Contact

The Observatory Telescope

 
Sherwood Observatory Telescope

Our observatory houses a Newtonian telescope

 
This powerful telescope uses an array of mirrors to collect light from celestial objects and focus it for us to view.

The current telescope has been built and maintained by the team at Sherwood Observatory and is one of the largest public-access optical telescopes in the UK.

Visit Us

How the telescope works

The main Sherwood Observatory telescope uses a system of mirrors, in a Newtonian configuration

A 60-cm diameter main (primary) mirror collects light from the observed object.

Light reaching the primary mirror is reflected along the optical tube in a converging cone of light, before reaching an optically flat oval mirror inclined at 45° to the light path. The secondary ‘flat’ mirror is supported by an adjustable ‘spider’ system of cross braces.

This spider is the cause of ‘crosses’ that can sometimes be seen superimposed on photographs of stars. The light cone reaching the secondary mirror is then deflected into an eyepiece fixed to the side of the telescope which enables the viewer to focus on the object.

As the Earth is constantly rotating, our telescope is programmed to counteract this movement and keep objects in our line of sight for longer.

Viewing objects through our telescopes

We can view and record the objects through a range of different eyepieces and recording equipment

Interchangeable eyepieces give us access to a range of magnifications. The lower and intermediate powers are most frequently used as weather conditions determine how much magnification can be applied. High magnifications are typically only effective when the atmosphere is stable, for example, on clear, dark nights.A single-lens reflex camera can be used in place of an eyepiece to photograph the moon, planets, stars and a wide range of other objects.
A charge-coupled device (CCD) camera captures images more rapidly and these can be transferred and analysed on a PC.

We often use video cameras connected to smaller telescopes to display objects to visiting groups on a larger screen. This method also shows how atmospheric turbulence – known as ‘seeing’, can impact the quality of the images being detected.

An astronomical video camera can also be connected to our telescopes to allow images to be recorded for posterity.

Detecting far-away objects

We use specialist equipment to view objects in deep space

Bright objects such as the Moon, planets, and stars down to naked eye visibility can be found by using one of two “Telrad reflex sights” mounted onto the rear of our main telescope. When viewed from the rear, the Telrad provides a heads-up illuminated target which is aligned with the direction the telescope is pointing.

For fainter objects, where pointing accuracy becomes more critical, the 60-cm reflecting telescope is fitted with a fully computerised Sidereal Technologies Servo II controller, again calibrated to the direction of the telescope. With this, we can use standard planetarium software to command the scope to point at objects that are not bright enough to be seen with the naked eye.

Visit Us

Amazing place. So much history involved. Now with the added knowledge that a planetarium is going ahead, this will be epic. All run by volunteers too.

Caravan Chick – TripAdvisor