Ken Hough's Website
Astronomy

Under The Night Sky

Spending a night under the stars can be memorable, but to enjoy it fully, some planning and practice will be needed. No doubt you will develop your own ways of doing things, but the following notes might help.

Warm clothes:
Even in summer time, nights can feel cold, especially while not moving about much. Do take a warm jacket, hat, gloves and shoes/boots and thick socks. Cold feet can really spoil an otherwise good night. Don't worry about how you look. It's far better to KEEP warm.

Red torch:
After stepping outside into the dark, it takes 20 to 30 minutes for your eyes to become 'dark adapted'. During this period, you will notice that stars seem to become brighter and more of them can be seen. The last thing that you then need, is someone switching on a bright torch to see what they are doing. You dark vision will be impaired. It is of course necessary to be able to use some form of light to be able to read star charts and to manipulate telescopes, etc.

An effective solution is to use a torch that provides a sensible amount of only RED light. This can be achieved by fitting a red filter over a normal torch. Recently, torches that use red LEDs (light emitting diodes) have become available. These often include a brightness controller. LED torches are very effective, convenient, and batteries can last a long time.

Star Maps, etc:
You will need a star map for the current month or a 'planisphere', or even a computer based planetarium program running on your laptop PC (refer to section on 'Computers and astronomy').

Fresh batteries:
Although modern batteries have longer useful lives than the old "dry" cells, ALL batteries are adversely affected by low temperatures. Make sure that batteries are new or well charged and that you have spares. This last point is very important if you intend to do long exposure astrophotography using a digital camera.

Power supplies:
If using mains power supplies, DO ensure that power is fed via an effective RCD (Residual Current Detector). Dew/condensation can cause potentially dangerous leakage of electricity.

If working near to a car, a 12 volt supply might be taken from the cigarette lighter socket, but do check that 12 volts is OK. Note that some astro equipment uses only 6 volts!

Storage/transport for equipment:
It's very easy to collect a lot of equipment. It's perhaps not so easy to decide on the equipment that you will really need for a particular viewing session. You will need some form of storage to keep the selected items safe and to make them easily accessible. Believe me, in the dark you will want to be able to find say an eyepiece simply by feeling for it.

I use a heavy duty plastic lockable tool box that includes a lift out tray. The lid is strong enough to sit or to stand on. If a long refractor telescope is to be used then the lid might be good to sit on. If a large Newtonian scope is used while pointing high in the sky, the additional height of the box can provide extra viewing height. When the lid is shut, the contents are kept free from condensation/moisture.

Seat:
If you intend to spend much time looking upwards to see the stars, say via a pair of binoculars, then a comfortable seat or even a lounger/sunbed will make the time much more enjoyable.

Viewing through a telescope can also benefit from the use of a comfortable seat. However, the seat will need to be easily adjustable in height. There are special astronomer's seats available and designs for DIY seats can be found via the Internet.

Table:
If notebooks and perhaps a computer are to be used, then some form of table will be needed. A simple folding camping table might suffice. Ideally the table should include a raised surround so as to prevent items from slipping over the edge.

Steps:
The eyepiece of a big/long Newtonian or Dobsonian telescope can be well above head height if the telescope is pointed towards the zenith. It might be necessary to use a small pair of steps to reach the eyepiece. Unless the telescope is quite large, a storage/tool box of the type described above should be sufficient.

Temporary storage:
DO NOT leave exposed items on or near to the ground! In the dark, they are very likely to be stood on by you or by others around you. They are also very likely to become wet from the effects of dew. Ensure that all equipment can be stored in appropriate containers that are resistant to, or are protected from, external damage.

Practice makes perfect:
Do adopt a 'standard' procedure for storage and layout of equipment. Practise routines for assembly and disassembly of equipment. This should be well rehearsed before going out into a night time situation. If this is not done, there is a high probability of incurring frustration, damage to equipment, or even personal injury.

Neighbours:
Don't forget that you will be working after your neighbours have gone to bed. They won't thank you for tripping over a telescope at 1 am in the morning! Even placing a metal object carefully into a metal box can generate disturbing noise at night. Better to use plastic/polythene containers.

Simple is best:
Don't try to be too ambitious. Decide on a program of work. Set out the equipment needed and take out only that equipment. A lot of clutter can spoil an otherwise enjoyable night.

Anti-dew devices: Those of us who don't live in very dry locations often have to contend with the formation of dew and even frost on our telescopes and associated equipment. This problem is particularly common on exposed optical surfaces such as the objective lens of a refractor telescope or the corrector element of an Schmidt Cassegrain or Maksutov Cassegrain telescope.

A simple and often effective remedy is to fasten a flexible tube around the front of these telescopes. Some refractor telescopes have built-in anti-dew protectors.

Newtonian telescopes are less prone (but not totally immune) to dew because the optical surfaces lie well within the main structure. The optics of my 10" Newtonian scope rarely suffers from dew, but the associated 'Telrad' finder device (similar in function to a red dot finder) often collects so much condensation that it becomes unusable.

Where simple dew shields are not appropriate or effective, it might be necessary to provide low voltage electric heating.


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19/02/13