Some facts about BPO

Benmore Peak Observatory is sited between 1,800m and 1,932m asl on the summit
plateau of the Benmore Range in New Zealand's Mackenzie Basin.

Winters in the Mackenzie Basin are generally considered to be ideal for astronomical
activities, when the nights are very long (up to 14 hours or more in June), and the
weather is usually settled for long periods.

Summer brings short nights and, usually, a brief "rainy season", typically from December
through January. The remainder of the summer season is generally warm, dry and clear.

Depending upon prevailing atmospheric conditions, the BPO site regularly and often
experiences a sky darkness equalling those described by Bortle's scale as being of
Class 1. To date, the darkest reading obtained from the BPO site with a Unihedron
SQM-LE is 22.02 magnitudes/arcsecond².

The nearest significant city, Dunedin, population 120,000, is 165 kilometres SSE, while
Timaru, a large town with a population of 27,000 people, is 90 kilometres due east of the
observatory, and the largest city in the South Island, Christchurch, with a population of
approximately 250,000, is 225 kilometres ENE. There are numerous mountain ranges
between BPO and these localities.

Aside from scattered farms and dwellings, there are four small settlements within the
Mackenzie Basin. (Omarama, Twizel, Mount Cook, and Lake Tekapo villages.) Total
permanent Mackenzie Basin inhabitants usually number fewer than 2,000.

The prevailing wind in the area of Benmore Peak is from the west. It commonly occurs
in the months of spring, and occasionally sometimes during autumn. A warm and dry
föhn wind from the norwest clears residual snow from the mountain during the spring, but
neither wind usually exceeds 50-60 kph.

Seasonal temperatures extremes on the mountain can range between -20 °C and +20 °C.
The diurnal variation tends to be minor. It is not uncommon for the relative humidity levels
to fall below 10% for extended periods.

Although snow can and does fall at any time throughout the year, most occurs in the early
winter period. Typically, the accumulated snowbase rarely exceeds a depth of one metre
and is generally absent from late October to early May.

Rain is relatively uncommon at the observatory site, with precipitation usually occurring
only in the form of snow, or moisture condensing directly from summit cloud, usually during
high summer (December to February).

Cloud cover tends to be greatest during the brief summer wet season, and is below the level
of the observatory for much of the rest of the year, usually as a result of inversions which
commonly extend over the Mackenzie basin. Fog, low cloud, dust, pollen and most other types
of pollutants are generally kept at a level below the BPO site as a result.

Physical access to the site is often difficult. The track is long, rough, and steep, and not
suited to the faint-of-heart. Unfortunately it does attract wannabe action heroes, so restrictions
are in force. As well as from BPO staff, permission to access the track must be gained from
two other private landowners, or legal consequences will result.

The Benmore Range is classified as being both an Outstanding Landscape Area and an Area
of National Significance. The apparent desolation of the summit plateau belies the delicate and
fragile nature of the site. Protecting it and preventing damage is a high priority. Drivers must keep
to the defined track and designated parking areas at all times, with no exceptions.

Smoking, and the consumption of alcohol, is not permitted under any circumstances. BPO is
a very long way from assistance should fire or medical emergencies occur. Would-be visitors
who suffer from serious medical conditions are strongly advised to seek alternative venues, such
as Mount John University Observatory.

Visitors must accept these rules, and that the observatory cannot be held responsible for
any misadventure, in any way. Failure to comply by any visitor will result in their immediate
removal from the site.