Although Astrolog 5.4 is a very useful program, it has several deficiencies. One of the problems is that hypothetical planets like Transpluto are not supported by the program. Astrolog 5.4 does provide a flag which permits the user to "define their own planets". This flag is discussed on page 65 of the Astrolog Helpfile. Unfortunately, the helpfile does not provide enough detail so that the user can easily "define" a new planet.
This article is intended to be used in addition to the Astrolog helpfile. It gives greater detail to the explanation of the YE switch. This switch allows the user to define the orbit of any planet by using six orbital elements. This method achieves an accuracy of within a few arc-minutes of heliocentric longitude when compared to an ephemeris such as the Swiss Ephemeris. Examples will be given of the insertion of the known planet Mars, and the hypothetical planet Transpluto.
The use of the YE switch to define the orbit of a planet using one of Astrolog's objects is limited to those versions of Astrolog which allow the use of the ephemeris files to be turned off and thus the Matrix routines to be used. Versions which enable this are those prior to the 32-bit version Astrolog32 1.10 for Windows. These include Astrolog32.1.0, and the 16-bit versions such as Astrolog 5.41G. The ephemeris files can be turned off in these versions by using the menus or the b switch.
A user can define the orbit of a real or hypothetical planet by using one of Astrolog's objects. In Astrolog32 1.10, this can be done through an alteration of one of the Swiss Ephemeris files. Please see the explanation near the end of this page.
First of all, a word on epochs. An epoch is a time at which a set of orbital elements are referred to. The most commonly used epoch today is that of "J2000.0", which is the notation used to refer to the Julian date of 2451545.0. This corresponds to Jan 1, 2000 at 12 noon GMT in our Gregorian calendar. This is also given the notation 2000 Jan 1.5.
When entering orbital elements into Astrolog, the program refers them to the epoch "J1900.0", or one Julian century of 36525 days prior to J2000. This corresponds to the Julian date of 2415020.0, or 1900 Jan 0.5 which is the same as December 31, 1899 at 12 noon GMT.
The YE switch takes 17 parameters, which specify all the data needed for any elliptical orbit around the Sun, to within an accuracy acceptable to most applications. Most of the orbital elements take 3 values. The primary value is the value of that orbital element at the epoch J1900. The secondary value is related to the linear rate of increase or decrease of that element's value over time. The tertiary value is related to the quadratic rate of increase or decrease of that element's value over time.
The 7 parts of the YE switch are:
The units that Astrolog wants are in AU for the semi-major axis (AU stands for astronomical units - the semi-major axis of the earth's orbit is one AU), dimensionless for the eccentricity, degrees for all the other primary terms, degrees per Julian century for the secondary terms, and degrees per Julian century squared for the tertiary terms.
Now we will give an example of the use of the YE switch to put Venus into the orbit of Mars. The orbital elements for Mars for J1900 are taken from the "Explanatory Supplement to the Astronomical Ephemeris & the American Ephemeris and Nautical Almanac". In the 1977 edition (page 113) it has:
Semi-major axis of the orbit a = 1.5236915 AU
Eccentricity of the orbit e = 0.09331290 + 0.000092064T - 7.7E-8T*T
Inclination of the orbit to the ecliptic i = 1 deg 51' 01".20 - 2".430T + 0".0454T*T
Longitude of the perihelion w = 334 deg 13' 05".53 + 6626".73T + 0".4675T*T - 0".0043T*T*T
Longitude of the ascending node Omega = 48 deg 47' 11".19 + 2775".57T - 0".005T*T - 0".0192T*T*T
Mean anomaly M = 319deg.52942 5 + 0deg.5240207666d + 0deg.000013553D*D + 2deg.5E-8D*D*D
where T is time in Julian centuries of 36525 days, d is time in days, and D = 3.6525T.
So calculating the argument of the perihelion and putting the terms in the units that Astrolog wants gives:
|Semi-major Axis (AU) (1 term)||1.5236915|
|Eccentricity (3 terms)||0.0933129||0.000092064||0|
|Inclination (deg) (3 terms)||1.850333||-0.000675||0.0000126|
|Argument of Perihelion (deg) (3 terms)||285.43176||1.06977||0.00013|
|Longitude of Asc. Node (deg) (3 terms)||48.78644||0.77099||0|
|Mean Anomaly (deg) (3 terms)||319.529425||19139.8585||0.0001808|
Venus is object number 4, so the switch we would use is:
YE 4 1.5236915 0.0933129 0.000092064 0 1.850333 -0.000675 0.0000126 285.43176 1.06977
0.00013 48.78644 0.77099 0 319.529425 19139.8585 0.0001808
Unfortunately however, the total length of that command string is too long for the Astrolog command line, so we have two options. The first option is to compromise on the precision of some terms and enter the following switch into the command line:
YE 4 1.5237 0.0933 0 0 1.8503 0 0 285.432 1.07 0 48.786 0.8 0 319.53 19139.86 0
This gives results within about 5 or 6 arc-minutes of the ephemeris heliocentric longitudes for the years 1800 - 2200. This is not a bad result considering the loss of accuracy.
To achieve greater accuracy however, our second option is to put the complete and accurate switch into the ASTROLOG.DAT file which would then be executed upon opening the Astrolog program. This method gives the position of 'Venus' within a few seconds of arc compared to the position of Mars using the matrix routines for any time period. That's pretty good. Of course, the ephemeris files give greater accuracy for Mars' position the further we go away from the 20th century.
MoveVenusToMars.DAT is an ASTROLOG.DAT file which includes this command. The ASTROLOG.DAT file will be discussed later in this article.
In order to "insert" Transpluto into Astrolog, you should select a planet in which you are not interested. We have selected the Uranian planet Vulkanus. We will move Vulkanus into the orbit of Transpluto. After that has been done, Astrolog will show us the location of Transpluto. However, it will be labelled as "Vulkanus".
The Swiss Ephemeris states: "This hypothetical planet was postulated 1946 by the French astronomer M.E. Sevin because of otherwise unexplainable gravitational perturbations in the orbits of Uranus and Neptune". Transpluto is also known as Isis, Persephone, Bacchus and Vulcan. The reader is not to confuse Transpluto with another proposed hypothetical planet named Proserpina, which has also been called Proserpine or Persephone. This has an orbital period longer than Transpluto.
In addition, it used to be thought that there was an intra-Mercurial planet which was also named Vulcan. Argument still rages over whether Transpluto exists or not. The aim here is not to enter into this debate, but to use this as an example of inserting a proposed planetary orbit into Astrolog.
The book by John Hawkins entitled "Transpluto or Should We Call Him Bacchus, The Ruler of Taurus?" on page 79 of the 1978 edition gives the orbital elements for this hypothetical planet for the epoch J1900:
|Semi-major Axis (AU)||77.755|
|Longitude of Perihelion (deg)||0.0438748|
|Longitude of Ascending Node (deg)||0|
|Mean Anomaly (deg)||66.806096|
|Epoch of Perihelion passage||1772.76|
|Sidereal Period (Julian years)||685.65|
|Daily movement (deg)||0.0014375063655|
In this case, because the longitude of the ascending node is taken to be 0, the argument of the perihelion is the same as the longitude of the perihelion. Assuming that the perihelion of Transpluto's orbit is stationary with respect to the stars, we have to account for precession in the linear or second term of the argument of perihelion. Taking the effect of precession to be +1.396 degrees per century, we can put this into the second term. The mean movement in degrees per Julian century is also calculated and entered into the second term for the mean anomaly.
So the terms are:
|Semi-major Axis (AU) (1 term)||77.755|
|Eccentricity (3 terms)||0.3||0||0|
|Inclination (deg) (3 terms)||0||0||0|
|Argument of Perihelion (deg) (3 terms)||0.0438748||1.396||0|
|Longitude of Asc. Node (deg) (3 terms)||0||0||0|
|Mean Anomaly (deg) (3 terms)||66.806096||52.50492||0|
Using the Uranian planet Vulkanus which is object number 39 to simulate Transpluto, the switch becomes:
YE 39 77.755 0.3 0 0 0 0 0 0.0438748 1.396 0 0 0 0 66.806096 52.50492 0
This gives a reasonably high amount of accuracy when compared to the Swiss Ephemeris heliocentric longitudes. Below is a graph which shows the difference between the Astrolog ephemeris heliocentric longitudes after the use of the above switch for Transpluto, and the Swiss Ephemeris values. The graph covers the time period 1550 to 2050. As you can see the greatest difference is about 0.0644 degrees, or about 3.8 minutes of arc. The Swiss Ephemeris says: "Even if Sevin's computation were correct, it could only provide a rough position. To rely on arc minutes would be illusory." Taking this into account, the result is very good.
When Astrolog runs, it searches for a file named ASTROLOG.DAT. This file contains the default settings for the program. You can view such a file by clicking ASTROLOG.DAT. Please use your BACK key to return to this page. This file is not very user friendly. Over the years, other versions of the file have become common. The Config.DAT file contains comments which are useful when you wish to change the default settings. A semicolon is used to mark a comment line. You must be certain that every portion of a comment begins with a semicolon.
You can view a file which contains the commands to move Venus into the orbit of Mars. The file is MoveVenusToMars.DAT. This file turns off all the planets except Venus and Mars. You will find that Astrolog shows the positions of Venus and Mars to be very close, no matter what the date.
Another file has been provided which moves Vulkanus into the orbit of Transpluto. The file is InsertTranspluto.DAT. If you use this file, you will find that Vulkanus has been added to the standard list of planets. However, its location is that of Transpluto. Transpluto (aka Vulkanus) is at 26 Leo 42.
Astrolog will only read the file named ASTROLOG.DAT. Therefore, you may edit that file using Notepad or Wordpad. OR, you may rename ASTROLOG.DAT to ASTROLOG-ORIG.DAT, and then select another file. After you have renamed the new file as ASTROLOG.DAT, the program will read that file upon opening. This will allow you to test new versions of the ASTROLOG.DAT file without harming your original version. Please remember that each comment line must begin with a semicolon. If your email program or editor inserts a carriage return at line 80, it will make the file unreadable by Astrolog.
In order to insert Transpluto into Astrolog32 1.10, you will need the Swiss Ephemeris file seorbel.txt that contains the orbital elements of the hypothetical planets that are supported by the Swiss Ephemeris.
For Astrolog32 1.10, the file must be placed in the same folder as your Swiss Ephemeris files. For Astrolog32 2.02, the file must be placed in the main folder.
Each hypothetical planet in this file has its orbit described by 9 orbital elements separated by a comma (actually, 8 elements + its name). All of these nine elements must be on the same line, not divided by a [RETURN]. The file gives us the order of the elements:
The orbital elements that the Swiss Ephemeris uses for Transpluto (which it calls Isis-Transpluto) are:
As Astrolog32 1.10 does not have to option to allow the selection of Transpluto, you again need to select a planet that is included in Astrolog32 1.10 and change its orbital parameters. We will again choose the Uranian planet Vulkanus/Vulcanus. In the provided seorbel.txt file, the Swiss Ephemeris orbital elements for Transpluto have replaced those for Vulcanus. The original Vulcanus orbital elements are listed above these new elements but they have been "commented out" by using a "#" at the start of the line.
Alternatively, the following line could have been added instead, which uses the J1900 epoch and equinox and the orbital elements which we used along with the YE switch and the older versions of Astrolog:
This could use either 77.755 or 77.775 for the semi-major axis and the results are very close to the longitudes obtained from using the Swiss Ephemeris orbital elements.