Instrument and Telescopes Used in the Rivkin Three Micron Asteroid Data Bundle ============================================================================== Date: 2025-07-09 The information was extracted from the sources cited below. Instruments ============ RC2 --- The IRTF RC2 Photometer is a single-element 1-5 micron InSb detector with passbands defined by a set of discrete filters and a circular variable filter (CVF) segment. The detector and aperture wheel are cooled by solid N2; the filters are cooled by liquid N2. Broadband filters J at 1.25 microns, H at 1.65 microns and K at 2.20 microns were available, as well as narrowband filters at 2.95 microns, and at 3.35 microns. Additionally, a narrowband filter at 3.12 microns was available for some observations in 1991. Spectrophotometry at wavelengths in microns of 1.25, 1.65, 2.20, 2.95, and 3.35 was used. NSFCam ------ NSFCAM is a 1.0-5.5 micron infrared array camera, incorporating a Santa Barbara Research Center 256x256 InSb array. Three user-selected pixel scales, 0.06 arcsec/pixel, 0.15 arcsec/pixel, 0.3 arcsec/pixel, are available. Circular variable filters (∆λ/λ = 1%) were used at wavelengths in microns of 1.65, 2.20, 2.40, 2.95, 3.12, 3.35, and 3.50. NSFCAM was funded by NSF. CoCo ---- The Cold Coronagraph(CoCo) was designed for use with the NSFCAM for imaging of very faint structures or sources in close proximity to very bright sources. System Specifications: wavelength region: 1-5 microns; FOV: 14-38 arcsec; number of focal plane mask positions: 4; available masks: K-band optimized apodized-occulting masks with 0.5 power points of 2, 4, 6, and 8 diffraction rings; number of pupil plane mask positions: 6 available mask: pupil plane masks to match the occulting masks; liquid nitrogen cooling. InfraRed Telescope Facility (IRTF) 3.2m telescope on Maunakea, HI ================================================================== Aperture (m): 3.2 Latitude (deg): 19.8262 Longitude (deg): 155.4719 Elevation (m): 4168.07 A 3.2-meter telescope optimized for use in infrared astronomy and located on Maunakea in Hawaii. It was first built to support the Voyager missions and is now the US national facility for infrared astronomy, providing continued support to planetary, solar neighborhood, and deep space applications. The IRTF is operated by the University of Hawaii under a cooperative agreement with NASA. According to the IRTF's time allocation rules, at least 50% of the observing time is devoted to planetary science. The IRTF is a 3.2 m classical Cassegrain telescope. The Cassegrain focus f/ratio is f/38 and the primary mirror f/ratio is 2.5. Several aspects of the design of IRTF are optimized for IR observations. The secondary mirror is undersized to prevent the instrument from seeing the thermal emission from the telescope structure around the primary mirror. The primary mirror itself is 126" in diameter, but only the center 118" is used. A small mirror in the center of the secondary mirror prevents the instrument from seeing its own thermal emission. The f/ratio is long to have a small secondary mirror, again to minimize the telescope's thermal emission. The mirror coatings are chosen to have minimal thermal emission. The emissivity of the telescope is usually below 4%. The secondary mirror is mounted on a chopping mechanism to rapidly switch the pointing of the telescope from target to sky at up to 4 Hz. The IRTF is mounted on a large English yoke equatorial mount. The mount is very stiff, reducing flexure and allowing for accurate pointing of the telescope. Since the telescope is on an equatorial mount, the telescope can observe targets through the zenith without concern for field rotation. The yoke mount prevents the telescope from pointing north of +69 degrees declination. Since the telescope was primarily intended for planetary science, this restriction was considered to be acceptable. Since the telescope is on a heavy mounting, it is relatively immune from vibration or wind shake. Telescope Limits Declination The Hour Angle Limits +69:56:00 -59:00:00 +/- 5:04:47 Sources: ======== IRTF: ----- Information was extracted from the telescope website. NSFCam: ------- Shure, M.A., Toomey, D.W., Rayner, J.T., Onaka, P.M., Denault, A.J. 1994. NSFCAM: a new infrared array camera for the NASA Infrared Telescope Facility. Proc. SPIE Vol. 2198, p. 614-622, Instrumentation in Astronomy VIII, David L. Crawford; Eric R. Craine; Eds. doi:10.1117/12.176769. RC2 --- Information was extracted from the IRTF RC2 Photometer website. Coco: ----- Wang, S-I., Owensby, P.D., Toomey, D.W., Brown, R.H. ; Stahlberger, W.E. ; Cavedoni, C.P., Hua, R., Ftaclas, C. 1994. CoCo: an infrared cold coronagraph for astronomical observations. Proc. SPIE Vol. 2198, p. 578-589, Instrumentation in Astronomy VIII, David L. Crawford; Eric R. Craine; Eds. doi:10.1117/12.176765. Toomey, D.W., Ftaclas, C., Brown, R.H., Trilling, D. 1998. CoCo: an experiment in infrared coronagraphy at the IRTF. Proc. SPIE Vol. 3354, p. 782-790, Infrared Astronomical Instrumentation, Albert M.Fowler; Ed. doi:10.1117/12.317214.