Accuracy of Degrees (and Minutes) of the Ascendant

Understanding the Degree (and Minutes) of the Ascendant in your Natal Chart

Different astrology software programs whether online or off can yield slightly different Ascendants and house cusps. How important are these discrepancies?

This article addresses this issue, but for those who only want a bottom line so they can move on…small differences that amount to a fraction of a degree are negligible, largely because we don’t record birth times to the second and birthplace coordinates are also approximate. Fortunately, there is truly no need to worry about this, even in the uncommon situation where it might change a house cusp from one sign to another.

Should you worry about small differences in the Degrees/Minutes of your Ascendant?

I’ve already answered this question above, but now I am going to show whoever is interested in why this is the case.

I am going to use a couple of examples. First, I entered the following details into the online software on my site and then into Sirius. Sirius uses the ACS Atlas which seems to be the industry standard and is used by many professional astrology software programs.

The information for this first example is for “L” and is as follows:

I’ve entered this information into the excellent Sirius software program, and as you can see, the coordinates used for the birthplace, Belo Horizonte, Brazil, are 19 S 55 and 43 W 56. These are rounded off but it’s absolutely fine to work with rounded off figures because cities fall within a latitude-longitude range.

How are a city’s coordinates determined? Very often, it’s the City Hall (or equivalent) coordinates. Sometimes it’s the geographical center. Other times, it’s the most populous area of a city, or it’s simply anywhere within the city limits.

Whatever is selected, the differences they make in a chart are equivalent to a difference of a fraction of a minute of birth time. In other words, it changes your chart in the same way that a difference between 7:00:00 PM and 7:00:06 PM would change your chart, and of course, we don’t (and don’t need to) record birth times with such precision.

Back to the example: The chart produced from the above birth data yields an Ascendant as follows:

The Ascendant is 4 Sagittarius 01. I am focusing on the Ascendant because it (along with the other house cusps) is the most sensitive to birth time and birth place differences, so the Ascendant is where you will look first to see if a chart is accurate. [Just to be precise, the Ascendant is often but not always also the start of the first house, or the first house cusp. For example, when using the rather popular Whole Sign Houses, the house cusps are all 0 degrees].

If I put the same information into the software in my Free Report section, I get the following:

As you can see, the Ascendant is different. While the degree position changed, the difference between the two Ascendants is actually only 0 degrees 02 minutes. This is because the minute position (which would be the “59” part of the expression 3 Sagittarius 59, for example) is out of 60.

So, we have 1 minute to take 3 Sagittarius 59 to 4 Sagittarius 00, plus one more to get to 4 Sagittarius 01, for a total of 2 minutes (0 degrees 02 minutes). [Note: 2 minutes of degrees is not the same as 2 minutes of an hour.]

For newcomers to astrology, the first thought usually is…which is the right one? The answer is: they’re both right. Even though we used the same time (which in this case is as precise as we usually get birth times – 6:29 PM), the city coordinates used by the two programs are slightly different, and that’s the reason for the discrepancy.

Now, to show why one value isn’t any more accurate than another, I think it’s best to use some visuals. I put in the coordinates of each program into Google Maps to illustrate the differences between the two sets of coordinates visually:

First, the coordinates that Google Maps gives for Belo Horizonte are as follows:

The following shows exactly where these coordinates fall in the city:

The following shows where the coordinates used by Sirius fall in the city:

Or, up closer:

While they’re slightly different, they’re still very much coordinates for Belo Horizonte.

The following shows where the coordinates used in my Free Reports section fall in the city:

The exact coordinates used in the online software’s atlas are -19.914564 -43.958639. Again, there’s not much of a difference and it’s still very much representative of the example person’s birthplace.

Importantly, I am in no way making a case for using the coordinates for the hospital or precise birth location–quite the opposite, in fact. We all start out wondering about these kinds of discrepancies, but the more we work with charts, the more we realize as astrologers or astrology hobbyists that it’s best not to stress over making one factor precise when the other isn’t. In fact, it’s entirely illogical.

And, even if the birthplace coordinates are precise AND the birth time is recorded to the second, we really haven’t accomplished anything impactful.

Box of data reads: Pronoun She; Belo Horizonte; 12, Minas Gerais, 55 Brazil, BR; Date 05/07/1993, Friday, Time 18:29; Julian Day 2449115.40; Time Zone -3.000; 3h00W; ST 9.36; Lat -19.9100, 19degrees 55 S; Longitude -43.9600, 43 degrees 58W

From Accuracy of the Ascendant Degrees and Minutes

Of course, there’s also the issue of precisely when should we “count” the birth of a person–at the first breath, when the head or legs emerge? This is yet another reason not to obsess over these details.

So, saying that one slightly different Ascendant value is “more accurate” than another is really quite pointless, not only because we’re working with approximate birthplace locations, but we’re also working with imprecise birth times (not recorded to the second).

This should also help take the pressure off for people who don’t know their precise birth time. It’s always good to research it, but it’s not something to worry too-too much about.

My Ascendant: Example

I had an easy time with my birth time. It was recorded on my birth certificate and “7:36 PM” was reiterated in my baby book.

I have never tried to adjust (or rectify) my birth time. It’s true that I will never know when someone decided to call me “born,” but the time of 7:36 PM has served me quite well. Early in my studies of astrology, I worried about its accuracy and hated to work with any chart that didn’t have an “absolutely” accurate time– as is often the case for many people starting out.

Or, I could say it’s because I am a Virgo and have a strong sixth house that I wanted everything to be perfect, or because I have a Mercury-Saturn opposition (all of these astrological factors are known for wanting details and precision), although I think it’s common enough that beginners worry a lot about the finer details.

But letting go of this comes naturally as you go along. For one, it’s because it’s purely logical once you start playing with birth times and locations, and the logic is as follows:

If I don’t know whether I was born at 7:35:45 PM or 7:36:30 PM, why would I worry about whether my birth location is recorded as a general Toronto or the precise hospital in which I was born which was not in the city center OR at City Hall (and I do know this detail)? It would be fruitless to pinpoint the hospital coordinates because this would impact my chart the same way as changing my time from 7:36:00 PM to 7:35:45 PM (15 seconds of time!) and I really don’t know and will never know the seconds of my birth time.

The following is the Ascendant of the chart that I go by. Again, I focus on the Ascendant because it is the most sensitive to variations of birth time and birthplace:

The chart above is for 7:36 PM and Toronto. If I change the location to the precise hospital where I was born, it produces the following:

My Ascendant is now 3 Aries 15. It’s 00 degrees 07 minutes away from the general city Ascendant, but it’s not enough for me to want to enter the precise hospital coordinates to generate my chart. This is because if I change my birth time to 7:35 PM and use Toronto coordinates, I get the following:

Just one minute of birth time brought my Ascendant to 2 Aries 54. It’s not so far off, actually, since it’s only half a degree away from the original chart and a little less for my hospital chart. In truth, I don’t know if the nurse who recorded my birth time looked at the clock a minute later and decided that was when I was born, or if they looked at the clock at 7:38 PM and decided that probably two minutes had transpired, and made the adjustment. And again…when was that precisely? I think most astrologers count first breath, but not all agree. And, I doubt the nurse was too worried about exactness.

Let’s say my birth time wasn’t recorded by the hospital or my mother as 7:36 PM and instead, my mother told me I was born around 7:30 PM. How much would that impact my chart?

Now we’re getting close to another Ascendant sign altogether, but we’re still not too far away from my go-to chart with the “exact” time. I may very well wonder if I actually had a Pisces Ascendant. I would have vibed with that more since my Moon is in Pisces and I didn’t identify with Aries traits at all when I was young and first studying astrology.

My 7:36 PM chart with an Aries Ascendant works best for me, however, since I was only twelve when I first drew up my chart and hadn’t grown up enough to know who I was. There are many reasons why I am on the quiet side and not especially aggressive yet still have an Aries Ascendant, some of which are right there in the chart snippet, but I’ve digressed.

Actually, as another aside, when I was twelve I was using books, charts, and tables to construct my chart. I had no other instruction and calculated my chart without DST the first time around, and was going with a Taurus Ascendant instead of Aries for a few months. I wrote about this many, many years ago in an article When You Don’t Identify with Parts of your Natal Chart which is relevant to this discussion.

The point I am making is that it’s best not to stress over these things. Instead, put in the effort to find your birth time, investigate a little if need be, but then work with your chart with an open mind and let things fall into place as you go. Try, too, NOT to identify with the second set of numbers in your Ascendant degree (at least).

What about the uncommon case when a slight variation in birthplace or birthtime changes the sign of the Ascendant (or a house cusp)?

Occasionally, an Ascendant changes from one sign to another upon a slight variation in birthtime or birthplace. An example would be if one software yields an Ascendant of 0 Aries 02 and another program yields 29 Pisces 59. These locations are very close–only 0 degrees 03 minutes apart.

Even when this happens, we cannot know the answer if we don’t know the precise second we were born, so this is going to be ambiguous no matter how much you fine-tune your birthplace. Over time and with experience, you might decide your Ascendant feels more like one or the other, but it’s a judgment call.

The point of this article is to try to coax students of astrology away from worrying about the preciseness of the Ascendant degree and minutes so that they can concern themselves more with learning and interpreting. Maybe if I had figured this all out sooner I wouldn’t have wasted my time trying to find the “most accurate” values in my beginning years. I feel the best approach is to keep an open mind about certain points in the chart.

I haven’t even broached the subject of house systems here (there are many systems, and many of which are favored and used successfully by different astrologers). These won’t affect the Ascendant, but the house cusps can vary widely between systems.

For some of you, as you go along, house cusp exactness may fade somewhat from your focus when interpreting charts as they did with me. It’s exciting to pan out and work on seeing the bigger picture of a chart. I feel it’s a moment when our understanding of charts increases many times over.

For some, a favored house system can eventually emerge, and they swear by it. This is fine, too, as some people are very much geared to wanting to find that one method that works, and this kind of thinking is also very much needed.

What if two programs yield different Ascendant signs or the Ascendant differs by significantly more than one degree?

This is where we should investigate further. After of course checking that the birth data entered into the two programs is the same and you still see results that vary more than described above, it is probable that the discrepancy is a time zone issue, usually amounting to a difference of 1 hour.

Historical time zones are generally known and recorded for birthdates after 1970. For some locations before 1970, there are unknowns. Software that uses the ACS Atlas most likely has more accurate data for dates before 1970. Software that uses Geonames may not reflect all the nuances of the complicated history of Daylight Savings Time before 1970 (at the time of this writing) but is excellent for dates after 1970.

I have addressed this issue elsewhere on the site, but if you want assistance with time zone issues, you can write to reports@cafeastrology.com. As always, I suggest checking your chart with astro.com (and perusing of their vast selection of chart services) as it is most likely to be correct and seems to be the best compilation of historical time zone changes currently, but always keep in mind that humans don’t have all the facts available for certain historical time zones. Keep open. If you see a major difference in the results on the software on my site (I am an individual, not a company), which is not as advanced as that of astro.com, then let us know.

I also highly recommend astrowin.org for a wide range of charts with accurate calculations. The work the author of that software has done is outstanding. There are many newer chart services emerging online that have great merit as well. I have not yet fully explored them, but many have mentioned to me that they are using and enjoying AstroSeek and AstroCharts for example. Checking your chart with various chart services can be helpful. You may end up returning to all, some, or only one of them since there is something a little different to offer in each.

I offer three different online chart calculation software programs. The Free Reports section uses its own atlas, the Free Report here uses the Geonames atlas, and my Zodiacal Charts site uses the ACS Atlas.

I love using different software program offline, too. I use many, but I seem to return to AstrolDeluxe and Sirius of my offline software the most.