The Sidereal Time column in the ephemeris

[Clair Y]

So this is a question mainly about the column in the ephemeris which tells us the sidereal time. I am using that one by Niel F. Michelson and Rique Pottenger, the revised and expanded third edition.

I understand what it is, but I would just like to see if anyone would like to share what they use it for or what other astrologers might use it for.

I know it is needed to calculate the MC, so I do know it is needed for chart calculation purposes.
I also did a little research and learned that the right ascension is given in sidereal time when astronomers are using the celestial coordinates. We use coordinates that give the right ascension in degrees and minutes, which looks very different. I mean, the positions are very different anyway as the astronomers don't provide each constellation with 30 degrees of the skies of course.

But what do other astrologers tend to use this column for when not for calculating the chart?

 

[Ecliptique]

Hello Clair Y,

I may calculate precisely and use Sidereal Time (ST) to calculate Local Sidereal Time (LST) in order to draw up the astrological natal chart of a person born beyond the Polar Circle in a very specific location obtained using GPS (longitude and latitude). With the ST you can calculate the astral positions and with the LST you can calculate the MC then the Ascendant. I also use the obliquity of the date, etc. in the calculation.

Ecliptique.

 

[FraterAC]

The Sidereal Time is the Right Ascension of the Sun at ephemeris noon (or midnight, if midnight emphemeris). If multiplied by 15 it gives RA in 360 degree format (24 hours x 15 = 360 degrees).
The Solar Arc in RA between two dates can be used to progress the MC in a progressed chart, or create Equatorial directions, either Primary directions or Equatorial SA directions.
The main use of Sidereal Time, however, is to calculate the Midheaven in the manual calculation of a horoscope.
Practically speaking, once astrological software became readily available, ephemerides and the data in them, including Sidereal Time, became mostly obsolete. Sidereal Time as found in ephemerides currently only finds application in fairly esoteric procedures.

 

[Clair Y]

The Sidereal Time is the Right Ascension of the Sun at ephemeris noon (or midnight, if midnight emphemeris). If multiplied by 15 it gives RA in 360 degree format (24 hours x 15 = 360 degrees).
The Solar Arc in RA between two dates can be used to progress the MC in a progressed chart, or create Equatorial directions, either Primary directions or Equatorial SA directions.
The main use of Sidereal Time, however, is to calculate the Midheaven in the manual calculation of a horoscope.
Practically speaking, once astrological software became readily available, ephemerides and the data in them, including Sidereal Time, became mostly obsolete. Sidereal Time as found in ephemerides currently only finds application in fairly esoteric procedures.

Thank you very much for your answer, this makes sense.

However, seeing as the sidereal time rotates 23 hours and 56 minutes per day, I don't understand how this column can be used to determine the points in the progressed chart. Do you have anything to hand you can link me to this information with please? I would love to see how this can be done.

 

[FraterAC]

One takes the solar arc in Sidereal Time (that is, Right Ascension) and advances the Midheaven by that amount.
To back up a bit:
To calculate Solar Arc directions (as Ebertin et al do) one takes the Solar Arc in longitude (as one would calculate it for Secondary [aka Major] progressions). This is done by the Cosmobiology school, the Uranian school, Noel Tyl, and others. If you're not already familiar with them, you can look up Solar Arc Directions online.
However, in a completely similar way, one can also calculate the solar arc in Right Ascension. That would mean, calculating the Sun's RA from the Sidereal Time in the ephemeris for the birth date, and calculating the amount of increase from the birthdate to the adjusted calculation date in the ephemeris. Or, one takes the difference in RA between the birthday and a number of days after birth approximately corresponding to the age of the native in years.*
That solar arc in Right Ascension can then be used to advance the Midheaven, but it can also be used in the creation of Primary Directions, That is the time measure Robert DeLuce used in The Complete Method of Prediction, in which he demonstrates various calculations involved in Primary Directions. Edward Johndro and Charles Jayne also used that time measure for Primary Directions.
Captain Schwickert and Charles Jayne suggested calculating solar arc directions in Right Ascension simply on the Equator, which has not achieved any significant traction, but which I'm currently investigating with (I think) interesting results. See here for application of that technique for Marie Antoinette

• #7

* For the sake of simplicity let's leave the question of the difference between the Sidereal and Solar day out of this for now, see here for that

• #1

I hope some of this answered your question -- ?

 

[Clair Y]

One takes the solar arc in Sidereal Time (that is, Right Ascension) and advances the Midheaven by that amount.
To back up a bit:
To calculate Solar Arc directions (as Ebertin et al do) one takes the Solar Arc in longitude (as one would calculate it for Secondary [aka Major] progressions). This is done by the Cosmobiology school, the Uranian school, Noel Tyl, and others. If you're not already familiar with them, you can look up Solar Arc Directions online.
However, in a completely similar way, one can also calculate the solar arc in Right Ascension. That would mean, calculating the Sun's RA from the Sidereal Time in the ephemeris for the birth date, and calculating the amount of increase from the birthdate to the adjusted calculation date in the ephemeris. Or, one takes the difference in RA between the birthday and a number of days after birth approximately corresponding to the age of the native in years.*
That solar arc in Right Ascension can then be used to advance the Midheaven, but it can also be used in the creation of Primary Directions, That is the time measure Robert DeLuce used in The Complete Method of Prediction, in which he demonstrates various calculations involved in Primary Directions. Edward Johndro and Charles Jayne also used that time measure for Primary Directions.
Captain Schwickert and Charles Jayne suggested calculating solar arc directions in Right Ascension simply on the Equator, which has not achieved any significant traction, but which I'm currently investigating with (I think) interesting results. See here for application of that technique for Marie Antoinette

• #7

* For the sake of simplicity let's leave the question of the difference between the Sidereal and Solar day out of this for now, see here for that

• #1

I hope some of this answered your question -- ?

Thank you so much for this. I was just talking about the fact that the sidereal time at noon (or midnight) changes by about 4 minutes each day, but not because it changes by 4 minutes only, rather because it changes by 4 minutes less than 24 hours. I wonder if the calculation kind of capitalises on this difference seeing as the times at midnight and noon are taken only. But of course I'm going to do this the proper way and look through all the parameters, which is all very interesting. I know what I am pointing at might not make sense.

Thank you very much for this!

 

[FraterAC]

24 hours of Sidereal Time is a Sidereal Day.
24 hours of clock time is a Solar Day (a mean solar day).
The Sidereal Day is 0.997269675925926 of a Solar Day, or 23 hours, 56 minutes and 4.09 seconds.

The difference between the Sidereal and Solar day is what lead Cyril Fagan and R. C. Firebrace, indirectly, to the conception of what they termed the Bija correction.
Again, anyone interested in this difference or why it's is important (IMO very important!) can find that discussion here

• #1

 

[JUPITERASC]

...the fact that the sidereal time at noon (or midnight) changes by about 4 minutes each day, but not because it changes by 4 minutes only, rather because it changes by 4 minutes less than 24 hours. I wonder if the calculation kind of capitalises on this difference seeing as the times at midnight and noon are taken only.

Sidereal Time and Solar Time differ
The Sun makes a complete circle in the sky
approximately every 24 hours
while the fixed stars make a complete circle in the sky
in 4 minutes less time
or 23 hours and 56 minutes 4 seconds

VISUAL ILLUSTRATION

But of course I'm going to do this the proper way and look through all the parameters, which is all very interesting. I know what I am pointing at might not make sense.

If unfamiliar with Sidereal Astrology, e.g. Vedic astrology is Sidereal
& there are also Western Sidereal Astrologers as well
KENNETH BOWSER is a Western Sidereal Astrologer
at https://www.westernsiderealastrology.com/


& Jim Eshelman https://www.solunars.com/viewtopic.php?t=3

FOR VIDEO ANIMATION WITH DESCRIPTIVE NARRATIVE


MOON travels each SIGN once a month aka "...moonth..."
but is not always in the same sign SIDEREALLY as Tropical
because although all Astrologers are commenting on & making predictions
regarding THE IDENTICAL MOON in the skies
interestingly a computer generated Tropical Chart
ALWAYS differs by DEGREE occuppied by the Moon
from the Sidereal DEGREE occupied by the Moon
& sometimes differs by sign as well

SIDEREAL location of Moon may be confirmed BY VISUAL observation
of local skies & Notice there is a minimum difference of 20°
up to a maximum of approximately 24°
between Tropical and SIDEREAL MEASUREMENT
ANY planet at 0° OF any Tropical SIGN is SIDEREALLY between
approximately 6° - 10°
to a maximum 24°
of the PREVIOUS SIGN
dependent on the ayanamsha

.