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This website has been created by the members of the Lucky Imaging team based within the Institute of Astronomy and the Cavendish Astrophysics group of the University of Cambridge, England, UK in order to provide information about this exciting new technique, how it works, the present status of our latest results, and some of our ideas for development of the technique in the future. October 1, 2008: New Research Grant Awarded: The Institute of Astronomy has recently been awarded a substantial research grant to develop a new instrument capable of giving much better resolution in the visible from ground-based telescopes than is possible with the Hubble Space Telescope. It uses techniques which were demonstrated recently on the Palomar 5 m telescope to give the highest resolution images ever taken of the centre of the globular cluster (Click Here for more details). The team, led by Dr Craig Mackay, will use the £625,000 grant from the STFC to develop methods of using the light from faint reference stars to correct a major part of the atmospheric turbulence that smears astronomical images so badly. In conjunction with a Lucky Imaging camera already under development in Cambridge the team aim to achieve a resolution nearly five times that of the Hubble Space Telescope on 8-10 m class telescopes using natural guide stars alone.July 3, 2008: Eleven New papers presented at the SPIE conference in Marseille, June 2008: Click Here for full list.November 2, 2007: Adaptive Optics plus Lucky Imaging Named one of Time Magazine's Inventions of the Year. Click Here for more details.Update: Press Releases and other Press Coverage on Palomar 200inch LuckyCam plus Adaptive Optics: Higher Resolution Imaging than HST!A recent observing trip (July 2007) to the Palomar 200 inch telescope has been extremely successful. The images we obtained are the highest resolution direct images, about 50 milliarcsec FWHM, ever obtained either from the ground or from space in the visible at about twice the resolution of the Hubble Space Telescope. We used the same LuckyCam which we had previously operated on the NOT telescope on La Palma, Canary Islands as well as the NTT telescope in Chile. This time we attached it not directly to the telescope but to the Palomar adaptive optic system, PALMAO. This is a relatively low order adaptive optic system in the sense that there are only about 12 actuators across the diameter of the telescope. Nevertheless it works well and gives good images even in the visible. In the infrared particularly at K-band it is essentially diffraction limited. In the visible (I band, 850 nm) it produces images that are about 100-200 milliarcsecs in diameter. With the LuckyCam as well the image size was reduced very substantially to about 50-60 milliarcsecs, close to the diffraction limit of the telescope and about a factor of two better than the highest resolution of the Hubble Space Telescope. Images shown below are of the core of globular cluster M 13. The pairs of images show what the telescope delivers on its own, followed by what it delivers with the adaptive optic system and LuckyCam. The images beneath that of are NGC 6543, a planetary nebula commonly known as the Cat's Eye Nebula. These images are all slightly lower resolution than those of the globular cluster but nevertheless show the considerable improvement over conventional ground-based imaging that the AO system produces with LuckyCam. A planetary nebula is formed when the central star evolves from a red giant to its final white dwarf phase. A relatively short time in the life of the star, possibly 10,000 years in total, gas is ejected from the surface of the dying star. We can look at the expansion velocity of these filaments and sure that the age of the bright inner shells is probably only about 1000 years. The nebula is about 3000 light years from Earth.
The Globular cluster M13 as imaged conventionally by the Palomar 200 inch telescope, followed by M13 as imaged with the Lucky Camera behind an adaptive optics system on the Palomar 200 inch telescope.
The above images show a direct comparison between the Lucky image (left) and the Hubble image from the ACS (right). The Hubble picture goes fainter because the exposure is longer and the wavelength shorter (where CCDs have a much higher sensitivity). The ACS image has been "drizzled" to improve its appearance. The Lucky image is as taken. The markedly better resolution of the Lucky image is clear. This is exactly what is predicted purely because the Palomar 5.1 m telescope is twice the size of the 2.5m Hubble. The Cat’s Eye Nebula (NGC6543) as imaged conventionally by the Palomar 200 inch telescope. The green light is oxygen emission, the red is hydrogen emission, and the blue is near-infrared radiation, again followed by the Cat’s Eye Nebula (NGC7543) as imaged with the Lucky Camera behind an adaptive optics system on the Palomar 200 inch telescope. The resolution in the Lucky image is lower than Hubble as the image covers four times the area of the M13 images above, but it is still a good demonstration of what can be done from the ground. *********************************************************************************************** The images below were taken on the NOT telescope in 2005 and 2006
Figure: A Lucky Imaged binary star with 0.12 arcsec separation, and about 2.5 mag flux difference in I-band. This image shows Hubble Space Telescope resolution from the ground (on the NOT).
Figure: Three-colour images of the central part of the Crab nebula showing the central pulsar. the Image on the left was taken on the NOT with our Lucky Imaging System in November 2005, the one on the right is a composite of three different colours taken on the VLT 8-metre telescope in Paranal, Chile.
Movie: By folding a fast sequence of Lucky Images we can construct a movie of the pulsar in the core of the Crab Nebula. It varies on a 30 millisecond cycle, with a bright flash as well as a fainter interpulse. Lucky Imaging: General Introduction and Results SummaryA telescope is an instrument that deflects all the rays of light from a distant star or galaxy to form a sharply defined focused image of the object. In space, a telescope will produce an image whose resolution is only limited by the diameter of the telescope and the wavelength of light being focused. If our telescope is on the ground, however, density fluctuations in the atmosphere cause the rays of light to be deflected slightly so that the focused images become slightly fuzzy. The atmospheric fluctuations change fairly rapidly, on timescales of tens of milliseconds, causing the quality of the focused image also to change rapidly. By using a high-speed camera we can choose those images that are least affected by the atmosphere and combine them to give a much higher resolution image then we would get if we simply added together all the images irrespective of their quality. By doing this we are selecting those fortunate moments when the fluctuations in the atmosphere are at the smallest. This is what we call "Lucky Imaging". Lucky imaging techniques may be used both for astronomical observations with telescopes and for ground-ground imaging such as surveillance work with long focus lenses. Lucky imaging is not a new idea. It was originally suggested by Fried (1978) and these principles have been used really quite extensively by the amateur astronomy community who have been able to take very high quality images of bright objects such as Mars and the other planets. There is more information about Amateur Lucky Imaging here. The results of Lucky Imaging can be quite dramatic. The effects of atmospheric density fluctuations mean that the detail that may be detected in an image is limited. Using a large diameter telescope will allow one to gather more light but will not increase the detail in the image once a certain size has been reached that depends on the atmospheric conditions locally (and these change from day-to-day), and the wavelength of light used. For typical atmospheric seeing of about one arc second this limits the maximum resolution to that obtained in the visible with a telescope of only 10 centimetres in diameter. With Lucky Imaging we can increase the maximum resolution we can be achieved from the ground by factors of as much as 5-7. With the ground based 2.5 metre telescope we can match the resolution obtained by the 2.5 metre Hubble Space Telescope, at a tiny fraction of the cost. The effect on the image quality obtained is shown below.
Two pictures are shown of the same region of a globular star cluster M15, taken on the same telescope within a few minutes of one another. The first was taken with a conventional high-quality scientific CCD camera while the second was taken with a high-speed CCD camera with the best 10% of images selected and combined to produce the image shown. To see the full frame images, Click Here. This Lucky imaging web site includes the following:
GFDLcontent The work on this page is licensed under the GNU Free Documentation License (http://en.wikipedia.org/wiki/GNU_Free_Documentation_License). The author states that the text and images can be used within the restrictions of this license |
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