SpeX
====

Up-to-date as of October 12, 2023 from the IRTF/SpeX website 

Introduction
-------------
SpeX is a medium-resolution 0.7-5.3 micron spectrograph built at the Institute for Astronomy (IfA), for the NASA Infrared Telescope Facility (IRTF) on Mauna Kea. The instrument saw first light in May 2000 and was upgraded in 2014. The primary reason for the upgrade was to replace obsolete array control and instrument control electronics although the opportunity was taken to upgrade the arrays as well. The Raytheon Aladdin 3 1024x1024 InSb array in the spectrograph was replaced by a Teledyne 2048x2048 Hawaii-2RG array and the engineering grade Aladdin 2 512x512 InSb array in the IR slit viewer was replaced by the science grade Aladdin 3 array from the spectrograph (only a 512x512 quadrant is used). Astronomical Research Cameras, Inc. controllers run both arrays. Most of the warm electronic hardware was also replaced: motors, motor controllers, Hall effect sensor control, power supplies, computers and GUIs. For most observing programs guiding is done with the IR slit viewer on spillover flux from the object in the slit. However, for optically visible objects selectable IR transmitting and visible reflecting dichroics in SpeX feed the MORIS CCD camera attached to the side of SpeX to enable guiding in the visible. MORIS is also used as a scientific CCD imager and for simultaneous optical and IR observations in conjunction with SpeX. The upgrade has resulted in increased simultaneous (one shot) wavelength coverage in all spectral modes and improved spectral sensitivity (0.25-0.5 mags). Due to the faster computers instrument control is more robust and there are fewer software problems. SpeX was originally funded by the National Science Foundation (NSF) in 1996 with additional funding from NASA for the detector arrays in 1998. The SpeX Upgrade was funded by NSF in 2008 but delays in procurement of a science grade H2RG array delayed completion until 2014.

New Spex (Aug 2014-) 
-------------------- 
• Spectrograph pixel size 0.10" (18 microns) 
• Slit widths: 0.3", 0.5", 0.8", 1.6" and 3.0" 
• PRISM 0.7-2.52 micron, R~200 matched to 0.3x15" slit or 0.3x60" slit 
• SXD 0.7-2.55 micron, R~2000 matched to 0.3x15" slit 
• LXD_short 1.67-4.2 micron, R~2500 matched to 0.3x15" slit 
• LXD_long 1.98-5.3 micron, R~2500 matched to 0.3x15" slit 
• Single order short 0.9-2.4 micron, R~2000 matched to a 0.3x60" slit 
• Single order long 3.1-5.3 micron, R~2500 matched to a 0.3x60" slit 
• Slit viewer: 60x60" FOV at 0.12" per pixel, selection of filters available (no change) 

Old SpeX (2000-Jan 2014) 
------------------------ 
• Spectrograph pixel size 0.15" (27 microns) 
• Slit widths: 0.3", 0.5", 0.8", 1.6" and 3.0"
• PRISM 0.8-2.5 micron, R~200 matched to 0.3x15" slit or 0.3x60" slit 
• SXD 0.8-2.4 micron, R~2000 matched to 0.3x15" slit 
• LXD1.9 1.95-4.2 micron, R~2500 matched to 0.3x15" slit 
• LXD2.1 2.15-5.0 micron, R~2500 matched to 0.3x15" slit 
• LXD2.3 2.25-5.5 micron, R~2500 matched to 0.3x15" slit 
• Single order short 0.9-2.4 micron, R~2000 matched to a 0.3x60" slit
• Single order long 3.1-5.4 micron, R~2500 matched to a 0.3x60" slit 
• Slit viewer: 60x60" FOV at 0.12" per pixel, selection of filters available


References
==========

Rayner, J.T., P. M. Onaka, M. C. Cushing and W. D. Vacca, 
Four Years of Good SpeX, 
in Ground-based Instrumentation for Astronomy, A. F. M. Moorwood and M. Iye, Eds.,  Proceedings of the SPIE, vol. 5492, pp. 1498-1509, 2004,
doi:10.1117/12.551107.

Rayner, J. T., D. W. Toomey, P. M. Onaka, A. J. Denault, W. E. Stahlberger, and 3 others, 
SpeX: A Medium-Resolution 0.8 - 5.5 micron Spectrograph and Imager for the NASA Infrared Telescope Facility, 
PASP 115, 362, 2003,
doi:10.1086/367745.  

