Scope DOCTOR Steve Richards

Our resident equipment specialist cures your optical ailments and technical maladies

Is it worth getting an equatorial Go-To mount when I have trouble seeing Polaris from my location? I only have a decent view from the northeast to the south-southwest.

TONY TEPEREK

Restricted viewing and not being able to see Polaris are common issues, however this shouldn’t dissuade you from purchasing a Go-To mount. If you are considering an equatorial Go-To it is normal to polar align it using a polarscope, but this is not the only method available to you. For observing, critical alignment with the north celestial pole is not essential and Go-Tos will be accurate enough using an approximate method.

A good approximation of polar alignment can be carried out using a magnetic compass to locate north and setting the altitude scales on your mount to your latitude, providing you have levelled your tripod with a spirit level first. You should check that the Your mount needs to be level for a rough alignment

to be effective altitude scale is accurate by setting it to 45°, placing the hypotenuse of a 45° set square on top of the RA axis and then checking that the horizontal side of the set square is level using the spirit level. Make a correction if there is any inaccuracy.

A better method, using a fixed location in your garden, is to carry out the above procedure and then perform a drift alignment. Once aligned by this method, mark the position of the tripod legs on the ground and always set up in this exact position and latitude marking.

In addition, many Celestron and Sky-Watcher mounts have a special polar alignment routine built into their handsets and these work very well without using Polaris. Condensation is a serious issue. If dew forms while you are observing, this can be ameliorated with dew bands or shields, but the dew that forms at other times can be a real problem and risks damage to both your scope and ancillary equipment.

Telescope covers such as the Orion Scope Cloak, TeleGizmos 365 Series Telescope Cover or Geoptik Telescope Cover will offer some level of protection. However, these should be supplemented by the use of a soft under-cloth of the type commonly used to protect greenhouse plants from frost in the winter as this will act as a ‘sacrificial’ dew catcher. A pouch containing silica gel should also be stored under the cover, but must be rejuvenated from time to time by baking in an oven.

A cover will only protect the telescope and mount, of course. By far the best solution is to run a desiccant type de-humidifier set to 60 per cent humidity to protect all the observatory’s contents.

Scope cloaks are best used in conjunction with greenhouse frost

covers and desiccant pouches