. Next: Unit Conversion Up: Calibration Previous: Feed Polarisation Index . Sometime the nominal Tsys measurement at the telescope is wrong due to an incorrect noise diode calibration. This can easily be corrected for with the scale function. By default, scale only scaless the spectra and not the corresponding Tsys. ASAP>scans.scale(1.05, tsys=True) . Malte Marquarding 2007-08-16

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. ...

... Osservatorio Astronomico, Bologna, Italy . ... Dipartimento di Astronomia, Universit? di Bologna, Bologna, Italy . Stellar photometry of simulated HST uncorrected and corrected images of a crowded star cluster has been carried out before and after deconvolution (with RMG, R-L, MEM, etc.) to optimize the reduction procedures and compare the degree of completeness and photometric accuracy actually achievable in the various cases. ... Surface Brightness Profiles . ...

... Ideally, this map contains the energy offset for each pixel (expressed in analog-to-digital units, adu). ... High-energy particles hitting the EPIC pn CCD during the offset map calculation may cause the affected pixels to get offset values which are incorrect by a few adu. ... Due to the specific method of deriving the offset map onboard, the affected areas occur often in blocks of four consecutive pixels along readout direction. ... The affected pixels usually get an offset which is too small. ...

. Please standby and you will be automatically connected to the new location of the unframed Supernova page. Or, click on the link above. If you have questions or problems, please email me at David Bishop dbishop@vhdl.org . Last modified: Mon Aug 27 12:40:15 EDT 2001

... If you elect to model the sky, you will see some graphs showing the progress of the fitting procedure. First, if some bright stars were observed, you see a plot of sky data (for a given band and night) as a function of the adjacent star's brightness. ... Second, if there are enough dark-sky data to model, you will see a plot of the dark-sky data (corrected for star light) as a function of airmass, with the fitted term drawn in as + signs. ... Again, the fit is shown with + signs. ...

... The Galactic low-mass X-ray binary GS 2023+338 was discovered during the burst on May 22, 1989 with the Japanise satellite Ginga (aka Galaxy). The flux reached 17 crabs (this unit of flux measurement is an bright X-ray source, Crab Nebula) at 10-35 keV. ... No other radio telescope worldwide carried out multi-frequency measurements. ... Upon 14 days the radio flux fell below the detection level at the RATAN-600 in relation to the decrease of the X-ray flux. ...

Microsymposium 38, MS083, 2003 (A4 format) MERCURY: LOCAL VARIATIONS OF THE PHOTOMETRIC RELIEF. ... Because of trajectory and pointing angle constraints the planet could be observed from Mariner 10 only over a small range of phase angles between about 75o and 110o. Therefore the photometric investigations are restricted to measuring the distribution of brightness on the Mercurian disk. ... Raw versions of real-time processing pictures FDS 0000984 and FDS 0000986 were used (images 196 and 202). ...

... Particle distribution: dN d - with =1- ln pcn ln g Electron-photon conversion e + _ + _ electron _ e e electron/ positron high- energy photon e+ positron -25 cm cross-section, 10 8 6 4 2 0.5 1.0 center-of-momentum energy , MeV (log scale) 2 e + _ Proton-neutron conversion cm cross-section, 10 proton u +2/3 2 -28 d -1/3 6 u +2/3 4 resonance _ u d d+1/3 -1/3 d u+2/3 +2/3 -1/3 2 150 340 center-of-momentum ... Does the peak (cut-off) energy decrease with observation angle? Not always. ...

Definitions of Magnitudes and Surface Brightness 1 The magnitude system 1.1 Apparent magnitude Astronomers are stuck with the antiquated old system of magnitudes and so a clear explanation of what this system is and how it relates to more sensible units is important. ... 1.2 Absolute magnitude Absolute magnitude is a logarithmic luminosity scale. ... One usually goes by the round about process of referring to the absolute magnitude of the sun. ... Magnitudes and surface brightness 6/6 ...

... A comparison of the computed and experimental relations F max ( H), as well as comparison of drift scans of point sources across different horizontal cross-sections of the BP with the corresponding computed cross-sections were made. ... The drift scans of the point source 3С84 (H=87 o ) at the wavelength 7.6 cm across the horizontal cross-sections of the BP (black lines) and the computed horizontal cross-sections of the BP corresponding to them (red lines). ...

... Credit: Jay Ouellet Explanation: Early risers are currently enjoying the sight of dazzling Venus , near the eastern horizon as the morning star . ... It also includes a crescent Moon and Saturn (lower left). ... Though the Moon has moved on, the tight triangle formed by Venus, Saturn, and Regulus (top), alpha star in the constellation Leo, will continue to look impressive in early morning skies over the next few days. ... Publications with keywords: Venus - Moon - Saturn . ... Crescent Saturn . ...

... We present the results of recent pulsar observations at frequencies between 27.9 GHz and 34.8 GHz, i.e. in a wavelength range of 10.75 mm to 8.61 mm, made with the Effelsberg radiotelescope. The measured flux densities of two out of nine detected pulsars suggest that the spectrum flattens at high frequencies or even shows a turn-over. ... In this work we will only focus on pulsar spectra. ... Figure 4: Derived spectra of the second strongest pulsar observed at mm-wavelengths. ...

... Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. 2005 August 30 . Albireo: A Bright and Beautiful Double . ... Such is the case of the bright double star Albireo . Seen at even slight magnification, Albireo unfolds from a bright single point into a beautiful double star of strikingly different colors. ... About APOD | ... NASA Web Site Statements, Warnings, and Disclaimers . ...

On April 14, 2000 UT a series of Shack-Hartmann measurements were made at varying altitudes. ... The tilts and sags shown are those given by the normal Shack-Hartmann analysis. ... Without this feedback, off-telescope tests showed positioning errors on the order of 10 arcseconds in the secondary mirror position. ... Tilt M2 Bk by X" . ... The coefficients m1 through m3 need to be added to those that are currently in the TCC to correct for the secondary translation with respect to the primary. ...

... Values have been scaled arbitrarily. High ratios are shown in blue, corresponding to blue colors, and low ratios are shown in red, corresponding to red colors. ... Noise combined with background subtraction difficulties in the lower left quadrant of the WISP1 data (see Fig. \ref{Fig:wisp_snr_mskd}) make colors in this area very unreliable. ... The values shown here are typically a factor of ~3 less than those calculated for the Schmidt data, shown in Figure \ref{Fig:bj_alpha}. ...

... Armagh Observatory, College Hill, Armagh BT61 9DG, +44 (0)28 3752 2928 . ... We study the magnetic field structure and evolution for 26 X-ray brightening events in coronal holes and quiet Sun regions, including bright points and jets. We found that all brightening events are associated with bipolar regions and caused by magnetic flux emergence followed by cancellation. ... Comparing coronal holes and the quiet Sun, we do not find differences in their corresponding magnetic field behavior. ...

... Science User Portal . ... Survey Telescopes . ... Taking advantage of the presence of light echoes, a team of astronomers have used an ESO telescope to measure, at the 1% precision level, the distance of a Cepheid - a class of variable stars that constitutes one of the first steps in the cosmic distance ladder. ... The light that travelled from the star to a dust grain and then to the telescope arrives a bit later than the light that comes directly from the star to the telescope ," explains Kervella...

... Tonight's Sky . ... The Magazine . ... Observing . ... The double star 54 Leonis, spiral galaxy NGC 3198, and emission nebula NGC 3199 . ... Astronomy for Kids . ... Observing springtime deep-sky objects with a large telescope . ... Bright planets meet at dusk . ... Astronomy magazine subscribers can read the full article for free. ... Get instant access to subscriber content on Astronomy.com! ... Receive news, sky-event information, observing tips, and more from Astronomy's weekly email newsletter....

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 | ...