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Astronomical instruments can be divided into two major categories. The first category might include all of the instruments which are used in the actual process of observing celestial objects. Some of these, like the meridian transit, are designed for specific tasks such as the precise determination of an observer's position on the earth or a star's position in the sky; other observational instruments are principally collectors of the radiation emitted by stars, planets, nebulas, and galaxies. These latter, which are generally referred to as telescopes, enable objects invisible to the naked eye to be seen, photographed, or otherwise detected.
In the second category may be grouped the auxiliary instruments which are used to standardize, record, or analyze the data obtained by the observational equipment. Devices to provide an accurate standard of time, to determine the brightnesses of stars, to record their spectra, or to measure the positions of stars on photographic plates.
Measuring the Brightness of Stars:
Photometry dates back more than 2,000 years to when the Greek astronomer Hipparchus divided the naked-eye stars into six brightness classes. The brightest visible stars he called stars of the first magnitude and the faintest visible he called stars of the sixth magnitude. Pogson in 1856 defined the magnitude scale so that a difference of 5 magnitudes was exactly a factor of 100 in brightness, which had earlier been shown by Herschel to be roughly the intensity ratio of first to sixth magnitude stars.
The human eye can detect differences of brightness of about 20% or 0.2 magnitudes and with training and use of special techniques this can be reduced to 10%.
The apparent brightness of any object in the sky is due to its intrinsic brightness and to its distance. For instance, the brightest known object in the Universe is a very faint quasar as seen from the Earth, and can only be seen with a large telescope. If it were as close as the nearest galaxy, it would be easily visible to the naked-eye
Other devices are available which can measure the brightness of an astronomical object in X-rays, the ultraviolet, the infrared and in radio-waves. Some of these have to be used outside the Earth's atmosphere, in rockets or satellites, because the radiation does not pass through the atmosphere.
By using filters to isolate particular parts of the spectrum, astronomers can make photometric measurements which enable them to determine the intrinsic brightness, the distance, chemical composition and age of individual stars and galaxies and discover quasars near the limit of the observable universe.
Astronomical spectroscopy:
Modern astronomical spectrographs can be very large complex instruments. The spectrograph designed for the William Herschel 4.2 metre telescope on La Palma is about the size of a small car but the optical components have to be kept in position to an accuracy of one thousandth of a millimetre. The spectrographs on La Palma are used for a wide variety of research programmes initiated by astronomers from the RGO and from University departments, often in collaboration with radio, infrared and X-ray astronomers.
Telescopes:
The atmosphere also stops us from seeing very sharp detail in images. When you look at the stars at night you can see them twinkle. This is the effect of layers of air at different temperatures, in the atmosphere, bending light towards and away from your eyes. The same bending affects optical telescopes and results in stars appearing as fuzzy blobs, not as pinpoints. Astronomers go to great lengths to put their telescopes where the atmosphere is most stable, but to get the best results we must go outside the atmosphere.
The Hubble Space Telescope was designed to give us this excellent resolution and to be able to work in the ultraviolet. It is giving us pictures better than any seen before and has changed our ideas about many things. Other satellites measure in the ultraviolet, the infrared, X-rays and gamma rays. They have revealed objects that we did not know existed and have resulted in an even greater demand for large ground-based optical telescopes to study these interesting objects.
Fourth Light at Paranal:
It was a historical moment last night (3-4 September 2000) in the VLT Control Room at the Paranal Observatory, after nearly 15 years of hard work. Finally, four teams of astronomers and engineers were sitting at the terminals – and each team with access to an 8.2-m telescope
Big Bang:
In the last decade scientists concluded that the Universe is about 13.7 billion years old. To put this in perspective, our Sun and solar system are around 4.5 billion years old so are relatively youthful. But the earliest stars are thought to have started life within a few hundred million years of the Big Bang – the event that marked the beginning of the Universe.
Light from even the nearest stars takes several years to reach us, so we see them as they were a few years in the past. As telescopes improve, fainter and more distant stars and galaxies can be seen. The more distant objects are seen as they were further back in time, so astronomers are able to deduce how the Universe has changed.The Hubble Space Telescope (HST), Chandra X-ray observatory and Spitzer infrared telescope are now operating together in orbit above the Earth. Their observations of the early Universe have been combined in the Great Observatories Origins Deep Survey (GOODS) with the goal of searching for the most distant galaxies.
International, with a notion of accelerating scientific discoveries is a forerunner in Open Access Journals and International scientific Conferences. ConferenceSeries is strongly supporting unrestricted access to the research by publishing around 400 Open access journals and conducting over 300 Scientific Meetings all over the globe annually with the support of more than 1000 scientific associations, 30,000 editorial board members marking its worldwide presence annually. OMICS Group, peer-reviewed open access journals is striving with the aid of 3 million readers, 30000 well-assembled Scientific Board and International Societies & Associations for making research a global public resource. At the same time ConferenceSeries Conferences is also promoting exchange of ideas by World class Keynote speeches, Poster presentations and Speaker Sessions. ConferenceSeries Conferences provides excellent opportunities for global networking and to promote collaborations in the field through ConferenceSeries Symposiums & ConferenceSeries Workshops.
Symposiums
1. LISA Symposium, 18 May 2014 - Friday, 23 May 2014, Florida
2. IAU Symposium 305 - Polarimetry: From the Sun to Stars and Stellar
Environments, 30 November 2014 - Friday, 5 December 2014, Punta Leona, Costa Rica
3. 2014 IEEE Nuclear Science Symposium and Medical Imaging Conference, 8 November 2014 - Saturday, 15 November 2014, Seattle, WA USA
4. Fifth International Fermi Symposium, Monday, 20 October 2014 - Friday, 24 October 2014, Nagoya, Japan
5. IAU Symposium 313: "Extragalactic jets from every angle", 15 September 2014 - Friday, 19 September 2014, Puerto Ayora, Capital of Galapagos Islands, Ecuador
6. Star Clusters and Black Holes in Galaxies across Cosmic Time IAU Symposium No. 312, Monday, 25 August 2014 - Friday, 29 August 2014, Beijing, China
7. IAU Symposium 311: Galaxy Masses as Constraints of Formation Models, Monday, 21 July 2014 - Friday, 25 July 2014, University of Oxford, UK
8. XIII International Symposium on Nuclei in the Cosmos, Monday, 7 July 2014 - Friday, 11 July 2014, Debrecen, Hungary
9. EWASS 2014, Symposium 2: The outer regions of extrasolar planetary systems, Thursday, 3 July 2014 - Friday, 4 July 2014, Geneva, Switzerland
10. 2014 Higgs Symposium: New Horizons in Particle Cosmology, Monday, 30 June 2014 - Wednesday, 2 July 2014, Edinburgh
Companies
1. Vacuum Plus Ltd
2. Synopsys, Optical Solutions Group
3. McPherson
4. Pfeiffer Vacuum
5. The Optoelectronics Company Ltd
6. Moxtek, Inc.
7. Piezo Technologies
8. Imagine Optic
9. Spectrum Metrology Ltd
10. Lasermet Ltd
11. Oelabs Inc
Societies
1. Amateur Astronomers Association of Pittsburgh
2. American Astronomical Society
3. Astronomical League
4. Astronomical Society of Australia
5. Astronomical Society of South Australia
6. Astronomical Society of the Pacific
7. Astronomical Society of Victoria
8. Birmingham Astronomical Society
9. British Astronomical Association
10. Confederation of Indian Amateur Astronomers
Conferences
1. Bright Emissaries conference, August 10, 2014, London
2. Bright Emissaries conference, August 13, 2014, Ontario CANADA
3. Lyman Continuum Leakage and Cosmic Reionization, 13-15 August 2014
Alba Nova University Center, Stockholm University, Stockholm, Sweden
4. Cosmo 2014, August 25-29, 2014, Chicago
5. 44th Young European Radio Astronomers Conference (YERAC), 8-12 September, 2014, Poland
6. Stellar N-body Dynamics, Sep 8-12, 2014, Sexten
7. XXI SIGRAV Conference on General Relativity and Gravitational Physics, September 15-19, 2014
8. APRIM 2014, 12th Asia Pacific regional IAU Meeting, Aug 18-22,2014, Korea
9. FIBER OPTICS IN ASTRONOMY – IV, August 19-21, 2014, Harvard-Smithsonian Center for Astrophysics, Cambridge, MA
10. The Early Life of Stellar Clusters: Formation and Dynamics, 03 Nov 2014, Copenhagen, Denmark
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This page was last updated on December 23, 2024
