Sensitivity Estimate for SPICA/SMI/HRS
The following estimates assume to employ Si:As detector array supplied by Raytheon.
Please visit here for the case of Si:As detector array supplied by DRS.
-array size; 1K×1K Si:As BIB detector
-dark current; 0.06 electron/pix
-read noise; 10.0 electrons per readout
-saturation full well; 2.0E+5 (electrons)
-pixel pitch; 25 (µm/pix)
-exposure time; 300 (sec)
-shortest exposure time; 2 (sec)
-detector qunatum efficiency; "DETQE_SIAS.DAT" (electron/photon)
【optics】
-diameter of the primary mirror; 2.5m
-secondary mirror shielding rate; 0.2
-plate scale; 0.67 (arcsec/pix)
-slit width; 1.7 (arcsec)
-energy fraction within 1st null radius; 0.9
-system efficiency (incl. lens and filters, etc); 0.3
-relative grating efficiency (echelle grating and cross disperser); "SMI-HRS_GEFF.DAT"
Data Format:
1st column; Echelle order
2nd column; wavelength (µm)
3rd column; relative grating efficiency; ηechelle(λ) x ηcross disperser(λ)
-peak efficiency (ηechelle(λ) x ηcross disperser(λ)); 0.4
【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
Data Format:
1st column; Echelle Order
2nd column; wavelength (µm)
3rd column; X (pix)
4th column; Y (pix)
5th column; PSF FWHM size on detector plate along X direction (µm)
6th column; PSF FWHM size on detector plate along Y direction (µm)
note: pixel pitch is 25 (µm/pix)
X [pix] =α [pix/µm2] λ2+β [pix/µm]λ+γ [pix]
(calculated for the adopted spectral resolution of R=λ/Δλairy)
ASKII Data:
"1H5S_SENSITIVITY_HRS_mJy_R.DAT"
Data Format:
1st column; wavelength (µm)
2nd column; 1-hour 5-sigma continuum sensitivity for a point source (mJy) [low background case]
3rd column; 1-hour 5-sigma continuum sensitivity for a point source (mJy) [high background case]
ASKII Data:
"1H5S_LINE_SENSITIVITY_HRS_Wm-2.DAT"
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]
(calculated for the adopted spectral resolution of R=λ/Δλslit)
ASKII Data:
"1H5S_SENSITIVITY_HRS_MJY-SR_R.DAT"
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]
ASKII Data:
"1H5S_LINE_SENSITIVITY_HRS_Wm-2-SR.DAT"
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]
ASKII Data:
"SATURATION_HRS_JY.DAT"
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]
version 2015.12.05 (Itsuki Sakon) [contact: isakon@astron.s.u-tokyo.ac.jp]
The following estimates assume to employ Si:As detector array supplied by Raytheon.
Please visit here for the case of Si:As detector array supplied by DRS.
1. Assumptions
【detectors】-array size; 1K×1K Si:As BIB detector
-dark current; 0.06 electron/pix
-read noise; 10.0 electrons per readout
-saturation full well; 2.0E+5 (electrons)
-pixel pitch; 25 (µm/pix)
-exposure time; 300 (sec)
-shortest exposure time; 2 (sec)
-detector qunatum efficiency; "DETQE_SIAS.DAT" (electron/photon)
【optics】
-diameter of the primary mirror; 2.5m
-secondary mirror shielding rate; 0.2
-plate scale; 0.67 (arcsec/pix)
-slit width; 1.7 (arcsec)
-energy fraction within 1st null radius; 0.9
-system efficiency (incl. lens and filters, etc); 0.3
-relative grating efficiency (echelle grating and cross disperser); "SMI-HRS_GEFF.DAT"
Data Format:
1st column; Echelle order
2nd column; wavelength (µm)
3rd column; relative grating efficiency; ηechelle(λ) x ηcross disperser(λ)
-peak efficiency (ηechelle(λ) x ηcross disperser(λ)); 0.4
【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 HRS Spectra
2.1. Point Spread Function
PSF FWHM size on detector plate; "SMI-HRS_PSF.DAT"Data Format:
1st column; Echelle Order
2nd column; wavelength (µm)
3rd column; X (pix)
4th column; Y (pix)
5th column; PSF FWHM size on detector plate along X direction (µm)
6th column; PSF FWHM size on detector plate along Y direction (µm)
note: pixel pitch is 25 (µm/pix)
2.2. Pixel-to-Wavelength Relation
Assumption for the pixel-to-wavelength relation;X [pix] =α [pix/µm2] λ2+β [pix/µm]λ+γ [pix]
| Echelle Order | λmin [µm] | λmax [µm] | α [pix/µm2] | β [pix/µm] | γ [pix] |
| 118 | 12.144 | 12.248 | 0.718578E+04 | -0.169792E+06 | 0.100221E+07 |
| 117 | 12.248 | 12.353 | 0.706963E+04 | -0.168455E+06 | 0.100270E+07 |
| 116 | 12.353 | 12.460 | 0.696656E+04 | -0.167421E+06 | 0.100508E+07 |
| 115 | 12.460 | 12.568 | 0.685513E+04 | -0.166156E+06 | 0.100605E+07 |
| 114 | 12.568 | 12.679 | 0.676397E+04 | -0.165385E+06 | 0.101017E+07 |
| 113 | 12.679 | 12.792 | 0.667097E+04 | -0.164549E+06 | 0.101393E+07 |
| 112 | 12.792 | 12.907 | 0.659423E+04 | -0.164115E+06 | 0.102033E+07 |
| 111 | 12.907 | 13.023 | 0.653264E+04 | -0.164066E+06 | 0.102936E+07 |
| 110 | 13.023 | 13.142 | 0.640413E+04 | -0.162267E+06 | 0.102710E+07 |
| 109 | 13.142 | 13.264 | 0.633833E+04 | -0.162087E+06 | 0.103548E+07 |
| 108 | 13.264 | 13.387 | 0.621092E+04 | -0.160263E+06 | 0.103307E+07 |
| 117 | 13.387 | 13.513 | 0.611692E+04 | -0.159302E+06 | 0.103640E+07 |
| 106 | 13.513 | 13.641 | 0.607307E+04 | -0.159682E+06 | 0.104890E+07 |
| 105 | 13.641 | 13.771 | 0.594396E+04 | -0.157734E+06 | 0.104569E+07 |
| 104 | 13.771 | 13.904 | 0.586089E+04 | -0.157022E+06 | 0.105096E+07 |
| 103 | 13.904 | 14.040 | 0.576656E+04 | -0.155979E+06 | 0.105401E+07 |
| 102 | 14.040 | 14.178 | 0.568408E+04 | -0.155250E+06 | 0.105935E+07 |
| 101 | 14.178 | 14.319 | 0.557636E+04 | -0.153787E+06 | 0.105956E+07 |
| 100 | 14.319 | 14.463 | 0.549297E+04 | -0.152993E+06 | 0.106457E+07 |
| 99 | 14.463 | 14.610 | 0.539190E+04 | -0.151671E+06 | 0.106586E+07 |
| 98 | 14.610 | 14.760 | 0.528165E+04 | -0.150048E+06 | 0.106494E+07 |
| 97 | 14.760 | 14.913 | 0.518700E+04 | -0.148857E+06 | 0.106724E+07 |
| 96 | 14.913 | 15.069 | 0.508256E+04 | -0.147346E+06 | 0.106718E+07 |
| 95 | 15.069 | 15.229 | 0.497672E+04 | -0.145759E+06 | 0.106651E+07 |
| 94 | 15.229 | 15.391 | 0.489548E+04 | -0.144889E+06 | 0.107132E+07 |
| 93 | 15.391 | 15.558 | 0.478910E+04 | -0.143225E+06 | 0.107010E+07 |
| 92 | 15.558 | 15.728 | 0.468304E+04 | -0.141533E+06 | 0.106863E+07 |
| 91 | 15.728 | 15.901 | 0.460792E+04 | -0.140779E+06 | 0.107453E+07 |
| 90 | 15.901 | 16.079 | 0.449558E+04 | -0.138820E+06 | 0.107093E+07 |
| 89 | 16.079 | 16.261 | 0.440763E+04 | -0.137602E+06 | 0.107322E+07 |
| 88 | 16.261 | 16.447 | 0.432569E+04 | -0.136554E+06 | 0.107695E+07 |
| 87 | 16.447 | 16.637 | 0.426024E+04 | -0.136025E+06 | 0.108507E+07 |
| 86 | 16.637 | 16.831 | 0.416147E+04 | -0.134367E+06 | 0.108390E+07 |
| 85 | 16.831 | 17.031 | 0.412513E+04 | -0.134783E+06 | 0.110025E+07 |
| 84 | 17.031 | 17.235 | 0.400727E+04 | -0.132416E+06 | 0.109317E+07 |
| 83 | 17.235 | 17.444 | 0.356419E+04 | -0.118747E+06 | 0.988231E+06 |
| 82 | 17.444 | 17.657 | 0.376820E+04 | -0.127392E+06 | 0.107595E+07 |
| 81 | 17.657 | 17.877 | 0.368085E+04 | -0.125927E+06 | 0.107630E+07 |
| 80 | 17.877 | 18.102 | 0.363065E+04 | -0.125758E+06 | 0.108827E+07 |
| 79 | 18.102 | 18.332 | 0.357074E+04 | -0.125227E+06 | 0.109723E+07 |
| 78 | 18.332 | 18.569 | 0.348822E+04 | -0.123856E+06 | 0.109872E+07 |
| 77 | 18.569 | 18.751 | 0.325617E+04 | -0.116881E+06 | 0.104809E+07 |
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:
"1H5S_SENSITIVITY_HRS_mJy_R.DAT"
Data Format:
1st column; wavelength (µm)
2nd column; 1-hour 5-sigma continuum sensitivity for a point source (mJy) [low background case]
3rd column; 1-hour 5-sigma continuum sensitivity for a point source (mJy) [high background case]
3.2. 1-hour 5-sigma line sensitivity for a point source
ASKII Data:
"1H5S_LINE_SENSITIVITY_HRS_Wm-2.DAT"
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:
"1H5S_SENSITIVITY_HRS_MJY-SR_R.DAT"
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:
"1H5S_LINE_SENSITIVITY_HRS_Wm-2-SR.DAT"
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:
"SATURATION_HRS_JY.DAT"
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]