THE VON RHETICUS MODEL TELESCOPE

The von Rheticus telescope is a ground-based instrument with two knobs on the eyepiece to adjust the power of the telescope. A larger button increases the magnification, while a smaller one decreases it. Magnification ranges from 10 to 250 and is displayed as a red number in the field of view. The knob on the left side adjusts the focus, and there's an autofocus feature that is disabled by pulling the knob. The telescope is small, about 15 cm long with a 2.5 cm wide objective lens, but its resolution is excellent due to magic.

The resolution of a telescope is measured in arcseconds and the wider the lens, the lower the resolution. The von Rheticus telescope has a resolution of one arcsecond, which is amazing for its size. The maximum useful magnifying power is approximately 250.

Unlike Muggle telescopes, the von Rheticus does not require a tripod, as it compensates for hand-shake with magic. It has charms to protect the objective lens from scratches and breakage, but it is still fragile. It is important to take care of it with caution.

The telescope is prohibited from looking at the Sun and the full Moon, as their magical power may damage the telescope and cause damage to the observer's eyes. A solar filter should be used to view the Sun, and it is always recommended to keep the lens cap on when the telescope is not in use.

THE LUNASCOPE AND THE LUNAR CHART

To organize a stargazing party, it is important to avoid nights with a full or near full moon, as the brightness of the Moon makes stargazing difficult. To determine which nights to avoid, two magical tools can be used: a lunascope and a moon chart. The lunascope shows the image of the Moon in the phase it will be in at a future date, while the moon chart shows images of the Moon on ten consecutive dates. Both tools allow you to plan the party on a night suitable for stargazing. The lunascope is quicker to switch to specific future dates, while the moon chart displays ten dates in a row with the option to view ten previous or future dates by touching dots on the scroll.

THE HEAVENLY GLOBE

A celestial globe is an astronomical tool similar to a terrestrial globe but shows the stars and constellations in the sky, with some showing mirror images of the constellations as normally seen from Earth. It is useful for identifying the stars and constellations, but it cannot show the Sun, the Moon, or the planets due to their movements. However, the magical version of the celestial globe, like the Marauders' Map, can show the Sun, Moon, and planets, including their positions on a specific day, making it a valuable tool for astrology and the location of the planets in the sky.

OTHER ASTRONOMICAL TOOLS

There are various astronomical tools used by both muggles and wizards. A planetarium is a model of the solar system with the planets moving around the Sun, used for educational purposes. Star charts, which are flat maps of the sky that help locate stars and constellations, are also used. To read star maps in the dark, astronomers use astronomer's lamps that emit a pure red light that does not affect the dark adaptation of the eyes.

VIEWING TIPS

When using a telescope, it is advisable to first locate the desired object with a scope or by setting the telescope to low power and then increasing the power. The telescope may have better resolution than a Muggle-built one, but it won't pick up any more light. To see dim stars, one can look away from the center of the field of view, since the central fovea of the eye is less sensitive to dim light than the periphery. To distinguish planets from stars, the planets do not blink due to their larger angular size. Furthermore, it is possible to estimate the angular separation of two celestial bodies using the hand as a reference.