Hubble Space Telescope map of Titan's surface
The latitude ranges from 60 deg South to 60 deg North, the
longitude from 0 to 360 (E longitude increasing to the right, following the
geographical--as opposed to astronomical--convention),
with 180 in the center. The grid is
30 deg in latitude and in longitude. The sub-Saturn point
is at 0 E, 0 N, and the sub-Earth latitude is 7 N. The contour lines are at
The Huygens landing site (assuming October 1997 launch) is 18 N,
208 E. This is somewhat right of center in the map, and left of the
main part of the bright region. The longitude is uncertain by 11 degrees
due to our lack of knowledge about the winds on Titan -- how strong
are they, and (more importantly), which way do they blow? A possible
prograde feature has been identified -- perhaps better observations
of clouds will be made as the project continues.
This map was made from the 14 F850LP images of Titan, which
are primarily sensitive to the 0.94 micron methane window. At
the beginning of our obsering period, the sub-Earth longitude was
about 240 E. The first seven images were taken approximately
every seven hours, and have been used to attempt to locate and
track clouds in a sort of Titanian weather movie. During the time
these first seven images were taken,
the large bright feature slowly moved off of the observable disk.
The next seven images were spaced about every 32 hours and gave us near
complete coverage of the surface, with the exception of a 96 hour gap
centered near 10 deg. The bright feature re-appeared in the last
To make the map, the haze background was subtracted from each image, leaving
only surface features.
The larger and brighter features are all real, that is, observed
in multiple images. Some of the smaller brightness may be from clouds, and
the very small and less contrasty "features" are likely to be noise.
Signal to noise in the original images was about 200:1, and the range
of contrast shown is plus or minus about 4% from the mean. Note that
the map is an albedo map -- the brightness may be related
to topography, but is not directly caused by topography.