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