The Canarias infrared camera experiment (CIRCE): opto- and cryomechanical design and manufacture
Michelle L. Edwards, Stephen S. Eikenberry, Miguel V. Charcos-Llorens, Antonio Marin- Franch, Nestor M. Lasso Cabrera, Steven N. Raines, Jeffrey A. Julian, Kevin T. Hanna, Christopher C. Packham, J. Michael Rodgers, Reba M. Bandyopadhyay

ABSTRACT



IR polarimetry system with the Canarias infrared camera experiment (CIRCE)
Charcos-Llorens ,M. L., Eikenberry, A. J., Edwards, S. S., Hanna, K. T., Julian, J., Lasso Cabrera, N. M., Marín-Franch, A., Packham, C, Raines, S. N., Rodgers, M, Varosi, F.

ABSTRACT
The Canarias Infrared Camera Experiment (CIRCE) will be the only near-infrared instrument at the Gran Telescopio de Canarias (GTC) with polarimetric capabilities -- both imaging polarimetry and spectropolarimetry. We expect to achieve 0.1% of accuracy in the degree of measured polarization using a four beam approach. A superachromatic quartz/MgF2 half waveplate will provide full coverage of the instrument’s wavelength range. We accomplish beam splitting with a MgF2 Wedged Double Wollaston prism. Combined with masks, these two components will allow the measurement of linear polarization states with a maximum of 2 exposures in 50’’x2’ FOV. Spectropolarimetry will also be available between 1.25 and 2.40 microns with simultaneous linear Stokes parameter measurement.



Readout electronics and fast photometry with the Canarias infrared camera experiment (CIRCE)
Nestor M. Lasso Cabrera, Kevin T. Hanna, Stephen S. Eikenberry, Michelle L. Edwards, Miguel V. Charcos-Llorens, Antonio Marin-Franch

ABSTRACT



IR Polarimetry System with the Canarias InfraRed Camera Experiment (CIRCE)
Miguel Charcos-Llorens, Stephen S. Eikenberry, Michelle L. Edwards, Nestor M. Lasso, Antonio Marin-Franch, Chris C. Packham

ABSTRACT
The Canarias InfraRed Camera Experiment (CIRCE) for the Gran Telescopio Canarias (GTC) is one of the few infrared instruments in the world using a four-beam polarimeter. The classical double-beam configuration consists of a half-wave plate (HWP) and a Wollaston Prism (WP) that allow measurement of both components of the light in a single exposure. Instead, our instrument includes a WeDoWo -- a dual-WP system with principal axis at 45 degrees that is inserted near the pupil plane. Thus, all linear STOKES parameters can be obtained in a single observation. Medium resolution spectroscopy (R=400-1500) can be combined with polarimetry when inserting a grism in the beam. The CIRCE focal plane mask includes two 10-arcsec slots for imaging polarimetry, one slit for spectropolarimetry and three slits for simultaneous regular spectroscopy of nearby sources. CIRCE also has a high-speed photometry mode that, combined with polarimetry on a large telescope such as the GTC, will provide important insights into highly-variable sources such as microquasars.



CIRCE: the Canarias InfraRed Camera Experiment for GTC
Charcos-Llorens, M. V., Cenarro, A. J., Edwards ,M. L., Eikenberry, S. S., Hanna, K. T., Julian, J., Lasso Cabrera, N. M., Marín-Franch, A., Packham, C, Raines, S. N., Rodgers, M, Varosi, F.

ABSTRACT
The Canarias InfraRed Camera Experiment (CIRCE) is a near-infrared (1-2.5 micron) instrument for the Gran Telescopio Canarias (GTC) 10.4-meter telescope. CIRCE has an off-axis aspheric all-reflective optical system that offers both excellent throughput and image quality. Observational modes include broad/narrow band imaging and low-resolution spectroscopy. High time-resolution data acquisition and polarimetry are available in both cases. We present an overview of the instrument and the current status of design and fabrication.