sources (MJy/sr) [high background case]


3.4. 1-hour 5-sigma line sensitivity for extended sources


ASKII Data:
POS#01, POS#02, POS#03, POS#04, POS#05, POS#06, POS#07, POS#08, POS#09, POS#10, POS#11, POS#12, POS#13, POS#14, POS#15, POS#16, POS#17, POS#18, POS#19, POS#20

Data Format:
1st column; wavelength (µm)
2nd column; 1-hour 5-sigma line sensitivity for extended sources (W/m2/sr) [low background case]
3rd column; 1-hour 5-sigma line sensitivity for extended sources (W/m2/sr) [high background case]

3.5. Saturation limit for a point source


ASKII Data:
POS#01, POS#02, POS#03, POS#04, POS#05, POS#06, POS#07, POS#08, POS#09, POS#10, POS#11, POS#12, POS#13, POS#14, POS#15, POS#16, POS#17, POS#18, POS#19, POS#20

Data Format:
1st column; wavelength (µm)
2nd column; saturation limit for a point source (Jy) [low background case]
3rd column; saturation limit for a point source (Jy) [high background case]