# Observing the Sky from 40°N/Tables

The tables below make use of the following symbols:
The best view of the star / the object is with binoculars.
The star / the object is visible with binoculars, but the best view is with small telescopes.
The star / the object is visible only with telescopes.

## The 40 brightest stars

Column Headings
* Proper name: the name of the star.
* Catalogue number: the Bayer designation of the star, a system developed by Henry Draper in 1603.
* RA(2000.0) and Dec.: right ascension and declination, referred to the 2000.0 equinox.
* Const.: the constellation in which the star is located.
* Magn.: the apparent magnitude of the star.
* Dist.(ly): approximate distance of the star, expressed in light-years.
* Spectral type: the spectral class, the luminosity class and peculiarity.
* Notes: notable notes about the star.

## Double stars

Column Headings
* Name: the Bayer or Flamsteed designation of the star.
* RA(2000.0) and Dec.: right ascension and declination, referred to the 2000.0 equinox.
* Const.: the constellation in which the star is located.
* Mag. A: the apparent magnitude of the primary component.
* Mag. B: the apparent magnitude of the secondary component.
* Sep.: the separation between the components, expressed in seconds of arc.
* Pos. angle: the position angle, counted in degrees from north (0°) through east (90°), south (180°), and west (270°). The position angles are for the component B with respect to the component A.
* Colours: the colours of the two components of the system, based on their spectral type.
* Notes: notable notes about the star system, membership in star clusters, physic of the system.
* Common name: the proper name of the star system.

## Variable stars

Column Headings
* Name: the Bayer, Flamsteed or variable designation of the star.
* RA(2000.0) and Dec.: right ascension and declination, referred to the 2000.0 equinox.
* Const.: the constellation in which the star is located.
* Min.: the apparent magnitude at maximum brightness.
* Max.: the apparent magnitude at minimum brightness.
* Period (days): the average period of variation in days.
* Type: the type of variability.
* Spectrum: the spectral class of the star. In eclypsing binaries, the spectra of both the components are indicated; in pulsating variables, the variation of the spectrum is showed.
* Common name: the proper name of the star.

## Open clusters

Column Headings
* Name: the cluster’s name as plotted on the maps.
* RA(2000.0) and Dec.: right ascension and declination, referred to the 2000.0 equinox.
* Const.: the constellation in which the cluster is located.
* Diam.: apparent diameter expressed in minutes of arc.
* Magn.: the apparent magnitude of the cluster; a symbol “:” after this value means an approximation.
* Dist.(pc): approximate distance of the cluster, expressed in parsec. To obtain the distance in light-years, multiply by 3.26.
* Galactic arm: the spiral arm of the Milky Way in which the cluster is located.
* Type: descriptive type based on the system developed by R. J. Trumpler in 1930. It is composed by three parts:
    Concentration
       I. Detached; strong concentration toward centre.
       II. Detached; weak concentration toward centre.
       III. Detached; no concentration toward centre.
       IV. Not well detached from surrounding star field.
    Range in brightness
       1. Small range in brightness.
       2. Moderate range in brightness.
       3. Large range in brightness.
    Richness
       p Poor (less than 50 stars).
       m Moderately rich (50 to 100 stars).
       r Rich (more than 100 stars).
* Notes: notable notes about the cluster, membership in OB associations, nebulosity.
* Common name: the proper name of the cluster.

## Globular clusters

Column Headings
* Name: the cluster’s name as plotted on the maps.
* RA(2000.0) and Dec.: right ascension and declination, referred to the 2000.0 equinox.
* Const.: the constellation in which the cluster is located.
* Diam.: apparent diameter expressed in minutes of arc.
* Magn.: the apparent magnitude of the cluster; a symbol “:” after this value means an approximation.
* Dist.(pc): approximate distance of the cluster, expressed in parsec. To obtain the distance in light-years, moltiply for 3.26.
* Class: concentration class of the globular cluster based on the system developed by H. Shapley in 1927. The values range from 1 to 12; the smaller is the number, the higher is the concentration of stars toward the centre of the cluster.
* Notes: notable notes about the cluster, strong X-ray sources.
* Common name: the proper name of the cluster.

## Bright nebulae

Column Headings
* Name: the nebula’s name as plotted on the maps.
* RA(2000.0) and Dec.: right ascension and declination, referred to the 2000.0 equinox.
* Const.: the constellation in which the nebula is located.
* Diam.: apparent diameter expressed in minutes of arc.
* Magn.: the apparent magnitude of the nebula; a symbol “:” after this value means an approximation.
* Dist.(pc): approximate distance of the nebula, expressed in parsec. To obtain the distance in light-years, moltiply for 3.26.
* Galactic arm: the spiral arm of the Milky Way in which the nebula is located.
* Type: the type of the nebula:
    H II regions are nebulae with an high rate of ionized hydrogen emitting light.
    Reflection nebulae are clouds of gas and dust illuminated by a nearby star.
    SNR is a supernova remnant, a bubble of filamentary gas expelled after the explosion of a supernova.
* Notes: notable notes about the nebula, membership in OB associations.
* Common name: the proper name of the nebula.

## Planetary nebulae

Column Headings
* Name: the nebula’s name as plotted on the maps.
* RA(2000.0) and Dec.: right ascension and declination, referred to the 2000.0 equinox.
* Const.: the constellation in which the nebula is located.
* Diam.: apparent diameter expressed in seconds of arc.
* Magn.: the apparent magnitude of the nebula; a symbol “:” after this value means an approximation.
* Dist.(pc): approximate distance of the nebula, expressed in parsec. To obtain the distance in light-years, moltiply for 3.26.
* Galactic arm: the spiral arm of the Milky Way in which the nebula is located.
* Type: the aspect of the nebula, according to the Vorontsov-Velyaminon system:
    1. Stellar image.
    2. Smooth disk (a, brighter toward the centre; b, uniform brightness; c, traces of ring structure).
    3. Irregular disk (a, very irregular brightness distribution; b, traces of ring structure).
    4. Ring structure.
    5. Irregular form (similar to a diffuse nebula).
    6. Anomalous form.
* Magn. of the central star: the apparent magnitude of the star that originates the nebula.
* Common name: the proper name of the nebula.

## Galaxies

Column Headings
* Name: the galaxy’s name as plotted on the maps.
* RA(2000.0) and Dec.: right ascension and declination, referred to the 2000.0 equinox.
* Const.: the constellation in which the galaxy is located.
* Diam.: apparent diameter expressed in minutes of arc.
* Magn.: the apparent magnitude of the galaxy; a symbol “:” after this value means an approximation.
* Dist.(Mpc): approximate distance of the galaxy, expressed in megaparsec (millions of parsec). To obtain the distance in light-years, moltiply *for 3,260,000.
* Type: the Hubble type of the galaxy, as described in the introduction.
* Nuclear class: the nuclear class according to the system developed by G. de Vancouleurs in 1976; numbers from 1 to 5 indicates the increasing *of the luminosity of the nucleus.
* Common name: the proper name of the galaxy.