IRIS

First Light Instrument for the Thirty Meter Telescope (TMT)

Overview Science Cases Simulations Filters/Gratings Team IRIS ETC

IRIS Filters

Each IRIS science case prefers specific filters for both the imager and the spectrograph. A cost effectiveness of the IRIS design is for the imager and spectrograph to operate simulataneously and share common filters. A great amount of care in the selection of filters is performed to determine the tradeoffs with field of view and spectral resolution in the spectrograph, as well as optimization of the imaging bands. For instance, optimizing narrowband filter (1%) wavelength ranges for imaging first light galaxies and for given redshift regimes for both CaII Triplet and CO bandheads in the spectrograph will play a critical role in the investigation. Selecting 5% narrowband filter bandpasses in both optimal atmospheric and astrophysical regimes has been performed for optimizing wavelength with field of view of the spectrograph.

Filter              Min λ Filter              Max λ Filter                Bandpass                
Zbb0.81070.996720
Ybb0.9331.15120
Jbb1.1351.38920
Hbb1.4741.820
Kbb1.9752.41220
ZN10.8260.8695
ZN20.86020.9055
ZN30.89580.94245
ZN40.93290.98145
YN10.97141.02195
YN21.01161.06415
YN31.05331.1085
JN11.1561.21535
JN21.20311.26485
JN31.25211.31635
JN41.30311.36995
HN11.4741.54955
HN21.5341.61265
HN31.59651.67835
HN41.66151.74675
HN51.72921.81785
KN11.962.06045
KN22.03982.14435
KN32.12292.23175
KN42.20942.32265
KN4.52.2752.3855
KN52.29932.41725
Filter              Min λ Filter              Max λ Filter              Bandpass              
Z0.830.92511
Y0.971.0710
J1.1661.3313
H1.4851.78118
Ks1.992.314.5
K22.418
CaII Trip0.84730.86882.5
HeI1.07761.10492.5
Pa-Beta1.2751.3082.5
FeII1.6371.6792.5
Br-Gamma2.1552.212.5
CO2.28772.3462.5
HeI1.07761.08841
J Cont1.20721.21931
Pab1.2751.2881
H Cont1.57251.58831
FeII1.6371.6541
H22.112.1321
K Cont2.1332.1541
Brg2.1552.1771
H22.2512.2731
CO2.2762.3021
J Methane1.1091.1441
J Off1.2251.2951
H Methane1.6171.6871
H Off1.5431.6131
H +K1.57202.412043
Y+J0.92501.340037

IRIS Gratings

IRIS uses several gratings in the Integral Field Spectrograph. Currently gratings with resolutions 4000, 8000, 10000 are being considered for the instrument. Depending on the resolution and the mode selected (Lenslet/Slicer) different combinations of Filters can be used with the instrument. The spaxels and FOV available is also depend on these modes. These combinations are shown in the following table.

#Groove DensitySlicer Filter and SpaxelsLenslet Filter and SpaxelsResolution
1365ZbbSlicer 88x 45Zn1-Zn4Lenslet 128x1284000
2317YbbSlicer 88x 45Yn1-Yn4Lenslet 128x1284000
3262JbbSlicer 88x 45Jn1-Jn4Lenslet 128x1284000
4203HbbSlicer 88x 45Hn1-Hn5Lenslet 128x1284000
5151KbbSlicer 88x 45Kn1-Kn5Lenslet 128x1284000
6166  H+KLenslet 16x1284000
7292  Y+JLenslet 16x1284000
8748Zn1-Zn4Slicer 88x 45ZbbLenslet 16x1288000
9650Yn1-Yn4Slicer 88x 45YbbLenslet 16x1288000
10536Jn1-Jn4Slicer 88x 45JbbLenslet 16x1288000
11415Hn1-Hn5Slicer 88x 45HbbLenslet 16x1288000
12323Kn1-Kn3Slicer 88x 45KbbLenslet 16x1288000
13292Kn4-Kn5Slicer 88x 45KbbLenslet 16x1288000
14310Kn1-Kn5Slicer 88x 45KbbLenslet 16x1288000
15932  ZbbLenslet 16x12810000
16808  YbbLenslet 16x12810000
17667  JbbLenslet 16x12810000
18515  HbbLenslet 16x12810000
19384  KbbLenslet 16x12810000