Dawn Mob - Spring Event Cache
Pprime (P`): Thanks all, see you in Summer
Hidden
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Monday, September 23, 2013
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Difficulty:
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Terrain:
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Size: 
(not chosen)
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A different sort of event, and part three of a series in 2013.
Twilight is the time between dawn and sunrise or between sunset and dusk, during which sunlight scattering in the upper atmosphere illuminates the lower atmosphere, and the surface of the earth is neither completely lit nor completely dark. The sun itself is not directly visible because it is below the horizon. Owing to the distinctive quality of the ambient light at this time, twilight has long been popular with photographers, who refer to it as Sweet Light, and painters, who refer to it as the "blue hour", after the French expression l'heure bleue.
The collateral adjective for twilight is crepuscular; it is most frequently encountered when applied to certain insects, fishes, mammals, and cachers that are most active during that time.
Civil dawn twilight
Morning civil twilight begins when the geometric center of the sun is 6° below the horizon (civil dawn) and ends at sunrise. The brightest planets can appear during this time. Venus, the brightest planet as observed from the Earth is known as the "morning star" due to its visibility during civil twilight. There is enough light from the sun during this period that artificial sources of light may not be needed to carry on outdoor activities.
This concept is sometimes enshrined in laws, for example, when drivers of automobiles must turn on their headlights; when pilots may exercise the rights to fly aircraft; restrictions on hunting; or if the crime of burglary is to be treated as nighttime burglary, which carries stiffer penalties in some jurisdictions. A fixed period (most commonly 30 minutes before sunrise) is typically used in such statutes, rather than how many degrees the sun is below the horizon. Civil twilight can also be described as the limit at which twilight illumination is sufficient, under clear weather conditions, for terrestrial objects to be clearly distinguished; at the beginning of morning civil twilight, the horizon is clearly defined and the brightest stars are visible under clear atmospheric conditions.
The Event
This event is only for the duration of Civil dawn twilight on the day of the Spring Equinox. That is, commencing promptly at 5:13 AM (yes, in the morning) of Monday 23rd September 2013, and you are requested to sign the logbook prior to sunrise at 5:37 AM. At that time the logbook will be closed.
The location is under a large tree near the river.
That's it. Please note that this is a school day morning, so you may need to get permission before logging a 'will attend'.
Afterwards
Afterwards you may do what and where you wish, legally, however at the posted coordinates is a council-provided BBQ, and one picnic table (another one not too far away as well). I will be hanging around and making myself some breakfast - and coffee will once again be available – new coffee van supply for Spring. 
Additional Hints
(Decrypt)
Gurer jvyy or n pyhr nggnpurq gb gur ybtobbx gung jvyy or arrqrq ng gur sbhegu naq svany Qnja Zbo rirag yngre va gur lrne. Lbh jvyy arrq gb pbyyrpg nyy pyhrf, naq xrrc gurz fnsr nyy lrne. Gur ybtobbx jvyy bayl or ninvynoyr qhevat gur pvivy gjvyvtug crevbq.
Treasures
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