Please help with local sidereal time

Hi
New to astrology here and I am having trouble calculating my local sidereal time of birth and in turn can not move on to the next step, calculating the ascendant. I have followed the instructions step by step on Ken Ward’s site and posted it all below, but I still seem to come up with an incorrect answer when comparing it to a Online Local sidereal calculator.

If its not to much trouble could someone please show me were my error is. All my birth info and calculations are below.
Thank you
Charlie

Year = 1974 , Month = 12, Day = 28
Time of birth = 00h:13m
Location of birth = 33° 56′ 54.6″ S 18° 28′ 31.08″ E (South Africa)

GMT
00h:13m + 2h = 22h:13, Dec 27

Local Mean Time (1minute of arc 4 seconds of time)
18° 28.518′ , 28.518×4 = 114.072 seconds is the correction
114.072 seconds = 1 minute 54.072 seconds correction of longitude.
00h:13 + 1 minute 55 seconds = 00h:14m 55s

Greenwich meridian mean time
00h:14m 55s + 2h = 02h:14m 55s

Midnight ephemeris for 28 Dec 1974
06h:24m 20s

Local sidereal time
00h:14m 55s + 06h:24m 20s = 06h:39m 15s (not corrected)

Acceleration
6.4056×10 = 64.056 seconds = 1minute 5seconds
06h:39m 15s + 1m 5s = 06h:40m 20s

Time zone correction
0.666666667×18.5 = 12.333333333
06h:40m 20s + 12s = 06h:40m 32s + 12h for Southern Hemisphere correction = 18h:40m 32s

Online local sidereal time calculator calculates my local sidereal time of birth as
9h:51m 34.15s

Online ascendant calculator put me 26° 21′ in Virgo. When I look this value up in Max Heindle table of houses for 33rd latitude it is for 5h:42m 34s.

I have gone over the manual method I worked out from Ken Ward’s Astrology site a few times now and I can’t seem to find anything wrong with my calculations, yet my final local sidereal time of 18h:40m 32s does’nt match the online local sidereal calculators time. In addition to that the ascendant calculator that put my ascendant in 26° 21′ in Virgo matches up to 5h:42m 34s. Sidereal time.

Could someone please be so kind as to show me perhaps where my mistake is being made here?
Charlie

Hi. Its a very long time since I did this but:

Should you have multiplied the 18 degrees by 4 as well as the odd minutes and seconds of arc? This would give a value of about 1 hour, 19 minutes and 36 seconds.

22:13 (27th) plus this value gives a local mean time of 23:32:36 (27th)

And I'm not sure about the time zone correction for Southern latitudes, because time zones change by longitude. These two possible errors add up to about 13 hours, which seems to be the the difference between your figure and the figure you think you could be getting.

I'm not very sure of myself with all this these days, but these might be useful things to look at..

Hi Miquar
Thank you for taking the time to assist me with this.

It makes sense what you say about the 18 deg x 4. So the adjustment I made is as follows:

Time of birth = 00h13m
Location = 18.4753°

Sun moves 1° in 4 minutes
18.4753°×4 minutes = 73.9012 minutes = 1h:13m 54.072s

Time of birth at Greenwich meridian
00h13m - 1h:13m 54.072s = 22h:59m 5.928s

That should take care of Greenwich

May I ask you how you calculated my local mean time ?

Once again thank you for your assistance with this.

Charlie

charliestars said:

Hi Miquar
Thank you for taking the time to assist me with this.

It makes sense what you say about the 18 deg x 4. So the adjustment I made is as follows:

Time of birth = 00h13m
Location = 18.4753°

Sun moves 1° in 4 minutes
18.4753°×4 minutes = 73.9012 minutes = 1h:13m 54.072s

Time of birth at Greenwich meridian
00h13m - 1h:13m 54.072s = 22h:59m 5.928s

That should take care of Greenwich

May I ask you how you calculated my local mean time ?

Once again thank you for your assistance with this.

Charlie

Click to expand...

Local Time = Local apparent time, which is based on the fact that
days are not actually all 24 hours long

TABLE OF THE EQUATION OF TIME http://www.wsanford.com/~wsanford/exo/sundials/equation_of_time.html


EXAMPLE
ILLUSTRATION OF THE EQUATION OF TIME DATA FOR THE YEAR 2013 JUST PASSED http://www.ppowers.com/info/EoT 2013.pdf


EQUATION OF TIME = LOCAL APPARENT SOLAR TIME = sundial time

Thank you once again JUPITERASC

I'll take a look at that now.

In the mean time I might have found a slightly less confusing way to calculate my local sidereal time of birth. I began with the midnight ephemeris and worked my way back. I corrected an erroneous input in the sidereal calculator and it gives me the same answer I calculated backwards from the ephemeris. The calculations are below.

Time of birth = 00h13m
Location = 18.4753°

Sun moves 1° in 4 minutes
18.4753°×4 minutes = 73.9012 minutes = 1h:13m 54.072s

Time of birth at Greenwich meridian
00h13m - 1h:13m 54.072s = 22h:59m 5.928s

Time at 18.4753° when midnight ephemeris was calculated on 28 Dec 1974

Solar time
00h:00 + 1h:13m 54.072s = 01h:13m 54.072s
I was born at 00h:13m which is 1h:00m 54.072s before 01h:13m 54.072s

Sidereal time
06h:24m 20s + (1h:13m 54.072s x 10sec per hour = 12.32s correction = 1h:14m 6.392s) =
06h:24m 20s + 1h:14m 6.392s = 07h:38m 26.392s

My local sidereal time of birth
I was born exactly (1h:00m 54.072s x 10sec per hour = 1h:01m 4.2s) before 7h:38m 26.392s = 06h:37m 22.19s sidereal time at 18.4753° E.

The local sidereal calculator gives me 06h:37m 8.22s. Close enough I hope for a shot in the dark.

But this still does not solve my ascendant problem. Software on the net (Astrology cafe) calculates my ascendant as 26° 21′ Virgo.

When I use Max Heindle simplified table of houses the closest sidereal time to my calculation of 06h:37m 22.19s is 06h:39m 11s which calculates my ascendant as 8° 20′ Libra.

Surely my local sidereal time of birth (06h:37m 22.19s) is right because a local sidereal calculator gives me the same answer, which leaves me with three choices.

1. The software on the net is giving me wrong readings.
2. Max’s table of houses is giving me wrong readings.
3. My calculations as well as the sidereal calculator’s calculations are wrong.

Wow, if anybody out there can help me figure this one out, it would be greatly appreciated because I can Imagine for all you experts out there this is boring stuff.

(Just as a matter of interest, if you had to calculate my local sidereal time of birth what would you get? I think if you get the same time as I did, then I will be able to eliminate the other possibilities because if you me and the sidereal calculator give the same results then that must mean the error lies elsewhere.)

Kind regards
Charlie

Hi. I put your birth data into Solarfire and it came up with the following:

Ascendant 26 VI 31
Sidereal time at 0 degrees longitude 04:37:02
Local Sidereal Time 05:50:58

The sidereal time at 0 degrees longitude at 0:00 UT on the 28th Dec 1974 was 06:24:20, according to your first post on the thread. Since you were born 1 hour and 47 minutes before 0:00 UT, the sidereal time at 0 degrees longitude at the moment of your birth comes out at 04:37 (presumably matching the value above once acceleration on the interval is factored in). Thus, the Local sidereal time at the moment of your birth is found by adding (4 X birth longitude = 1 hour 14 minutes) to this figure, which gives the Local Sidereal Time.

I'm not sure what's going on with the sidereal calculator you're using, but since the local sidereal time is coming out at (the sidereal time at 0 degrees longitude + 2 hours) perhaps you are adding the time zone rather than (4 X birth longitude) when converting from sidereal time to local sidereal time.

I think that the error in your calculation of local sidereal time would throw the MC out by just under 12 degrees, and since Virgo and Libra are the signs of shortest ascension for southern hemisphere locations, the ascendant would be changed more by this error, but perhaps only slightly because you weren't born at a particularly high latitude. The ascendant given by your calculations does in fact vary from the computer generated one by 12 degrees.

So the problem seems to be the way you are using the local sidereal time calculator. Remember that local sidereal time shifts from one degree to the next, unlike time zones. Hope everything is clear to you now. Well done for learning the proper methods of casting a chart!

When you first begin calculating a chart by hand it can take an hour or two.
With some experience you'll get that down to 15 or 20 minutes to completed chart.
No calculator.
Always check for errors. Use the sun as the hour hand on a clock to catch gross errors in time.

Why are you using a computer program if what you want to learn is to cast a chart without a computer.

You only need an ephemeris and a book of houses to calculate a chart. DeltaT should be in the ephemeris for each year. It's best to use secondary differences to plot the Moon, because of her rapid and variable motion.

Again, there is no point in carrying your calculations beyond the point that is practical. Save yourself the time and mental effort. You gain absolutely nothing with such needless precision. Positions to the minute of arc are sufficiently accurate.

Jan Smuts wrote a book called Holism. Good read for an astrologer.

I have a question for you. Are you learning the method for calculating the "whatever" by rote, or are you understanding the astronomy behnd the method? If you understand the astronomy you will know how to calculate the LST, or "whatever."

Hi Miquar

Thank you for the reply.

The local sidereal calculator that I used can be found here:
http://www.csgnetwork.com/siderealjuliantimecalc.html

The local sidereal calculator requires an input of valid UTC data therefore the data I entered into it was:
Year = 1974, Month = Dec, Day = 28
Hours = 22, Minutes = 59, Seconds = 54.072

The way I calculated this time was as follows:
Sun moves 1° in 4 minutes
18.4753°×4 minutes = 73.9012 minutes = 1h:13m 54.072s

Time of birth at Greenwich meridian
00h13m - 1h:13m 54.072s = 22h:59m 5.928s

The problem I have found seems to be with the online astrology software, and this is why:

South Africa’s time zone is UTC + 2h. That however takes you to Johannesburg, the capital which is approximately 30° East of the Meridian, hence the 2 hours. I was however born 18.4753° E in Cape town .

I notice that if I input the 2h corrected time for Johannesburg (22h13m) I get 05h 54m 51.28s Which is the same time you get, more or less. Your time 05h: 50m 58s

The rest of the data I entered into the local sidereal calculator was:
Latitude = 33° 56′ 54.6″ S Longitude = 18° 28′ 31.08″ E

The output then was:
Greenwich mean 0h sidereal time = 06h: 24m 18.23s which is only 1.77 seconds difference from the Swiss midnight ephemeris for 28 Dec 1974.
The following output then was:
Local sidereal time:
06h:41m 4,78s
This calculator seems to give different values by 2 or three minutes when I continue to enter in the same values. Any way I am not going to fuss about it.

The important thing discovered here is that the online astrology software is only taking my time zone of +2h into consideration when making there calculations which is why they all calculating my local sidereal time as approximately 5h:54m 51s which puts me in about Virgo 26° 21′.

So if I am correct, but welcome any correction if I am not, then my true local sidereal time of birth is between 06h:37m 22.19s and 06h:41m

This time puts me in 8° 20′ Libra.

This also means that I don’t have any software to cast my chart, therefore I am going to have to do it by hand. So I have a feeling I’m going to be visiting this forum quite often.

If I am still mistaken with regards to my local sidereal time of birth, I as always welcome any insight offered.

Thank you so much everyone for taking the time to help me with all of this, it has been very kind of you all.

Kind regards
Charlie

Hi Greybeard

Thank you for the reply.

To answer your first question “Why are you using a computer program if what you want to learn is to cast a chart without a computer.”

I was hoping to use the computer generated calculations to verify mine were correct, as I am not aware of any other means of verifying my own calculations. I’m glad I chose to do it that way now, because a miscalculation seems to have been discovered with the software. It was only taking my time zone of +2h into consideration and disregarding the fact that I was born only 1h:13m from the meridian.

That slight miscalculation puts my rising ascendant in 8° 20′ Libra and not in 26° 21′ Virgo.
I posted this in my last reply to Miquar.

You also mentioned that it is best to use secondary differences to plot the moon. I will keep that in mind. Unfortunately I have no idea what you are trying to tell me yet with regards to that as I am only in the beginning stages of learning how to cast this chart of mine. In fact I have only taken the first step and calculated my local sidereal time of birth and rising ascendant sign.

I look very forward to any assistance and insight into astrology matters you wish to share with me as I continue to learn more about this interesting subject.
I’m beginning to see your point on “needless precision” as far as working times out to the mili second there as well.

As far as “rote” is concerned, I continue to use that for certain things to memorize, bad habit from school days I guess. There are such great mnemonic techniques now that have come to my attention over the years though. I do however always seek to understand the mechanics of things first, other wise it just makes no sense to me.

Thank you for taking the time to point me in the right direction with these matters, it has been very kind of you and I will be on the look out for Holism, Jan Smuts hey, who would have thought.

Kind regards
Charie

Hi. The Virgo ascendant is undoubtedly correct. Both the charts you have computed and the one I computed using solarfire give this ascendant. The LST given by solar fire is also correct.

I think the problem is that you are confusing time zones with LST. At your place of birth, the clocks area always two hours ahead of Universal Time, and this applies to all locations that use that time zone, whichever longitudinal line they occupy within the area which uses that time zone. So when you convert the clock time of your birth into UT, you must always subtract 2 hours exactly.

Once you have the found the time of your birth in UT, you can find the sidereal time of your birth at 0 degrees longitude. Then you convert back to your place of birth to find LST. Only this time you take into account the actual longitude of your birth place, because LST is specific to longitudinal degree rather than time zone.

UT and the clock time at the place of your birth are measures of 'civil time' which are contrived and averaged out. Sidereal time and LST are astronomically defined - a completely different way of marking time, even though both ways use the same units.

I hope this makes things clearer. Basically, I think the problem lies in that you used your longitude rather than your time zone to find the Universal Time of your birth, and this throws things out by about three quarters of an hour.

Use the Sun to check your work, always. It's a clock hand that shows the hour.
At sunup (call it 6 am) the Sun is on the eastern horizon. If it isn't (in your chart as calculated) there is a mistake. At noon it is on the MC, at sundown on the Dsc, at midnight on the IC. The Second House (Sun there) shows that it is between 2am and 4am....these positions are approximate, vary with the season, latitude and the type of time the clock is on, but with experience you will learn to see when something is wrong.

Your one hour mistake would show up (to experienced eyes) by using this method of checking your work. The sun would appear to be 15 degrees out of place, enough to cause one to question the accuracy of the chart. One-hour mistakes are very common, due (usually) to daylight time. Even though I no longer cast charts by hand, I still check the sun in computer generated charts; I might have plugged in the wrong time, or the place coordinates might be in error. I have an astrologer friend who once cast a chart with an error of 1000 years; wrong button. The sun won't show such an error, but Pluto might.

I commend you for doing these calculations. Another thing that will help you a lot is to spend some time outside at night, observing the sky. Go out and find the MC up there in the heavens. Watch Mars during a retrograde period. Find major stars like Spica and Regulus that are on the ecliptic. Watch the rising of the Moon -- look how one night she rises far in the south, and then another night far in the north; why? Find Mercury. Learn what a conjunction actually looks like.

Miquar has taken you under wing, so I'll butt out. You're in good hands.

charliestars said:

Thank you once again JUPITERASC

I'll take a look at that now.

My local sidereal time of birth
I was born exactly (1h:00m 54.072s x 10sec per hour = 1h:01m 4.2s) before 7h:38m 26.392s = 06h:37m 22.19s sidereal time at 18.4753° E.

The local sidereal calculator gives me 06h:37m 8.22s. Close enough I hope for a shot in the dark.

But this still does not solve my ascendant problem. Software on the net (Astrology cafe)
calculates my ascendant as 26° 21′ Virgo.

When I use Max Heindle simplified table of houses the closest sidereal time to my calculation of 06h:37m 22.19s is 06h:39m 11s which
calculates my ascendant as 8° 20′ Libra.

Surely my local sidereal time of birth (06h:37m 22.19s) is right because a local sidereal calculator gives me the same answer, which leaves me with three choices.

1. The software on the net is giving me wrong readings.
2. Max’s table of houses is giving me wrong readings.
3. My calculations as well as the sidereal calculator’s calculations are wrong

Click to expand...

There is another important factor to consider at this stage
and that is the reliability of the official time of birth
Keep in mind that

timepieces are frequently inaccurate
....often slow or fast

and also

the medical team at the precise time of your delivery were not seated at a computer
ready to input an accurate time of birth for your natal chart
but were instead focused on the health and safety of mother and newborn

for this reason
times of birth are routinely noted at varying times AFTER the event

and

after the newborn has had airways checked, been weighed, washed, clothed
and the mother made comfortable

so
worth checking whether the degree of Virgo currently calculated is your actual time of birth

or

whether potentially a different sign is rising on the ascendant
or not

charliestars said:

Wow, if anybody out there can help me figure this one out, it would be greatly appreciated because I can Imagine for all you experts out there this is boring stuff.

(Just as a matter of interest, if you had to calculate my local sidereal time of birth what would you get? I think if you get the same time as I did, then I will be able to eliminate the other possibilities because if you me and the sidereal calculator give the same results then that must mean the error lies elsewhere.)

Kind regards
Charlie

Click to expand...

I'm no expert
simply someone with an interest in accuracy of official times of birth
because
the official time of birth determines the entire Horoscope
so it is evidently crucial


fortunately
there are several ancient rectification techniques
that may interest you
and
Since you clearly enjoy the minutiae of maths
rectification would be fun

Rectification Tips
- Verifying Ascendant/Descendant/MC/IC angles at http://www.astrologyweekly.com/forum/showthread.php?t=51626


by the way The word HOROSCOPE is derived
from Latin horoscopus,
from Greek horoskopos
hor = hour, season;
+ skopos = observer;


QUOTE

Etymology

The Sanskrit term for horo is Hora (होरा).
Horo -Scope is hora - shastra( होरा -शास्त्र ).

The Latin word horoscopus,
ultimately from Greek ὡρόσκοπος "nativity, horoscope",
literally "observer of the hour [of birth]",
from ὥρα "time, hour"
and
σκόπος "observer, watcher".


In Middle English texts from the 11th century, the word appears in the Latin form,
and
is anglicized to 'horoscope' in Early Modern English.

The noun horoscopy for "casting of horoscopes" has been in use since the 17th century (OED).

In Greek, ὡρόσκοπος in the sense of "ascendant"
and
ὡροσκοπία "observation of the ascendant"
is in use since Ptolemy (Tetrabiblos 33, 75) SOURCE http://en.wikipedia.org/wiki/Horoscope

Hi Miquar

Thank you for the reply.

You are absolutely correct. Thank you so much for pointing that out to me.

I see now that I was converting to UT from 18.4753° not considering the fact that the time the doctors recorded my birth was UT + 2h, which as you correctly state is what all the clocks here would be displaying at that time.

That’s two important errors you have pointed out to me, thank you so much.

Kind regards
Charlie

Hi Jupiterasc

There is another important factor to consider at this stage
and that is the reliability of the official time of birth
Keep in mind that

timepieces are frequently inaccurate
....often slow or fast

and also

the medical team at the precise time of your delivery were not seated at a computer
ready to input an accurate time of birth for your natal chart
but were instead focused on the health and safety of mother and newborn

for this reason
times of birth are routinely noted at varying times AFTER the event

and

after the newborn has had airways checked, been weighed, washed, clothed
and the mother made comfortable

so
worth checking whether the degree of Virgo currently calculated is your actual time of birth

or

whether potentially a different sign is rising on the ascendant
or not

Click to expand...

Thank you, I will definitely take that under consideration. I also had a look at the link you posted on birth rectification. Another interesting angle to consider, so thank you for pointing that additional aspect out to me.

Kind regards
Charlie

Hi. No problem. It was good for me to be reminded of some of the maths behind the chart. I've been reliant on computers for a long time now.