Constellations: Reticulum 'the Reticle'
Created | Updated Nov 8, 2017
Camelopardalis | Cancer | Canes Venatici | Canis Major | Canis Minor | Capricornus | Carina | Cassiopeia | Centaurus
Cepheus | Cetus | Chamæleon | Circinus | Columba | Coma Berenices | Corona Australis | Corona Borealis | Corvus
Crater | Crux | Cygnus | Delphinus | Dorado | Draco | Equuleus | Eridanus | Fornax | Gemini | Grus | Hercules | Horologium
Hydra | Hydrus | Indus | Lacerta | Leo | Leo Minor | Lepus | Libra | Lupus | Lynx | Lyra | Mensa | Microscopium | Monoceros
Musca | Norma | Octans | Ophiuchus | Orion | Pavo | Pegasus | Perseus | Phoenix | Pictor | Pisces | Piscis Austrinus
Puppis | Pyxis | Reticulum | Sagitta | Sagittarius | Scorpius | Sculptor | Scutum | Serpens | Sextans | Taurus
Telescopium | Triangulum | Triangulum Australe | Tucana | Ursa Major | Ursa Minor | Vela | Virgo | Volans | Vulpecula
Name: | Reticulum ('Reticle') |
Genitive: | Reticuli |
Short form: | Ret |
Area: | 114 sq deg |
Co-ordinates1: | 04h, −60° |
Origin: | Modern |
So what is a reticle? The name comes from the Latin for net, and it is an overlay bearing a grid of fine lines, used to mark or measure positions. Reticulum is best seen by observers in the Southern Hemisphere. It makes its highest appearance in November. The constellation is bordered by Horologium, Dorado and Hydrus.
History
Before Reticulum was first drawn, an earlier constellation by the astronomer Isaac Habrecht (1589 - 1633)2 stood in this position. Nicolas Louis de Lacaille (1713 - 1762) set up an observatory in South Africa where he worked from 1751 to 1753. At that observatory he used a rhomboidal reticle. He named this constellation 'le reticle romboide' in honour of this instrument. Reticulum does not have any myths because it is a modern constellation.
Stars
Johannes Bayer set up the current system of calling the brightest star 'alpha' and then proceeding down the Greek alphabet for subsequent stars. The combination of this letter with the genitive of the constellation name is known as the 'Bayer Designation'. Many dimmer stars such as HD 27894 have neither a name nor a Bayer Designation.
Gamma Reticuli varies slightly over the space of 25 days. Its magnitude varies between +4.42 and +4.61.
Star Table
Star | Designation | Name or
catalogue number | Magnitude | Distance
(light years) | Spectral classification and/or comments |
α Ret | alpha | HR 1336 | +3.35 | 250 | G8 |
β Ret | beta | HR 1175 | +3.85 | 78 | K1 |
γ Ret | gamma | HR 1264 | +4.513 | 490 | M4 |
δ Ret | delta | HR 1247 | +4.56 | 530 | M2 |
ε Ret | epsilon | HR 1355 | +4.44 | 59 | K2 |
ζ1 Ret | zeta1 | HR 1006 | +5.54 | 40 | G2 |
ζ2 Ret | zeta2 | HR 1010 | +5.24 | 40 | G2 |
η Ret | eta | HR 1395 | +5.24 | 380 | G8 |
θ Ret | theta | HR 1372 | +5.87 | 462 | B9 |
ι Ret | iota | HR 1266 | +4.97 | 47 | K4 |
κ Ret | kappa | HR 1083 | +4.72 | 70 | F5 |
- | unnamed | HD 27894 | +9.20 | 138 | K2 |
Deep Sky Objects
NGC 1313 is a barred spiral galaxy 15 megalight-years away. Observed at shorter wavelengths it is more ordered than in visible light, and exhibits signs of being rich in hydrogen which would make it a nursery for new stars.
The New General Catalogue by J Dreyer was published by the Royal Astronomical Society in the late 19th Century. It was expanded to include two Index Catalogues (IC). This list of star clusters, nebulae and galaxies was revised again in 1973 and is continually updated by the NGC/IC Project.
Cat. No. | Type of Object | Brightness (m) | Distance
(Mega-light years) |
NGC 1313 | galaxy | +9.2 | 15 |
NGC 1536 | galaxy | +12.7 | 54 |
NGC 1543 | galaxy | +10.3 | 52 |
NGC 1574 | galaxy | +10.7 | 47 |
IC 2037 | galaxy | +14.7 | 364 |
IC 2049 | galaxy | +14.5 | 65 |
IC 2056 | galaxy | +12.5 | 50 |
IC 2060 | galaxy | +15.17 | 294 |
Extrasolar Planets
Here are some planetary systems that have been found in this constellation. The size of these extrasolar planets is compared to the mass of Jupiter. This is known by astronomers as the 'Jovian scale'.
The star HD 27894 has a proper motion about 26% of that of Barnard's Star. There have been claims that it has planets at 0.07, 0.12, and 0.41 Astronomical Units, but only the one at 0.12 AU (HD 27894 b) has been confirmed.
Star name or
catalogue number | Planet
catalogue number | Planet mass
(Jovian scale) | Distance
(AU) | Orbital period
(Earth days) |
epsilon Reticuli | HD 27442 b | 1.28 | 1.18 | 423.8 |
HD 23079 | HD 23079 b | 2.61 | 1.16 | 738.45 |
HD 23127 | HD 23127 b | 1.5 | 2.4 | 1,214 |
HD 27894 | HD 27894 b | 0.62 | 0.12 | 18 |
HD 25171 | HD 25171 b | 0.95 | 3 | 1,845 |
zeta2 Reticuli | HD 20807 b4 | 0.27 | 0.14 | 18.9 |
WASP-100 | WASP-100 b | 2.03 | 0.0457 | 2.85 |
WASP-119 | WASP-119 b | 1.23 | 0.036 | 2.5 |
HD 21693 | HD 21693 b | 0.03 | 0.15 | 22.66 |
HD 21693 | HD 21693 c | 0.06 | 0.26 | 53.88 |
Ufology
It may be a hoax, a delusion, or a hidden truth; but there are those who believe that we have been visited by beings from zeta2 Reticuli. In 1961 two people in New Hampshire saw an object in the sky. They claim they stopped the car and the husband trained a pair of binoculars on the object. The next thing they knew (according to their testimony) it was two hours later. Under hypnosis the story emerged that they were taken aboard a UFO and the woman was shown a map. The stars on the map were not labelled. The map she said she saw was three dimensional. The one she drew under hypnotic regression was not. The Boston psychiatrist5 who examined her and her husband concluded that the story was not a deliberate fabrication. It was several years before any star names were added to this map. A tentative map was drawn up by an amateur astronomer in Ohio, connecting it to the star zeta2 Reticuli, and then a professor at OSU6 had his students enter star locations in a computer and generated a map. Finally Mark Steggert of the University of Pittsburgh used a program he had written and the maps were compared. This whole incident was written up in the December 1974 issue of Astronomy magazine.
Four decades later, following the death of her husband, the woman still believes that she was taken aboard a UFO by extra-terrestrials and that the star system from which her abductors came was that of zeta2 Reticuli. In 1995 a group of extrasolar planets was listed in the Extrasolar Planet Encyclopedia including zeta2 Reticuli. However, when the link to ufology was realised, the listing was rejected. The reason given was that 'the data may have been misinterpreted'.