<title>CoCo: an infrared cold coronagraph for astronomical observations</title>

Abstract

This paper deScribeS the design of an infrared Cold Coronagraph (CoCo) built for use at the NASA 3-rn Infrared Telescope Facility (IRFF) at Mauna Kea Observatory for the imaging of faint infrared sources in proximity to bright sources. The coronagraph is designed to obtain high contrast photometric images by use of an occulting mask and a pupil mask. The coronagraph is to be used in combination with the 111ff NSFCAM, which covers 1-5 jim and uses a 256x256 InSb array. The platescale can be varied from 0.06"/pixel to 0.1 5/ucl. covering a field of view of 14" and 38", respectively. Selectable apodized and hard occulting masks are mounted an a ibed as the first element in the system to reduce scattered light. Selectable pupil masks are cooled to 77K within tbe ('Co cryostat. The cryostat consists of a liquid nitrogen can for cooling the optics, masks, and baffles. The CoCo dewar is mounted on a slide in a housing to allow it to move out of the beam path so that the NSFCAM may be used with or without the coronagraph during the same observing period.

Near-Infrared Spectrophotometry of Phobos and Deimos

“…We used NSFCAM paired with the Cold Coronagraph (CoCo) (Shure et al 1994, Wang et al 1994, Toomey et al 1998 to facilitate IR imaging of the faint martian satellites, which are 7-8 magnitudes fainter than Mars and in close proximity to the planet (less than ∼20 arcsec for Phobos and ∼50 arcsec for Deimos). Pairs of images were taken using the circular variable filter (CVF) available on NSFCAM, at wavelengths of 1.65, 1.80, 2.00, 2.20, 2.40, 2.95, 3.05, 3.12, 3.20, 3.35, and 3.50 µm.…”

Revised Fluxes for Gliese 229B

“…We obtained JHKL ′ photometry for Gliese 229B on 1999 January 14 using the NASA Infrared Telescope Facility on Mauna Kea in Hawaii. We used the facility infrared camera NSFCAM (Shure et al 1994) together with the coronographic instrument CoCo (Wang et al 1994, Toomey et al 1998. CoCo is a cold coronographic attachment to NSFCAM that utilizes an apodized focal plane mask and a pupil mask that stops the telescope outer diameter down to 80% of the full aperture and also obscures the inner 30%.…”

A Redetermination of the Mass of Procyon

“…As one might expect, the e †ect ÈÈÈÈÈÈÈÈÈÈÈÈÈÈÈ 10 At http ://astro.estec.esa.nl/Hipparcos. Wang et al (1994). It features selectable, apodized focal-plane masks.…”