Is this the clearest picture of space ever taken?
Claims of the "sharpest" photos of space are a little fuzzy.
Earlier this week, a group of researchers at Cambridge University and the California Institute of Technology in Pasadena reportedly released the sharpest images of space ever taken. The team boasted that the images were twice as good as those taken by the Hubble Space Telescope. Moreover, the Earth-based camera used to take them is 50,000 times cheaper than Hubble.
Comments
Having spent more time talking to and e-mailing Geoff Brumfield about our results I was disappointed that he has got his facts so wrong. The images of the Cat's Eye Nebula were never claimed to be of better resolution than Hubble so the comparison, with the Hubble picture which anyway had been seriously processed to exaggerate low contrast sharp features (our pictures are unprocessed) was quite inappropriate and clearly spelled out to Geoff in my e-mails and conversations.
The real comparison is with our pictures of M13 where the resolution in our pictures is better than the Hubble one. This can be seen on our website at: http://www.ast.cam.ac.uk/~optics/Lucky_Web_Site/index.htm as a pair of black and white images (under the orange one) that show that resolution is indeed higher than Hubble's. In fact this should not be a surprise because the Palomar telescope at 5.1 m diameter is twice the size of the Hubble space telescope. Our better resolution is a consequence of elementary physics.
His article also implies that we throw away 99% of the data. In practice we throw away between 50 and 90% but still end up with a very high observing efficiency and overall cost effectiveness.
His conclusion that this will not replace Hubble is, however, absolutely correct and not something I or my colleagues have ever suggested.
Posted by: Craig Mackay | September 8, 2007 10:04 AM
If Lucky imaging researchers post more pictures to compare we can judge further.
Posted by: Jeyaganesh Rajamanickam | September 10, 2007 01:47 PM
The highest resolution image of astronomy by far is from 3mm VLBI. The resolution in this first paper was 50 micro-arcseconds: The Microarcsecond Structure of 3C273 at 3mm. Bååth,L.B., Padin,S., Woody,D., Rogers,A.E.E., Wright,M.C.H., Zensus,A., Kus,A.J., Backer,D.C., Booth,R.S., Carlstrom,J.E., Dickman,R.L., Eemrson,D.T., Hirabyashi,H., Hodges,M.W., Inoue,M., Moran,J.M., Morimoto,M., Payne,J., Plambeck,R.L., Predmore,C.R., Rönnäng,B.: 1991, Astron.Astrophys., 241, L1
Posted by: Lars Baath | September 11, 2007 11:56 AM
The opening paragraph contains a glaring error, one that is becoming increasing common but not what I would expect from a scientist who should know better, or a journal that should of had a correction made.
"50,000 times cheaper than Hubble." is not what was meant, 50,000th of the cost of Hubble is perhaps what is meant. The implication of this poor use of language is that if Hubble cost $1 then this telescope would cost $(1-(50,000*1)) = -$49,999 that is building this would have produced a profit and not a loss.
Posted by: Rhian Geleick | September 11, 2007 01:12 PM
The claim that "these are the highest resolution images taken from ground or space" ir wrong by a factor of 2000 (see my previous post). The 50 micro-arcsecond resolution from 3mm VLBI correspond to the size of a golf ball on the surface of the moon as seen from earth.It requires a diffraction limited optical telescope of 2 km diameter to achieve the same resolution. These claims therefore have to await the building of such a telescope.
Posted by: Lars Baath | September 11, 2007 03:30 PM
Keck Observatory has been producing infrared images at 50 milliarcseconds for years now (with the laser guide star). See work by UCLA at http://www.astro.ucla.edu/~ghezgroup/gc/pictures/lgs.shtml.
Also, it's important to compare apples to apples, in terms of wavelengths and instruments. I didn't see any Strehl information in the Lucky press release.
Measurements also vary with seeing, wavelength and a host of other factors.
Posted by: Laura Kinoshita | September 11, 2007 06:07 PM
Whilst in no way wishing to denigrate the efforts of other astronomers to obtain sharp images, either with ground-based or space-based telescopes, optical or radio, it might be of interest to note that gravitational lenses can achieve remarkable precision, when the geometry is right. For some years limb-darkening has been measured on stars in the galactic bulge by various gravitational microlensing groups. Typically, a gravitationally induced 'caustic' - a line of very high magnification - passes over a star, thereby profiling it with sub-micro-arcsec resolution. On one particularly fortuitous occasion, a star was profiled simultaneously by two pairs of caustics at right angles, enabling its shape to be profiled with resolution 0.04 micro-arcsec. See http://www.phys.canterbury.ac.nz/moa/stellar_atmospheres.html. Perhaps this could be regarded as the present record holder? Details at Rattenbury, N.J., Abe, F., Bennett, D.P., Bond, I.A., Calitz, J.J., Claret, A., Cook, K.H., Furuta, Y., Gal-Yam, A., Glicenstein, J.-F., Hearnshaw, J.B., Hauschildt, P.H., Kilmartin, P.M., Kurata, Y., Masuda, K., Maoz, D., Matsubara, Y., Meintjes, P.J., Moniez, M., Muraki, Y., Noda, S., Ofek, E.O., Okajima, K., Philpott, L., Rhie, S.H., Sako, T., Sullivan, D.J., Sumi, T., Terndrup, D.M., Tristram, P.J., Wood, J., Yanagisawa, T., Yock, P.C.M., Astronomy & Astrophysics, 439, 645-650 (2005).
Posted by: Philip Yock | September 15, 2007 11:02 PM