Generic term for sunrise and sunset

Question

Is there a single generic term to refer, either collectively or arbitrarily, to both sunrises and sunsets?

I'm looking for something that could be used in the same vein as twilight can be used (formally or informally) to refer to both the pre-sunrise dawn period and the post-sunset dusk period, without specifying which.

I'm aware of the concept of a golden hour within the photography and cinematography communities, but I'm looking for something which refers more to the specific astronomical event, as a particular instant in time, while still being agnostic to the direction the sun is going.

Edit: To clarify, I'd like something that could describe, even informally, any or all of:

1. Instants when the sun is exactly at the horizon, or 0°,
2. Periods when the sun is near the horizon on either side, e.g., –2° to +2°, or
3. Periods when the sun is near the horizon, but strictly above it, e.g., 0° to +2°.

I am aware of the various astronomical definitions of twilight, but unfortunately none of them meets any of these.

Answer 1

The word twilight actually means what you're looking for:

twilight, n.: the light from the sky between full night and sunrise or between sunset and full night

Animals that are active during twilight are said to be crepuscular, so if you're looking for an adjective to apply to that period, crepuscular (which is itself derived from the Latin for twilight) should serve.

Edit: Lacking the context in which you wish to use the term you're looking for, I can offer these suggestions:

Sunset/sunrise occur at the instant that the sun's upper limb is tangent to the horizon. You could then, for example, have science officer of some enterprising starship reporting, "Two degrees to limb tangency, Captain" to mark some impending sunrise/sunset/moonrise/moonset/et ceteraset.

Sunset/sunrise occur at a precise zenith distance of 90.8333 degrees. You could coin a term for this value, so that the same science officer could report, "Two arc seconds from zenith distance alpha, Captain."

Answer 2

Nautical twilight occurs right after civil twilight in the evening, and right before civil twilight in the morning. This phase occurs when the center of the sun is between 6 and 12 degrees below the horizon in the morning and evening. This period also usually lasts around 30 minutes and the primary color cast across the atmosphere is usually a deep blue tone with still noticeable orange and yellow hues left over from the fading sun. The horizon is still visible during this time... The light has started to dissipate quickly and silhouettes are going to be more prevelent... Details will be harder to make out during this time but there is still some remaining light on the horizon from the sun.

Answer 3

Look up crepuscular... see if that fits your needs.

Definition of crepuscular in English:
adjective

1. Resembling or relating to twilight.

1.1. Zoology (Of an animal) appearing or active in twilight.

Source:
http://www.oxforddictionaries.com/definition/english/crepuscular

Answer 4

There is the twilight zone, or the terminator:

A terminator or twilight zone is a moving line that divides the daylit side and the dark night side of a planetary body. A terminator is defined as the locus of points on a planet or moon where the line through its parent star is tangent. An observer on the terminator of such an orbiting body with an atmosphere would experience twilight due to light scattering by particles in the gaseous layer.
_Wikipedia

Answer 5

Horizon crossing, or solar horizon crossing? That doesn't account for non-flat terrain though.