Target Acquisition Reference Information . ... In almost all cases where an onboard acquisition will not work (because the object is in a crowded field, or is variable, or is a moving target), it is sufficient to use an early acquisition to get a WFPC2 or FOC image a few weeks in advance of the GHRS observation. ... Explicit BRIGHT and FAINT limits may be specified if you desire, although there is an increased risk of a failed acquisition unless you are confident of those fluxes. ... MAPs . ...

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. ...

The parameter brief (with its actual uncertainty sbrief) is the mean effective surface brightness in B-band , i.e. the mean surface brightness inside the effective aperture (the circular aperture enclosing one-half the total flux). It is expressed in mag arcsec -2 . ... 2) from the mean surface brightness "LV" inside the effective isophote (elliptical isophote enclosing one half the total flux) measured by Launberts&Valentijn (1989) . ... Effective radius . ... HyperLeda . ...

... real . ... All sources with MASKFRAC mfraclimit will have flag 1 set to T (see description). brcolumn . ... Name of column to be used to define a circle of influence of a bright source (used to set flags 2 and 4) . ... Number by which the 'brcolumn' is multiplied to obtain the 'circle of influence' radius in arcs (for flag 2) . ... Number by which the column EXT is multiplied to obtain the 'circle of extended emission' radius in pixels (internally converted to arcs) (for flag 3 and 5) . ...

Old subtables of the extended ``HIPASS Bright Galaxy Catalog'' . ... Koribalski, Staveley-Smith, Kilborn, + HIPASS/ZOA teams 2004, AJ 128, 16 . The 1000 Brightest HIPASS Galaxies: HI Properties . ... The 1000 Brightest HIPASS Galaxies: The HI Mass Function . ... The 1000 Brightest HIPASS Galaxies: Newly Cataloged Galaxies . ... To download the gzipped ps-file click here . ... The Brightest Galaxies from HIPASS . Presented is the distribution of the 700 brightest HIPASS galaxies. ...

... Guider functions . ... Guide Sensor Performance . ... Guide Sensor Sky Coverage/ Star Availability . Guide Star Selection Criteria . ... Guide fiber organization and reach at plug plate . ... Plug plate holes for guide stars are identical to those for science FO . ... FOV for each of 9 guide stars is 7.4 arcsec dia. (0.45 mm FO, Sumitomo IGN-05/10) . ... Selected guide stars must have no neighbor stars within TBD (5 arcsec) radius that have a brightness within TBD (5 mag.) of guide stars . ...

... We demonstrate through numerical simulations that model parameters estimated with our technique are essentially bias-free, even when the average number of counts per bin is 1. ... The IW technique avoids such biases by estimating through successive iterations, where for each iteration, j, , and the best-fit parameters are determined by minimization of . ... In our sample, we find that the minimum values and best-fit parameters converge after about 6 iterations. ...

THE PHOTOMETRIC RESEARCHS OF THE MERCURY'S SURFACE BY MEANS OF DIGITAL MODELS. ... The surface brightness of Mercury was measured Danjon (1933, 1949, 1953) and Harris (1961) in phase angle 3o-123o. The analysis of the various data of the integral photometric gives the results of determination of the main photometric constants for Mercury. ... THE PHOTOMETRIC RESEARCHS OF THE MERCURY'S SURFACE: S.G. Pugacheva The surface brightness of the Mercurian images was established on the geologic map Mercury. ...

The night sky brightness, together with number of clear nights, seeing, transparency, photometric stability and humidity, are some of the most important parameters that qualify a site for front-line ground--based astronomy. ... Night sky at ESO-Paranal (Chile). ... Night sky brightness data . ... UBVRI night sky brightness at ESO-Paranal during sunspot maximum (A 2003, PDF) . ... The Dancing Sky: six years of night sky observations at Cerro Paranal (Starlight 2007 conference proceedings, PDF) . ...

... Posts tagged ?parameter estimation? ... Leccardi & Molendi (2007) have a paper in A&A ( astro-ph/0705.4199 ) discussing the biases in parameter estimation when spectral fitting is confronted with low counts data. Not surprisingly, they find that the bias is higher for lower counts, for standard chisq compared to C-stat, for grouped data compared to ungrouped. ... Tags: bias , C-stat , chi-square , chisq , Cstat , Fitting , parameter estimation , Peter Freeman , spectra . ... 1 Comment . ...