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| M |
- |
Messier object number |
| NGC |
- |
NGC catalog number |
| Const |
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Constellation |
| Type |
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Object type: Gal=Galaxy, Pln=Planetary Nebula, OCl=Open Cluster, GCl=Globular Cluster, Dbl=Double Star, C-N=Cluster with Nebula, DfN=Diffuse Nebula, SNR=Supernova Remnant, Grp=Group, Pat=Patch |
| S.B. |
- |
Surface Brightness |
| Mag |
- |
Visual Magnitude |
| Size |
- |
Object size in arcminutes unless specified.
°=degrees, "=arcseconds |
| Rise |
- |
Object rise in local time |
| Set |
- |
Object set in local time |
| RA |
- |
Right Ascention |
| Dec |
- |
Declination |
| Mag A |
- |
For double stars. Visual magnitude of star A |
| Mag B |
- |
For double stars. Visual magnitude of star B |
| Sep |
- |
For double stars. Separation of stars A & B |
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| Sunrise & Sunset |
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Sunrise and sunset conventionally refer to the times when the upper edge of the disk of the Sun is on the horizon,
considered unobstructed relative to the location of interest. Atmospheric conditions are assumed to be average, and the location is
in a level region on the Earth's surface.
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| Moonrise & Moonset |
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Moonrise and moonset times are computed for exactly the same circumstances as for sunrise and sunset. However, moonrise and
moonset may occur at any time during a 24 hour period and, consequently, it is often possible for the Moon to be seen during daylight,
and to have moonless nights. It is also possible that a moonrise or moonset does not occur relative to a specific place on a given date.
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| Civil Twilight |
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Civil twilight is defined to begin in the morning, and to end in the evening when the center of the Sun is geometrically 6 degrees below
the horizon. This is the limit at which twilight illumination is sufficient, under good weather conditions, for terrestrial objects to be
clearly distinguished; at the beginning of morning civil twilight, or end of evening civil twilight, the horizon is clearly defined and
the brightest stars are visible under good atmospheric conditions in the absence of moonlight or other illumination. In the morning before
the beginning of civil twilight and in the evening after the end of civil twilight, artificial illumination is normally required to carry
on ordinary outdoor activities. Complete darkness, however, ends sometime prior to the beginning of morning civil twilight and begins
sometime after the end of evening civil twilight.
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| Astronomical Twilight |
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Astronomical twilight is defined to begin in the morning, and to end in the evening when the center of the Sun is geometrically 18 degrees
below the horizon. Before the beginning of astronomical twilight in the morning and after the end of astronomical twilight in the evening
the Sun does not contribute to sky illumination; for a considerable interval after the beginning of morning twilight and before the end of
evening twilight, sky illumination is so faint that it is practically imperceptible.
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| Solar Noon |
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Solar noon is when the sun appears the highest in the sky (nearest zenith), compared to its positions during the rest of the day.
It is also the point of time during the day when the sun is aligned with True North and True South.
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