2 Magnitude limits

The concept of a magnitude limit is a numerical means of assessing the quality of the sky and the capabilities of the equipment you are using.

In theory instruments such as binoculars and telescopes with increasingly larger apertures collect more light allowing them to detect fainter and fainter objects.

However, as you have seen the Earth’s atmosphere forms an important part of the overall imaging system and the quality of the sky – in particular the transparency of the air and amount of stray light at a particular site – can limit the ability to see and to detect very faint objects. This can vary with height above sea level and also with the weather conditions on any particular observing evening.

In this section you will explore what makes Tenerife such a good observing site, explore the capabilities of the COAST telescope and imaging sensor (CCD camera), and find out how to estimate magnitudes of stars from astronomical images.