Bug fixes
* Fix to admit absolute directory notation in VT ImageDirectory
* Implemented encoding of special characters when saving cel URLs
* Fixed flickering of models with missing texture coordinates
* Fixed appearance non-ellipsoid star geometry in pre-OGL2 render paths
* Improved appearance of point stars when multisample antialiasing is enabled
* Fix for crash when viewing a star barycenter in an empty system
* Fixed off by one error assertion testing for number of lights used by shaders
* Windows: fixed UTF8 bugs in tour guide, star browser, and context menu
* Fixed crash bug that was triggerred by xyz and xyzv files with duplicate
times
* Fixed bug that caused dim stars in orbits distant from the primary to not
be drawn.
* Fixed strange appearance of cloud textures at times in the distant
past/future.
* Fixed memory leak in multiview handling
* Fixed ambient light in the ARB shader path
* Fixed bugs in comet rendering (corrects overbright coma)
* Fixed code to compile without errors with gcc 4.3; fixed some warnings
* Fixed g++ compier errors in cmodfix tool
* Fixed search path for Lua scripts
* Fixed numerous bugs that occurred when an object's orbit center was different
* Fixed a bug in the celx function celestia:getscreendimension
* Fixed bug with returning Hubble type for galaxies
* Eliminated error-prone min/max macros; use STL functions instead
* Fixed discrepancy between apparent magnitudes shown in the 3D view and
the star browser.
* Change "Day Length" string to the correct and more general term "Rotation
Period"
* Show 'planetary companions' message for stellar barycenters (instead of
just stars.)
* Improved location drawing so that location labels can be occluded by
foreground objects.

Data file updates
* Implemented data base globulars.dsc with all known 150 globulars around the Milky Way
* Renamed galaxy database deepsky.dsc into galaxies.dsc
* Implemented SIMBAD compatible cross-listing for globular clusters
* Updated Iapetus texture based on a new Ciclops map from Oct 2008
* Significant update of the database on binary orbits, including SIMBAD
compatibility of barycenter nomenclature and alternative names
* Updated the near stars catalog
* Updated texture for Mercury; includes imagery from MESSENGER
* Updated textures for some Saturnian moons: Tethys, Dione, Mimas,
Enceladus, and Rhea
* Added CHARM2 catalog of measured stellar radii
* Added model of asteroid Itokawa
* Regenerated star catalog using the new reduction of the HIPPARCOS data
* Cassini updates:
- Updated Cassini trajectory to include extended mission
- Switched to using xyz+velocity files for a more accurate trajectory
- Separated Cassini mission into cruise and orbital phases
- Improved appearance of Huygens separation from Cassini
* Added IAU rotational elements for most major solar system bodies
* Made visible the orbit and label for Pluto-Charon barycenter
* Correctly centered Galileo spacecraft
* Rebuilt cross-indices from SIMBAD data
* Added alternative names for many solar system bodies (e.g. preliminary
designations for asteroids in addition to proper names.)
* Updated extrasolar planet catalog with discoveries made up to Apr 2009
* Changed class of Pluto, Ceres, Eris, ... to dwarf planet
* Changed class of small outer planet moons to minormoon
* Included new and updated solar system body features from the IAU
* Added provisional rotation period for Eris

Tools
* Added Perl script globulars.pl used to extract the globular data from scientific publications and as documentation
* Added spice2xyzv tool for extracting xyzv files from a pool of SPICE kernels
* Added Perl script to build cross-indices
* Added Perl script to generate CHARM2 catalog
* Added Perl script to build star database

Platform-specific changes
* Mac OS X: Fixed rerun script menu item
* Mac OS X: fixed issue with some checkbox settings not getting saved properly
* Mac OS X: Fixed potential crash in eclipse finder if the user specified
an object that wasn't a planet or moon
* Mac OS X: Fixed keyboard shortcuts not working when GL window not frontmost
* Mac OS X: eliminated beep when clicking splash screen on multi-core machines
* Mac OS X: fixed compiler warnings, removed -fpermissive flag
* Mac OS X: Refactored Mac disk image build into separate target, made default
builds more efficient.
* Mac OS X: Fixed bug where time zone was ignored when setting time zone
* Mac OS X: look for user config file in ~/.celestia.cfg
* Mac OS X: Fixed blank names for location bookmarks
* Mac OS X & Windows: Added texture resolution setting to GUI
* BSD: Fixed tm_zone handling
* Linux: Install scripts at during "make install"
* Linux: Added workaround for broken include_x11 define from acinclude.m4
* Linux: Updated admin directory to KDE 3.5.10, regenerated acinclude.m4
* Linux: Added the missing menu entries related to globulars for KDE version
* Linux: Added globular and grid selection options in GTK interface

Internationalization
* Added Polish translation
* Added Lithuanian translation
* Added Romanian translation of constellation names
* Mac OS X: Japanese localation of eclipse finder added
* Added Chinese localization
* Localize surface names in alternate surfaces menu
* Prevented English name 'Milky Way' from being displayed when a translated
version is present.
* Extended localization to DSO and star names

Features
* Added light from secondary sources (i.e. "planetshine")
* Implemented depth sorting for markers so that they are correctly occluded
by foreground objects.
* Implemented code package rendering globular clusters
* Implemented new cel URL version with observer position and orientation stored
in frame coordinates (for forward compatibility)
* Added a long term (+-5000 centuries) precession model for Earth based on
work by Jan Vondrak
* Improved celestial coordinate grids:
- Added new grid types: ecliptic, horizontal, and galactic
- Made grid resolution adapt to the field of view
- Positioned coordinate labels at edges of field of view
* Added animated selection indicator
- Switches to direction pointer when the selection is off screen
- Changes color when the selected object is occluded
* Implemented more flexible system for reference marks and added new
reference marks:
- Planetographic grid
- Terminator
- VisibleRegion
* Enabled display of the phase angle for the currently selected object
* Improved eclipse rendering: correctly calculate depth and umbra radius
for eclipses.
* Improved star handling code so that stars can be placed more than 16k light
years from Earth.
* Switched to using sd prefix for hot subdwarfs per arXiv:0805.2567v1
* Added symbols for locations

Add-on features:
* Added SemiAxes property for ssc objects, which allows triaxial ellipsoid
geometry for solar system objects like Haumea and Mimas.
* Added new boolean properties for ssc/stc/dsc objects: Visible and Clickable
* Added new classes for solar system objects: dwarfplanet, minormoon,
surfacefeature, component, and diffuse
* Implemented Modify and Replace dispositions for star catalogs
* Added SPICE rotation model, allowing the orientation of an ssc object to
be controlled by a SPICE frame.
* SPICE orbit improvements:
- Allow multiple kernels to be specified for a SPICE orbit
- Automatically calculate start and end times when possible
* Added Timeline, which allows multiple frame, trajectory, and rotation
models for a single ssc object.
* Implemented CustomRotation, the rotation model analogue of CustomOrbit
* Added support for InfoURL for stars (already exists for deep sky objects and
solar system objects)
* Improved SampledTrajectory to handle files with positions and velocities
* Added LabelColor property for locations
* Implemented new Topocentric frame (a simplified two vector frame for placing
objects on the surface of a planet.)
* Added support for premultiplied alpha blend mode in cmod files
* Extended FixedPosition to support spherical coordinates as well as
cartesian coordinates.
* Added FixedAttitude rotation model, with more intuitive paramters for
orientation
* Added new SurfaceObject type for ssc files--like an ordinary body except
with different default frames that make it easy to position an object on
the surface of a planet.
* Added CloudShadowDepth property for atmospheres
* Improved control over mesh scaling with NormalizeMesh and MeshScale
properties for ssc objects.
* Added new locations types: eruptive center, insula (islands), and
tholus (domical hills and mountains)
* Added support for comment headers in xyz and xyzv files

Code optimization and reorganization
* Reimplemented observer frames in terms of Celestia 1.5.0 frames
* Improved performance of complex frames by caching last calculated orientation
* Added velocity method for all classes derived from Orbit
* Added angularVelocity method for rotation models
* Optimized solar system rendering by maintaining a bounding sphere hierarchy
* Switched to using 2 64-bit integers for storing high precision coordinates;
simplifies code and improves performance of operations using high precision
coordinates (dramatically on 64-bit systems)
* Optimized creation of render lists

Scripting
* Celx scripting functions:
- object:addreferencemark, object:removereferencemark
- object:visible, object:setvisible, object:catalognumber
- object:setorbitcolor, object:orbitcoloroverridden, object:setorbitcoloroverridden
- object:orbitvisibility, object:setorbitvisibility
- object:locations (returns an iterator over all the locations associated with an object)
- new phase object type (for timeline phases)
- permit any X11 color name
- observer:makeactiveview
- showconstellations, hideconstellations, setconstellationcolor
- getlabelcolor, getlinecolor
- getsystemtime, ispaused
- gettextureresolution, settextureresolution
- windowbordersvisible, setwindowbordersvisible
* Split celx scripting support into several modules
* Cel scripting
- splitview, deleteview, singleview, setactiveview
- setgalaxylightgain
- setradius
- setlinecolor
- setlabelcolor
- settextureresolution
* Made the package library (except loadlib) available for celx scripting
regardless of the ScriptSystemAccessPolicy setting
* Added an "AddonPath" value that is available to a ScriptedOrbit or
ScriptedRotation when it is created.
* Pass control modifier to Lua keyboard handlingfunctions

Miscellaneous:
* Bound P and M keys to toggle dwarf planet and minor moon labels
* Bound U and E keys to toggle globular clusters and globular cluster labels
* Group reference mark menu items in a separate submenu
* Changed star name lookup priority in stc parser: check proper names before
cross indices.
* Eliminated R and Shift+R key bindings for changing texture resolution
* Added new leap second 31-Dec-2008 23:59:60

Cleanup:
* Removed obsolete 'LabelledStars' section from standard celestia.cfg
* Updated README: removed obsolete sections, reorganized credits, added
information application to 1.6.0
* Purged out of date controls documentation
* Reorganized spacecraft add-ons in standard package