AST05 - Astronomy Instrumentation PDF

AST05 - Astronomy Instrumentation Terms to Remember Telescope - an instrument that aids in the observation of remote objects by collecting electromagnetic radiation (such as visible light). The word "telescope" was coined in 1611 by the Greek mathematician Giovanni Demisiani...

AST05 - Astronomy Instrumentation Terms to Remember Telescope - an instrument that aids in the observation of remote objects by collecting electromagnetic radiation (such as visible light). The word "telescope" was coined in 1611 by the Greek mathematician Giovanni Demisiani ○ Hans Lippershey is known for being the inventor of the first known practical telescopes. ○ Galileo Galilei was the first one to use the telescope to observe the planets, the Moon, the Sun and other astronomical phenomena like supernovae. ○ Sir Isaac Newton is an English scientist who invented the Newtonian Telescope which uses a concave mirror as its primary mirror and a flat diagonal mirror as its secondary mirror. Types of Telescopes Radio telescopes ○ are directional radio antennas used for radio astronomy. The dishes are sometimes constructed of a conductive wire mesh whose openings are smaller than the wavelength being observed. ○ It has a lower frequency but longer wavelength which is ideal for wide and distant observation. X-ray telescopes ○ can use X-ray optics, such as a Wolter telescope composed of ring-shaped 'glancing' mirrors made of heavy metals that are able to reflect the rays just a few degrees. Gamma-ray telescopes ○ refrain from focusing completely and use coded aperture masks: the patterns of the shadow the mask creates can be reconstructed to form an image. ○ X-ray and Gamma-ray telescopes are usually on Earth-orbiting satellites or high-flying balloons since the Earth's atmosphere is opaque to this part of the electromagnetic spectrum. Optical telescopes ○ gathers and focuses light to a focal point mainly from the visible part of the electromagnetic spectrum (although some work in the infrared and ultraviolet). There are three main optical types: ○ Refracting telescope A refracting or refractor telescope uses a lens as its objective to form an image. Its design was originally used in spy glasses and astronomical telescopes but is also used for long focus camera lenses.  Although large refracting telescopes were very popular in the second half of the 19th century, for most research purposes the refracting telescope has been superseded by the reflecting telescope which allows larger apertures. A refractor's magnification is calculated by dividing the focal length of the optical tube by the focal length of the eyepiece. ○ Reflecting telescope Also called a reflector, is an optical telescope which uses a single or combination of curved mirrors that reflect light and form an image. The reflecting telescope was invented in the 17th century as an alternative to the refracting telescope which, at that time, was a design that suffered from severe chromatic aberration. It is a design that allows for very large diameter objectives. Almost all of the major telescopes used in astronomy research are reflectors. Since reflecting telescopes use mirrors, the design is sometimes referred to as a "catoptric" telescope. ○ Catadioptric system A catadioptric optical system is one where refraction and reflection are combined in an optical system, usually via lenses (dioptrics) and curved mirrors (catoptrics). Catadioptric combinations are used in focusing systems such as search lights, headlamps, and early lighthouse focusing systems, optical telescopes, microscopes, and telephoto lenses. Other optical systems that use lenses and mirrors are also referred to as "catadioptric" such as surveillance catadioptric sensors. Mounts ○ It holds your telescope securely and allows you to move the telescope so that it can be pointed precisely at the objects in the night sky you want to observe. Types of Mounts Altazimuth Mounts (Alt-Az Mounts) ○ These mounts allow the telescope to move in two axes: altitude (up and down) and azimuth (left and right). ○ Dobsonian Mounts: A type of alt-azimuth mount designed specifically for Newtonian reflectors, known for its simplicity and large aperture. ○ Advantages: Simple to use and set up. Generally more affordable. Great for terrestrial viewing and casual astronomy. ○ Disadvantages: Not ideal for long-exposure astrophotography due to field rotation. Requires manual adjustment to track celestial objects.  Equatorial Mounts ○ These mounts have one axis aligned with Earth's rotational axis, allowing the telescope to track celestial objects by rotating along one axis (right ascension). ○ German Equatorial Mount (GEM): Most common type, suitable for a wide range of telescopes. ○ Fork Mount: Often used with Schmidt-Cassegrain telescopes; easier to set up but can be less stable for very large telescopes. ○ Advantages: Ideal for long-exposure astrophotography. Simplifies tracking of celestial objects. ○ Disadvantages: More complex to set up and polar align. Typically more expensive than alt-az mounts. Parts of a Telescope  1. Finderscope 2. Focuser 3. Eyepiece 4. Release Control For Mount 5. Mount Base or Mounting Plate 6. Outer Tripod Leg 7. Tripod Leg Extension 8. Tripod Support Brace 9. Accessory Tray 10. Tripod Leg Clamp 11. Mount Axis 12. Mount 13. Mirror Cell – Primary 14. Telescope Tube 15. Slow Motion Control Lock 16. Finderscope Eyepiece 17. Finderscope Bracket Tips in Taking Care of Equipment 1. Clean Your Optics Carefully - To maintain sharp and clear images, clean your telescope's optics carefully. Use a soft camel-hair brush or blower bulb to remove loose particles, avoiding compressed air. For lenses and mirrors, use a specialized optical cleaning solution and a microfiber cloth, gently wiping in a circular motion. Avoid household cleaners and rough materials to prevent damage. 2. Keep Dust and Moisture at Bay - To protect your telescope from dust and moisture, use dust covers or caps for the lenses and mirrors, and avoid storing it in damp or humid environments. Use a dehumidifier in the storage area and consider desiccant packs to absorb excess moisture. Regularly check for moisture buildup or condensation and address any issues promptly to prevent damage. 3. Align Your Telescope Properly - Proper alignment is essential for accurate tracking and precise viewing with your telescope. Periodically check and calibrate your telescope's mount and finderscope according to the manufacturer's instructions. Use bright stars or specific alignment targets for this process. Accurate alignment enhances your viewing experience and makes celestial objects easier to locate. 4. Regularly Inspect and Adjust the Mount - Regularly inspect and maintain your telescope's mount to ensure stability and support for the optics. Look for signs of wear, such as loose screws, rust, or misalignment. Tighten loose components and lubricate moving parts as recommended by the manufacturer. A well-maintained mount ensures smooth tracking and reduces vibrations, enhancing image quality. 5. Store Your Telescope Properly - Proper storage is crucial for protecting your telescope and ensuring its longevity. Store your telescope in a dedicated case or a clean, dry area away from direct sunlight. Avoid placing heavy objects on it to prevent misalignment or damage. If you transport your telescope often, invest in a padded carrying case for additional protection against bumps and scratches. 6. Perform Regular Collimation - Regular collimation is necessary to keep your telescope's optical elements properly aligned, preventing blurry or distorted images. Over time, the primary and secondary mirrors can shift, so refer to the manufacturer's instructions or seek guidance from experienced astronomers to collimate your telescope. The process usually involves adjusting screws or knobs to align the mirrors. With practice, collimation becomes easier and ensures your telescope maintains optimal performance. 7. Use a Solar Filter for Solar Viewing - When viewing the Sun with your telescope, always use a solar filter to protect your eyes and equipment from the Sun's intense brightness. Observing the Sun directly through an unfiltered telescope can cause severe eye damage and potentially harm your telescope. Solar filters are designed to block harmful radiation, allowing safe observation of solar phenomena like flares and sunspots. Follow the manufacturer's instructions for using the solar filter to ensure safe and enjoyable solar viewing. 8. Regularly Update Firmware and Software - If your telescope has electronic components or computerized features, regularly update its firmware and software to ensure optimal performance, fix bugs, and access new features. Check the manufacturer's website periodically or subscribe to their newsletters for update notifications. Follow the manufacturer's instructions to perform updates correctly and avoid potential issues.