Heliacal Rise Dates — Medieval Astrology Guide

Approximate Helical Rise Dates of Algol
60N	None	20N	May 14^th	20S	June 4^th
55N	None	15N	May 17^th	25S	June 8^th
50N	None	10N	May 20^th	30S	June 13^th
45N	March 25^th	5N	May 22^nd	35S	June 16^th
40N	April 16^th	0	May 25^th	40S	June 23^rd
35N	April 29^th	5S	May 27^th	45S	July 3^rd
30N	May 6^th	10S	May 29^th	50S	None
25N	May 10^th	15S	June 2^nd	55S	None

Heliacal Rise Dates of Fixed Stars Reference

The heliacal rise of a fixed star is a significant moment in a star’s cycle where it rises just before dawn allowing it to be briefly seen before the rising Sun. For most stars, this event will occur after the star had been hidden by the Sun for some length of time, making the heliacal rise the moment when the star re-emerges into the world and celebrates its rebirth into the nighttime sky. Heliacal rises of various stars or asterisms have been important building blocks in historical calendars as they have marked the timing of rituals, holidays, agricultural processes, and seasonal changes.

As we have become increasingly disconnected from the sky and found other, more stable ways to measure and record time, the heliacal rise of the stars has faded from cultural relevance. However, it is seeing a resurgence in astrology and magic where this important moment in a star’s cycle is being used to develop ritual and meaning. Unfortunately, the date of any star’s heliacal rise is notoriously difficult to find online as the date of any given helical rise is very location specific. This page is the first step to correcting that and making this more accessible.

Below are tables that list the approximate heliacal rise dates of 19 fixed stars as calculated for cities at the listed degrees of latitude. While they cannot replace a location-specific calculation, they should be able to provide a guidepost to help plan and narrow down dates for this event.

(Please forgive any ugly formatting or awkward spacing. Squarespace does not have a built-in tool to allow easy editing and displaying of table information. If you’d prefer, please check out the graphics at the bottom of the page)

Approximate Helical Rise Dates of Pleiades
60N	None	20N	June 5^th	20S	June 6^th
55N	July 23^rd	15N	June 5^th	25S	June 7^th
50N	June 25^th	10N	June 5^th	30S	June 8^th
45N	June 17^th	5N	June 5^th	35S	June 9^th
40N	June 13^th	0	June 5^th	40S	June 10^th
35N	June 9^th	5S	June 5^th	45S	June 12^th
30N	June 7^th	10S	June 5^th	50S	June 15^th
25N	June 6th	15S	June 6^th	55S	June 19^th

Approximate Helical Rise Dates of Aldebaran
60N	Aug 2^nd	20N	June 17^th	20S	June 12^th
55N	July 13^th	15N	June 16^th	25S	June 11^th
50N	July 6^th	10N	June 15^th	30S	June 11^th
45N	July 1^st	5N	June 14^th	35S	June 11^th
40N	June 25^th	0	June 13^th	40S	June 11^th
35N	June 23^rd	5S	June 13^th	45S	June 11^th
30N	June 21^st	10S	June 12^th	50S	June 11^th
25N	June 19^th	15S	June 12^th	55S	June 12th

Approximate Helical Rise Dates of Capella
60N	None	20N	June 10^th	20S	July 5^th
55N	None	15N	June 13^th	25S	July 10^th
50N	None	10N	June 16^th	30S	July 18^th
45N	None	5N	June 19^th	35S	July 25^th
40N	May 4^th	0	June 22^nd	40S	Aug. 10^th
35N	May 24^th	5S	June 25^th	45S	None
30N	June 2^nd	10S	June 28^th	50S	None
25N	June 6^th	15S	July 2^nd	55S	None

Approximate Helical Rise Dates of Sirius
60N	Sept. 5^th	20N	July 26^th	20S	June 27^th
55N	Aug. 27^th	15N	July 21^st.	25S	June 23^rd
50N	Aug. 22^nd	10N	July 18^th	30S	June 18^th
45N	Aug. 17^th	5N	July 14^th	35S	June 15^th
40N	Aug. 13^th	0	July 11^th	40S	June 9^th
35N	Aug. 7^th	5S	July 8^th	45S	June 4^th
30N	Aug. 2^nd	10S	July 4^th	50S	May 30^th
25N	July 30^th	15S	June 29^th	55S	May 23rd

Approximate Helical Rise Dates of Procyon
60N	Aug. 24^th	20N	Aug. 2^nd	20S	July 22^nd
55N	Aug. 19^th	15N	July 31^st	25S	July 21^st
50N	Aug. 16^th	10N	July 30^th	30S	July 19^th
45N	Aug. 13^th	5N	July 28^th	35S	July 18^th
40N	Aug. 11^th	0	July 27^th	40S	July 16^th
35N	Aug. 8^th	5S	July 26^th	45S	July 16^th
30N	Aug. 5^th	10S	July 25^th	50S	July 12^th
25N	Aug. 4^th	15S	July 23^rd	55S	July 9th

Approximate Helical Rise Dates of Regulus
60N	Sept. 9^th	20N	Sept. 5^th	20S	Sept. 9^th
55N	Sept. 7^th	15N	Sept. 5^th	25S	Sept. 11^th
50N	Sept. 6^th	10N	Sept. 5^th	30S	Sept. 14^th
45N	Sept. 6^th	5N	Sept. 5^th	35S	Sept. 16^th
40N	Sept. 5^th	0	Sept. 6^th	40S	Sept. 20^th
35N	Sept. 5^th	5S	Sept. 7^th	45S	Sept. 26^th
30N	Sept. 5^th	10S	Sept. 7^th	50S	Oct. 8^th
25N	Sept. 5^th	15S	Sept. 8^th	55S	Nov. 9th

Approximate Helical Rise Dates of Alkaid
60N	None	20N	Oct. 7th	20S	Dec. 9th
55N	None	15N	Oct. 15th	25S	Dec. 20th
50N	None	10N	Oct. 22nd	30S	Jan. 3rd
45N	None	5N	Oct. 29th	35S	Jan. 13th
40N	None	0	Nov. 5th	40S	Jan 13th
35N	Sept. 11	5S	Nov. 12th	45S	None
30N	Sept. 22nd	10S	Nov. 21st	50S	None
25N	Sept. 29th	15S	Dec. 2nd	55S	None

Approximate Helical Rise Dates of Algorab
60N	Nov. 5th	20N	Oct. 21st	20S	Oct. 15th
55N	Nov. 1st	15N	Oct. 20th	25S	Oct. 15th
50N	Oct. 30th	10N	Oc.t 19th	30S	Oct. 15th
45N	Oct. 28th	5N	Oct. 18th	35S	Oct. 14th
40N	Oct. 27th	0	Oct. 17th	40S	Oct. 15th
35N	Oct. 25th	5S	Oct. 17th	45S	Oct. 16th
30N	Oct. 23rd	10S	Oct. 16th	50S	Oct. 18th
25N	Oct. 22nd	15S	Oct. 15th	55S	Oct. 20th

Approximate Helical Rise Dates of Spica
60N	Nov. 4th	20N	Oct. 29th	20S	Oct. 31st
55N	Nov. 2nd	15N	Oct. 29th	25S	Nov. 1st
50N	Nov. 1st	10N	Oct. 29th	30S	Nov. 4th
45N	Oct. 31st	5N	Oct. 29th	35S	Nov. 5th
40N	Oct. 31st	0	Oct. 29th	40S	Nov. 9th
35N	Oct. 30th	5S	Oct. 30th	45S	Nov. 13th
30N	Oct. 30th	10S	Oct. 30th	50S	Nov. 23rd
25N	Oct. 29th	15S	Oct. 31st	55S	Nov. 28th

Approximate Helical Rise Dates of Arcturus
60N	Oct. 4th	20N	Oct. 28th	20S	Nov. 25th
55N	Oct. 8th	15N	Nov. 1st	25S	Dec. 1st
50N	Oct. 12th	10N	Nov. 3rd	30S	Dec. 8th
45N	Oct. 14th	5N	Nov. 7th	35S	Dec. 13th
40N	Oct. 17th	0	Nov. 10th	40S	Dec. 21st
35N	Oct. 20th	5S	Nov. 13th	45S	Dec. 30th
30N	Oct. 23rd	10S	Nov. 17th	50S	Jan. 9th
25N	Oct. 25th	15S	Nov. 22nd	55S	Jan 20th

Approximate Helical Rise Dates of Alphecca
60N	Oct. 5th	20N	Nov. 15th	20S	Dec. 21st
55N	Oct. 15th	15N	Nov. 20th	25S	Dec. 28th
50N	Oct. 21st	10N	Nov. 24th	30S	Jan 4th
45N	Oct. 25th	5N	Nov. 28th	35S	Jan. 9th
40N	Oct. 29th	0	Dec. 2nd	40S	Jan. 17th
35N	Nov. 3rd	5S	Dec. 6th	45S	Jan. 25th
30N	Nov. 8th	10S	Dec. 11th	50S	Feb. 3rd
25N	Nov. 11th	15S	Dec. 18th	55S	Feb. 14th

Approximate Helical Rise Dates of Antares
60N	Jan. 10th	20N	Dec. 15th	20S	Dec. 13th
55N	Dec. 29th	15N	Dec. 14th	25S	Dec. 13th
50N	Dec. 25th	10N	Dec. 14th	30S	Dec. 14th
45N	Dec. 22nd	5N	Dec. 13th	35S	Dec. 14th
40N	Dec. 20th	0	Dec. 13th	40S	Dec. 16th
35N	Dec. 18th	5S	Dec. 13th	45S	Dec. 18th
30N	Dec. 17th	10S	Dec. 13th	50S	Dec. 22nd
25N	Dec. 16th	15S	Dec. 13th	55S	Jan. 3rd

Approximate Helical Rise Dates of Vega
60N	None	20N	Dec. 16th	20S	Feb. 1st
55N	None	15N	Dec. 24th	25S	Feb. 7th
50N	Oct. 22nd	10N	Dec. 29th	30S	Feb. 15th
45N	Nov. 6th	5N	Jan. 4th	35S	Feb. 21st
40N	Nov. 15th	0	Jan. 9th	40S	March 1st
35N	Nov. 26th	5S	Jan. 15th	45S	March 11th
30N	Dec. 4th	10S	Jan. 20th	50S	March 25th
25N	Dec. 10th	15S	Jan. 28th	55S	None

Approximate Helical Rise Dates of Deneb Algedi
60N	June 11th	20N	March 5th	20S	Feb. 27th
55N	April 9th	15N	March 3rd	25S	Feb. 26th
50N	April 14th	10N	March 2nd	30S	Feb. 26th
45N	March 30th	5N	March 1st	35S	Feb. 27th
40N	March 22nd	0	Feb. 28th	40S	Feb. 27th
35N	March 15th	5S	Feb. 28th	45S	Feb. 27th
30N	March 10th	10S	Feb. 27th	50S	Feb. 28th
25N	March 8th	15S	Feb. 27th	55S	March 1st

Approximate Helical Rise Dates of Canopus
60N	None	20N	Aug. 12th	20S	June 2nd
55N	None	15N	July 31st	25S	May 21st
50N	None	10N	July 23rd	30S	May 6th
45N	None	5N	July 14th	35S	April 23rd
40N	None	0	July 6th	40S	None
35N	Sept. 19th	5S	June 28th	45S	None
30N	Sept. 1st	10S	June 20th	50S	None
25N	Aug. 22nd	15S	June 8th	55S	None

Approximate Helical Rise Dates of S’ad al Su’ud
60N	March 10th	20N	Feb. 23rd	20S	Feb. 27th
55N	March 7th	15N	Feb. 24th	25S	Feb. 28th
50N	March 2nd	10N	Feb. 24th	30S	March 1st
45N	Feb. 27th	5N	Feb. 24th	35S	March 2nd
40N	Feb. 25th	0	Feb. 24th	40S	March 3rd
35N	Feb. 25th	5S	Feb. 25th	45S	March 4th
30N	Feb. 24th	10S	Feb. 25th	50S	March 6th
25N	Feb. 24th	15S	Feb. 26th	55S	March 8th

Approximate Helical Rise Dates of Alphard
60N	Sept. 26th	20N	Sept. 3rd	20S	Aug. 19th
55N	Sept. 21st	15N	Sept. 1st	25S	Aug. 17th
50N	Sept. 18th	10N	Aug. 30th	30S	Aug. 13th
45N	Sept. 15th	5N	Aug. 28th	35S	Aug. 11th
40N	Sept. 13th	0	Aug. 27th	40S	Aug. 8th
35N	Sept. 10th	5S	Aug. 25th	45S	Aug. 4th
30N	Sept. 7th	10S	Aug. 23rd	50S	July 30th
25N	Sept. 5th	15S	Aug. 20th	55S	July 24th

Approximate Helical Rise Dates of Ras Alhague
60N	Nov. 18th	20N	Dec. 17th	20S	Jan. 11th
55N	Nov. 24th	15N	Dec. 21st	25S	Jan. 15th
50N	Nov. 28th	10N	Dec. 23rd	30S	Jan. 20th
45N	Dec. 1st	5N	Dec. 27th	35S	Jan. 23rd
40N	Dec. 4th	0	Dec. 29th	40S	Jan. 29th
35N	Dec. 8th	5S	Jan 1st	45S	Feb. 3rd
30N	Dec. 12th	10S	Jan. 4th	50S	Feb. 9th
25N	Dec. 14th	15S	Jan. 9th	55S	Feb. 15th

How were these dates calculated?

The above tables were created based on calculations provided by the Planetary, Lunar, and Stellar Visibility program created by Alcyone Software. This is one of the only software I’ve been able to find that will accurately determine visibility phenomenon while also providing the means to customize the bodies and locations. I’ve also double-checked the information the PLS Visibility software generates alongside available tables from NASA or other aeronautic agencies and the two have always agreed. I recommend anyone interested in exploring the heliacal rise of celestial bodies download and utilize this program if they can (unfortunately there is not a version compatible with Mac or Linux). Please see this YouTube video for more information about getting set up. PLS Visibility is not a complicated program, but it is not what I would call user friendly.

The dates are a little different from what our sources are telling me, why is that?

This is a complicated question. Helical rise dates are highly variable based on several factors, the most important being location. Some stars, depending on other criteria, may appear on dates slightly before or after those listed if you do not live in a city that lies on the same line of latitude as the ones included on the table. The dates, while accurate, are approximate and do not replace a location-specific calculation that you can find through downloading the PLS Visibility program linked to above.

It’s also worth noting that some of the criteria involved in determining a heliacal rise are difficult to plan for. While location and elevation can be accounted for, other variables that might effect viewing conditions such as weather and light pollution cannot be. For those of us who live in or near to cities with large amounts of light pollution, only the brightest stars are visible, if any at all. This will have a huge impact on the ability to directly observe heliacal rises with the light being so bright that some stars in the above table will never be visible. Even those with smaller amounts of light pollution will have to contend with unexpected cloudy conditions. The PLS Visibility software calculates the heliacal rise with the assumption that there is little to no light pollution and fair observing conditions. I leave it up to the reader to decide if this is good enough or not.

Finally, those who are used to seeing helical rise dates determined by the Starlight software, Astrodienst, or other programs associated with Bernadette Brady may be surprised at the discrepancy in those reports and these tables. That is because those programs do not actually calculate helical rises. On page 329 of Brady’s Book of Fixed Stars, Brady states that all of the graphs in the book are set to determine not the helical rise of a star, but its cosmical rise. The cosmical rise is the day that the star rises at the same time as the Sun, a helical rise is when a star rises far enough ahead of the Sun to be visible for the first time. During a cosmical rise the star is still hidden by the light of the Sun. In her book, Brady most often calls the cosmical rise a “true heliacal rise” which makes conversation about these topics difficult, the actual helical rise is referred to as an “apparent heliacal rise” in this text.

The Starlight software and Astrodienst will provide information regarding the dates of cosmical rises, while the above tables will provide information regarding dates of heliacal rises and that is why the information is different.

Star Phase Weirdness

Typically, when we think about heliacal rises we are envisioning a complete synodic cycle with the Sun. This takes place over several steps.
1) The Sun moves close enough to a star to visibly obscure it, hiding it from sight for a period of time
2) The Sun moves far enough past the star for it to become briefly visible and reintroduced into the night sky during its heliacal rise
3) The star appears earlier and earlier each night until it rises as the Sun sets
4) The star begins to set earlier and earlier each night as the Sun moves closer.
5) Repeat step 1

This will not be true of every star. Even some stars in the above list will experience these phases differently or not at all depending on location. Some stars will be circumpolar, or stars that will never set below the horizon. Other stars will not rise above the horizon and never be visible. This is why some of the stars will have “None” listed for a particular location. For whatever reason, these stars will not experience a heliacal rise phase for this location on earth. This is not the only way stars can have “abnormal” phases.

Another phenomenon that may impact a star’s phase is what is referred to as “curtailed passage”. This is what happens when a star will both set and rise within the same night and occurs when a star is getting closer to becoming circumpolar. Basically, a star is visible in the night sky after sunset, will dip beneath the horizon and set sometime during the night, but will then rise up again and be visible before dawn. Because these stars will have a date when they rise immediately before sunrise I have included them in the above dates, but these stars will not fully experience a period of being hidden by the Sun.

Gallery

Approximate Heliacal Rise Dates of Unukhalai
60N	Nov. 9th	20N	Nov. 26th	20S	Dec. 17th
55N	Nov. 11th	15N	Nov. 28th	25S	Dec. 21st
50N	Nov. 13th	10N	Nov. 30th	30S	Dec. 26th
45N	Nov. 15th	5N	Dec. 3rd	35S	Dec. 30th
40N	Nov. 17th	0	Dec. 5th	40S	Jan. 5th
35N	Nov. 18th	5S	Dec. 7th	45S	Jan. 11th
30N	Nov. 22nd	10S	Dec. 10th	50S	Jan. 19th
25N	Nov. 24th	15S	Dec. 14th	55S	Jan. 29th