We derive the first secondary eclipse map of an exoplanet, HD 189733b, based on Spitzer IRAC 8 ?m data. We develop two complementary techniques for deriving the two-dimensional planet intensity: regularized slice mapping and spherical harmonic mapping. Both techniques give similar derived intensity maps for the infrared dayside flux of the planet, while the spherical harmonic method can be extended to include phase variation data which better constrain the map. The longitudinal offset of the dayside hot spot is consistent with that found in prior studies, strengthening the claim of super-rotating winds, and eliminating the possibility of phase variations being caused by stellar variability. The latitude of the hot spot is within 125 (68% confidence) of the planet's equator, confirming the predictions of general circulation models for hot Jupiters and indicative of a small planet obliquity.

http://iopscience.iop.org/article/10.1088/2041-8205/747/2/L20/pdf

A TWO-DIMENSIONAL INFRARED MAP OF THE EXTRASOLAR PLANET HD 189733b

UBV photometry of the Galilean satellites

Since 1985, planetary astronomers have been working to take advantage of a once-per-century apparent alignment between Pluto and its satellite, Charon, which has allowed mutual occultation and transit events to be observed. There events, which will cease in 1990, have permitted the first precise determinations of their individual radii, densities, and surface compositions. In addition, information on their surface albedo distributions can be obtained.

Pluto‐Charon mutual events

In photoelectric observations of a series of occultations of the Jovian satellite Europa by the Jovian satellite Io it was observed that increasingly larger fractions of the north polar region of the former were covered at mid-event with each successive occultation. One of the possible explanations of the observed phenomena involves the existence of a bright north polar cap for Europa. The reported investigation shows that a second explanation may be more plausible. This explanation is related to the possibility that at mid-event the projected minimum distance between the centers of the satellites was smaller than predicted by Sampson's theory.

K. Aksnes

Papers

Mutual phenomena of the Galilean satellites in 1973. I - Total and near-total occultations of Europa by Io