by neufer » Tue Dec 28, 2010 9:23 pm
Leena wrote:
I love looking at the Orion constellation. It is so prominent, even my 4 year old son can figure it out in the sky.
The horsehead nebula is one of the most breathtaking nebula silhoutted against the reddish backdrop.
I would do anything to spend some months in an observatory and peer through the cosmos and the heavenly bodies. its Amazing.
Pre-20th century astronomers working at the biggest observatories would have done anything
to spend some months just looking at the APOD images on your computer screen.
http://en.wikipedia.org/wiki/Astrophotography wrote:
<<
Astronomical photography did not become a serious research tool until the late 19th century, with the introduction of dry plate photography. It was first used by Sir William Huggins and his wife Margaret Lindsay Huggins, in 1876, in their work to record the spectra of astronomical objects. In 1880 Henry Draper used the new dry plate process with an 11-inch (28 cm) refracting telescope to make a 51-minute exposure of the Orion Nebula, the first photograph of a nebula ever made. A breakthrough in astronomical photography came in 1883, when amateur astronomer Andrew Ainslie Common used the dry plate process to record several images of the same nebula in exposures up to 60 minutes with a 36-inch (91 cm) reflecting telescope that he constructed in the backyard of his home in Ealing, outside London. These images for the first time showed stars too faint to be seen by the human eye.
1887 saw the Astrographic Catalogue and Carte du Ciel, the first all-sky photographic astrometry project. It was conducted by 20 observatories all using special photographic telescopes with a uniform design called normal astrographs, all with an aperture of around 13 inches (330 mm) and a focal length of 11 feet (3.4 m), designed to create images with a uniform scale on the photographic plate of approximately 60 arcsecs/mm while covering a 2° × 2° field of view. The attempt was to accurately map the sky down to the 14th magnitude but it was never completed.
The beginning of the 20th century saw the worldwide construction of refracting telescopes and sophisticated large reflecting telescopes specifically designed for photographic imaging. Towards the middle of the century, giant telescopes such as the 200-inch (5 meter) Hale Telescope and the 48-inch Samuel Oschin telescope at Palomar Observatory were pushing the limits of film photography.
Some progress was made in the field of photographic emulsions and in the techniques of forming gas hypersensitization, cryogenic cooling, and light amplification, but starting in the 1970s after the invention of the CCD, photographic plates have given way to electronic imaging in professional observatories. CCD's are far more light sensitive, do not drop off in sensitivity to light over long exposures the way film does (reciprocity failure), have the ability to record in a much wider spectral range, and simplify storage of information. Telescopes now use many configurations of CCD sensors including linear arrays and large mosaics of CCD elements equivalent to 100 million pixels, designed to cover the focal plane of telescopes that formerly used 10-to-14-inch photographic plates.
The late 20th century saw advances in astronomical imaging take place in the form of new hardware, with the construction of giant multi-mirror and segmented mirror telescopes. It would also see the introduction of space based telescopes, such as the Hubble Space Telescope. Operating outside the atmosphere’s turbulence, scattered ambient light and the vagaries of weather allows the Hubble Space Telescope, with a mirror diameter of 2.4 m, to record stars down to the 30th magnitude, some 100 times dimmer than what the 5-meter Mount Palomar Hale telescope could record in 1949.>>
[quote="Leena"]
I love looking at the Orion constellation. It is so prominent, even my 4 year old son can figure it out in the sky.
The horsehead nebula is one of the most breathtaking nebula silhoutted against the reddish backdrop.
I would do anything to spend some months in an observatory and peer through the cosmos and the heavenly bodies. its Amazing.[/quote]
Pre-20th century astronomers working at the biggest observatories would have done anything
to spend some months just looking at the APOD images on your computer screen.
[quote=" http://en.wikipedia.org/wiki/Astrophotography"]
[float=right][img3="Andrew Ainslie Common 1883 photograph of the same nebula, the first to show that a long exposure could record new stars and nebula invisible to the human eye."]http://upload.wikimedia.org/wikipedia/commons/thumb/9/9f/Orion-Nebula_A_A_Common.jpg/762px-Orion-Nebula_A_A_Common.jpg[/img3][/float][img3="Henry Draper's 1880 (first ever) photograph of the Orion Nebula"]http://upload.wikimedia.org/wikipedia/en/f/fe/Henry_Drape_Orion_nebula_1880_inverted.jpg[/img3]
<<[color=#FF0000][b]Astronomical photography did not become a serious research tool until the late 19th century, with the introduction of dry plate photography. It was first used by Sir William Huggins and his wife Margaret Lindsay Huggins, in 1876, in their work to record the spectra of astronomical objects. In 1880 Henry Draper used the new dry plate process with an 11-inch (28 cm) refracting telescope to make a 51-minute exposure of the Orion Nebula, the first photograph of a nebula ever made. [/color][color=#0000FF]A breakthrough in astronomical photography came in 1883, when amateur astronomer Andrew Ainslie Common used the dry plate process to record several images of the same nebula in exposures up to 60 minutes with a 36-inch (91 cm) reflecting telescope that he constructed in the backyard of his home in Ealing, outside London. These images for the first time showed stars too faint to be seen by the human eye.[/b][/color]
1887 saw the Astrographic Catalogue and Carte du Ciel, the first all-sky photographic astrometry project. It was conducted by 20 observatories all using special photographic telescopes with a uniform design called normal astrographs, all with an aperture of around 13 inches (330 mm) and a focal length of 11 feet (3.4 m), designed to create images with a uniform scale on the photographic plate of approximately 60 arcsecs/mm while covering a 2° × 2° field of view. The attempt was to accurately map the sky down to the 14th magnitude but it was never completed.
The beginning of the 20th century saw the worldwide construction of refracting telescopes and sophisticated large reflecting telescopes specifically designed for photographic imaging. Towards the middle of the century, giant telescopes such as the 200-inch (5 meter) Hale Telescope and the 48-inch Samuel Oschin telescope at Palomar Observatory were pushing the limits of film photography.
Some progress was made in the field of photographic emulsions and in the techniques of forming gas hypersensitization, cryogenic cooling, and light amplification, but starting in the 1970s after the invention of the CCD, photographic plates have given way to electronic imaging in professional observatories. CCD's are far more light sensitive, do not drop off in sensitivity to light over long exposures the way film does (reciprocity failure), have the ability to record in a much wider spectral range, and simplify storage of information. Telescopes now use many configurations of CCD sensors including linear arrays and large mosaics of CCD elements equivalent to 100 million pixels, designed to cover the focal plane of telescopes that formerly used 10-to-14-inch photographic plates.
The late 20th century saw advances in astronomical imaging take place in the form of new hardware, with the construction of giant multi-mirror and segmented mirror telescopes. It would also see the introduction of space based telescopes, such as the Hubble Space Telescope. Operating outside the atmosphere’s turbulence, scattered ambient light and the vagaries of weather allows the Hubble Space Telescope, with a mirror diameter of 2.4 m, to record stars down to the 30th magnitude, some 100 times dimmer than what the 5-meter Mount Palomar Hale telescope could record in 1949.>>[/quote]