Images of Io and Jupiter from the IRTF SpeX camera during the outburst event of 2019 May 8. Io is in eclipse. The images are the infrared photometric filters (a) narrowband Kcont 2.3 μm, (b) broadband Lprime 3.8 μm, and (c) broadband 4.5–5.1 μm M band (see Table 2). The double effect in the images is due to the subtraction of A and B frames when the telescope nods by 5″ in the north–south direction to remove the telescope's and atmosphere's first-order thermal effects. The frames are 30″ across. Notice the other Jovian moons visible in the contK-band image that disappear in the longer-wavelength images. The Lprime is used for the occultations both because of its sensitivity to thermal anomalies on Io and because Jupiter itself is less bright due to its methane absorption. The signal-to-noise ratio is noticeably lower for the M-band images.