Interferometric coupling of the Keck telescopes with single-mode fibers.

Here we report successful interferometric coupling of two large telescopes with single-mode fibers. Interference fringes were obtained in the 2- to 2.3-micrometer wavelength range on the star 107 Herculis by using the two Keck 10-meter telescopes, each feeding their common interferometric focus with 300 meters of single-mode fibers. This experiment demonstrates the potential of fibers for future kilometric arrays of telescopes and is the first step toward the 'OHANA (Optical Hawaiian Array for Nanoradian Astronomy) interferometer at the Mauna Kea observatory in Hawaii. It opens the way to sensitive optical imagers with resolutions below 1 milli-arc second. Our experimental setup can be directly extended to large telescopes separated by many hundreds of meters.

Deep Impact: observations from a worldwide Earth-based campaign.

On 4 July 2005, many observatories around the world and in space observed the collision of Deep Impact with comet 9P/Tempel 1 or its aftermath. This was an unprecedented coordinated observational campaign. These data show that (i) there was new material after impact that was compositionally different from that seen before impact; (ii) the ratio of dust mass to gas mass in the ejecta was much larger than before impact; (iii) the new activity did not last more than a few days, and by 9 July the comet's behavior was indistinguishable from its pre-impact behavior; and (iv) there were interesting transient phenomena that may be correlated with cratering physics.

An infrared flash contemporaneous with the gamma-rays of GRB 041219a.

The explosion that results in a cosmic gamma-ray burst (GRB) is thought to produce emission from two physical processes: the central engine gives rise to the high-energy emission of the burst through internal shocking, and the subsequent interaction of the flow with the external environment produces long-wavelength afterglows. Although observations of afterglows continue to refine our understanding of GRB progenitors and relativistic shocks, gamma-ray observations alone have not yielded a clear picture of the origin of the prompt emission nor details of the central engine. Only one concurrent visible-light transient has been found and it was associated with emission from an external shock. Here we report the discovery of infrared emission contemporaneous with a GRB, beginning 7.2 minutes after the onset of GRB 041219a (ref. 8). We acquired 21 images during the active phase of the burst, yielding early multi-colour observations. Our analysis of the initial infrared pulse suggests an origin consistent with internal shocks.

Vegetarian lifestyle and bone mineral density.

The amount and type of dietary protein affect bone mineral loss after the menopause. This observation was substantiated in 10 y of studies by direct photon absorptiometry, four results of which follow. 1) Studies of 1600 women in southwestern Michigan revealed that those who had followed the lactoovovegetarian diet for at least 20 y had only 18% less bone mineral by age 80 whereas closely paired omnivores had 35% less bone mineral. 2) A study of self-selected weighed food intake showed no statistical difference in nutrient intakes but a difference in Ca:P ratio and acid-base formation of diet, each significant to p less than 0.001. 3) When sulfur intake of a fixed diet was increased, the titratable acidity of the urine increased proportionately. 4) Bone mineral densities of 304 older women from the continental United States closely paralleled those from earlier Michigan studies.

Bone mineral mass in adult lacto-ovo-vegetarian and omnivorous males.

Past studies indicate postmenopausal women who eat meat may experience greater bone mineral loss than lacto-ovo-vegetarian women. The present study extends those findings by comparing bone mineral in adult lacto-ovo-vegetarian and omnivorous males. Bone mineral mass was determined by direct photon absorptiometry in 320 lacto-ovo-vegetarian and 320 omnivorous males 20 to 79 yr old. Lacto-ovo-vegetarians were Seventh-day Adventists committed to their diet for at least 20 yr. Measurements were made at a cortical site along the radius. No statistical differences were identified between bone mineral mass in the lacto-ovo-vegetarian and omnivorous males in any decade examined. When contrasted against significant differences between bone mineral mass in postmenopausal omnivores and lacto-ovo-vegetarians, the data presented here may be interpreted as indicating that some factor associated with meat consumption is increasing bone mineral losses in postmenopausal females while having no observable effect in males.

Single electron counting by self-scanning diode array in a Kron camera.

A linear self-scanning array of 512 elements was exposed to photoelectron bombardment in a Kron camera tube. This is a demountable tube in which the photocathode and the electron focal plane can be separated by means of a special coin valve. The diode array was mounted in the electron optical focal plane. The video signal amplitude distributions were analyzed when the diode array was exposed to electrons between 30 keV and 35 keV. The distribution of the signals due to single electrons could be resolved from the distribution of signals when no photoelectrons were present. The impairment of the SNR due to the lack of perfect resolution of the distributions amounts to no more than the loss of a few percent of the photoelectrons. The result of these tests encourages the immediate application of the diode array Kron tube spectrography to high resolution spectroscopy of very faint objects.