The Canarias InfraRed Camera Experiment (CIRCE) will be the only near-infrared instrument for the Gran Telescopio Canarias (GTC) 10.4-meter telescope with polarimetric capabilities. Both, image and spectroscopic polarimetry as well as high time resolution readout and lower spectral resolution will complement the capabilities of EMIR. Its 2048x2048 HawaiiII-2 detector and its aspheric optics described by Edwards et al (2007) will provide a pixel scale resolution of 0.1 arcsec/pixel in 3.4' FOV in the range of 1-2.5mm. Low spectroscopy resolutions of 410 (at 1.25mm) and 725 (at 2.20mm) will be avalaible in the range 1.25- 2.40mm. CIRCE will reach this depth (see below image) in Ks with an on-source integration time of less than 1 minute, slightly faster than NIRC/Keck with 25x greater FOV and 50% faster then NIRI/Gemini with 3x greater FOV.





CIRCE is an asymmetric reflective system except for the entrance windows, filters, grisms and the polarimetric components. Its 8 diamond-turned aspheric mirrors offer both excellent throughput and image quality. We assure low-level background noise from the telescope and instrument by inserting the optical elements in a cryostat with liquid nitrogen. The optical quality analysis Edwards et al (2005) shows that images are seeing-limited with less than 0.25 arcsec. The team of the instrument is as follow Stephen Steve Eikenberry (PI), Antonio Marin Franch (software), Michelle Edwards (optics), Nestor Lasso Cabrera (electronics), Miguel Charcos Llorens (mechanics). Engineers in the department are an important support for the instrument conception: Kevin T. Hanna (electronics), Jeffrey A Julian (mechanics) and Steven Raines (system engineering).



General Concepts mode
Focal Station Nasmyth/Cassegrain
Wavelength range 0.9 - 2.4 microns
Scales at detector 0.25 arcsec / pixel
Maximum FOV 3.4'x3.4'
Observing modes Imaging, spectroscopy (slits 0.4'', 0.7'' and 1''), imaging polarimetry, spectropolarimetryy (slits 0.4'', 0.7'' and 1''). All modes can be combined with high speed read-out
Technical Descriptions
Seeing limited (less than 2 pixels) along the entire FOV for all wavelength range
Camera Focal Length X
Collimator Focal Length X
Array format 2048x2048 HawaiiII-2 detector 1024x1024 HgCdTe
Temperature Liquid Nitrogen Cooling at 77 K
Observing Modes
Broad Band Imaging J, H, K filters. FOV=3.4'x3.4'
Narrow Band Imaging N/A. FOV=3.4'x3.4'
Spectroscopy Three Long-slits of 0.4'', 0.7'' and 1''. Two grisms: R=410 (at 1.25mm) and R=725 (at 2.20mm)
Imaging Polarimetry Same filters as standard imaging. FOV is 2'x50'' divided into 3 slots of 50''x12''. The central slot includes a HWP for accurate polarimetry. 5" 
Spectropolarimetry Same grisms and slits widths as standard spectroscopy. FOV is 2'x50'' divided into 3 slits of 50''x12''. The central slit includes a HWP for accurate polarimetry. 5"