... Mindful of these biases, I can now explore the relations between the measured rotation periods and various other observables. The hypothesis behind monitoring stellar variability is that active stars have asymmetric spot distributions on their photospheres. ... They found that only stars with rotation periods greater than seven days show variations greater than 0.4 magnitudes at I. Bouvier et al . ... 1993a) demonstrated a relation between X--ray flux and spectral type in ZAMS stars. ...

... All the information about the propagation of a given plasma wave mode is contained in the appropriate dispersion relation, which relates the angular frequency w to the wave number k (magnitude of the propagation vector k ). ... Phase velocity . ... Group velocity . ... Wave propagation can also be described using diagrams called phase velocity or wave normal surfaces , which give the variations of the magnitude of the phase velocity of plane waves with respect to the magnetic field direction: . ...

Next: CAL_getBoresightMatrix Up: Routines of the Calibration Previous: List of CCF Components Contents . ... The CAL functions CAL_getBadPixelList & CAL_getBadPixelMap use the CAL state variable temperature only to check that the current operating temperature is consistent with the CCF constituent BadPix . ... Used CAL State Variables . List of CCF Components used . ... Next: CAL_getBoresightMatrix Up: Routines of the Calibration Previous: List of CCF Components Contents Michael Smith 2011-09-20 ...

... The Cross-Quarter Days thus mark the middle of each season under our current system, or seasonal boundaries under the alternative system. ... Beltane / Bealtaine - Celtic bonfire festival May 4-7 2nd Cross-Quarter Day May 5 - Cinco de Mayo (Mexico) May 2nd Sunday - Mother's Day May last Monday - Memorial Day ( Decoration Day , officially May 30) June 14 - Flag Day June 3rd Sunday - Father's Day June 20-22 2nd Quarter Day - Summer Solstice June 21 - Litha (Norse/Anglo-Saxon for ...

... Paranal and La Silla general information and long term statistics of various parameters relevant for observational astronomy. on meteorology, telescope environment, atmospheric turbulence, and related topics (includes links to some other sites) . ... Databases for the Characterization of Astronomical Observatories Workshop La Laguna, Tenerife, Canary Islands, Spain; 22-23 June 2015 . ... Astroclimatology of Chajnantor . ... Photometry: Night Sky Quality at Mauna Kea , Cerro Pachon , CTIO and IAC . ...

... A universal physical relation for quasars . ... Harvey Tananbaum and his collaborators have first observed a relation between the soft X-ray and the optical/ultraviolet emission in AGN in 1979. Such relation is nonlinear, and it is usually parameterized as dependence between the logarithm of the monochromatic luminosities at 2500 †Е ( L 2500†Е ) and 2 keV ( L 2keV ) . ... Yet, the dispersion along the L 2500†Е тАУ L 2keV relationship is found to be rather high, typically ~0.35тАУ0.4 in log units. ...

The distance modulus, mod0 [mag] is either computed from the distance catalogue or using the Tully-Fisher or Faber-Jackson relations. When measurements are available in the distance catalogue , mod0 is computed as the weighted average of those measurements. ... The Tully-Fisher relation uses the corrected total magnitude btc and the maximum velocity of rotation vmaxg . ... Another parameter, modz (redshift distance modulus), estimates the luminosity-distance using the redshift. ...

... ATNF Home . About ATNF . ... About ATNF overview . ... Australia Telescope Steering Committee . ... Murchison Radio-astronomy Observatory . ... Parkes radio telescope . ... Mopra radio telescope . ... Parkes | ATCA . ... Digital systems . ... Visiting Parkes radio telescope . ... Parkes radio telescope webcam . ... The ATCA 3mm installation is now completed . ... ATCA 12-mm system . ... First tests of 12mm system at the ATCA were carried out in October 1999. ... Go to MNRF1996 Projects Page . ...

... Early on, our interest in chirping analysis functions was motivated by a different kind of chirping phenomenon: chirping due to perspective. ... Our interest in radar, however, drew us toward processes that are more accurately analyzed by linear-FM chirplets. ... We have also constructed other chirplet transforms, such as a three-parameter Doppler chirplet representation that models a source producing a sinusoidal wave, while moving along a straight line (e.g. a train whistle). ...

A Model Based Approach to LOFAR Calibration and Imaging Stefan J. Wijnholds e-mail: wijnholds @astron.nl AAVP Workshop Cambridge (UK), 8 ­ 10 December 2010 AAVP Workshop , Cambridge , 8 ­ 10 December 2010 -1- The model based approach Traditional approach Model based approach relation between visibility and image planes (FT) ... AAVP Workshop, Cambridge, 8 ­ 10 December 2010 -7- SP example: KL-transform S.J. Wijnholds & A.J. van der Veen, ICASSP 2011, submitted LS-image vs. ...

... Armagh Observatory, College Hill, Armagh BT61 9DG, +44 (0)28 3752 2928 . ... News Feed . ... 2012 December 18th . ... Cooler November . ... Relative Humidity at Armagh Observatory, 1838-2008 . 2012 November 29th . ... 2012 November 28th . ... 2012 November 22nd . ... Armagh Observatory 2012 Robinson Lecture . ... 2012 November 1st . ... 2012 October 1st . ... Armagh Observatory Business Plan 2012-2013 (PDF) . ... Armagh Observatory and Planetarium Management Committee Minutes November 2011 - PDF . ...

... Recent Topics . ... MAO main . ... The third-order space-by-time relation . ... Тема: The third-order space-by-time relation . ... The mass m experiences a gravity force toward the sun and . ... will experience the Coriolis force or Coriolis acceleration. ... differentiated space-by-time twice and discovered equation2. ... If one differentiates . ... time differentiation of space-by-time. ... third-order space-by-time relation. ... understand the third-order space-by-time relation. ... MAO NASU . ...

Next: The Gravimagnetic Parameter Up: ``Ecology'' of Magnetic Rotators Previous: Nomenclature . ... One can introduce two critical periods and such that their relationship with period p of a magnetic rotator specifies the rotator's type: . ... Instead of , we introduce the potential accretion luminosity L . ... Treating the rotator's magnetic dipole moment and as parameters, we find that an overwhelming majority of the magnetor's stages can be shown on a `` '' diagram (Lipunov 1982a[ 98 ]). ...

... SUN MOON MERCURY VENUS MARS, JUPITER SATURN . ... Mars . ... Previously understood that magnetic fields were directly related to rotation, so when I read that Mars, like Venus, didn't have one, my understanding crumbled. What exactly causes magnetic fields in planets? ... RELATED TOPICS: MAGNETIC FIELD . Planetary magnetic fields are definitely related to rotation, but directly not so much. ... Get instant access to subscriber content on Astronomy.com! ...

... CV & PUBLICATIONS | ... Nicholls, DC, Dopita, MA, Sutherland, RS, Jerjen, H, & Kewley, LJ " Metal-poor Dwarf Galaxies in the SIGRID Galaxy Sample. ... Nicholls DC, Jerjen, H, Dopita MA, & Basurah, H. (2014) " Nebular Metallicities in Two Isolated Local Void Dwarf Galaxies ", Astrophysical Journal 780, 88 * . ... Sweet SM, Drinkwater MJ, Meurer G, Bekki K, Dopita MA, Kilborn V, & Nicholls DC, " CHOIRS H I Galaxy Groups: The Metallicity of Dwarf Galaxies" , (2014) Astrophysical Journal , 782, 35 * . ...

... 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. ...

The ESA/ESO Astronomy Exercise Series 2 . The Distance to Messier 100 as Determined by Cepheid Variable Stars . ... The small variations in distance to the individual Cepheid variable stars in the Cloud are negligible compared with the much larger distance to the SMC. ... In this way Cepheid variable stars can be used as one of the 'standard candles' in the Universe that act either as distance indicators themselves or can be used to calibrate (or set the zero point for) other distance indicators. ...

We compare atomic gas, molecular gas, and the recent star formation rate (SFR) inferred from HЮБ in the Small Magellanic Cloud (SMC). ... This allows us to disentangle conversion factor effects from the impact of metallicity on the formation and star formation efficiency of molecular gas. ... At a fixed total gas surface density the SMC has a 5-10 times lower molecular gas fraction (and star formation rate) than large spiral galaxies. ...

... Sun images . ... December : 2015 . ... Image of Sun's photosphere obtained 09.12.2015 at 23:40 UT with HMI instrument on board SDO spacecraft . ... Image of Sun's magnetic field obtained 09.12.2015 at 23:28 UT with HMI instrument on board SDO spacecraft . ... Image of Sun's transition region obtained 09.12.2015 at 23:39 UT with AIA instrument on board SDO spacecraft . Image of Sun's corona . Image of Sun's corona obtained 09.12.2015 at 23:39 UT with AIA instrument on board SDO spacecraft . ...

... The HST uses an onboard model of its orbit to perform in real-time various control functions relating to spacecraft operations and observation support. ... New coefficients for the ephemeris are updated every other day, and are archived as FITS keywords for each HST observation data set. Using these coefficients,an observer can perform a variety of calibration and characterization calculations relating to the orbital position and velocity of the telescope. ...