... In order to obtain a quantitative estimate of the accuracy and reliability of our data reduction procedures and results, we have performed a data reduction pipeline based on the following steps: i) define a set of simulated HST-like images with synthetic globular cluster stellar distributions, which provide the ``true'' data for comparison; ii) convolve these images with appropriate assumptions of PSF and noise in order to construct simulated `` observed '' ... It contains 470 stars. b) ...

Once students get the hang of it, they can find and measure the brightness of Delta Cephei in a few minutes. ... of Delta Cephei . ... Oct. ... The following table lists the measurements of Delta Cephei made by one amateur astronomer in autumn 1990. ... 4.0 . ... This activity is a simplified version of one that appeared in Hands-On Astrophysics, a series of activities prepared by the American Association of Variable Star Observers with support from the National Science Foundation. << previous page | ...

... About ATNF overview . ... Australia Telescope Steering Committee . ... Murchison Radio-astronomy Observatory . ... Parkes radio telescope . ... Australia Telescope 20GHz Survey . ... Bright prospects: Comparing the H Survey with large-scale radio continuum emission . ... Prospects for comparisons between the AAO/UKST H \ survey and large-scale radio continuum emission are considered, with particular reference to the recently completed Parkes 2.4-GHz survey of the southern Galactic Plane. ...

Star formation is often best manifested by bright H II regions.These are regions of hydrogen which have been ionized by ultraviolet photons which are emitted from massive stars (typically stars more than 20 times the mass of the Sun). ... A narrowband filter image centered on this wavelength will then readily reveal these H II regions and hence the current sites of star formation in a galaxy, The luminous blobs that can be seen here are all H II regions . ... NGC 3558 Visual . NGC 3558 Infrared . ...

... 6.06.2013 . ... Credit Copyright: morn1415 (YouTube) Explanation: How big is our Sun compared to other stars? In a dramatic and popular video featured on YouTube , the relative sizes of planets and stars are shown from smallest to largest. ... Note that the true sizes of most stars outside of the Sun and Betelgeuse are not known by direct observation, but rather inferred by measurements of their perceived brightness , temperature , and distance. ... Publications with keywords: star - planets . ...

... The sample of the Local Volume galaxies (distance smaller than 10 Mpc) gives a unique opportunity to study the properties of galaxies including the weakest objects: the absolute magnitude M B -10 and the virial mass M vir 10 9 M x263C;. ... Luminosity function of the Local Volume galaxies. ... The luminosity functions for galaxies are presented: red dashed line - from the 2dFGRS survey (Norberg et al. 2002); blue dash-dotted line - from the SDSS survey (Blanton et al. ...

... Mass . 17a. Measuring Mass . ... A medium-size (1.25 inch wide) binder clip, as is used in offices to hold papers together--the type made of flat blue steel, with two wire handles. ... The theory predicts that the oscillation period should be proportional to the square root of the oscillating mass, including the mass of the clip. Note that gravity plays no part here: the oscillation period would be the same on the Moon or in zero-g. Denoting square root by SQRT, we have . ...

... Three ` flavours'of binning and discard: · Discard 9 rows , readout 1 row, cut 10:1, resolution 1.75ms · Discard 90 rows , bin 10 rows , cut 10:1, resolution 2.76ms · Discard 95 rows , bin 5 rows , cut 20:1, resolution 2.76ms · Compared with normal timing : · 100 rows and readout, no cut, resolution 1.75ms Bin · Tested on XMM on Crab during rev 333 - 3 October 2001 Crab - rev 333 - Bright timing ... Counting mode and FIFO full errors. ... Crab - rev 333 - Bright timing mode ...

... 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 bright supernova (hereafter SN) in the galaxy NGC 4527 was first sighted by S. Knight (USA) on April 13.17UT at magnitude ~14.0v. The report of the sighting was subsequently forwarded by phone to the AAVSO. ... SN 1991T. The galaxy NGC 4527 is an Sb(s)II type galaxy with an apparent Blue magnitude of 11.32 (Shapley-Ames, 1981). ... An analysis of this event utilizing visual observations by amateurs, plus a light curve is presented.. ... THE LIGHT CURVE: . ... ISN SN 1991T web page . ...

... 2011 February 22 . Star Size Comparisons . ... Explanation: How big is our Sun compared to other stars? In a dramatic and popular video featured on YouTube , the relative sizes of planets and stars are shown from smallest to largest. ... Note that the true sizes of most stars outside of the Sun and Betelgeuse are not known by direct observation, but rather inferred by measurements of their perceived brightness , temperature , and distance. ... About APOD | ...

... Fitting the observed dependence includes calculations of the polarization cross-sections averaged over particles orientation and size distribution, their normalization and the comparison of obtained dependencies with Serkowski's curve representing observational data for a chosen star. ... Variations of the polarization factors with wavelength are shown in Fig. 16 for homogeneous spheroidal particles with PF orientation. ... The distinction between prolate and oblate spheroids is also clearly seen. ...

New reduction of minor planets photographic plates obtained with Pulkovo Normal Astrograph A.A. Berezhnoy Pulkovo Observatory of RAS, Saint-Petersburg, Russia Minor Planet observations at Pulkovo Periodical observations of 14 bright asteroids named Selected Minor Planets (SMP) were performed at Pulkovo since 1948 within the international framework started by works of B.V. Numerov and D. Brouwer. ... 108 133 113 74 124 67 97 88 14 84 64 5 20 19 Epochs (YYYY.MM) 1200 Mean values of total obs. ...

From: TerryMosel aol.com Date: Sat, 12 Jun 2004 19:59:21 EDT Subject: Delta Sco IS bright! Hi all, I got a much better brightness estimate later tonight, when Delta Sco Spica were about the same altitude above the horizon. ... At 00.50 (23.50 UT on 12 June) I estimated that Delta Sco was only 0m.4 fainter than Spica, making it 1m.4, or 0m.9 brighter than its quoted magnitude of 2m.3. ... Clear Skies, Terry Moseley . Last Revised: 2004 June 14th . ...

... In short, ROMAFOT performs the best fit by comparing a given pixel to the value of the PSF at the centre of the pixel. This approximation is valid if the pixel size is small compared with the scale length of the point images. ... With the commands below the integral of the PSF over the pixel area is computed via the Gauss - Legendre integration formulae which are characterized by a high precision for a correspondingly small number of subpixels where the PSF must be calculated. ... MODEL/ROMAFOT . ...

. Image of the inner 3 square degrees of the NGFS survey footprint compared with the size of the Moon. Low surface brightness dwarf galaxies are marked by red circles. Gray circles indicate previously known dwarf galaxies. The dwarf galaxies, which vastly outnumber the bright galaxies, may be the missing satellites predicted by cosmological simulations. NOAO

... Submitted by Paul Benni on 11/27/2013 18:38:14 . Comet C/2013 R1 Lovejoy (November 8) . Morning image (Nov. 8) of Comet Lovejoy. ... C8 EdgeHD SCT with Hyperstar (f/2.1) and ST-8300C ccd. Image is uncropped from the Hyperstar setup. Compare to my Comet ISON image with the same image scaling. Interesting how much brighter and larger Comet Lovejoy is now compared to ISON. ... Copyright (c) Amateur Telescope Makers of Boston, Inc. ...

... BLUE STRAGGLER STARS are unusually hot and bright stars found in the cores of ancient star clusters known as globulars. ... BACKGROUND (from wikipedia): Blue straggler stars are stars in open or globular clusters that are hotter and bluer than other cluster stars having the same luminosity. ... There is evidence in favor of this view, notably that blue straggler stars appear to be much more common in dense regions of clusters, especially in the cores of globular clusters. ...

... Bad Astronomy . ... Bitesize Astronomy . ... Keep Bad Astronomy close to your heart, and help make me filthy rich. ... When Venus is on the far side of the Sun, we see the entire near side lit by the Sun. ... When it is on the near side of the Sun, it shows a beautiful thin crescent, because it is between us and the Sun and we see the mostly unlit dark half. ... To see this for yourself, draw a circle one centimeter across, then, next to it, draw a circle 6 centimeters across. ... 2008 Phil Plait. ...

... PROBLEMS: "Unknown" (i.e. no physics model) components; What's a "Good-Enough-Fit" (e.g. Poisson)? ... ASIDE: MULTI-SCALE FOR POISSON - called Multiplicative Multiscale Innovation Models MMI Slides courtesy of R.Willett, SAMSI 2006 Timmermann Nowak, 1999 Kolaczyk, 1999 ASIDE: MULTI-SCALE FOR POISSON - called Multiplicative Multiscale Innovation Models MMI Slides courtesy of R.Willett, SAMSI 2006 Timmermann Nowak, 1999 Kolaczyk, 1999 ASIDE: MULTI-SCALE FOR ...