What’s Out Tonight?

Names and Designations of Stars

The naming of stars is mostly historical. 
And, the designations given to stars is not only historical but confusing because there are several overlapping/competing systems, and some are incomplete.

Various Designations for 2 Stars

Sirius (a star in Canis Major)
1)  Assigned the lowercase Greek letter alpha:  𝛂  
       Examples:  𝛂 CMa  or ​𝛂 Canis Majoris 
2)  Assigned the number designation:  9
       Examples:  9 CMa  or  9 Canis Majoris
3)  HD 48915
4)  HIP 32349  

Bellatrix (a star in Orion)
1)  Assigned the lowercase Greek letter gamma:  𝜸  
       Examples:  ​𝜸 Ori  or ​​𝜸 Orionis 
2)  ​Assigned the number designation:  24
       Examples:  24 Ori  or  24 ​Orionis
3)  HD 35468
4)  HIP 25336
5)  NSV 1972
6)  TYC 113-1856-1  

Explanations for the Above Numbers 1 through 6

1  •  Greek Letters 
Greek letters were assign by Johann Bayer (1572–1625) to the brighter stars within each constellation visible from the Northern Hemisphere in his 1603 Uranometria celestial atlas. They began anew with each constellation and assigned in order of brightness. For a few constellations, he ran out of the 24 Greek letters of that alphabet and used lowercase Roman letters (except he used capital A so it would not be confused with alpha which often looks like the Roman lowercase a). So, the brightest star in each constellation received the lowercase Greek letter alpha (𝜶). There are no Greek letters assigned to the constellations in the “deep” southern hemisphere because Bayer charted the constellations from his northern hemisphere location in Germany. A few other historical astronomers continued to assign Greek letters to the stars in the southern hemisphere after Bayer. The two examples show the use of the assigned Greek letter with the 3-letter abbreviation of the constellation name and the use of the Greek letter with the Latin Genitive of the constellation name. See farther below for a discussion on the Latin Genitive. See the Greek alphabet at the end of this page.

2  •  Number Designations 
John Flamsteed (1646-1719) had the idea of designating stars in each constellation using numbers and assigning those numbers from west to east, not by brightness. However, he never fully engaged in this “project” so the Flamsteed numbers that we use today are actually from Jerome Lalande (1732–1807) assignment in his 1773 Éphémérides des mouvemens célestes star atlas. The assignment of numbers begin anew with each constellation.
The two examples show the use of the assigned Flamsteed number with the 3-letter abbreviation of the constellation name and the use of the ​Flamsteed number with the Latin Genitive of the constellation name. See farther below for a discussion on the Latin Genitive. 

3  •  HD Catalogue
The Henry Draper Catalogue (HD) is an astronomical star catalogue originally published between 1918 and 1924, and which has been expanded ever since to include about 360,000 stars as faint as magnitude 11 (remember, our naked eyes can see about 6,000 stars and as faint as magnitude 6). The numbering is sequential from west to east ​starting at the Right Ascension of 0h (zero hours), which is the “line” where the Vernal Equinox starts. HD1 is a 7.42 magnitude star in the constellation Cepheus.

4  •  HIP Catalogue
HIP stands for Hipparcos and this 1997 catalogue was created from the Hipparcos satellite launched in 1989 and operated until 1993. The Hipparcos Catalogue is a high-precision catalogue of more than 118,000 stars. HIP 1 is a 9.1 magnitude star located in the constellation of Pisces. The stars in this catalogue are numbered sequentially from west to east starting at the Right Ascension of 0h (zero hours), which is the “line” where the Vernal Equinox starts.  

5  •  TYC Catalogue
The TYC catalogue or Tycho catalogue lists more than 2.5 million stars with data collected from the Hipparcos satellite (1989 to 1993). The numerical designation system is unique. It divides the sky into 9537 regions and then numbers the stars in each region (separated by hyphens). There is most often an annotation with the number 1 at the end of designations.

A closeup of Orion's belt from Johann Bayer's 1603 Uranometria star atlas. The three belt stars were assigned the Greek letters zeta (𝜻), epsilon (𝜺) and delta (𝜹). Orion has many brighter stars. In this image the Roman letters of b and p were used to designate two of the stars because Bayer used up the 24 letters of the Greek alphabet. Click on the image to see the whole constellation of Orion from Uranometria.

Johann Bayer (1572–1625) was a German lawyer. There were no professional astronomers during his time—astronomy was his passion.

John Flamsteed (1646–1719) was an English astronomer and first Astronomer Royal of the Royal Observatory in Greenwich (next to London).

Jerome Lalande (1732–1807) resided in Paris and was quite a character—most people would have found him interesting.

Some, almost FUN, Facts About the Names of Stars

Navigational stars.  There are 57 stars that are traditionally used for celestial navigation, generally for boats/ships at sea. Polaris in not formally one of them because its stationary position is not helpful in determining longitude. I have seen tables listing 60 stars, including Polaris, so there has been a slight variation in the list.

Name a star after someone?  There are a least a few businesses that will take your money to name a star after someone. This is all a sham! However, a good friend of mine did this for his girlfriend whose son had suddenly died. It had meaning to her. And, I went over to my friend’s house with my telescope to show her the star—it was not visible to the naked eye.

Number of named stars.  The International Astronomical Union (IAU) has approved 451 names of stars as of 2022. They also standardized the spelling. They are the only body that can formally name stars. They added many star names in 2019 and 2022 using submissions from cultures around the world.

Origin of names.  Most of the traditional names of stars, that is, the names used for the last several hundreds of years are derived from Arabic. For many stars, their names (meaning and origin) became culturally mixed over the centuries. The names of the constellation are mostly Greek/Roman. Star Names, Their Lore and Meaning, a book by Richard Allen is an in depth review of the origin of the names of many stars and constellations.

The star named Navi.  The star that has been designated gamma (𝜸) in Casseopeia since 1603 was named Navi in the 1960s for amusement by astronaut Gus Grissom who was the second American astronaut in space and who died in a fire while testing the Apollo 1 capsule in 1967. Navi is the reverse spelling of his middle name, Ivan. Navi was official adopted by the IAU in 1970.

Latin Genitive
Genitive refers to a grammatical case resulting in a spelling variation of a word that indicates or implies a relationship of possession. Genitives are not used in modern English. Where they exist, they are a holdover from Latin and other languages. Genitives of the constellations are still used today in conjunction with the Bayer letters, Flamsteed numbers or similar designation to “name” stars. For example, the “alpha” star in Orion (𝜶), as assigned by Bayer, but best known as Betelgeuse, could also be referred to as alpha (𝛂) Orionis, where Orionis is the genitive form of Orion, indicating possession of the alpha star. Betelgeuse can also be indicated as 58 Orionis when referring to it by its Flamsteed number. Most of us have heard of Alpha (𝛂) Centauri, one of the closest stars to us. This is its genitive name using its Bayer letter designation. This star is also commonly known by its name, Rigel Kentaurus.

The Lowercase Greek Alphabet

These Greek letters are designations used for the brightest stars in each constellation visible from the northern hemisphere. They were initially assigned in 1603 by Johann Bayer, a German lawyer but are still widely used today. The assignment starts anew with each constellation so the brightest star in each constellation is usually designated alpha ( 𝜶 ).