The June 28th 1996 stellar occultation by Europa

Observations:

John Stansberry, with assistance from Glenn Orton and John Spencer, observed the occultation with NSFCAM at the IRTF on 6/28. They got high S/N observations of the occultation egress at 3.5 microns with 0.05 second time resolution. Diffraction fringes were seen but, as expected, there was no sign of an atmosphere.

The occultation ingress was observed by Hubbard et al. from Kitt Peak, and showed very tentative evidence for pre-occultation fading of the starlight, perhaps due to an atmosphere.

Results from both groups were presented at the 1996 DPS meeting (Hubbard et al. and Wasserman et al.)

Pre-Event Prediction Info:

Europa will occult the star PPM 269153 (2000.0 coordinates, RA 18:58:44.129, Dec. -22 48 25.99) at 11:38:40 UT (geocentric) on June 28th, 1996. A central event will last 228 seconds. The star has visual magnitude 8.9 and is of type K0, giving estimated IR magnitudes of 7.1 (J), 6.7 (H), 6.6 (K), and 6.5 (L). The star will be brighter than Europa at L (certainly) and K (maybe?). The event was discovered by Beisker in Germany.

 The event will be almost central as seen from Hawaii, and will be observable in morning twilight, low in the West, from the western US, and shortly after sunset, low in the East, from the Phillipines and southern and central Japan.

 We expect a sharp occultation due to Europa's apparent lack of a significant atmosphere, but observations of the immersion and emersion with a time resolution of a second or better are useful just in case of a temporary atmosphere produced by endogenic activity, or other serendipitous possibilities. You never know...

 Technical details in ASCII format, from Larry Wasserman of Lowell Observatory. 


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