Jupiter observations from
the NASA Infrared Telescope Facility

These observations of Jupiter represent quick-look images of the planet made using the scientific-grade guide camera (commonly called “Guide Dog”) on the moderate-resolution near-infrared facility spectrometer, SpeX, at NASA’s Infrared Telescope Facility (IRTF).

The files are in NASA-standard Flexible Image Transport System (FITS) format, with details of the observations provided in the headers.  The observations are the final composites of several exposures on Jupiter that were taken within seconds of each other with the telescope pointing dithered in order to fill in bad-pixel locations.  They have also been corrected for inhomogeneities in the sensitivity in the incoming radiation field across the array, i.e. “flat-fielded”, using observations of a uniformly illuminated field (either the telescope dome for nighttime observations or the daytime sky). No absolute calibration in physical radiance units or reflectivity with respect to incident solar radiation has been performed. A limb-fitting procedure has been performed with the resulting disk center denoted in the header.  The longitude of the central meridian at the mid-point of the observations is also provided in the image headers.

Most of the images were obtained by IRTF staff in brief intervals in a program designed to monitor changes in atmospheric properties at strategic wavelengths of:

• 1.58 microns (sensitive to deep-cloud reflectivity),
• 2.16 microns (sensitive to reflectivity from particles in Jupiter’s upper troposphere and lower stratosphere),
• 3.42 microns (sensitive to H3+ emission from auroral regions),
• 3.80 microns (sensitive to reflectivity from clouds near 2-3 bars of atmospheric pressure with some emission from H3+ at the poles), and
• 5.10 microns (sensitive primarily to thermal emission from the atmosphere as deep as the 5-bar atmospheric pressure level). 

Images at additional wavelengths were also recorded during more intensive observing shifts of several hours, including 1.64 microns, 1.65 microns, 2.12 microns (sensitive to particle reflection of sunlight from over an intermediate range of atmospheric pressures), and 2.30 microns (sensitive to very high-altitude particles in Jupiter’s lower stratosphere).  Including November of 2016 and onward, additional observations at these wavelengths may be obtained from other IRTF programs observing Jupiter using the Guidedog camera on SpeX.

Questions can be directed to Juno team member Glenn Orton ( glenn.orton@jpl.nasa.gov).

SpeX details can be obtained from the IRTF website: https://irtfweb.ifa.hawaii.edu/~spex/.

Detailed questions about SpeX should be directed to IRTF staff member (and Director-elect) John Rayner (rayner@ifa.hawaii.edu).