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The NEAR Sunglint Event of 9 January 1998

Last modified on January 12, 1998 by A. Richichi



On January 9, 1998 a mail was circulated by D. Dunham, announcing a peculiar type of event to take place later on the same day, namely a glint produced by solar panels of the space probe NEAR as they reflected shortly the solar light towards the Earth from a distance of about 8 million km. Click here for more details.

At the TIRGO observatory, we set out to measure the event although last minute revised predictions by Dunham were now pessimistic about the actual chance of observation. The observation was carried out by A. Richichi and M. Sozzi . We used the NICMOS3-based infrared camera ARNICA, in conjunction with a special data acquisition software developed by Carlo Baffa for lunar occultation observations, which allows continuous fast integration on a small area of the infrared array. A total of 5 minutes were recorded on a 32 by 32 arcsec area at a rate of 5 Hz, starting at 21:27:00 UT. The event, if any, was predicted as a brightening to about V=12 for a duration of about 1 second, any time in the 1-2 minutes after 21:28:03 UT. It was unknown to us how this would translate at 2.2 micron, our wavelength of observation, but in any case given the V-K solar spectrum and the sensitivity of the camera, it was estimated that we should be able to detect the glint.

The results are shown here as a plot of the integrated flux as a function of time, and as a MPEG movie: large format full data , (2.7Mb), or small format, 1:10 undersampling , (33kb). In the plot, a brightness variation is visible on a scale of about 1-2 minutes: this is too slow to be the sunglint event and is probably only a sky fluctuation. After this preliminary analysis, we conclude that the event was not visible from the Earth. Nevertheless, we are prepared to try again at the next opportunity!



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