Tabular predictions for the currently selected satellite may be made
by using TRAKSTAR by Dr. TS Kelso. STSPLUS has been arranged to operate
seamlessly with TRAKSTAR by simply pressing Function Key F4 from the Main
Menu. All data required by TRAKSTAR is automatically supplied by STSPLUS.
See the section above "Predicting Satellite Passes with TRAKSTAR" and the
TRAKSTAR documentation for full information.
F5 Set Launch Time and Date
-------------------------------
Orbital data for the satellite must be loaded using the F2 command on
the Main Menu before the launch date and time may be set or changed. Once
saved in file STSPLUS.LTD, the launch date and time will be automatically
read from that file each time the satellite is selected (see below).
********************
* IMPORTANT NOTE *
********************
LAUNCH TIME AND DATE MUST EITHER BE INCLUDED IN FILE STSPLUS.LTD
OR BE MANUALLY ENTERED FOR EACH SATELLITE OR MISSION SINCE THAT
INFORMATION IS NOT INCLUDED IN 2-LINE ELEMENTS.
Launch date and time are most important for manned missions such as
the Space Shuttle since the mission timeline is reckoned using Mission
Elapsed Time. However, MET may be used whenever actual launch date and time
are known. The only requirement is that 2-line orbital elements must be
available for the satellite. Since launch date and time are NOT included in
the 2-line orbital elements, this means that you obtain the launch date and
launch time independently and manually enter that data.
Pressing F5 to enter launch date and time begins with the prompt:
Enter Launch Time (HH:MM:SS):
[Add 'U'or 'G' for UTC/GMT]
Enter the time in the format shown using 24-hour notation. Add the letter
"U" to signify UTC (Coordinated Universal Time) or the letter "G" to
signify GMT (Greenwich Mean Time, essentially identical to UTC for the
purposes of this program). Use no suffix for local time; it will be
internally converted to UTC/GMT. If you enter "U" or "G", the abbreviation
used in the menus will be set to "UTC" or "GMT" respectively. One or two
digit numbers may be used as required. [The comma is also acceptable as a
separator in place of the colon.] You may omit seconds [or minutes and
seconds] if desired. For example, an entry of "16" will be entered as
16:00:00 or 4:00 PM. Press ENTER to leave the entry unchanged.
Enter Launch Date (MM/DD/YYYY):
[Enter '*' to clear LAUNCH DATE]è
Enter the date in the format shown. Note that if you requested UTC or GMT
when entering the time, the date is interpreted as the UTC/GMT date. The
Program STSORBIT PLUS Satellite Orbit Simulation Page 92
full four digit year may be used OR two digits as in "92". Be sure to use
the SLASH "/" rather than the MINUS "-" as the separator; STSPLUS's
internal date algorithms will interpret the minus sign as just that and
some rather strange dates can result! You may also use relative dates: -1
will use the prior day, +2 will use two days hence, and so forth. Press
ENTER to leave the date unchanged. Press "*" (followed by ENTER) to clear
the launch date and time; this does NOT remove it from file STSPLUS.LTD.
Press ENTER to accept, SPACE BAR to repeat:
When all data have been entered, the program pauses for your approval. If
all data are correct, press ENTER. Press the SPACE BAR to start over. You
are next asked if you wish to save this data:
Add/Update this data in file STSPLUS.LTD [Y,n]:
Press "Y", "y" or ENTER to add or update the data in file STSPLUS.LTD (see
below). Press "N" or "n" to use the data but not add or update it in file
STSPLUS.LTD. Adding or updating the data to file STSPLUS.LTD makes sure
that the launch date and time data will be available the next time this
particular satellite is selected.
Using File STSPLUS.LTD for Launch Date & Time
---------------------------------------------
An alternative and automatic method to set launch date and time is to
use file STSPLUS.LTD. This file contains the NORAD number and launch date
and time (UTC Julian date) for selected satellites. A sample entry appears
as:
22194,2448918.21503472,0
--+-- -------+-------- +
| | |
| | +--- (Reserved, must be present)
| |
| +------------- Launch Date (UTC Julian date)
|
+------------------------ NORAD Number
The Sample above shows the data for Space Shuttle mission STS-52 (NORAD
#22194) and corresponds to a launch date and time of 22 OCT 1992 @ 17:09:39
UTC. The file is in standard ASCII format and may be edited with any
standard editor; word processor users use the "non-document" mode. Use care
when manually editing the file as STSPLUS performs NO ERROR CHECKING!
Estimated 2-line orbital elements are usually available prior to a
Space Shuttle launch, and actual 2-line orbital elements within about 8 to
12 hours after a launch. Note, however, that the NORAD number is not
assigned until actual launch and a "dummy" NORAD number is used for
estimated pre-launch elements; for example, "00052" for STS-52. Once the
launch has taken place, the permanent NORAD number is assigned. This change
in NORAD number will require either that file STSPLUS.LTD be edited OR that èa new entry be made. Note that there are still a few satellites around with
low NORAD numbers!
Program STSORBIT PLUS Satellite Orbit Simulation Page 93
If file STSPLUS.LTD is present and if the selected satellite is found,
the launch time and date will be set and Mission Elapsed Time (MET) will be
used automatically; otherwise, T+Epoch (T+E) will be used. When MET is
displayed, it may be changed to T+E by pressing F6 from the Main Menu
(below) or F5 while the map is displayed.
File STSPLUS.LTD is read each time a new satellite is selected using
F2 from the Main Menu. If file STSPLUS.LTD is NOT present, the launch date
and time will be saved in file STSPLUS.INI and must be MANUALLY MAINTAINED
as in versions prior to 9245! If you wish to use the old method, rename or
NOTE: The first two satellite slots, #1 and #2, are reserved for the
standard TDRS East and TDRS West satellites, currently NORAD
Numbers 19833 and 21639. Instead of conventional circles of
visibility, these two satellites generate commumications coverage
circles. Assigning different satellites, especially satellites
which are not geostationary, may produce unpredictable results.
The Satellite Setup table headings indicate:
Sat# Satellite Assignment Number, 1 to 16.
NORAD# The NORAD Number of the assigned satellite, or "0" if no
satellite is assigned to this slot.
Abbr The five character abbreviation assigned to this satellite.
Use only letters and numbers; the common satellite name or
NORAD Number are the recommended choices. This abbreviation
will be used as a label on the map if the Label is ON.
Mode Three classifications are available: "Static" for
geosynchronous or geostationary satellites; "Real Time" for
satellites to be tracked dynamically; and, "(not used)" for
unassigned slots.
Color A number selected from the Color Chart at the right which
indicates the color to be used to display the satellite icon
and label (if enabled). Each "XXXXX" in the Color Chart
appears on color monitors as a bar of the corresponding è color. The "o" character to the right of the number is
displayed as a small diamond in the selected color.
Program STSORBIT PLUS Satellite Orbit Simulation Page 95
Size For Static satellites only, selects the relative size of the
icon used to represent the satellite. Values may range from
3 to 6. This column is blank for Real Time satellites since
the icon size is fixed for these satellites.
Label May be set to "ON" or "OFF" to indicate if the satellite
abbreviation is to be displayed. The label color will be the
same as that selected for the satellite.
Vis May be set to "ON" or "OFF" to indicate if the satellite
circle of visibility is to be drawn. The circle of
visibility is drawn only for Static satellite on normal maps
but is drawn for all satellites on Motion maps.
Color The color chart displays the 15 available icon and label
Chart colors (BLACK is omitted). When a monochrone display is used
and the "/M" command line option is specified, two levels of
gray will normally be displayed instead of colors. Each
color is assigned a standard color number which is used for
all data entries.
As indicated by the prompt, simply press ENTER if all data in the
Satellite Setup is correct. You will return to the F6 menu above. If you
wish to add a satellite or change the selections for an existing satellite,
enter the satellite slot number (Sat# in the left column of the table). The
following prompts will be displayed in turn:
Enter NORAD Number:
(Enter 0 to clear the satellite entry)
STSPLUS expects the NORAD number for the desired satellite. This number
will be used to "capture" the 2-line elements when this satellite is
subsequently displayed.
Enter Satellite Abbreviation:
Enter any desired abbreviation, 5 characters or less, or the NORAD number.
Use only letters and numbers with no leading spaces.
Enter Mode (0=STATIC, 1=REAL TIME):
Enter "0" or "1". STATIC mode satellites are drawn each time the map is
redrawn on the screen. REAL TIME satellites are updated every 10 seconds or
as often as the processor can complete the required calculations.
Enter satellite color (1 to 15):
Enter the number for the desired color, as shown on the Color Chart at the
right of the screen. An illegal color number will default to YELLOW.
Display satellite Label (0=NO, 1=YES):
èEnter "0" or "1". The label will be displayed directly below the satellite
icon in the same color as that selected for the icon in the preceeding
step. For Real Time satellites, the label is only drawn when the map is
Program STSORBIT PLUS Satellite Orbit Simulation Page 96
redrawn and remains stationary EXCEPT when using the Motion Map (in which
case it follows with the icon).
Display Cir of Visibility (0=NO, 1=YES):
Enter "0" or "1". The circle of visibility is drawn (when enabled) for all
Static satellites, and also for all Real Time satellites when using the
Motion Map.
When a new satellite is entered, a double asterisk ("**") will appear
at the right for that satellite slot. This is to remind the user to display
the ground track for that satellite so that 2-line elements may be stored
in the TLE memory associated with that slot. The following message will
also appear below the chart:
** Display ground track for this satellite!
To display the ground track, press F2 from the Main Menu, select the file
of 2-line elements which includes the satellite in question, and enter the
NORAD Number ("#nnnnn", where "nnnnn" is the NORAD Number). Once the
satellite has been displayed on the map, the 2-line elements will be saved
for future use.
Although 2-line elements are saved for all TDRS and Real Time
satellites, the user is reminded that these elements have a limited
lifetime. That lifetime varies considerably from satellite to satellite.
For geosynchronous satellites, 4 to 8 weeks is probably reasonable; for
other active satellites, 1 to 2 weeks should be an upper limit before new
elements are used. Use F2 from the Main Menu and enter the satellite name
as "&" to scan through the 2-line elements file and update all elements
which are more recent than those now saved.
F2 Save SCF Satellite Configuration File
-----------------------------------------
Users may wish to switch among several sets of TDRS and Real Time
satellites from time to time. Since it can be tedious to re-enter all the
information repeatedly, STSPLUS can save and read Satellite Configuration
Files, identified by the filetype .SCF. All parameters are saved and
restored, exactly as if entered at the time. The current satellite
configuration is automatically saved in file STSPLUS.INI each time the
program is exited and is restored when the program is restarted. The
following prompt is displayed:
Save SCF Satellite Configuration File
Enter FILENAME (without .SCF filetype), ENTER to quit:
Enter any desired filename WITHOUT the .SCF filetype; STSPLUS automatically
appends the filetype and will reject any filename which includes a
filetype. Filenames may be no longer than 8 characters. If the file already
exists, it will be overwritten; if it does not exist, it will be created.
Do not use filename STSPLUS since a sample file by that name is included
with the distribution package (unless you wish to overwrite the supplied èfile).
Program STSORBIT PLUS Satellite Orbit Simulation Page 97
F3 Read SCF Satellite Configuration File
-----------------------------------------
See the comments above for saving SCF files. The following prompt is
displayed:
Read SCF Satellite Configuration File
Enter FILENAME (without .SCF filetype), ENTER to quit:
Enter any desired filename WITHOUT the .SCF filetype; STSPLUS automatically
appends the filetype and will reject any filename which includes a
filetype. Filenames may be no longer than 8 characters. If the file does
not exist, an error message will be displayed.
F7 Set FILENAMES and PATHS
------------------------------
Function Key F7 allows the user to select the paths and/or filenames
for the various files that STSPLUS uses to select satellites, tracking
stations, and other features:
Select path or filename to set, press ENTER when done:
F1 Set 2-LINE ELEMENTS path: [I:\TLE\]
F2 Set TRACKING STATION filename: [STSPLUS.TRK]
F3 Set MAP DATABASE FILES path: [D:\MAPDATA\]
F4 Set FEATURES LABEL filename: [STSPLUS.LOC]
F5 Set TRAKSTAR path: [D:\STSPLUS\]
F6 Set CITYFILE filename: [STSPLUS.CTY]
Enter selection or ENTER:
Press the indicated function key for the item you wish to change. The
current path or filename is shown in square brackets for each selection.
Press ENTER to leave a path or filename unchanged. The following is a
typical prompt for filename:
Enter TRACKING STATION filename: _
(Press ENTER to leave unchanged)
For filenames, enter the full filename including filetype. A drive and
directory may also be included if desired. If no filetype is entered,
STSPLUS will automatically supply ".TRK" for tracking station files, and
".LOC" for features label files. If the desired file has no filetype,
include the period in the filename entered (e.g. "STATION.") to prevent the
automatic addition of a filetype.
For the path selections, enter the desired drive and subdirectory. The
trailing backslash will automatically be added if it is omitted. If the
path cannot be found, an error message will be displayed and the path will èdefault to the current drive and directory. For best performance, use a RAM
disk for Map Database Files; see the section "Using a RAM Disk" for further
information.
Program STSORBIT PLUS Satellite Orbit Simulation Page 98
After each entry, the Path and Filenames Menu is again displayed with
the current selections. Press ENTER when done to return to the STSPLUS Main
Menu.
F8 Set Program TIME and DATE
--------------------------------
This menu provides a number of time and date functions for use
with STSPLUS. The program clock may be set to real or simulated time
using several methods, current clock corrections applied by program
RIGHTIME may be displayed, and the UTC OFFSET and DAYLIGHT Flag may be
adjusted.
It is often convenient to set the TIME and DATE within STSPLUS to
something other than the current system time and date, or to return to the
current system time and date if the program time and date have been
changed. Press F8 to go to the TIME and DATE Menu:
Program STSORBIT PLUS
Space Shuttle and Satellite Orbit Simulation
Version 9334
Current time: 14:52:24 PST 22:52:24 UTC
Current date: 03/10/1993 03/10/1993
ACTUAL SYSTEM DATE AND TIME SHOWN ABOVE
(Assisted by RIGHTIME)
F1 Restore SYSTEM date and time (use "real time")
F2 Set DOS SYSTEM CLOCK using calendar date and time
F3 Set SIMULATED date and time using calendar date and time
F4 Set SIMULATED date and time using Mission Elapsed Time
F9 Display Current RIGHTIME Corrections
F10 Set UTC OFFSET and DAYLIGHT Flag
ENTER Return to MAIN MENU
Select desired function:
The Date and Time Menu, shown above, displays the available time
setting functions along with the actual system date and time as determined
by the DOS software clock in your computer (even if simulated time is in
effect). If program RIGHTIME Version 2.5+ is currently enabled, the message
"(Assisted by RIGHTIME)" will also appear. Both your local date and time,
"PDT" or Pacific Daylight Time in the example, and "UTC" (Coordinated
Universal Time) date and time are displayed. If times have been set using
the letter "G", the abbreviation at the right will be "GMT" (Greenwich Mean
Time).è Press ENTER to return to the Main Menu with the date and time as
displayed on the screen (Current or Simulated).
If you wish to execute STSPLUS in "real time", cancelling any
Program STSORBIT PLUS Satellite Orbit Simulation Page 99
simulated time that may be in effect, use the F1 command. This will restore
the time and date used for the tracking display to that shown at the top of
the menu. If the actual system date or time displayed is incorrect, use
program TIMESET (if available) or the F2 command to correctly set your
system clock.
Some organizations, NASA for example, continue to use the wording
"Greenwich Mean Time" or "GMT" for what is now usually referred to as
"Coordinated Universal Time" or "UTC" (and sometimes, depending upon the
application, as "UT", "UT1" or "UT2"). STSPLUS uses Coordinated Universal
Time or "UTC", the time used for civil timekeeping and broadcast by radio
stations such as WWV and the BBC. Although technically these different time
standards are not exactly the same, the difference is only a maximum of 0.9
seconds and the program treats them all as identical. STSPLUS defaults to
the abbreviation "UTC" but if you prefer to use "GMT", enter any simulated
time using F3 and include the letter "G" (upper or lower case) at the end.
The time abbreviation at the top of the screen will change from "UTC" to
"GMT" and will continue using that abbreviation until a time is entered
suffixed with "U".
Times are always entered as "HH:MM:SS" where HH is HOURS, MM is
MINUTES, and SS is SECONDS. The time entry format is very flexible. Leading
zeroes are not required. The comma (",") may be used in place of the colon
(":") as a separator if desired. SECONDS or MINUTES and SECONDS may be
omitted if desired. Time entries are assumed to be local time; to enter UTC
or GMT times, add the letter "U" or "G" (upper or lower case) respectively
following the entry. For example, the following are valid time entries:
Entry Interpreted as
------ --------------------------
12 12:00:00 (LOCAL TIME ZONE)
13,1 13:01:00 (LOCAL TIME ZONE)
4:1:15 04:01:15 (LOCAL TIME ZONE)
1,1,1 01:01:01 (LOCAL TIME ZONE)
13,45U 13:45:00 UTC
1:20g 01:20:00 GMT
Dates are entered as "MM/DD/YYYY" or "MM/DD/YY" where MM is MONTHS (as
a number from 1 to 12), DD is DAYS, and YYYY is the full four-digit YEAR or
YY is the last two digits of the YEAR. Except for the two digit year
option, the full date must always be entered; leading zeroes are not
required. The date entered is assumed to be for the same time zone as the
time entered. If local time is entered, the date will be treated as the
local date; if UTC (or GMT) time is entered, the date will be treated as
the UTC/GMT date.
After a time or date entry has been accepted (after you press the
ENTER key), STSPLUS reformats the entry to its standard format, clears the
characters you entered, and replaces them by the standard format in both
local and UTC/GMT time zones. This provides a double check that the program
has interpreted your entry as you wished.
F1 Restore System Date and Time
-----------------------------------
è Press F1 to restore the program date and time to the system date and
time. This command reads the DOS clock and restores the program to "real
time" operation. If the program date and time have not been changed with
Program STSORBIT PLUS Satellite Orbit Simulation Page 100
the F3 or F4 commands, this command will have no effect.
F2 Set DOS System Clock
---------------------------
Press F2 to set the DOS system clock. Use this command if you wish to
change the actual date and time on your system. Note that on many systems
using DOS 3.3 or higher, this command will set BOTH the software clock AND
the hardware clock.
*************
* CAUTION *
*************
This function should NOT be used when program RIGHTIME is
regulating the DOS clocks UNLESS no other method is available.
Use program TIMESET to set the DOS clocks accurately instead!
Program STSORBIT PLUS
Space Shuttle and Satellite Orbit Simulation
Version 9334
Current time: 19:59:10 PST 03:59:10 UTC
Current date: 02/24/1993 02/25/1993
CAUTION: This function will change the computer's SYSTEM CLOCK!
Press ENTER to leave an item unchanged
Enter TIME (HH:MM:SS): 16:34:24 PST
Enter DATE (MM/DD/YYYY): 4/08/1992
Press ENTER to accept, SPACE BAR to repeat: _
The sample above shows the screen after the time and date entries have been
completed. The current ACTUAL system date and time are displayed for
approval. Press ENTER to accept the time and date displayed, or press the
SPACE BAR to repeat the entries.
F3 Set Simulated Date and Time using Calendar Method
Press ESC (the key marked "ESC" or "Esc", not the letters E+S+C) to
quit program STSORBIT PLUS. If you press ESC to quit the program and have
manually entered orbital data, STSPLUS will save all required mission data
in file STSPLUS.INI prior to terminating. This will be the data available
with the ENTER key the next time you execute the program. The demonstration
data will not be saved, preserving any previously saved mission data.
When you have finished with STSPLUS, press ESC at the Main Menu to
return to DOS. The data (and any adjustments you have made) for the current
mission are saved in file STSPLUS.INI, but the map data is lost and will be
re-read when you next use program STSPLUS.
Program STSORBIT PLUS Satellite Orbit Simulation Page 104
PROGRAM OPTIONS AND FEATURES MENU
---------------------------------
A number of program features and display options are set using the F10
Program Options Menu. When used with CGA displays, the features shown below
as selected by function keys F3 and F4 are not available because of the low
resolution of the CGA display. The following Options Menu is displayed when
the F10 command is entered from the Main Menu:
Program STSORBIT PLUS
Space Shuttle and Satellite Orbit Simulation
Version 9334
Current time: 19:59:10 PST 03:59:10 UTC
Current date: 02/24/1993 02/25/1993
F1 Program STSORBIT PLUS Information
F2 Set New Local Coordinates (Rancho Palos Verdes, CA)
F3 Select Display Features
F4 A/A Select Satellite Coordinates: RA/DEC, Alt/Az or XYZ
F5 OFF Show Ascending & Descending Node Data
F6 ORTHO Set Map Projection and Size
F7 OFF Enable/Disable EVENT TIMERS
F8 ON Enable/Disable Audible ALARMS
F9 -7.00 Set UTC Time Offset and Daylight Flag
F10 OFF Enable/Disable Printer Logging
ENTER Return to MAIN MENU
Select desired function:
F1 Program STSORBIT PLUS Information
----------------------------------------
Function Key F1 displays information about program STSORBIT PLUS
including the copyright notice, version number, my name and address, and
the telephone number of my RPV ASTRONOMY BBS (Bulletin Board System). The
current version of STSORBIT PLUS is always posted on the BBS. The BBS has a
power controller; if it hasn't answered after the THIRD RING, hang up and
call back in two minutes. The BBS is available 24 hours per day at 9600,
2400 and 1200 baud.
F2 Set New Local Coordinates
--------------------------------
In order to perform the calculations related to satellite visibility
and altitude/azimuth, STSPLUS must know the geographic coordinates for the èuser's location. The name of the current location is shown in parentheses.
When STSPLUS is first started, the default coordinates are set to Rancho
Palos Verdes, California, near Los Angeles. The current location is
Program STSORBIT PLUS Satellite Orbit Simulation Page 105
indicated by the name in parentheses on the Options Menu. The program
provides two methods for setting your own coordinates: reading a file of
city names and coordinates (STSPLUS.CTY); or manually entering the
information.
Pressing F2 will display the following reminder:
STSPLUS searchs STSPLUS.CTY for the CITYNAME you enter anywhere in the
city names. 'SAN' appears in 'SAN DIEGO', 'SANTA ANA', 'THOUSAND OAKS.
Press ENTER to delete SECOND LOCATION, or enter '*' to manually enter
a city name and coordinates (and optionally add it to STSPLUS.CTY).
In other words, when you enter a name or partial name, STSPLUS will
attempt to match that group of characters anywhere in the names which
appear in the city file. For example, 'SAN' matches 'SAN diego' as well as
'SAN jose' and 'thouSANd oaks'. To get 'SAN FRANCISCO' on the first try,
enter 'SAN F' with a space between the 'N' and 'F'. Case is not
significant; upper and lower case letters are treated identically. If you
change your mind and wish to cancel the operation, simply press ENTER by
itself. Use BACKSPACE to make corrections.
To begin the search, enter the desired name after the prompt. In the
example which follows, the name 'ran' was entered for the search.
Enter CITYNAME to match: ran
Processing record 1
City Name: Rancho Palos Verdes CA
Latitude: 33.7675
Longitude: -118.4033
Elevation: 186 meters
Press ENTER to ACCEPT this city as your location, OR
Press TAB to also display this city's location, OR
Press SPACE to search for next city: _
If the city displayed is the one you wish to use as your local
coordinates, press ENTER. If you wish to display this city as a second
location on the display, press TAB. The data will be entered into STSPLUS
and subsequently saved in file STSPLUS.INI. If you wish to search further
in the file, press the SPACE BAR.
NOTE: The elevations contained in file STSPLUS.CTY are almost all zero
except for Rancho Palos Verdes, CA for which I have accurate elevation
above mean sea level. If you know the correct elevation for your
location, edit the file using any ASCII text editor and change the
last number on the line. STSPLUS.CTY contains over 800 cities. If
users send me their correct elevations (or additional cities they wish
added), I will incorporate that data into subsequent versions of file
STSPLUS.CTY.
To enter location data manually, press "*" (without the quotation
marks) followed by ENTER. You will be prompted for the city name, latitude, èlongitude, and elevation. Latitude and longitude may be entered using three
different formats for convenience (note the use of comma and decimal
point):
Program STSORBIT PLUS Satellite Orbit Simulation Page 106
DDD.DDDDD Degrees and decimal fraction
DD,MM.MMM Degrees, minutes and decimal fraction
DD,MM,SS.SS Degrees, minutes, seconds and fraction
Note that SOUTH latitude and WEST longitude must be entered as NEGATIVE
numbers as measured south of the Equator or west of the Prime Meridian at
Greenwich, respectively. The default unit for elevations is meters above
mean sea level; add "F" (upper or lower case without the quotation marks)
if you wish to use feet.
After the elevation has been entered, the data will be displayed for
approval. All data are converted to degrees or meters as appropriate,
regardless of the units used on input.
City Name: Rancho Palos Verdes CA
Latitude: 33.7675
Longitude: -118.4033
Elevation: 186 meters
Press ENTER to ACCEPT this city, OR
Press SPACE to cancel this data: _
Press ENTER to accept the data as shown or SPACE to cancel the data and
return to the Options Menu. If the data is accepted, STSPLUS will ask if
you wish to append (add) this city/location to the existing file
STSORBIT.CTY so that it will be automatically available thereafter.
Do you with to append this data to file STSPLUS.CTY (Y/n): _
Press "Y" or ENTER to append the data to the file, or press "N" to not
modify the STSPLUS.CTY file.
F3 Set Display Features
---------------------------
A number of display features may be enabled or disabled using a
separate sub-menu. See the section SET DISPLAY FEATURES below for a full
description.
F4 Select Satellite Coordinates
-----------------------------------
The F4 command may be used to select the units used to display the
current coordinates for the satellite. The choices are:
RA/DEC Right Ascension and Declination (Equator and Equinox of
Date).
Alt/Az Altitude and Azimuth. Altitude is the elevation above the
horizon (assuming mean sea level), and azimuth is the è direction in the sense NESW (North to East to South to
West).
Program STSORBIT PLUS Satellite Orbit Simulation Page 107
XYZ Geocentric Cartesion Coordinates. The X-Axis and Y-Axis are
aligned with the Equator with the X-Axis pointing in the
direction of the Vernal Equinox. The Z-Axis points toward
the North Pole.
F5 Show Ascending & Descending Node Data
--------------------------------------------
The nodes of an Earth orbit are the points on the ground track where
the path crosses the Equator. The ascending node crosses from South to
North and the descending node crosses from North to South. Orbit numbers
normally increment at the ascending node. This command adds two additional
lines of data at the lower left of the screen giving the time (MET or time
since epoch) and longitude of the most recent ascending and descending
nodes. This information is useful when comparing STSPLUS's data against
other sources such as the wall map in Mission Control.
F6 Set Map Projection and Size
----------------------------------
The F6 command selects the size and field of view of the displayed
map. By default, the map is displayed using the orthographic projection,
"ORTHO", shows one complete hemisphere, and is centered so that the
selected satellite is visible. This corresponds to a magnification factor
of 100%.
Pressing F6 will select between WORLD, QUAD, ZOOM, and ORTHO maps.
Selecting WORLD will display the full world using rectangular projection
centered on the Prime Meridian at Greenwich, England at 0 degrees
longitude or at the International Date Line at 180 degrees longitude.
Selecting QUAD will select one of twelve Quadrant Maps showing a field of
view (horizontal size) of 180 degrees using rectangular projection.
Selecting ZOOM will select a Zoom Map with field of view adjustable from 45
degrees to 180 degrees; the default field of view is 75 degrees; the Zoom
Map is approximately centered on the current ground track position of the
satellite. Selecting ORTHO will select the orthographic projection. See the
sections ORTHOGRAPHIC MAPS, QUADRANT MAPS, ZOOM MAPS, and AUTOMATIC MAP
GENERATION for additional information.
F7 Enable/Disable EVENT TIMERS
----------------------------------
Press F7 to enable or disable all event timers. Event timers are
enabled by default if file STSPLUS.INI is present. Especially while the map
is being drawn, the calculations associated with the event times require
appreciable time. If the event timers are disabled, the audible alarms will
also be disabled. See the section "Event Timers and Audible Alarms" for a
full discussion of the event timers.
èProgram STSORBIT PLUS Satellite Orbit Simulation Page 108
F8 Enable/Disable Audible ALARMS
------------------------------------
Provided event timers are enabled (above), you may press F8 to enable
or disable audible alarms. Many users allow their computer to run STSPLUS
while performing other tasks and the audible alarm will alert them to an
imminent AOS (Acquisition of Signal) or LOS (Loss of Signal) event
associated with either their local circle of visibility or the TDRS
communications satellites.
For the local circle of visibility, an "up/down" tone sounds six times
two minutes prior to AOS and five tones sound thirty seconds prior to LOS.
Provided TDRS coverage is enabled (F10+F3+F2 from the Main Menu), three
brief tones sound thirty seconds prior to AOS or LOS. Provided Sun features
are enabled (F10+F3+F8), two tones will sound approximately thirty seconds
before orbital sunrise and sunset. The characteristics of the audible tones
will thus allow the user to identify what kind of AOS or LOS event is about
to happen.
Depending upon the computer and the version of DOS being used, "music"
such as these audible alarms may cause the DOS clock to lose a small amount
of time each time an alarm sounds. The amount of time loss is quite small
but may accumulate over long periods of time. (The DOS clock may also run
either fast or slow and effectively mask the time loss due to sound
effects.)
F9 Set UTC Time Offset and Daylight Flag
--------------------------------------------
STSPLUS uses UTC or Coordinated Universal Time, an adjusted version
of Universal Time (which STSPLUS considers the same as GMT or Greenwich
Mean Time), for certain functions such as launch time. The difference
between UT, UT1, UT2 and UTC is never more than 0.9 seconds. UTC is used
because it is the standard for civil timekeeping and agrees with standard
atomic time, TDB or Terrestrial Barycentric Time, used by astronomers.
However, NASA continues to use the GMT designation, a holdover from earlier
days before the introduction of UTC. Using UTC permits critical data to be
used across many time zones without conversion. However, it also means that
STSORBIT must know what number of hours to add to UTC in order to obtain
your local time, and whether or not you are currently using daylight
savings time (summer time in the UK).
When prompted, enter the time offset in hours from your local time to
Coordinated Universal Time. Examples are shown for most time zones in North
America. STSPLUS then asks if you are using daylight savings time; enter
"0" if not, and "1" if so. The sum of these two values is shown on the Main
Menu; for example, if the computer is set to Pacific Daylight Time (UTC
offset is -8.00 hours and Daylight Flag = 1), the sum will be -7.00. For
most time zones in North America, the correct zone abbreviation will be
shown on the ground track display for Local date and time. When you change
your computer from/to daylight savings time, use this command to update
STSPLUS. The following shows the display when using the F9 command:
èSet UTC TIME ZONE OFFSET and DAYLIGHT FLAG
STSPLUS must know the difference between your local time zone and
Program STSORBIT PLUS Satellite Orbit Simulation Page 109
Coordinated Universal Time (UTC), also sometimes known as Greenwich Mean
Time (GMT). With this information, STSPLUS can automatically adjust launch
or Epoch times and dates for your local time zone. In addition, STSPLUS
must know if your computer is now set to STANDARD or DAYLIGHT time.
First, enter the difference between your STANDARD time zone and UTC in
hours. Do NOT include the hour for daylight time if you are now on DAYLIGHT
time; it will be entered separately. For most time zones in the United
States and Canada, the entries required are:
Eastern Standard Time EST -5.0
Central Standard Time CST -6.0
Mountain Standard Time MST -7.0
Pacific Standard Time PST -8.0
Enter UTC Offset (hours): -8
Enter DAYLIGHT Flag (0=OFF, 1=ON): 1
Once this information has been entered, it will be saved in file
STSPLUS.INI and will not be requested again. If you change from Standard to
Daylight Time or vice versa, use the F10+F9 command to update the Daylight
Flag.
If you change the setting of the Daylight Flag, STSPLUS will ask if
you wish to adjust your DOS software clock:
You have changed the setting of the Daylight Flag.
Do you wish to adjust your DOS clock to reflect the
change [y/N]:
If you have already made the change at the DOS prompt (or using some other
software) or do not wish to change the DOS clock, press ENTER (or type "N"
followed by ENTER). If you wish to adjust the DOS clock to correspond to
the new setting of the Daylight Flag, press "Y" followed by ENTER. When
STSPLUS changes the DOS clock, it synchronizes the time change to the
nearest second but there may be a small error introduced; only if your
computer is precisely set would the error be detectable.
*************
* CAUTION *
*************
For computers equipped with 80286 or higher processors AND using DOS 3.2 or
higher, changing the DOS clock will ALSO change the hardware clock. 8088-
based computers may or may not have a hardware clock installed and, even if
a hardware clock is present, it may or may not be compatible with the DOS
time setting commands.
F10 Enable/Disable Printer Logging
-------------------------------------
I have found it interesting to log the orbital data and the ascending èand descending node information on my printer when analyzing the mission
data over long periods of time. The F10 command toggles the printer logging
function on and off. The first page of the log includes the current orbital
Program STSORBIT PLUS Satellite Orbit Simulation Page 110
data and subsequent pages contain only node information. In addition to the
information presented on the display, the printer log also calculates the
current orbital time, the time from one ascending (descending) node to the
next, for the third and subsequent nodes. A typical log is shown below.
IMPORTANT: BE SURE THE PRINTER IS TURNED ON PRIOR TO ENTERING THE
F10 COMMAND.
STSORBIT: Space Shuttle Tracking Program, Version 9334 Page 1