		xsky - an interactive sky atlas for X



Version 2.0 of xsky is not really that much different from version 1.0.  Here
is a summary of the chief differences:


1)  a few unnecessary fields were stripped out of var.dat.  The correct
	version of var.dat for xsky v2.0 is 2,273.134 bytes long

2)  code written by Brian Wing has been added which greatly speeds up display
	updates for large databases such as SAO

3)  support has been added for several databases from the NASA CD-ROM
	"Selected Astronomical Catalogs, volume 1"

4)  a lot more work has gone into the translation of the RNGC descriptions of
	objects into English; there are only a few ambiguities left which fail
	to translate properly

5)  support has been added for a user-supplied catalog to allow easy creation
	of finder charts for comets, asteroids, etc.

6)  code was rearranged so that addition or deletion of catalog support only
	requires recompilation of one small module and a relink

7)  a very few minor bug fixes were incorporated


Version 2.1 differences from version 2.0:

1)  constellation boundaries are now available, with a correction to the
	UMi boundary with Cepheus (a change from the EQ2000 boundary file
	on the NASA ADC CD-ROM)

2)  all catalogs were updated so that you can change COMMON_EQUINOX and
	recompile to view the sky at some time other than 2000.0

3)  expose events during a resize are handled more intelligently for
	increased efficiency

4)  vastly improved line and dot intervals in RA/declination grid lines

5)  RNGC objects marked "nonexistent" now get displayed anyway, and their
	descriptions translate correctly

6)  shift-MB1 now does a rubber-band box action which causes the rubber-
	banded area to expand to fill the display

7)  an "Undo" command button has been added, providing a single-level undo;
	this is primarily intended for undoing rubberband actions

8)  scrollbars are now selectable by resource and command-line option

9)  a zoom slider has been added, selectable by resource and by command-
	line option; the "Zoom In" and "Zoom Out" buttons have been retained

10)  a continuously-updated display for the current pointer position was
	added, selectable by resource and command-line option

11)  users in the Southern Hemisphere might like to try out the "downunder"
	option

12)  I made the -L option functional via a work procedure; it's kind of odd,
	but I can't seem to get it to work any other way


Version 2.2 differences from version 2.1:

1)  the "Chart" button now brings up a filename input dialog.  The filename
	defaults to "starchart.ps", but can be specified by the user by
	editing the filename text buffer.  The "filename" can also be any
	UNIX command string, if preceded by a "!"

2)  the "Find" and "User Label" button popups have been repositioned to come
	up near the button that invoked them

3)  the window manager message WM_DELETE is handled, and xsky does a graceful
	exit upon receipt

4)  the window manager message WM_SAVE_YOURSELF is handled; xsky writes an
	initialization file and a restart command file, and registers a re-
	start command with the window manager

5)  the "-I <filename>" option is used to start xsky with values written by
	xsky in response to WM_SAVE_YOURSELF

6)  xsky no longer fools with the window *position* on a rubberband; it only
	changes the window size

7)  an icon bitmap is provided to give xsky a distinguishing icon

8)  the "Undo" button is now multi-level, and remembers all size, scale, and
	center position changes back to initial startup

9)  I even fixed a couple of bugs ...


Version 3.0 differences from version 2.2:

1)  support for the New General Catalog of Nebulae and Clusters - 2000.0,
	from the NASA ADC CD-ROM, has been added, including Dreyer descrip-
	tion expansion into readable text

2)  support for the Uppsala General Catalog of Galaxies, also from the NASA
	ADC CD-ROM, has been added

3)  control-MB2 now brings up a constellation label, in a similar manner as
	MB2 brings up an object label (thanks to Bill Owen at JPL and Mike
	Delevoryas for showing me the right way to find the constellation)

4)  control-shift-MB2 allows repositioning of existing labels

5)  the -N option has been added, for "night mode"; xsky does everything in
	red on black

6)  another correction has been made to the boundary database on the boun-
	dary between Serpens and Ophiuchus (thanks to Bill Owen at JPL for
	figuring out which line was correct)

7)  bug fix:  rubberbanding would defeat the full-screen effect of the -L
	option



A word about future directions:

xsky is probably not going to get much more functionality.  Adding new astro-
nomical catalogs has to become easier, though.  I'll work on that a bit.

Some folks dislike all the environment variables; I'll think about the various
suggestions to get rid of them, but they don't really bother me all that much.

xsky will become more and more dependent on the above-mentioned CD-ROM.  I'd
like to get completely out of the business of distributing any catalogs what-
soever.
