... Since the fast mode window is necessarily small, the source PSF fills much of the window (clearly evident for bright sources). ... As such, the source and background extraction apertures may be truncated by the window. ... While often there will be only one object in the image, one should check for spurious detections which could affect the analysis of the target source and also for missed sources or prominent objects in the window, which may contaminate the target. ...

Next: Code II: Unknown Up: Image Restorations of High Previous: Construction of Algorithms . ... The positions of the designated point sources ( ) must be given as well as initial amplitudes for and . ... The integrated flux of the point sources ( ) plus that of the distributed emission ( ) is constrained to equal that of the observed image ( ). ... This is investigated in Fig. 1 where all emission derives from point sources but only one - the brightest - is designated as such. ...

... Archives . ... keV vs keV [Eqn] . ... As mentioned before, background subtraction plays a big role in astrophysical analyses. For a variety of reasons, it is not a good idea to subtract out background counts from source counts, especially in the low-counts Poisson regime. What Bayesians recommend instead is to set up a model for the intensity of the source and the background and to infer these intensities given the data. ... C = Poisson(? ... Chandra Blog . ... SAMSI AstroStat Prog. ...

In this gallery are many images of Low Surface Brightness Galaxies which have recently been discovered and analyzed. ... The central surface brightness of this galaxy is 24.28 . Malin 2 This galaxy is another huge disk galaxy with a scale length of 15 kpc and a redshift of 15000 km/a. The high surface brightness knot in one of its spiral arms actually has the same color, luminosity and H-alpha equivalent width as the entire Large Magellanic Cloud . ... Truly it is a Low Surface Brightness Galaxy. ...

. This is a new popup window - close it when you are done . Submitted by Michael Brown on 11/01/2014 15:21:30 . M-15 - globular cluster in Pegasus . 10/27/14 . I made this image from 11 - 30-second individual exposures. It's surprising how overexposed the center is, even with such short exposures. I remember Al Takeda warning me about that with bright globulars! . Logon to post a follow-up comment or review comments from others . Copyright (c) Amateur Telescope Makers of Boston, Inc. About Us Contact Us

... This paper describes the main algorithms used by the Einstein Level One processing to create the exposure masks and the background maps for Einstein IPC images, and how these algorithms were recreated in the IRAF environment. Our goal was to recreate the algorithms used by the Level One Processing to create exposure masks and background maps for Einstein Image Proportional Counter (IPC) data (cf. sections 2.5 and 2.7 of Harnden et al. ...

... The J, H and K bands are characterized by a bright background, such a background is mainly due to the emission of atmospheric lines and of thermal radiation. ... If the source cover a large fraction of the slit, spectra off-source must be observed to adequately sample the sky background. ... The on chip integration time (time spent in each position of the slit) must not exceed 40 seconds in J and H bands and 60 seconds in K band. ... We suggest a sequence of 10 for each elementary integration time. ...

... 1Haynes+ A catalogue at 5 GHz of 915 sources in the Galactic plane is presented. Sources with a peak beam brightness temperature of at least 0.2 K above the surrounding background are included, except in confused regions; a point source of 0.2 K corresconds to 0.26 Jy. ... It was assumed that Hydra A was a point source with a peak flux density of 13 Jy at 5 GHz; this is equivalent to a mean beam brightness temperature of 10.0 K for a beamwidth of 4.1x4.4'. ...

. Comment on J1130-1449 . There are two dominant components in our image. Comparison with the 15 GHz image of Kellermann et al. (1998) reveals that the western component is brighter at the higher frequency, indicating that the brighter (eastern) component in our image may have a steep spectrum. VLBApls home page . Last modified: 16 Oct 2000

... Copyrightї1997 Bob Yen (byen@ix.netcom.com) (http://www.comet-track.com/hb/hb.html) . ... Information on Comet Hale-Bopp for the Non-Astronomer Hale-Bopp rotates about twice a day (3/14/97) . ... The Comet Observation Home Page was been selected to receive the Griffith Observatory Star Award for the week of February 2 - 8, 1997 for excellence in promoting astronomy to the public through the World Wide Web. ... Typically, about 1,000 individual users/computers access this page every day. ...