Object identification window

This window displays information about the object or area clicked on.

If an object was found, its type and name (if available) are listed. Also listed are positional coordinates: right ascension, declination, azimuth, and altitude (at the time the object was selected). If this is not the first identification done, then the angular separation from the previous identify is listed.

Also displayed are J2000 coordinates, which describes the location without precession and nutation. These are the coordinates commonly seen in star charts. Precession is the slow wobble the earth's axis makes (like a gyroscope) over a 25,800 year cycle. Additionally there is a small nodding of the axis which is called Nutation. The two combined shift the J2000 coordinates into the observed coordinates.

For the Sun and the planets, the distance in astronomical units (AU) is given. (1 AU is approximately the mean distance from the Earth to the Sun.) For the Moon, the distance in kilometers (KM) is given. To convert from AU to KM, multiply by 149,597,870.691. To convert from KM to miles, divide by 1.609344. Also the angular size is given in seconds for the planets, and in minutes for the Sun and Moon. (Jupiter and Saturn have noticeable differences between equatorial and polar diameters due to their rapid rotations. The larger (equatorial) size is given. Multiply Saturn's size by 2.27 to get the width of its (readily) visible rings. The size for Venus includes its thick cloud layer.) The angular size is also given for most deep sky objects.

Depending on availability, the (apparent) magnitude is given, and for stars, their designation (Bayer and/or Flamsteed labels followed by a 3 letter constellation abbreviation) and spectral type are listed.

Corrections applied to coordinate positions

Although the speed of light is very fast (299,792,458 meters per second), it is not infinite. This requires adjustments for the following:

Additionally the sun, moon, and planets are adjusted to account for the observer's longitude and latitude. (This corrects for diurnal parallax - also called geocentric parallax.)

Some adjustments not done, but may be included in later versions of Night Vision, are: