Blu-MICHI Summary
Wavelength Range
Field of View
Pixel Scale
Spectral Resolution
Pixel Scale
Wavelength Range
Spectral Resolution
Slit
Pixel Scale
Wavelength Range
Spectral Resolution
Slit
Slit Viewer
Wavelength Range
Field of View
Pixel Scale
Spectral Resolution
Disperser
Slicing Mirror Unit
Operational Modes
Methodology
Wavelength Range
Field of View
Wavefront Quality
Sky Coverage
Strehl Ratios
Wavelength Range
L (3.42-4.12µm)1, M (4.57-4.79µm),
N band (7.3-13.8µm) [Q band (16.0-25.0µm) TBC]
Imager
24.4x24.4” at L&M bands
28.1x28.1” at N [&Q TBC] band
11.9 mas per pixel at L&M bands
27.5 mas per pixel at N [&Q TBC] band
R~10-100
Long-Slit Moderate Dispersion Spectrometer
11.9 mas per pixel at L&M bands
27.5 mas per pixel at N [&Q TBC] band
L, M, & N bands [Q band TBC]
R~600 L, M, & N bands [Q band TBC]
28.1” length, diffraction limited to ~0.1”
High Dispersion Spectrometer
11.9 mas per pixel at L&M bands
27.5 mas per pixel at N band
L, M, & N bands
R~120,000 at L&N, R~100,000 at M,
[R~60,000 at Q TBC]
2” length, diffraction limited to ~0.1”
Imager used as slit viewer
IFU Spectrometer
N band (only)
~0.175” (length) x ~0.07” (width), 10 slices
35.0 mas per pixel
R~1,000
Reflective gratings
10 spaxels
Polarimetry (TBC)
Imaging- and spectro-polarimetry, both modes TBC
Dual-beam (Wollaston and Half Wave Retarder)
L, M, & N bands
MIR Adaptive Optics System
10” with 1 arcmin goal
Requirement wavefront rms phase < 750nm, goal <
350nm rms
“All sky” and limited only by natural tip-tilt stars
L & M Bands up to 80%
N & Q Band 80%
We have defined our L band transmission following Tokunaga, Simons & Vaca (2001), but
recognize that the L band atmospheric window it partially transmissive ~2.8-4.1 µm. We
will invite requests for special filters to cover specific features (i.e. water ice at 2.9 µm)
within the L band atmospheric window.
1
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Imaging Sensitivity Estimates
The imager has a 5-sigma, 1-hour on-target sensitivity shown in Table 1.
lambda 3
5
F_nu
0.0078 0.095
lambda 8
F_nu
0.075
9
0.081
10
0.11
11
0.12
12
0.14
13
0.23
14
0.73
lambda 17
18
19
20
21
22
23
24
25
F_nu
0.81
0.40
0.43
0.48
0.67
0.80
0.89
1.6
2.8
(lambda in microns; F_nu in mJy; bandpass is for whole of L&M windows or 1
micron for N and Q bands)
Table 1. 5-sigma, 1-hour on-target sensitivity for the imager.
Spectroscopy Sensitivity Estimates
For moderate spectral resolution, N band and Q band, the 5 sigma, 1 hour
integration flux densities are shown in Figure 1.
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Figure 1: Moderate resolution 5-sigma, 1 hour sensitivity limits for the N and Q bands.
The sensitivity of the high-resolution spectrograph (R=120,000) depends highly on
the specific wavelength of interest. This shown in Figure 2.
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Figure 2: High resolution 5-sigma, 1 hour sensitivity limits for the high-resolution spectrograph. This
illustrates that at high spectral resolution clear regions of the atmosphere can be exploited.
For the high spectral resolution L&M bands, we estimate the sensitivity of a Vega
magnitude 10 star of uniform brightness at L&M in 900 seconds. We also calculate
the magnitude of a star which gives a S/N =10 in 900 seconds on the TMT.
Wavelength
Mag 10 star in
900s S/N
3
167.972
S/N = 10 in 900s
13.06
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3.2
103.726
12.54
3.4
120.568
12.70
3.6
118.608
12.69
3.8
122.85
12.72
4
101.234
12.51
4.6
23.87
10.94
4.8
23.044
10.91
5
23.142
10.91
5.2
19.124
10.70
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