How to read your Star Area Co-ordinates Sheet
Last updated 1 November 2026
Your Star Area Co-ordinates Sheet is the scientific record of your star: where it is, how bright it is and when to look for it. Here is what each part means, for sheets from every year.
The left-hand panel
Name and catalogue
At the top is your star's name. Underneath, the catalogue line gives the number astronomers use for the same star. Stars registered from November 2026 are listed by their HIP number, from the Hipparcos catalogue made by the European Space Agency.
On sheets from before November 2026 you'll see an NGC or M number instead. NGC is the New General Catalogue and M the Messier catalogue: lists of galaxies, star clusters and nebulae. On those sheets the number names your star area, the region of sky your star was registered in, and the lines below (type, size, shape, distance) describe that object. More about older registrations.
Brightness and magnitude
Magnitude measures how bright something looks from Earth, and the scale runs backwards: the lower the number, the brighter it is. The brightest stars are around magnitude 0 or 1. On a dark night the eye can see down to about magnitude 6, and binoculars reach magnitude 9 or 10. The Brightness and Visibility lines put that into words.
Colour
Stars glow in different colours depending on how hot they are, from blue-white for the hottest to orange and red for the coolest. B-V is the number astronomers use for colour: below 0 is blue-white, around 0.6 is yellow like the Sun, above 1.4 is red.
Right Ascension and Declination
These are your star's address on the sky, like longitude and latitude on a map. Right Ascension runs around the sky in hours, minutes and seconds, from 0h to 24h. Declination is degrees north (+) or south (−) of the celestial equator. Type both into a star-gazing app or planetarium program and it will point to your star. Epoch J2000.0 means the position is given for the year 2000, the standard astronomers use.
Constellation and hemisphere
The constellation is the star pattern your star sits in, with its standard three-letter abbreviation. Stars in the northern celestial hemisphere are easiest to see from the UK.
Galactic and ecliptic co-ordinates
These give the same position measured from the plane of our Milky Way galaxy (galactic) and from the path the Sun takes through the year (ecliptic). You won't need them to find your star, but they show where it sits in the wider sky.
The Altitude graph
The graph shows how high your star is above the horizon at 10pm on each night of the year, seen from the UK. The curve is its height; 90° would be straight overhead. Cross-hatched months are when the star is below the horizon at that time. The best months to look are when the curve is highest.
Older sheets show a single night instead, from noon to noon, with the shaded part of the graph being night-time.
The Chart View
The Chart View is a map of the stars around yours, as you'd see them through binoculars. North is at the top. The grid lines mark Right Ascension (running up and down) and Declination (running across), labelled around the edge. Your star, or your star area on older sheets, is in the centre of the circles.
Database Number
The number beginning ISD at the bottom is your star's entry in the Intergalactic Star Database. For stars registered from November 2026, enter it here to see the star online and print new copies of your documents.
Ready to look for it outside? Here is how to find your star in the night sky.