SkyMap Release History
----------------------

01-JAN-95 v2.2

New features added:

When displaying comets and asteroids, a limiting magnitude can now be
specified. This is useful to prevent 17th magnitude comets being
shown if you only have a pair of binoculars!

The information dialogs now all explicitly use the "Arial" font rather
than simply asking for a "default" Swiss font. The previous method
led to a strange font being used to display information on some
machines with lots of fonts installed.

If a date a long way (more than 50 years by default) from the 2000AD
"epoch" is entered, and the program is in "low precision" calculation
mode, the program will display a warning that the resulting map could
have significant errors, and will offer to switch on high precision
calculation mode before calculating the map.

The line of the ecliptic can now be displayed.

A new panel on the status bar displays the limiting magnitude of the
stars on the map.

Maps can now be saved as a Windows bitmap format (.BMP) file. This is
a much-requested feature for saving a permanent record of a map. It's
also a great way of creating Windows "Wallpaper" files!

A new View/Copy menu item now copies the contents of the currently
active view onto the clipboard, from where it can be pasted into a
word processor or other application.

SkyMap can now display on an Area Map stars (and other objects) read
from the "Hubble Guide Star Catalog" (GSC) CD-ROM database. This set of
2 CD-ROMs, published by the Space Telescope Science Institute, contains
approximately 19 million objects covering the entire sky to below
magnitude 14. This facility is NOT available in the shareware version of
SkyMap, but is provided as a new program "SkyMap/GSC", details of which
are on the registration form.
                             
Added two new buttons to the toolbar to respectively add and subtract
half a magnitude from the limiting magnitude of the map. This gives a
quick way of rapidly changing the number of stars displayed. These
operations have F4 and Shift+F4 as keyboard shortcuts.

Added an option to automatically scale star image sizes to the limiting
magnitude of the map. This, when combined with the above facility to
rapidly alter the map's limiting magnitude, assures that maps retain a
"realistic" appearance when the magnitude limit is altered.

The program now carries out better checks to decide quickly if an
object is visible on the area map. This has reduced the time taken to
compute an area map by 25-40%, depending on the circumstances.

We now use a much more efficient method of drawing the altitude/azimuth
grid on the Horizon map. This significantly speeds up map drawing for
slow machines when the map field of view is small.

Added "Tool Tips" to the Toolbar. These are short help messages which
pop up after the mouse has been over a button for a brief period,
describing the function of that button. This feature can be disabled
using a new option on the global preferences dialog.

The N,E,S,W buttons on the horizon map toolbar now remain "pressed in"
when the map is drawn for those directions. This makes it easy to see
at a glance which (if any) cardinal direction the map is facing.

A grid of right ascension and declination lines can now be displayed on
the horizon map.

A new option on the Area Map popup menu allows the user to draw TelradŽ
finder circles centred on the point clicked on. The Telrad finder is a
very popular device, and this is a much requested feature.

The program now has user-maintainable databases of eyepiece and
telescope data in files "EYEPIECE.SKY" and "SCOPE.SKY" respectively.
An "Eyepiece" item on the "Tools" menu displays the database, allowing
the user to add, edit or delete entries, and to see the magnification
and field of view resulting from using any eyepiece on any telescope.
On the area map, the field of view can be displayed as a circle on the
map with a new "Eyepiece" option on the popup menu.

The map size calculations now take acount of the presence of the tool
and status windows. The effect of this is that a maximized map window
now never has scroll bars.

The time of rise, transit and set can now be displayed for all objects
on the map, not just planets.

We now cache rise, set and transit times of planets, so they only have
to be computed (a slow process) once, appearing instantly when
displayed subsequently.

The program can now display the tracks of an arbitrary number of moving
objects at the same time. Previously, only one object at a time could
have its track shown. Tracks are also now saved with files, which
didn't happen previously.

Object track settings are now stored as a part of the Area Map defaults.

The status bar now contains a panel which displays the angular
separation of the last two points to be clicked on with the left mouse
button.

A new area map can now be drawn from an existing one by dragging a
selection rectangle with the left mouse button. It was not previously
possible to draw a new area map from an existing one.

An area map can now be drawn from a horizon map by dragging a selection
rectangle with the left mouse button. This is a much more convenient
method than the current one of pressing the right button over a point
on the map because it allows the map size, as well as the centre, to be
specified.

Bugs fixed:

On all the information dialogs, fixed the formatting problems with
angles and times which occasionally resulted in displays such as
"2m 60s" instead of "3m 0s".

On the area map, deep sky objects drawn with the "general" circle were
being drawn at twice the correct size.

On the "Planetary Phenomena" dialog, display times correctly rounded to
the nearest minute, rather than just "chopping off" the seconds.

We no longer get spurious "Identify Star" menu items appearing on the
popup menu for stars whose position has been computed, but which are
fainter than the current limiting magnitude of the map.

In the map status dialog, the sign of the observer's longitude (ie E or
W) was being set from the sign of the latitude, not the longitude.

Very odd things happened under certain circumstances when an Area Map
was printed showing the Moon with the "dark limb visible" option turned
on. These included stars being printed as hollow rather than solid
circles, and stars being labelled with a Latin rather than Greek font.
I'm still not exactly sure of the cause of this, but changing the method
used to draw the Moon bitmap appears to have fixed it.

If the horizon map was precisely centred in the window (eg if it was full
screen with no scroll bars) and we attempted a zoom, the program crashed
with a "Floating Point Invalid" error due to attempting to evaluate 0/0.
We now check for this special case and act correctly.

A missing term involving the Moon's semidiameter meant that the time
of rise and set of the Moon was about 1 minute in error.

On the area map information dialog for planets, display negative
altitudes correctly.

The horizon map "high precision" flag setting and the Moon dark limb
visibility flag weren't being correctly saved when default settings
were saved.

When computing the times of rise and set, use the local date, not the
UT date. This was causing the program to occasionally display times
for the previous or following day when used in time zones other than
GMT.


01-JUL-94 v2.1

Times of rising, meridian transit, and setting can now be calculated for
the Sun, Moon and planets. This is displayed on the "local" page of the
planet information dialog, and can also be displayed in a tabular form for
all the planets from a new "Planetary Phenomena" item on the "Tools" menu.

Added a "Planet visibility" dialog giving a quick method of showing the
positions of all the visible planets.

Added the option to label planets with names, rather than symbols. A new
planet options dialog allows selection of options for planet display.

Added an option to display the dark limb of the Moon with a dotted line.
This is useful for eclipses and occultations.

Improved comet orbit calculation algorithm to avoid problems with
comets in near-parabolic orbits. This problem sometimes caused the
program to crash previously.

Changed from the RNGC to the SAC v6 deep sky object database (by kind
permission of the Saguaro Astronomy Club). Deep sky objects are now
displayed on the Area Map with their correct size and (for galaxies)
orientation. This is a major improvement in the program!

Added a "black on white" display mode option to the "Colour" sub-menu.
Selecting this option changes the map to all-black on a white background,
similar to a printed map. This is a very useful mode in which to do a
screen dump for pasting into a word processor or other application.

Added a "night vision" display mode option to the "Colour" sub-menu. When
selected, all displayed items change colour to red or black. This colour
combination is the best for preserving night vision.

Added the ability to display the tracks of moving planets, asteroids, and
comets on the astrometric area map. This is extremely useful, especially for
comets and asteroids. Also has educational value when used for such things
as displaying the retrograde loops of objects.

Added a catalogue of asteroids in the file "ASTEROID.SKY". This works in the
same way the existing comet catalogue does - ie, asteroids can be selected
for map display, and can be added to, edited, or deleted from the catalogue.

Added topocentric RA and declination to planet information dialogs.

Replaced "High Accuracy" option on the Area Map with the more meaningful
"Astrometric" option. When this is enabled, maps are drawn to epoch J2000;
when disabled, maps are drawn to the current epoch. It has much the same
effect as switching off the old "High Precision", but in a more quantifiable
manner.

Added "double click" processing to all listboxes as a shortcut.

Added file load/save facilities for maps.

The user can now set the map window title on both the Horizon and the Area
maps.

Added a "time skip" option to the Horizon Map, allowing it to automatically
update at specified time intervals.

Added a "Map Status" option to the "Help" menu, When invoked, this displays
a dialog showing information about the time, observation location, etc.

Created a separate "SKYIMAGE" application for displaying pictures. Having
pictures shown in a separate window greatly improves the user interface,
since both the image and map can be viewed simultaneously.

Added the facility to display the embedded comments in GIF files. These
often contain useful information about the image, especially in the case
of NASA/JPL images.

Added altitude and azimuth display to Area map information dialogs.

Added screen and printer font selection for all text drawn on maps.


27-DEC-93 v2.0

Major release. A total rewrite of the program to make it much faster and
to dramatically improve the user interface. Many new features added
including display of comets.


10-Sep-93 v1.33

Bug-fix release:

Images of RNGC objects couldn't be displayed automatically on a horizon
map, because I'd forgotten to add the line of code to do so! Fixed.


25-Aug-93 v1.32

Bug-fix release:

An error in the floating point emulation libraries of Microsoft's Visual C++
compiler, causing the "tan" function to return the wrong sign, was resulting
in the effects of refraction being applied in reverse on some machines
without a maths co-processor.  Applied a "work around".

The colour of RNGC objects and their labels was defaulting to black on the
horizon map.  This was difficult to see against the black map background!


04-Jul-94 v1.31

Minor bug fix release:

It wasn't possible to save a configuration in which the faintest stars were
drawn as a single pixel.  Single pixel stars were replaced by 4-pixel stars
by over-zealous error checking code when the configuration was reloaded.

RNGC objects on the Area map were being incorrectly drawn and labelled using
the star, rather than the RNGC object colours.

An extra line connecting the two halves of the constellation "Serpens" was
being drawn on the constellation outlines, because the drawing code regarded
Serpens as a single constellation whose points were to be connected.  Fixed
by treating the two halves of Serpens as two separate constellations as far
as the outline drawing code is concerned.


29-May-93 v1.3

New features:

The program can now display non-stellar objects.  The database used is the
Revised New General Catalogue (RNGC).

Constellation boundaries can now be displayed.

The printing options have been greatly expanded.  When a map is printed the
user can now select whether to print the entire map, or the current zoomed
view, and also whether to print in black and white or colour.  For colour
maps a dialog allows the user to select the colour of each component of
the map.

All map features are now present on both the horizon and sky area maps
(eg star labels can now be displayed on the horizon map).  The user interface
has been made more consistent between the map types.

The program now has an optional ToolBar at the top of the screen, which
provides short-cuts for the commands on the "View" menu.

The program now (finally!) has a complete on-line help system.  This is
basically a copy of the manual.

Bug fixes:

I'd forgotten to apply the correction for diurnal parallax to planetary
positions on the Sky Area map.  Consequently, the planets were being shown
in their geocentric, rather than topocentric positions, resulting in errors
of up to 2 degrees in the apparent position of the Moon.  Fixed.

The size of the image of the Sun and Moon on the Sky Area map was being
incorrectly calculated, resulting in images that were about 50% too large
when the map was printed on a portrait orientation page.  Fixed.


07-Mar-93 v1.2

New features:

Added a new "Sky Area" map type, centred on a right ascension and
declination.  This is intended to be used to draw a detailed map of a
small region of the sky.

Added the ability to display photographic images in either GIF or BMP
format.  Images can either be explicitly opened, or associated with specific
objects (currently planets) and automatically displayed.

Bugs fixed:

Single pixel stars were being printed on the printer in the screen colour,
which almost certainly mapped to white on the printer, resulting in them
not being printed.  On a mono print, single pixel stars are now correctly
printed black.

When the right mouse button was pressed over a horizon map to display the
pop-up menu, then the *right*, rather than the *left* button pressed (ie,
a user input error!) an incorrect cursor position was stored.  If the left
button was subsequently used to select an information dialog a wildly
inaccurate position or a GPF resulted.  This is probably the cause of all
the "random number" errors previously reported.  Thanks to Don Munro for
tracking down a reproducable case of this puzzling error!  Fixed.

Removed the incorrect, uninitialized data displayed on the information dialogs
for the Sun and Moon. (Eg phase 0.000 for the Sun.)


05-Feb-93 v1.11

When the start of a constellation figure was off the edge of the map,
the first visible line of the constellation was being drawn incorrectly in
certain circumstances.  Fixed.

The correction for refraction was being correctly calculated and correctly
displayed in the "About" box for a star, but not applied to the plotted
position of the stars on the map.  This led to stars being plotted with
slightly too low an altitude (the maximum error being about half a degree
at the horizon).  Fixed.

If the star position calculation was aborted by the user pressing the "Cancel"
button, the subsequent constellation figure setup calculation code displayed
an error message for each star it was unable to find.  Pressing the "Cancel"
button now aborts the map calculation cleanly.


31-Jan-93 v1.1

Test release to BIX only for testing.

In the "Observer" dialog, the "Time Difference" edit field was only wide
enough to allow two digits to be entered, making the program not too
useful for anyone outside the GMT time zone.  Fixed.

Version 1.0 of SkyMap simply plotted stars in their mean catalog position.
This version now rigorously calculates the apparent place for the time of
observation, correcting for proper motion, aberration, precession, nutation,
and refraction.

Added code to verify that dates are in the range 4000BC-8000AD (the
range over which the planetary position equations are valid.


24-Jan-93 v1.0

Release of SkyMap 1.0, with basic facilities for drawing horizon map and
plotting planetary and lunar positions.
