CHARIS


For detailed information, please consult the CHARIS website.

The Coronagraphic High Angular Resolution Imaging Spectrograph (CHARIS) is an IFS for the Subaru telescope. It sits behind the SCExAO coronagraphic and extreme AO system and AO188 adaptive optics systems at the Subaru telescope.

Pulpit rock

HD1160 data cube


Capabilities

Targets with an H-band magnitude brighter than 1 can only be observed with the internal CHARIS ND3 filter in-beam, which restricts the user to broadband mode.

The current instrument capabilties are below:

Basic Parameters
Field of view2.07''x2.07''
2.07''x1.0'' Spectro-polarimetric mode (Wollaston prism in)
Plate Scale16.2 mas/lenslet
Recommended Satellite Spot Contrast1x10-1 - 1x10-3Tunable
Satellite Spot Location15.9 λ/D (~0.63" at 1550 nm)Scales linearly with λ
Detector Hawaii 2RG See CHARIS instrument description
Wavelength coverage 1154 nm to 2387 nmm SCExAO feeds CHARIS with wavelengths longer than 950nm
CHARIS throughput Low resolution mode: 65-70% ~15% from atmosphere to detector
High resolution mode: 55-60%
Spectral resolution Low resolution mode: R~19 J, H or K band
High resolution mode: R~70-90 J, H and K bands combined
Coronagraph modes Lyot, vAPP, PIAACMC, Vortex See SCExAO coronagraph section
Angular Differential Imaging YES SCExAO operates in fixed pupil mode
Speckle control YES (static WF map) Speckle control performed using SCExAO
internal science camera
Tip-Tilt control YES Tip-Tilt control performed using SCExAO
Low Order Wavefront Sensor
Spectro-polarimetric imaging YES A Wollaston prism, combined with a field stop, is now available for spectro-polarimetry
Dithering ±2" It is now possible to offset the field-of-view with respect to the guide star

Wavelength modes


Filters Dispersion Modes
Band50% Transmission Range (nm)In-Band Filter Transmission Band Avg. Spectral Resolution (2x2 pixels) # Output ChannelsCHARIS Internal Throughput
J1176-1328 >80% JR=75.2 15>40%
H1490-1783 >90% HR=65.2 20>40%
K2019-2375 >90% KR=77.1 17>40%
Broadband 1154-2387 >93% BroadbandR=18.4 22>53%
Cold ND3 1165-2365 >OD 3.258 BroadbandR=18.4 22 -

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