The Jupiter Space Station Ephemeris
User Guide
Dr. John D. Bernard
Copyright: April 1994 and March 2013
Introduction
So you are interested in the radio noises made by the Jovian magneto-sphere and it’s closest moon Io? All you will need is a
15 meter radio
receiver, a loop, or dipole, or yagi antenna and a recorder to record the music. [and of course the events table generated by
this program
so you know WHEN to listen for the S-bursts and L-bursts.]
A little background information: in the Summer of 1993 when a group of C students and faculty Tri-County Tchnical College
initiated this project, we were unaware that the astronomical event of all mankind was in the making. Earlier in the Fall it was
announced by the Jet Propulsion Lab and other scientific sources that a comet, Shoemaker-Levy 9, was broken up into a
"string of pearls" the previous year by the gravity of Jupiter. In the Summer, July 17-25, these pearls slammed into Jupiter
with megatons of hydrogen bomb power, creating atmospheric chaos and an extraordinary opportunity to reveal things about
Jupiter never known before. The JSS Project was "locked on" to this event, but we needed accurate positional, physical, and
Jovian storm event information, and we needed to collect a complete set of radio telescope survey data prior to this event.
We wanted some software which would accurately predict Jovian storms to increase our chances of capturing the music.
This software was derived from algorithms, formulas, and software routines written by Jean Meeus and Jeffrey Sax of
Belgium. This software was developed for use on the JSS project, the SARA Jupiter Group, and to monetarily benefit the R.
M. Sickles Radio Astronomy Student Fund.
JSSE Design Concept
This software provides accurate radio-astronomy positional, physical, and storm event prediction data about our big brother
Jupiter. Positional means the relative placement relationship between the Earth, Sun, and Jupiter. Physical means the
viewing characteristics such as magnitude, phase, atmospheric aberration, tilting of the Jovian north pole, etc. Radio
astronomy, being different from optical astronomy, is concerned with the Central Meridian Longitude (CML) of the
geocentric disk of Jupiter; not the illuminated disk. Radio astronomy is primarily focused on the CML System III of radio
emissions, not the gas layers (Systems I and II).
This software maps swings, jiggles, jangles, and other perturbations of heavenly bodies; this software takes into account
precession, nutation, obliquity, aberrations (both planetary and atmospheric), light-time iterations, parallax, Fundamental
Katalog conversions using the J2000 epoch.
Time for positional calculations are based on atomic clock based Dynamical Time (DT), not flittering Universal Time (UT). UT
is converted to DT using the famous DeltaT. DeltaT is "dead-nuts" for 1980-1992 and is estimated for 1993 - 2001. A
recommended DT value after 2001 is 87. The user can optionally pick his own DeltaT in this software for any year. You can
comfortably compare the calculations in this program with the tables of the Astronomical Almanac.
Installation
This software is designed to run on IBM AT/CLONE (286, 386, 486, etc) equipment with a VGA monitor and at least 512K of
memory. The software is written for a 16 bit OS. This software should be installed on a hard drive (recommended).
There are two versions:
MS VISTA and below
MS WIN 7 and above [using DOS-BOX as a DOS immulator]
MS VISTA and below INSTRUCTIONS:
Simply unzip the files onto your C drive into a folder you create called JSSephemeris. Drag the jss.exe shortcut onto
your desktop. Now click this icon.
MS WIN 7 and above INSTRUCTIONS:
WIN 7 will not execute a DOS file… so we use DOS-BOX as a DOS immulator. Simply unzip the files and folder on
your C drive into a folder you create called JSSephemeris. Drag the
Jupiter shortcut onto your desktop. Now click
this icon. The difference between the VISTA version and the WIN 7 version is that the WIN 7 version brings up a DOS-BOX
window which in turn will bring up jss.exe… automatically.
JSS Data Entry Screen
The directions for the format of the input data is found on the lead-in screen. If you are interested in the Jupiter calculations
for your location, enter your exact Longitude, Latitude, and Time Zone. If you are interested in a specific time at your
location, enter that time at the Local Time prompt. Now, if you are interested in calculations for Universal Time (say to
compare against an almanac or other ephemeris) then simply enter 0 for Longitude, 0 for Time Zone, and 0 for Local Time
(making it 0h UT). Simply hitting the Enter key at a prompt will accept the default value to the left, and if you
make a "typo boo-boo" you will be asked to re-enter the value.
Simulation Instructions
The instructions on the Jupiter/moon simulation are found on the lead-in screen. The simulation starts up ticking once a
minute and changing the speed by 50% is done by simply pressing the arrow-up/arrow-down keys. If you increase the speed
then the accuracy of the radio events prediction decreases by 50%. When in a hurry we do jack the simulation speed up while
Jupiter is below the horizon, then drop it down again when Jupiter is up. An events table is written to disk as events.txt after
5 events are simulated. Each time you run the old events.txt is wiped out. If you wish to save the previous events.txt, rename
it to something different, like events.apr, before running jssephemeris again.
During the simulation radio events are simulated by both sounds and radio waves emanating from Jupiter and Io. The sound
and waves are proportional to the predicted strength of the event. We predict six events: Weak Non Io B, Weak Non Io C,
Strong Non Io A, Moderate Io B, Moderate Io C, and Strong Io A. If you do not want the sound then simply press the S key to
toggle it off or S key to toggle it on again. To pause the simulation toggle with the P key. Any other key will end the program.
Explanation of Terms
If you would like details about astronomical calculations may we recommend almost any introductory book on astronomy or
Astronomical Algorithms by Jean Meeus, otherwise here are some thumbnail definitions:
Az/Alt/AtmR
Horizon Coordinate System; Azimuth is measured westwardly from
the South. Altitude is the angle from the horizon to Jupiter.
These two measures are important in a "gun-turret" altiazimuth telescope mount. Atmospheric Refraction is the
apparent shift in altitude due to refraction (not included in
the JSS Alt measure).
CML I, II, III
Central Meridians of System I, II, III of Jupiter; Three
systems for two different rotational speeds for two gas bands
and the radio band of Jupiter (CML III is the radio band).
DeltaT
See JSSE Design Concepts.
Ds/De
Jovocentric declination of the Sun/Earth; when positive
Jupiter's northern pole is tilted toward the Sun/Earth.
Important for directivity towards Earth.
Ecliptic
Coordinate system of the Sun/Earth; Sun's path around the
celestial sphere, as seen from Earth, defines the ecliptic
plane. Mean-Ecliptical coordinates are for a circular Sun
path without nutation.
Equatorial
Coordinate system of the Earth; Earth's equator projected into
space is the Celestial Equator; Great circles from the Earth
North/South Pole are the Hour Circles. Mean Equatorial
presumes a circular orbit without nutation. Topocentric
refers to an observer on the surface of the Earth rather than
at the center.
Hour Angle
Local hour angle measured along the Celestial Equator
westwards from the South. On an equatorial telescope mount,
this is where you point to lock on Jupiter. Jupiter east of
the observer's meridian would be -, west would be +.
JD
Julian Day; begins at 12:00 Greenwich Noon or 12 hours Universal Time.
Latitude
Earth coordinates measured with east/west great circles; 0 degrees being the equator.
Local AST
Local Apparent Sidereal Time; the hours, minutes, and seconds
from the Vernal Equinox to the observer's meridian.
Local Time
Your actual local time; Your Time Zone is collected to calculate this.
Longitude
Earth coordinates measured with north/south great circles; 0 degrees being Greenwich.
Time Zone
EST, EDT, CST ...; EST is 5 hours while EDT is 4 hours from Greenwich.