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1992-04-26
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"THE EARTH CENTERED UNIVERSE"
Sky Visualization Software
User's Manual
Version 1.3
Shareware and Registered Versions
Released in May 1992
for Microsoft(R) Windows 3.0 and 3.1
Written by:
David J. Lane
4-26 Randall Avenue
Halifax, Nova Scotia
Canada B3M 1E2
Phone: (902) 443-5989
Compuserve E-Mail: 71601,247
Internet E-Mail: 71601.247@compuserve.com
Manual Revision 1.3
1. Getting Started
Thank you for choosing to try "The Earth Centered Universe",
ECU for short. ECU is a Sky Visualization Program capable of
simulating many of the phenomenon of the earth centered sky. This
includes, but is not limited to, the stars, planets, sun, and moon,
comets, and "deep sky" objects. ECU is designed as an observing
tool for the observing amateur astronomer, but is equally useful to
the "armchair" astronomer or other interested person.
Many of the concepts and terms used in this manual are common
in amateur astronomy, but may not be familiar to all users. The
author recommends the purchase of a good beginner book in astronomy
as a guide to the understanding of the concepts provided by this
program. An excellent beginner's book is: NIGHTWATCH: An Equinox
Guide to Viewing the Universe by Terence Dickinson, which is
available in most well stocked bookstores or libraries.
ECU is designed to operate on a PC from within the Microsoft
Windows 3.0 or 3.1 environment. This environment provides all of
the "tools" necessary to support a highly graphical program like
ECU. This manual assumes that the user is familiar with the
operation of typical Windows 3 programs.
ECU was written, because of the obvious lack of good,
reasonably priced astronomy programs. Most "commercial" software
products (and the author has purchased three of the high profile
programs) suffer from very awkward (not intuitive at all) user
interfaces and ssllloooowwwww operation (especially without a math
processor). ECU, therefore, attempts to fill an obvious need at
the reasonable prices of shareware.
1.1 Registration of ECU
A large amount of effort in software development has gone into
the "The Earth Centered Universe". It currently is comprised of
about 280 pages of program listing. This release, V1.3, includes a
several enhancements over previous versions (ECU was first released
as V1.1 in March of 1992). Prior to the first release, a round of
"beta testing" was executed. The user feedback resulted in many
changes and a wish list from Earth to the Moon (see section 7.).
The most notable enhancements to ECU in this version are
listed below:
1. The substitution of the previous star database to the use of
the Yale and Smithsonian Astrophysical Observatory star
catalogs; the later being optional and containing about
250,000 stars.
2. The number of comets is increased to six and their names now
appear in menus.
3. A menu item has been added to center the sky display on a
specified Azimuth/Altitude.
4. On screen "Speed Buttons" are added for several commonly used
functions.
5. A menu item has been added to set the field size to a
specified number of degrees.
6. The deep sky object symbols have been changed so they are more
recognizable.
In order to ensure that ECU is supported and greatly improved
in the future, I ask that you register ECU. Registration will
bring a laser printed manual and an enhanced version of ECU. This
enhanced version includes several databases, which are too large to
distribute by normal shareware methods (eg: bulletin board
systems). Also, several computational enhancements (which require
one of the database files) are enabled in the REGISTERED VERSION.
I ensure you that the SHAREWARE VERSION is not "crippled"
software. It only lacks some of the advanced features, such as
catalogue identification of stars, descriptions of "deep sky"
objects, ultra-high accuracy solar system calculations (lower
accuracy versions are included), comets, etc. The executable file
is the same.
A form that can be used to register ECU is found in the file
REGISTER.TXT.
The author would be most pleased in hearing your comments and
suggestions for improvements of ECU or this manual. I would also
like to hear about any "bugs" which you detect so they can be fixed
in a future release. ECU is a SHAREWARE product, thus is user
supported. I can be reached at any of the addresses (post office
and e-mail) listed on the cover page of this manual.
1.2 System Requirements
As stated in section 1., ECU operates within the Microsoft
Windows 3 environment. It will not run under DOS alone. However,
it has been tested for operation in the soon to be released OS/2
2.0. The minimum system requirements are listed below:
Hardware: 286/386/486 100% PC Compatible Computer
Math Co-processor: 80x87 supported, but not required
Software: DOS 3.x or higher
Microsoft Windows 3.0 or 3.1
(standard or enhanced mode)
Memory: Minimum 700K bytes free from within Windows
Minimum 1M bytes free with enhanced stellar
database
Disk Capacity: SHAREWARE VERSION - 500K bytes
REGISTERED VERSION - 2.2M bytes
WITH ENHANCED STELLAR DATABASE - 5.5M bytes
Graphics Card: An EGA or better graphics card (VGA
recommended)
Monitor: Color required for good screen displays
Mouse: Windows compatible
ECU has been tested with slower 286-based computers and
operates perfectly satisfactorily with them. In fact it operates
faster on a 286 computer than many commercial programs operate on
the author's 386!
The use of a math co-processor is supported, but not required.
With most commercial programs, this statement means that it works,
but is untolerably slow! ECU's sky drawing routines are written
almost entirely in integer math, thus operate quickly with or
without the math processor. During development, the author's
computer did not have a math co-processor. I have one now.
The math processor, however, does speed up local horizon,
planet, sun, moon, and comet orbit calculations significantly.
1.2 Installation Instructions
ECU is normally distributed as one file (ECUREG.EXE) in self
uncompressing format. The compressed file contains the following
files for the SHAREWARE, REGISTERED, and ENHANCED STELLAR DATABASE
VERSIONS:
SHAREWARE VERSION
ECU.EXE - the main executable program file
ECU.CFG - the default configuration file
YBSC1.ECU - the main Yale Bright Star file
SAC1.ECU - the main "deep sky" object file
CONS.ECU - the constellation data file
LABELS.ECU - the text labels data file
LOCATION.ECU - the geographic location data file
REGISTER.TXT - the ECU registration form
MANUAL.TXT - this manual
REGISTERED VERSION
ALL ABOVE FILES PLUS:
YBSC2.ECU - the secondary Yale Bright Star file
SAC2.ECU - the secondary "deep sky" object file
PTERMS.ECU - the orbital terms used for high accuracy
calculations
PINDEX.ECU - the index file for PTERMS.ECU
ENHANCED STELLAR DATABASE VERSION
ALL ABOVE FILES PLUS:
SAO1.ECU - the primary Smithsonian Astrophysical Observatory
star file
SAO2.ECU - the secondary Smithsonian Astrophysical
Observatory star file
Installation of ECU is straight forward. The example below
assumes that your hard disk is drive 'C', and your floppy disk is
drive 'A'. You can install ECU from DOS or from a "DOS Window"
within Windows 3.
TYPE
1. Log to your hard disk: C: <return>
2. Make a directory to store ECU: MD \ECU <return>
3. Change to the ECU directory: CD \ECU <return>
4. Install the ECU program disk in drive 'A'
5. Extract the files from ECUREG.EXE: A:\ECUREG<return>
6. If you don't have the enhanced stellar database go to step 11.
7. Install the ECU SAO1 disk in drive 'A'
8. Extract the files from SAO1.EXE A:\SAO1<return>
9. Install the ECU SAO2 disk in drive 'A'
10. Extract the files from SAO2.EXE A:\SAO2<return>
11. Start Windows: WIN <return>
(ignore if already running)
12. Start the "File Manager" use the mouse
13. Open the ECU directory such that the ECU.EXE file is visible.
14. Arrange the screen so that ECU.EXE and a suitable program
group in the "Program Manager" are both visible.
15. Drag ECU.EXE from the "File Manager" to the "Program Manager".
A colorful Icon should appear.
16. Proceed to section 1.3: Starting ECU.
1.3 Starting ECU
ECU is started by double-clicking the ECU Icon. Loading ECU
typically takes less than 15 seconds, however, the SHAREWARE
version takes somewhat longer the first time it is started. This
is because the file MATH.ECU needs to be created. This file is
used by ECU to speed up its sky drawing functions. It is not
distributed in the SHAREWARE version so as to reduce the "download"
time (and therefore the cost) of ECU from bulletin boards.
Subsequent startups will occur normally.
Before the "main window" appears, several data files, plus the
configuration file are loaded into memory. If any problem is
encountered while loading ECU (due to bad or missing files, not
enough memory, etc.), a small dialog box displaying a descriptive
message is displayed on the screen. Pressing 'OK' will return
control to Windows 3.
If all is successful, the opening screen will appear greeting
the user with a colorful display of the constellation of ORION.
At this time, only one copy of ECU can be running at any one
time. If the user attempts to run a second copy of ECU, a small
dialog box will appear describing the problem.
The ECU "main window" always begins centered on the screen,
however, it is designed it operate optimally "full screen". Press
the "maximize" button to facilitate this.
By default, ECU always uses the configuration file "ECU.CFG"
located in the current directory. If a file name is specified on
the command line, ECU uses the specified file. This is useful for
setting up ECU 'icons' to quickly bring up saved astronomical
events.
I suggest you read sections 2. and 3. next, which introduce
the operation of the program, and address all of the menu
selections. If you just want to explore, that's fine, too. I
think you will find ECU quite intuitive. Section 4. then describes
the built-in databases.
2. Introduction
This section assumes that ECU is installed and is running. As
indicated in Section 1.3, ECU runs optimally "full screen", which
is obtained by pressing the "maximize" button.
Mouse operations are integral to the operation of ECU, and
will be described in Section 2.3. The on-screen controls, such as
the check boxes and scroll bars will be described in Section 2.4
and the menu selections in Section 3. But first, the on-screen
status displays and sky display area will be described.
2.1 The Status Display
The left portion of the ECU window comprises the status
display area. This area contains the following items:
a) Geographic Location - the top line shows the city where the
observer is located. If a city was not selected (but rather a
specific latitude/longitude was entered), the message "By
Lat/Long" will be displayed. Immediately below, the latitude
(Lat) and longitude (Long) of the observer is displayed as
degrees and minutes. Positive latitudes are North of the
equator and positive longitudes are West of the Greenwich
meridian. To set your geographic location, see section 3.3.2,
which describes the "Set -> Geographic Location" menu
selections.
b) Local Mean Time (LMT) - contains the date and time of the
local civil time. The date is always in the format
year/month/date. The time is either displayed as hh:mm in 24
hour time or hh:mmpm in am/pm format. See section 3.3.1.4.
c) Universal Time (UTC) - contains the universal date and time
(that of the Greenwich meridian). The date is always in the
format year/month/date. The time is always displayed as hh:mm
in 24 hour time format.
d) Right Ascension (RA) - contains the right ascension of the
center of the sky display. It is formatted in hours and
minutes as hh:mm.m.
e) Declination (Dec) - contains the declination of the center of
the sky display. It is formatted in degrees and minutes as
+dd mm'.
f) Azimuth (Azim) - contains the azimuth of the center of the sky
display. The azimuth is the angle, in degrees and minutes,
from the Northern horizon towards the East at the current Date
and Time and Geographic Location.
g) Altitude (Alt) - contains the altitude of the center of the
sky display. The altitude is the angle, in degrees and
minutes, measured vertically from the horizon at the current
Date and Time and Geographic Location.
h) Field Size (Field) - contains the number of vertical degrees
currently shown in the sky display. The minimum field size is
2 degrees and the maximum is about 60 degrees.
i) Magnitude (Mag) - contains the minimum magnitude for which
stars are displayed in the sky display. This number is
usually the same as that set in the "Set -> Magnitude
Limits..." menu selection, however to keep the sky drawing
speed fast, the maximum magnitude of stars displayed changes
with the field size. This ranges from magnitude 5.5 for
fields larger than 50 degrees to magnitude 8.5 for field sizes
from 10 to 15 degrees. See section 3.4.2, which describes the
"Set -> Magnitude Limits..." menu selection.
2.2 The Sky Display
The right portion of the ECU window is the sky display area.
The sky display area displays celestial objects using one of two
"projections". These two projections were selected for the speed
of their calculation, however there is some distortion at the
limits of their usefulness.
When displaying the sky from -45 to +45 degrees Declination, a
simple modified-Mercator projection is used. This projection
causes the objects at high Declinations to be distorted (spread-
out), most noticeable in constellations like Ursa Major (the big
dipper). This is the same distortion that makes Canada appear much
larger than the United States on world maps with similar
projections (Canada is only about 10% larger).
When displaying the sky either North of +45 or South of -45
degrees in Declination, the Zenithal Equidistant Projection is
used. This projection is quite good, but does spread out objects a
bit at low Declinations.
With both projections, North is always up (South is down) and
East is to the right (West is to the left).
The objects and items displayed in the sky display area are
listed below. Each will be discussed in detail in sections 3. and
2.4 by the specific menu selection or screen resource which
controls their operation.
a) Grid - the coordinate grid helps illustrate the sky
projections just described. Lines of Right Ascension are
drawn every hour (coarse grid) or every 20 minutes (fine
grid). Lines of Declination are drawn every 10 degrees
(coarse grid) or every 5 degrees (fine grid).
b) Stars - stars are displayed as varying sized dots according to
the star's brightness. The larger the dot, the brighter the
star.
c) Lines - there are many lines displayed by ECU. These include
the constellation lines, horizon line, and ecliptic line.
Markers are also displayed at the Zenith (the overhead point)
and the North and South poles.
d) Labels - there are text labels displayed for solar system
objects, bright stars names, Messier objects, constellation
names, and labels for the ecliptic and horizon lines, and
markers.
e) Solar System objects - the planets, sun, moon, and comets are
displayed. The sun and moon are displayed to their correct
size and the phase of the moon is shown. Planets are
displayed as either a point or by their standard symbol.
Comets are displayed as points. Comets are not available in
the SHAREWARE VERSION of ECU.
f) Deep sky objects - deep sky objects are displayed in six
different categories. These are Galaxies, Open Clusters,
Globular Clusters, Bright Nebulae, Planetary Nebulae, and
Other; each displayed using a different symbol.
2.3 Mouse Operations
The mouse forms a vital part of the ECU user interface and has
many uses from within ECU. The cursor (the shape of the mouse
pointer) is used to inform the user of how the mouse is currently
being used. If it is a cross-hair, it is used for selecting a
window, identifying an object, centering, or measuring an angle.
The cursor is always a cross-hair while in the sky display area.
If it is an arrow, it is used for operating the scroll bars or
buttons.
Each mouse button will be described separately in the next two
sections.
2.3.1 Left Mouse Button
The left mouse button, while the cursor is in the sky display
area, is used for the following functions.
a) Select an object - if the left mouse button is pressed (and
released) within a few pixels of the center of an object, a
dialog box, called the "Identify Object" dialog box, will
appear identifying and describing the object. Section 5.
details the contents of the "Identify Object" dialog box. A
cross-hair will appear on the screen identifying the object
currently selected. The dialog box is always placed in the
diagonally opposite corner from the object selected, so that
it doesn't cover the object selected. The dialog box can, of
course, be moved about the screen as the user wishes.
If more than one object is in the vicinity, the "Next"
button can be pressed to update the dialog box with new
information for the next object.
The dialog box can be terminated in four ways. If the
"Quit" button is pressed, the dialog box will terminate
immediately. If another object is selected, the current
dialog box will be replaced with a new one. If the left mouse
button is pressed while the cursor is not near an object, the
dialog box will terminate. Finally, the <ESC> key can be
pressed.
b) Zoom a window - the second function performed by the left
mouse button is its ability to draw a rectangle on the screen
which is used to re-position and re-scale the sky display.
The rectangle is drawn by positioning the mouse at one corner,
dragging the mouse (with the left mouse button pressed) to
another corner, and then releasing the button. The center of
the rectangle defines the new display center and the vertical
height is used to scale the display.
2.3.1 Right Mouse Button
The right mouse button, while the cursor is in the sky display
area, is used for the following functions.
a) Center the mouse position - if the right mouse button is
pressed (and released), the current mouse position will become
the center of the sky display at the current scale. This
feature is very useful for quickly "panning" about the sky.
b) Measure an angle - the second function performed by the right
mouse button is its ability to measure angles on the sky.
Angles are measured by positioning the mouse at one location,
dragging the mouse (with the right mouse button pressed) to
another location, and then releasing the button. A dialog box
will appear which displays the angular measure between the two
points in degrees.
2.4 On-Screen Controls
The on-screen controls include the scroll bars, zoom buttons,
check boxes, and time step arrows and buttons. Each is described
below:
a) Scroll Bars - Two scroll bars are used to rapidly move the
center of the sky display about the celestial sphere. The
scroll bars are used in two modes as controlled by the menu
selection described in section 3.4.10.
1) The vertical bar is used to change the Declination. +90
degrees is at the top; -90 degrees is at the bottom. Pressing
the end arrows will move the pointer (and the sky display) by
one degree and pressing along the bar will move the pointer by
10 degrees. The horizontal bar is used to change the Right
Ascension. 23 hours 59 minutes is at the left; 0 hours is at
the right. Pressing the end arrows will move the pointer by 4
minutes and pressing along the bar will move the pointer by
one hour. When sliding the scroll bars by dragging the
pointer, observe at the Right Ascension and Declination
displays to know when to stop.
2) The vertical bar is used to change the Altitude with
reference to the local horizon. +90 degrees is at the top
(the Zenith); -90 degrees is at the bottom (the Nadir).
Pressing the end arrows will move the pointer (and the sky
display) by one degree and pressing along the bar will move
the pointer by 10 degrees. The horizontal bar is used to
change the Azimuth with reference to the local horizon. 0
degrees (North) is at the left; 358.5 degrees is at the right.
Pressing the end arrows will move the pointer by 1.5 degrees
and pressing along the bar will move the pointer by 15
degrees. When sliding the scroll bars by dragging the
pointer, observe at the Azimuth and Altitude displays to know
when to stop.
b) Zoom buttons - the zoom buttons, identified as "zoom in" and
"zoom out", are used to change the scale of the sky display.
Each press of the respective button changes the scale by a
factor of two.
c) Check boxes - the six check boxes: Stars, Deep Sky, Solar
System, Grid, Lines, and Labels are used to toggle whether the
respective item is displayed in the sky display. Note that
when operating with graphics boards providing less than 350
pixels in vertical resolution, only the Stars and Deep Sky
check boxes are available.
d) Time step arrows and buttons - the time buttons "+" and "-"
are used to change the current time by the amount shown at the
immediate left. Pressing the black arrows causes the amount
at which the time changes to be altered in steps from a
minimum of 1 minute to a maximum of 4 years.
e) Speed buttons - the boxes in the status area, which are used
to display the current settings of parameters ranging from the
Geographic Location to the Stellar Magnitude Limit (see
section 2.1), are also used to provide quick access to the
menu items which control the respective parameter. When the
left mouse button is pressed while the mouse is within one in
the boxes cause the appropriate dialog box to "pop-up". For
example, the left mouse button is pressed within the "Mag"
box, the "Magnitude Limits..." dialog box will pop-up.
3. Menu Selections
The menu selections control most of the features of ECU and
are divided into seven categories as listed below. Each is
described in detail in the identified sections:
a) File - the file menu handles the loading and saving of the
configuration settings of ECU (see section 3.1).
b) Edit - edit allows the last operation to be nullified (see
section 3.2).
c) Set - the set menu allows the time, geographic location, sky
display color, comet orbits, and calculation settings to be
adjusted (see section 3.3).
d) Field - the field menu controls if and how the stars, deep sky
objects, planets, sun/moon, grid, lines, and labels are
displayed. It also allows for various zoom settings (see
section 3.4).
e) Center - the center menu allows many ways to set the center of
the sky display. These ways include centering on a specified
Right Ascension/Declination, a constellation, a bright star, a
Messier object, a Solar System object, a point on the local
horizon, or by a text search of the databases (see section
3.5).
f) Animation - the animation menu controls the various features
of the animation mode (see section 3.6).
g) About - the about menu lists the program credits, the version
number, etc. (see section 3.7).
Many of the common menu items have "short cut" keyboard keys
to allow quick access to their features. The keys used are
identified by an underline under the key used. The Alt key is to
be pressed in conjunction with the identified key. Also, some menu
items identify their keyboard equivalent to the right in their menu
item.
3.1 File Menu
The File menu allows the configuration settings of ECU to be
loaded (opened) and saved. Virtually every setting in ECU is
stored in the configuration file. This allows ECU to be "set up"
for a particular astronomical event and this event saved to a
configuration file for later quick retrieval.
3.1.1 Open...
The Open... menu selection presents a dialog box allowing a
new configuration file selected, then subsequently loaded. It
defaults to file names with the extension ".cfg". I will not
detail the operation of this dialog box, since it is identical to
every other MS-Windows application that has an Open... function.
3.1.2 Save
The Save menu selection saves the current configuration
settings to the current configuration file name. The current file
name is always displayed on the ECU Window title.
3.1.3 Save As...
The Save As... menu selection saves the current configuration
settings to the file specified by the file name selected in the
dialog box presented. I will not detail the operation of this
dialog box, since it is identical to every other MS-Windows
application that has a Save As... function.
3.1.4 Exit
The Exit menu selection is used to exit ECU. If the
configuration settings have changed, a message box appears ensuring
that the user wishes to exit without saving.
ECU can also be exited by "double-clicking" on the Control-
menu box or by selecting "Close" in the window's system menu.
3.2 Edit Menu
The Edit menu currently has only one entry: Undo. The Undo
menu selection nullifies the last operation. This is very useful
when you have made a "slip of the mouse" and wish to get back to
where you were.
3.3 Set Menu
The Set menu allows the time, geographic location, Solar
System calculation settings, comet orbits, and sky background color
to be adjusted. Each is described in the sections below.
3.3.1 Time
The time can be set in one of three formats: local civil time,
Universal time (GMT), or set to your pc's system clock (using local
civil time). The current time format used is identified in the
Time menu selections sub-menu, by a check mark in front of the
current mode. The following sections describe the time settings.
3.3.1.1 Enter Local Time
The Enter Local Time menu selection presents a dialog box
allowing the user to enter the year, month, date, hour, and minute
in local time format. The year can be from 1000 to 3000 AD and the
hour must be in 24 hour format. The time is always initialized to
the current time.
Ending the dialog box is accomplished by pressing the 'OK'
button. Aborting, without changing the time, is accomplished by
pressing 'Cancel'. If an error is detected when ending the dialog
box, a 'beep' will sound and the cursor will be placed at the
offending field.
This menu selection can also be activated by pressing the left
mouse button while the mouse is in either of the boxes which
display the local mean date and time (LMT) in the ECU status
display area.
3.3.1.2 Enter Universal Time
Entering the Universal time is accomplished identically to
entering the local time. This menu selection can also be activated
by pressing the left mouse button while the mouse is in either of
the boxes which display the universal date and time (UTC) in the
ECU status display area.
3.3.1.3 Use System Time
Selecting Use System Time causes ECU's time base to become
synched to the pc's system clock. This will cause the sky to
update automatically once per minute, therefore simulating the
actual sky's movements.
3.3.1.4 Local Time Format
The local mean time (LMT) display in the status area is
displayed in either 24 hour or am/pm format. The Local Time Format
menu selection is a sub-menu of AM/PM and 24 Hour selections, each
selection setting the respective format. The current format is
identified by a 'check mark'.
3.3.1.5 Daylight Savings
The Daylight Savings menu selection toggles whether the
current local time is to be interpreted as a daylight savings time.
It is used by ECU to convert from local time to Universal time. If
a 'check mark' is present, daylight savings mode is enabled. If
ECU is using the pc's system clock and the daylight savings time
'check mark' is present, the pc's time should be set to the
daylight savings time.
3.3.2 Geographic Location
The Geographic Location menu selection provides a sub-menu
containing two methods of entering a location on the Earth's
surface. These are By Latitude/Longitude and By City/Town.
3.3.2.1 By Latitude/Longitude
The By Latitude/Longitude menu selection presents a dialog box
allowing the user to enter the latitude, longitude, and time zone
of the location used in the sky display calculations. The latitude
is entered as degrees (North is positive, South is negative) and
minutes. The longitude is also entered as degrees (West of the
prime meridian is positive, East is negative) and minutes. The
time zone is entered in hours West of UTC (the time of the Grenwich
meridian; enter a negative for the Eastern hemisphere). The
location is always initialized to the current location.
Ending the dialog box is accomplished by pressing the 'OK'
button. Aborting, without changing the location, is accomplished
by pressing 'Cancel'. If an error is detected when ending the
dialog box, a 'beep' will sound and the cursor will be placed at
the offending field.
This menu selection can also be activated by pressing the left
mouse button while the mouse is in either of the boxes which
display the current latitude and longitude in the ECU status
display area.
3.3.2.2 By City/Town
The By City/Town menu selection presents a dialog box allowing
the user to select the location from a set of pre-defined
locations. A list box is presented containing the available list.
The user is to select the desired location, then exit the dialog
box.
Ending the dialog box is accomplished by pressing the 'OK'
button. Aborting, without changing the location, is accomplished
by pressing 'Cancel'.
This menu selection can also be activated by pressing the left
mouse button while the mouse is in the box which displays the
current city/town at the top the ECU status display area.
If your location is not in the list of available locations,
you can use a text editor (the Windows NotePad will do fine) to
edit the file LOCATION.ECU. The file format is quite simple, as
shown by the sample entries below:
49.0 59.0 3.5 Corner Brook NFLD
53.3 60.1 4 Goose Bay, LAB
47.5 52.9 3.5 St. John's NFLD
46.1 59.8 4 Sydney NS
The first three entries, which are separated by spaces, are
the latitude (decimal degrees North of the Equator), longitude
(decimal degrees West of the Prime meridian), and time zone (hours
West of UTC). The fourth entry is the name of the location. The
order of lines in the file does not matter since ECU sorts the file
in order when it is loaded.
3.3.3 Solar System
The Solar System menu selection provides a sub-menu allowing
several calculation options pertaining to the Solar System to be
changed. A 'check mark' in front of a menu item indicates that it
is enabled. Each menu item is described below.
3.3.3.1 High Accuracy Calculations
This menu selection controls the precision of the solar system
calculations. The high accuracy calculations are not available
when using the SHAREWARE VERSION of ECU.
3.3.3.2 Precess to Sky Display
This menu selection controls whether the Solar System object
positions and the horizon line are to be adjusted (due to the
effect of precession of the Earth's axis of rotation) to match the
J2000.0 coordinates used by the sky display.
3.3.3.3 Nutation
This menu selection controls whether the Solar System object
positions (except the comets) are to be corrected for the effects
of Nutation. Nutation is at maximum, a 9 arc-second wobble in the
precession circle primarily caused by the gravitational pull of the
Moon.
Nutation can only be calculated when the High Accuracy
Calculations selection is enabled.
3.3.3.4 Aberration
This menu selection controls whether the Solar System object
positions (except the comets) are to be corrected for the effects
of Aberration. Aberration is the apparent displacement of the
position of an object due to the finite speed of light (whatever
that means?).
Aberration can only be calculated when the High Accuracy
Calculations selection is enabled.
3.3.3.5 Light Travel Time
This menu selection controls whether the Solar System object
positions (except the Moon) are to be corrected for the effects of
the Light Travel Time. The Light Travel Time correction recognizes
that the observer sees an object at where it used to be in the
past.
Light Travel Time corrections can only be calculated when the
High Accuracy Calculations selection is enabled.
3.3.3.6 Observer's Parallax
This menu selection controls whether the Solar System object
positions (except the comets) are to be corrected for the effects
of the Observer's Parallax. The Observer's Parallax is the effect
of an apparent shift of an objects position for observers located
at different locations on the Earth. This effect is what causes
the Solar Eclipses and Occultations of the Moon to be only
observable from certain locations on the Earth's surface. Be sure
to enable this selection when simulating events which are location
specific like solar eclipses.
3.3.4 Atmospheric Refraction
This menu selection controls whether the local horizon,
Azimuth and Altitude displays, and Rise/Set calculations are to be
corrected for the effects of Atmospheric Refraction. Atmospheric
Refraction causes an object to appear higher in the sky that it
actually is. The bending (or refraction) of light as it passes
through the Earth's atmosphere causes this effect.
3.3.5 Define Comet Orbit
The Define Comet Orbit menu selection provides a sub-menu of
the six comets which can be defined. Each selection is identical
except for the comet number.
Each sub-menu selection presents a dialog box allowing the
orbital elements of a comet to be entered. The following items can
be entered.
a) Comet Name - a textual name that can be displayed next to the
comet in the sky display.
b) Date of Perihelion - the date of perihelion can be entered as
either decimal years or as year, month, and decimal days. If
the month is set to zero, the decimal years are used and the
month and date are ignored. If the month is valid (1 to 12),
the year, month, and date are used.
c) Perihelion Distance - the distance of the comet to the Sun in
astronomical units (AU) at Perihelion.
d) Eccentricity - the eccentricity of the comet's orbit from 0 to
1.
e) Argument of Perihelion - the argument, in degrees, of the
perihelion.
f) Longitude of Ascending Node - the longitude, in degrees, of
the ascending node.
g) Inclination of Orbit - the inclination of the orbit in
degrees.
h) Epoch of the Elements - the epoch of the elements, either
B1950.0 or J2000.0.
i) Magnitude Constants - the magnitude constants g and k, are
used to estimate the brightness of the comet. Each comet has
a different set of constants. Comet brightness predictions
are notoriously extremely unreliable.
g) Enable Comet - this flag enables the comet for display.
Ending the dialog box is accomplished by pressing the 'OK'
button. Aborting, without changing the comet orbital elements, is
accomplished by pressing 'Cancel'.
If a comet has a name and is 'enabled', it will be
subsequently be referred to in the menus by its name instead of
just "Comet 1", etc.
3.3.6 Sky Background Color
The Sky Background Color menu selection provides a sub-menu
allowing the sky background to be set to either black or white. I
find the black background more pleasing, but the white background
is required for printing of sky charts. The current mode is
identified by the 'check mark'.
3.4 Field Menu
The Field menu controls various parameters pertaining to the
sky display. Each menu selection is described separately in the
following sections.
3.4.1 Display
The Display menu selection provides a sub-menu allowing the
user to toggle the display of stars, deep sky objects, solar system
objects, the grid lines, lines and labels on the sky display. This
menu selection duplicates the on-screen check boxes. The current
state of each display setting indicated by a 'check mark' in front
of the menu item.
3.4.2 Magnitude Limits...
The Magnitude Limits... menu selection presents a dialog box
allowing the user to set the limiting magnitude for stellar and
deep sky objects. The magnitude is set by dragging the scroll bars
to the desired magnitude as displayed immediately below each scroll
bar.
The actual stellar limiting magnitude is dependant on the
field size, however, the setting here sets the upper limit. If the
deep sky magnitude limit is set to 20, all objects will be
displayed, even those whose magnitude is unknown.
Pressing 'OK' exits the dialog box and activates the new
magnitude limits. Pressing 'Cancel' exits without making any
changes.
This menu selection can also be activated by pressing the
left mouse button while the mouse is in box which displays the
current Magnitude Limit in the ECU status display area.
3.4.3 Object Selection...
The Object Selection... menu selection presents a dialog box
allowing the user to select which types of deep sky objects are
displayed. The dialog box has 7 check boxes; one for each of
Galaxies, Globular Clusters, Open Clusters, Bright Nebulae,
Planetary Nebulae, Other, and Unknown Magnitudes. If the check box
of the respective object type is true, that type will be displayed
(if deep sky objects are also 'turned on').
Note that the 'Unknown Magnitude' type allows for the display
of objects whose magnitude is unknown, without littering the
display with hundreds (or thousands) of faint objects, as would be
the case if the limiting magnitude were set to 20 as described in
Section 3.4.1.
Pressing 'OK' exits the dialog box and activates the new
object selections. Pressing 'Cancel' exits without making any
changes.
3.4.4 Planets...
The Planets... menu selection presents a dialog box which
allows the user to control various display parameters for the eight
planets. The three entries for each planet include a check box
indicating if the respective planet is displayed, a set of radio
buttons which determines if it is displayed as either a point or as
the planet's symbol, and a check box indicating if the planet's
name is also displayed.
Pressing 'OK' exits the dialog box and activates the new
planets settings. Pressing 'Cancel' exits without making any
changes.
3.4.5 Sun
The Sun menu selection toggles whether or not the Sun is
displayed on the sky display. If marked by a 'check mark', the Sun
will be displayed (assuming the Solar System objects are also
'turned on').
3.4.6 Moon
The Moon menu selection toggles whether or not the Moon is
displayed on the sky display. If marked by a 'check mark', the
Moon will be displayed (assuming the Solar System objects are also
'turned on').
3.4.7 Grid
The Grid menu selection provides a sub-menu allowing the
resolution of the coordinate grid to be set. If 'Fine' is
selected, the grid will mark every 20 minutes in Right Ascension
and every 5 degrees in Declination. If 'Coarse' is selected, the
grid will mark every 1 hour in Right Ascension and every 10 degrees
in Declination. A 'check mark' marks the current setting.
3.4.8 Lines/Points
The Lines/Points menu selection provides a sub-menu allowing
the user to toggle the display of lines and points on the sky
display. These include the constellation lines, ecliptic line,
horizon line, zenith point, and celestial pole points. The current
state of each line/point is indicated by a 'check mark' in front of
the menu item.
3.4.9 Labels
The Labels menu selection provides a sub-menu allowing the
user to toggle the display of text labels on the sky display.
These include the constellation labels, bright star labels, Solar
System labels, Messier labels, horizon line/zenith point labels
(N,S,E,W, etc.), and ecliptic point labels (VE - vernal equinox, SS
- summer solstice, etc.). The current state of each label is
indicated by a 'check mark' in front of the menu item.
3.4.10 Scroll Bars
The Scroll Bars menu selection provides a sub-menu allowing
the mode of the scroll bars to be set. If 'RA/Dec' is selected,
the scroll bars are used to move about the celestial sphere using
Right Ascension and Declination coordinates. If 'Azim/Alt' is
selected, the scroll bars are used to move about the local sky
display using Azimuth and Altitude coordinates. A 'check mark'
marks the current setting.
3.4.11 Field Size...
The Field Size... menu selection presents a dialog box
allowing the user to enter the vertical size, in degrees, of the
ECU sky display. The valid range is 2 to 60 degrees in integer
divisions.
Ending the dialog box is accomplished by pressing the 'OK'
button. Aborting, without changing, is accomplished by pressing
'Cancel'. If an error is detected when ending the dialog box, a
'beep' will sound and the cursor will be placed at the offending
field.
This menu selection can also be activated by pressing the
left mouse button while the mouse is in box which displays the
current Field Size in the ECU status display area.
3.4.12 Zoom In Full
The Zoom In Full menu selection causes the ECU sky display to
zoom in to the minimum allowable field size, which is 2 degrees in
height.
3.4.13 Zoom To 10 Degrees
The Zoom To 10 Degrees menu selection causes the ECU sky
display to zoom a field size, which is 10 degrees in height.
3.4.14 Zoom To 20 Degrees
The Zoom To 20 Degrees menu selection causes the ECU sky
display to zoom a field size, which is 20 degrees in height.
3.4.15 Zoom To 40 Degrees
The Zoom To 40 Degrees menu selection causes the ECU sky
display to zoom a field size, which is 40 degrees in height.
3.4.16 Zoom Out Full
The Zoom Out Full menu selection causes the ECU sky display to
zoom out to the maximum allowable field size, which is about 60
degrees in height.
3.5 Center Menu
The Center menu allows the user to quickly center on most
objects in ECU's databases. This includes centering on a specified
Right Ascension/Declination, a specified Azimuth/Altitude, a
constellation, a bright star, Messier object, Solar System object,
a point on the local horizon, or on a text search of the databases.
When an object is centered on the sky display, a cross-hair is used
to mark it. Each centering menu selection is described separately
below.
3.5.1 On RA/Dec...
The On RA/Dec... menu selection presents a dialog box allowing
the user enter a specific Right Ascension and Declination to center
the sky display on. The Right Ascension is entered as hours and
minutes. The Declination is entered as degrees and minutes.
Ending the dialog box is accomplished by pressing the 'OK'
button. Aborting, without changing the sky display, is
accomplished by pressing 'Cancel'. If an error is detected when
ending the dialog box, a 'beep' will sound and the cursor will be
placed at the offending field.
When the dialog box ends, ECU centers the sky display at the
coordinates entered. This menu selection can also be activated by
pressing the left mouse button while the mouse is in either of the
boxes which display the current Right Ascension/Declination in the
ECU status display area.
3.5.2 On Alt/Az...
The On Alt/Az... menu selection presents a dialog box allowing
the user enter a specific Azimuth and Altitude, with reference to
the local horizon, to center the sky display on. Both the Azimuth
and Altitude are entered as degrees and minutes.
Ending the dialog box is accomplished by pressing the 'OK'
button. Aborting, without changing the sky display, is
accomplished by pressing 'Cancel'. If an error is detected when
ending the dialog box, a 'beep' will sound and the cursor will be
placed at the offending field.
When the dialog box ends, ECU centers the sky display at the
local horizon coordinates entered. This menu selection can also be
activated by pressing the left mouse button while the mouse is in
either of the boxes which display the current Azimuth/Altitude in
the ECU status display area.
3.5.3 On Constellation...
The On Constellation... menu selection presents a dialog box
allowing the user to select a constellation to center the sky
display on. A list box is presented containing the available list
of 88 constellations in alphabetical order. The user is to select
the desired constellation, then exit the dialog box. ECU then
centers the sky display on the selected constellation.
3.5.4 On Bright Star...
The On Bright Star... menu selection presents a dialog box
allowing the user to select a bright star to center the sky display
on. A list box is presented containing the available list of
bright stars in alphabetical order. The user is to select the
desired bright star, then exit the dialog box. ECU then centers
the sky display on the selected bright star.
3.5.5 On Messier Object...
The On Messier Object... menu selection presents a dialog box
allowing the user to select a Messier Object to center the sky
display on. A list box is presented containing the available list
of 110 Messier objects in numerical order. The user is to select
the desired object, then exit the dialog box. ECU then centers the
sky display on the selected Messier object.
3.5.6 On Solar System Object
The On Solar System Object menu selection contains a sub-menu
of all the Solar System objects (Sun, Moon, Planets, and Comets).
The menu item selected is centered on the sky display.
3.5.7 On Point on Horizon
The On Point on Horizon menu selection contains a sub-menu of
all the cardinal points on the local horizon plus the Zenith (the
overhead point). The menu item selected becomes centered on the
sky display.
3.5.8 On Database Search...
The On Database Search... menu selection is used to search the
ECU databases for a specified object. If a match is found, the
specified object is centered on the sky display. The user is
presented with a dialog box which prompts for a line of text. If
the 'OK' button is pressed, the search commences. The line of text
entered is immediately converted to upper case to avoid ambiguities
and all spaces are removed. The object types which can be searched
for are listed below:
a) Constellations - the 88 constellations can be searched by
entering their complete formal name (eg. 'Ursa Major').
b) Bright Stars - bright stars can be searched by entering their
complete formal name (eg. 'Deneb').
c) Stars - any star in the Yale Bright Star (YBSC) database can
be searched by entering either its Smithsonian Astrophysical
Observatory (SAO) catalogue number with the prefix 'SAO', its
Yale number with the prefix 'HR', or its Henry Draper (HD)
catalogue number with the prefix 'HD'. For example, to find
the SAO star number 49898, enter 'SAO49898'. Note that
entering 'sao 49898' would be just as effective because the
case of the input and spaces are ignored. This search in
limited to searches of stars in the Yale Bright Star Catalogue
database. SAO stars which are fainter than 6.5 magnitude (the
extended stellar database) are not searched, primary due to
the excessive time that it would take to search the entire SAO
database of about 250,000 stars. Searching for YBSC stars is
not available in the SHAREWARE VERSION of ECU.
d) Deep Sky Objects - deep sky objects can be searched by
entering either their primary name or 'Other Names:' as stored
in the SAC deep sky database (see Section 4.). For example,
the Andromeda Galaxy can be found by entering either its
official name 'NGC224' or its common name (other name) 'M31'.
Searching for deep sky objects is not available in the
SHAREWARE VERSION of ECU.
If the search is not successful, a message box will appear
informing the user of this.
3.6 Animation Menu
The Animation menu controls all of the functions of ECU's
animation mode. The animation mode is used to simulate
astronomical events which are affected by changes in the time. The
animation mode has the following features.
a) Time can be automatically stepped in any step from 1 minute to
4 years.
b) Time can be stepped in either forward or reverse.
c) The time between time steps can be set from 0 to 60 seconds.
d) The trail history can be stored as either the objects Right
Ascension/Declination or its Azimuth/Altitude.
e) The solar system objects can be trailed with dots drawn behind
them.
f) The number of dots used in the trail can be set from 10 to
100.
g) The sky display can be made to 'lock' on any solar system
object, or point with reference to the local horizon.
h) The time can be manually stepped, either forward or in
reverse.
i) All of the features of ECU can be used while the animation
mode is running due to the multi-tasking nature of Windows,
and thus of ECU.
Animation mode is best learned by experimentation, however,
the menu items which control the animation mode are described in
the sections below.
3.6.1 Start
The Start menu selection starts the animation mode. If a
'check mark' preceeds the menu selection, animation mode is
running.
3.6.2 Stop
The Stop menu selection stops the animation mode. The ESC key
can also be used to stop the animation mode.
3.6.3 Forward One Step
The Forward One Step menu selection steps the time forward by
one time step. The time step is displayed to the left of the time
step buttons in the status area. This menu selection can also be
executed by pressing the '+' key or the '+' button.
3.6.4 Reverse One Step
The Reverse One Step menu selection steps the time in reverse
by one time step. The time step is displayed to the left of the
time step buttons in the status area. This menu selection can also
be executed by pressing the '-' key or the '-' button.
3.6.5 Trails On
The Trails On menu selection enables the drawing of trails
behind the Solar System objects. If the trails are enabled, a
'check mark' will preceed this menu selection.
3.6.6 Maximum Trails...
The Maximum Trails... menu selection presents a dialog box
allowing the user to enter the number of trails (10 to 100) to be
drawn behind Solar System Objects.
Ending the dialog box is accomplished by pressing the 'OK'
button. Aborting, without changing, is accomplished by pressing
'Cancel'. If an error is detected when ending the dialog box, a
'beep' will sound and the cursor will be placed at the offending
field.
3.6.7 Animation History
The Animation History menu selection presents a sub-menu of
the selections: RA/Dec and Anim/Alt. These selections control
whether the animation history is saved as the Right Ascension and
Declination of the object or as its Azimuth and Altitude with
reference to the local horizon. The latter setting is useful for
observing an object's path relative to the local horizon. A good
example of this would be to plot the positions of the planet
Mercury as it passes through an eastern or western elongation and
becomes visible in the evening or morning sky. Beware, however,
that the actual positions shown in the object trails (except for
the current position) are not correct with reference to the
background stars. Also, this setting operates slowly, because the
computational overhead is higher. A 'check mark' will immediately
preceed current setting.
3.6.8 Lock On Current RA/Dec
The Lock On Current RA/Dec menu selection causes the animation
mode to be locked on the current Right Ascension and Declination.
In fact, it turns 'lock mode' off. If locked on the current
RA/Dec, a 'check mark' will immediately preceed this menu
selection.
3.6.9 Lock On Current Azim/Alt
The Lock On Current Azim/Alt menu selection causes the
animation mode to be locked on the current altitude and azimuth,
with respect to the local horizon. This feature is very useful for
'watching' a particular horizon as the constellations rise or set,
or as a planet such as Mercury crests above the horizon. If locked
on the current Azim/Alt, a 'check mark' will immediately preceed
this menu selection.
3.6.10 Lock On Solar System Object
The Lock On Solar System Object menu selection presents a sub-
menu of all the Solar System objects (Sun, Moon, Planets, and
Comets). The menu item selected becomes locked to the center of
the sky display in animation mode. A 'check mark' will immediately
preceed the Solar System object locked.
3.6.10 Time Direction
The Time Direction menu selection presents a sub-menu of the
selections: Forward and Reverse. These selections control the
direction in which time is stepped when the animation mode is
running. A 'check mark' will immediately preceed the time
direction setting.
3.6.11 Time Step
The Time Step menu selection presents a sub-menu of the
selections: Increase and Decrease. These selections increase or
decrease, by one notch, the amount of the animation mode time step.
The current time step is shown as the third sub-menu item. These
two selections are duplicates of the time step arrows in the status
area.
3.6.12 Animation Speed...
The Animation Speed... menu selection presents a dialog box
allowing the user enter the number of seconds between animation
mode updates (0 to 60 seconds).
Ending the dialog box is accomplished by pressing the 'OK'
button. Aborting, without changing, is accomplished by pressing
'Cancel'. If an error is detected when ending the dialog box, a
'beep' will sound and the cursor will be placed at the offending
field.
3.7 About Menu
The About menu has two entries. The first selection, ECU...,
presents a message box identifying ECU, its version number, its
copyright notice, and how to contact the author.
The second selection, Willman-Bell..., presents a message box
identifying that ECU contains source code that which is copyrighted
by Jeffrey Sax. The source code referred to, provides high
accuracy astronomical calculations based on the algorithms
described in the book: Astronomical Algorithms by Jean Meuss
(distributed by Willman-Bell). The message given in the message
box is a requirement of distributing programs containing Jeffrey's
source code.
4. Databases
This section will describe the databases built-in to ECU. ECU
contains several databases. The databases which will be covered in
this section are the stellar database and the deep sky database.
Other databases include the label, constellation line, and
geographic location databases.
4.1 Stellar Database
The stellar database is divided into two parts. The first
part, the Yale Bright Star Catalog (files YBSC1.ECU and YBSC2.ECU),
is standard with the REGISTERED version of ECU. It contains 9110
stars to magnitude 6.5 with a wealth of information about each
star. The other star database is the optional extended stellar
database, the Smithsonian Astrophysical Observatory (SAO) Star
Catalogue. The entire SAO catalog contains some 259,000 stars.
The Yale stars and those with the magnitude unknown were extracted
leaving a database of 245654 stars to about magnitude 9.5.
Each database contains the magnitude (visual, if available),
Right Ascension, Declination in J2000.0 coordinates and are
displayed on the sky display using this epoch. The Yale Catalogue
provides several calogue numbers and names for each star. These
include the Bayer/Flamsteed identification, the Yale Catalogue
number, the SAO Catalogue number, and the Henry Draper Catalogue
number. The full spectral classification, color as B-V, and the
proper motion of each star. The SAO Catalogue provides the SAO
Catalogue number and the spectral type.
The object positions in each database are stored in integer
format obtaining a resolution of about 10 arc-seconds in
Declination and 20 arc-seconds in Right Ascension at the celestial
equator. The SHAREWARE VERSION of ECU only contains the primary
data file of the Yale Catalogue which only provides the Right
Ascension, Declination, and Magnitude.
4.2 Deep Sky Database
The deep sky database (files SAC1.ECU and SAC2.ECU) contains a
complete database of 10367 deep sky objects. The members of the
Saguaro Astronomy Club (SAC) (pronounced sa-war-oh) of Phoenix,
Arizona have provided much of the effort to compile this database
(database version 5.2). The database includes the entire NGC
catalog, plus other interesting deep sky objects. Selected fields
of the SAC database were extracted for use in ECU. The object
positions are stored in integer format obtaining a resolution of
about 10 arc-seconds in Declination and 20 arc-seconds in Right
Ascension at the celestial equator. Only the object type,
magnitude, and position are available with the SHAREWARE VERSION of
ECU. These fields are described below:
a) Object Name - usually the NGC number, but for objects with no
NGC value, other catalogs are used. The abbreviations listed
below are used to represent the other catalogs.
Abell - George Abell (planetary nebulae and
galaxy clusters)
AM - Arp-Madore (globular clusters)
Antalova - (open clusters)
Bark - Barkhatova (open clusters)
B - Barnard (dark nebulae)
Basel - (open clusters)
Berk - Berkeley (open clusters)
Be - Bernes (dark nebulae)
Biur - Biurakan (open clusters)
Blanco - (open clusters)
Bochum - (open clusters)
Ced - Cederblad (bright nebulae)
Cr - Collinder (open clusters)
Czernik - (open clusters)
Do - Dolidze (open clusters)
DoDz - Dolidze-Dzimselejsvili (open clusters)
Dun - Dunlop (globular clusters)
Fein - Feinstein (open clusters)
Frolov - (open clusters)
Gum - (bright nebulae)
H - William Herschel (globular clusters)
Haffner - (open clusters)
Harvard - (open clusters)
He - Henize (planetary nebulae)
Hogg - (open clusters)
HP - Haute Provence (globular clusters)
Hu - Humason (planetary nebulae)
IC - 1st and 2nd Index Catalogs to the NGC
(All types of objects except dark nebulae)
Isk - Iskudarian (open clusters)
J - Jonckheere (planetary nebulae)
K - Kohoutek (planetary nebulae)
King - (open clusters)
Lac - Lacaille (globular clusters)
Loden - (open clusters)
LDN - Lynds (dark nebulae)
Lynga - (open clusters)
M - Messier (all types of objects except
dark nebula)
Mrk - Markarian (open clusters and galaxies)
Mel - Melotte (open clusters)
M1 - Minkowski (planetary nebulae)
NGC - New General Catalog of Nebulae &
Clusters of Stars.
(All types of objects except dark nebulae)
Pal - Palomar (globular clusters)
Pismis - (open clusters)
PK - Perek & Kohoutek (planetary nebulae)
RCW - Rodgers, Campbell, & Whiteoak (bright
nebulae)
Roslund - (open clusters)
Ru - Ruprecht (open clusters)
Sa - Sandqvist (dark nebulae)
Sher - (open clusters)
Sh - Sharpless (bright nebulae)
SL - Sandqvist & Lindroos (dark nebulae)
Steph - Stephenson (open clusters)
Stock - (open clusters)
Ter - Terzan (globular clusters)
Tombaugh - (open clusters)
Ton - Tonantzintla (globular clusters)
Tr - Trumpler (open clusters)
UGC - Uppsala General Catalog (galaxies)
UKS - United Kingdom Schmidt (globular
clusters)
Upgren - (open clusters)
vdB - van den Bergh (open clusters, bright
nebulae)
vdBH - van den Bergh & Herbst (bright nebulae)
vdB-Ha - van den Bergh-Hagen (open clusters)
Vy - Vyssotsky (planetary nebulae)
Waterloo - (open clusters)
Westr - Westerlund (open clusters)
b) Other Name - contains other catalog designations that the
object is known by. The same abbreviations as in a) are used.
c) Object Type - the type of object from the list below.
Asterism
Bright Nebula
Cluster with Nebulosity
Dark Nebula
Galaxy cluster
Galaxy
Globular Cluster
Diffuse Nebula in a Galaxy
Globular Cluster in a Galaxy
Cluster with Nebulosity in a Galaxy
Cluster with Nebulosity in the LMC
Diffuse Nebula in the LMC
Globular Cluster in the LMC
Open cluster in the LMC
Nonexistent in RNGC
(means Sulentic and Tifft couldn't find it on the POSS plates for
inclusion in the RNGC)
Open Cluster
Planetary Nebula
Cluster with Nebulosity in the SMC
Diffuse Nebula in the SMC
Globular Cluster in the SMC
Open cluster in the SMC
Quasar
Unverified Southern Object
Multiple Star
d) Position - the object's position, Right Ascension and
Declination, in the J2000.0 epoch.
e) Magnitude - the object's brightness to the nearest tenth.
There are many objects which have no published magnitude; they
are listed as ??.?. Dark nebulae obviously have no magnitude,
so they are also listed as ??.?.
f) Description - a visual description of the object. Most of
these are from the NGC, some are from prominent amateurs.
Back issues of Deep Sky Magazine, Astronomy magazine, Sky and
Telescope magazine and Burnham's Celestial Handbook are used
as a source of some of these descriptions. The descriptions
use the abbreviations from the NGC and Burnham's. They are
given below:
! remarkable object !! very remarkable object
am among n north
att attached N nucleus
bet between neb nebula, nebulosity
B bright P w paired with
b brighter p pretty (before F,B,L or S)
C compressed p preceding
c considerably P poor
Cl cluster R round
D double Ri rich
def defined r not well resolved, mottled
deg degrees rr partially resolved
diam diameter rrr well resolved
dif diffuse S small
E elongated s suddenly
e extremely s south
er easily resolved sc scattered
F faint susp suspected
f following st star or stellar
g gradually v very
iF irregular figure var variable
inv involved nf north following
irr irregular np north preceding
L large sf south following
l little sp south preceding
mag magnitude 11m 11th magnitude
M middle 8... 8th magnitude and fainter
m much 9...13 9th to 13th magnitude
g) Size - the size of the object in minutes of arc (') or seconds
of arc (").
h) Class - the class of the object. Several professional
classification schemes are contained here.
Trumpler type for open clusters
Concentration
I. Detached, strong concentration toward the center
II. Detached, weak concentration toward the center
III. Detached, no concentration toward the center
IV. Not well detached from surrounding star field
Range in brightness
1. Small
2. Moderate range
3. Large range
Richness
p Poor (<50 stars)
m Moderately rich (50-100 stars)
r Rich (>100 stars)
An "n" following the Trumpler type denotes nebulosity in cluster
Shapley-Sawyer concentration rating for globular clusters
The values range from 1 to 12, smaller numbers are more
concentrated clusters.
Vorontsov-Velyaminov type for planetary nebulae
1. Stellar
2. Smooth disk (a, brighter center; b, uniform brightness; c,
traces of ring structure)
3. Irregular disk (a, very irregular brightness; b, traces of
ring structure)
4. Ring structure
5. Irregular form similar to diffuse nebula
6. Anomalous form, no regular structure
Some very complex forms may combine two types.
Hubble type for galaxies
E elliptical, E0 is roundest to E7 is flattest subgroups; 'd'is
dwarf, 'c'is supergiant, 'D' has diffuse halo
S Spiral, 'a' has tightly wound arms, 'b' has moderately wound
arms and 'c' has loosely wound arms
SB Spiral with central bar
Ir Irregular
5. Identify Objects
The identify objects dialog box contains various information
pertaining to the currently selected object. The information
common to all object types includes the Right Ascension and
Declination, the Altitude and Azimuth with reference to the local
horizon, and the time the object rises and sets. Each object type
is listed below with each one's specific information displayed in
the identify objects dialog box.
a) Sun - the sun's distance, in astronomical units; and its size,
in minutes of arc are displayed.
b) Moon - the moon's distance from the Earth, in kilometres; its
size, in minutes of arc; its age, in days; and its phase are
displayed.
c) Planets - the planet's magnitude; its distance from the Earth,
in astronomical units; its size, in seconds of arc; and its
phase (0 to 1) are displayed.
d) Comets - the comet's magnitude; and its distance from the
Earth and the Sun in astronomical units are displayed.
e) Yale Bright Star Catalogue Stars - the star's magnitude; its
Bayer/Flamsteed identification; its Yale Catalogue number; its
SAO Catalogue number; its Henry Draper Catalogue number; its
spectral classification; its color as B-V; and its proper
motion.
f) Deep Sky Objects - the object's magnitude (if known); its
primary and other names; its description; its size; and its
object class are displayed. See section 4.2.
6. Printing Star Charts
ECU does not currently support the direct printing of star
charts. However, the SHAREWARE graphics program "Paint Shop",
produces excellent charts with ECU. The procedure that I use is
listed below.
a) Start up Paint Shop.
b) Set up ECU as desired in "full screen" mode.
c) Switch Sky Background Color to White.
d) Use the Control Menu's "Switch To..." selection to Select
Paint Shop.
e) Use Paint Shop's "Capture" menu to grab ECU's full screen, or
part there of.
f) Use Paint Shop's "Print" selection to print out the results.
The lack of the feature of printing high-quality star charts
is the most obvious deficiency present in ECU. The next release
will have direct printing of star charts as well as several other
new features from the list in section 7.
7. The Future of ECU
The future of ECU depends on you. If you register it, it
gives me the signal that you are using it, which will give me lots
more incentive to improve it (if no one uses it, why improve it?).
Below is a partial list of the features, in no particular order,
which are coming in future releases of ECU.
- add the position angle into moon phases
- draw the moon and sun on the sky exactly as it would appear, even
if it look a bit odd (ie. not round)
- add dialog boxes for label and lines settings
- add Dreyer deep sky object description help dialog box
- add an observing list output of objects currently on the screen
- add Earth's shadow for simulating lunar eclipses
- add ability to paste the screen to the clipboard
- add direct high-quality sky chart printing
- add solar system empheris printer output
- provide more realistic star brightness displays using a
combination of white/black and greys and possibly colors
- add more common star names and cross reference them to their Yale
equivalent
- add common deep sky object names and cross reference them to the
deep sky database
- Hubble Guide Star Catalog CDROM support
- add text labels on the coordinate grid
- add ability for the user to add objects
- add ability to set the colors of nearly everything, plus a red
mode for dark adaptation in observatory use
- add support for the SGT-MAX / MicroGuider digital setting circle
device
- allow the user to add descriptions (an observing log) of stars
and deep sky objects
- add display of Jupiter's moons
- add display of Saturn's moons/rings
- enhancements to the manual, particularily information pertaining
the astronomical calculations used and information pertaining to
the accuracy obtained
- improve the appearance of the sky display by adding better sky
projections which will allow for larger field sizes
- allow the fonts used to display text labels to be set by the user
- add constellation boundaries
- provide facility for the identify object dialog box to precess
the objects coordinates to the current date
- add changing mouse pointers during the sky redrawing process
which will identify what is currently happening.
- add separate deep sky magnitude limits for each deep sky type