... Bad Astronomy . ... Bitesize Astronomy . ... Last week's Snack talked about how black holes can affect the environment around them in such a way as to be very bright . ... It's a common misconception that black holes always have matter swirling into them. ... As this matter gets closer and closer to the black hole it piles up and a large, fairly flat disk forms. This is called the accretion disk , because matter from this disk accretes (that is, falls in) on the black hole. ... 2008 Phil Plait. ...

... Category: CLEAN, MANIPULATION, RADIO, TABLES File: clean.c Author: K.G. Begeman Description: CLEAN finds point source components and subtracts them with their antenna response. ... Keywords: INSET= Set and subset(s) of dirty map(s)/line(s). Maximum number of subset(s) is 2048. ... DEFSET= Set and subset(s) for definition of search area [Search area defined by box]. CLEAN looks for components only where the values in these maps/lines are not equal to BLANK. ... CUTOFF= Cutoff level [0.0]. ...

Seven months ago, on Mar 19, 2008, at 09:12 Moscow time, a new star appeared on the sky. The Sun had already risen over the Russia, but people of the Western hemisphere might be able to see by their eyes a faint starlet near one of Bootes constellation stars. This starlet appeared and faded by an order of magnitude in a minute. Astronomers named it GRB080319B or, informally, the Naked-Eye Burst, as it was twice as bright as human eye can see a star. ... Royal Astronomical Society . ...

... Previous: ESO C Library for an Image Processing Software Environment (eclipse) . ... A new CLEAN-type algorithm searches for model components not in the dirty image but in the multi-resolution wavelet transform of the dirty image based on the dirty beam. ... The improvement of this prototype Wavelet CLEAN, which does convolve with the dirty beam, can be attributed to a suppression of noise and aliasing in the dirty image by use of information in the sidelobes of the whole image domain. ...

... 2005 June 6 . Saturn: Dirty Rings and a Clean Moon . Credit: Cassini Imaging Team , SSI , JPL , ESA , NASA . Explanation: Eating surface ice from Enceladus might be healthier than eating ice from Saturn's rings -- it certainly appears cleaner. From their apparent densities and reflectance properties, both the rings of Saturn and its shiniest moon, Enceladus , are thought to be composed predominantly of water ice . ... About APOD | ... NASA Official: Jay Norris. ...

... Saturn: Dirty Rings and a Clean Moon . ... Credit: Cassini Imaging Team , SSI , JPL , ESA , NASA Explanation: Eating surface ice from Enceladus might be healthier than eating ice from Saturn's rings -- it certainly appears cleaner. ... For reasons that are not yet understood, however, many of Saturn's ring particles have become partly coated with some sort of relatively dark dust, while the surface of Enceladus appears comparatively bright and clean. ... Saturn s Ancient Rings . Ring Scan . ...

CCD Performance . ... The dark current appears to have two components: one from electronic sources in the CCD, and a second component whose strength correlates with the cosmic ray flux. ... As of this writing, the " DARKTIME" keyword in the WFPC2 image headers does not reflect correctly the actual time during which the CCD collects dark current. ... External exposures of 180s or longer made with the serial clocks off (CLOCKS=NO; the default setting) suffer an additional 60s of darktime (restart=1). ...

... On 11mar08 a sine wave was injected into the pdev baseband mixers to measure the mixer and pdev A/D levels. ... Onset of compression. 7dbm input, 9 dbm output , 15 dbm attenuation. ... A 9 dbm output will generate a sine wave with an amplitude of 2047 A/D counts. -8dbm input, 9 dbm output, 0 dbm attenuation. ... with 15 db attenuation, the mixer input is 7 dbm, H3-5 amp needs to output 22.5 dbm . with 0 db attenuation , the mixer input is -15 dbm, the H3-5 amp needs to output 22.5 dbm. ...

2009-05-20 O.Hainaut There are many steps between the data coming out of a camera on a professional telescope and the final image that appears in magazines or on our web sites. ... preliminary: from the telescope to Photoshop. cleaning: remove the artifacts remaining in the image . ... In each filter, several images are acquired. ... Fig 1: a raw image (click for full scale) . ... At this stage, the images are still in FITS, the astronomical format, with one FITS file per filter. ... The final image. ...

... Mike Carr and John Brinkmann breathe a sigh of relief as the camera makes it's way towards the clean room. Maki Sakaguchi/JPG, Craig Loomis/APO, Allyn Smith/UNMi, and Dave Summers/NMSU, along with Mike and Jon B., gather round for a last opportunity to see the camera before beginning it's hybernation in the clean room. These are the last of these minute-by-minute images. 35mm pictures have been extensively taken of all these activities. ...