... the time of observation . ... Observing the Changing Position of the Sun To Establish Cardinal Directions . ... Observations of the Sun's apparent movement across the sky and its pattern of rising and setting in the east and west horizon helped to establish the cardinal directions. ... The final stage of the Sun's return was marked by the observation that the Sun had reached its highest altitude when the full width of your mitted hand could fill the gap between the Sun and the horizon. ...

The CHIANTI database consists of 4 primary ASCII files for each ion in the database. contains the energy levels in cm^(-1) It includes both experimental data and theoretical values of the levels energies. References: %observed energy levels (n=2): Fuhr, J.R., et al., NIST Atomic Spectra Database" ver. ... NIST Physical Reference Data %observed energy levels (12,19,23-26,65-67,69,70,72-74,78-82,84,85): Fuhr, J.R., et al., ...

... The first task assumes the searching for chemical composition and sizes of particles which give the wavelength dependence of the extinction efficiencies close to the observed dependence of . Figure 7: Wavelength dependence of the extinction efficiency factors for homogeneous spherical particles of different sizes consisting of astronomical silicate and amorphous carbon. The dashed segment shows the approximate wavelength dependence of the mean galactic extinction curve at optical wavelengths. ...

The Sun is our nearest star and the source of energy for life on Earth. ... For centuries astronomers wondered whether they were clouds floating in the Sun's atmosphere, but we now know that they really are huge regions of magnetic field, about as intense as the field at the poles of an iron magnet. ... Such abrupt events were named solar flares , and what made them especially interesting was that occasionally, after a prominent flare, a magnetic storm would erupt on Earth. ...

Next: Blind Deconvolution Up: Better HST Point-Spread Functions: Previous: Examples . Fig. 3 shows the result of deconvolving the observed PSF . ... Differences in the structure left in the PSF halo are apparent. There are also substantial differences in flux conservation and in the sharpness of the stellar images among the different restorations, as shown in Table 1 below. The observed PSF has a total of 74,400 counts, so flux is conserved better with the phase-retrieval PSFs. ...

Plans are under way to create a new way of performing non-interactive observations which will be called auto-observing . ... Non-interactive observing with CIMA has for a long time been available with the use of CIMA command files. Contrary to normal command file observing which requires a command file with a set of commands to be executed sequentially, auto-observing will use a list of sources and a list of instructions on how to observe each of the sources. ...

... The first step to improve the FORS calibration is therefore to obtain data to allow a computation of the illumination correction across the field. ... Another limitation on the calibration accuracy has been the brightness of the Landolt standards which have forced the use of extremely short exposures introducing small but non-negligible shutter-time errors and also resulting in a very small number of useful standards per frame. ...

Next: Radial velocity of the Up: Optical spectrum of IRAS04296 Previous: Observations and spectra reduction . ... However, molecular emission features are only very rarely observed in the optical spectra of PPNe. ... On the other hand, it is well known that cometary nuclei spectra show prominent Swan band emission. In both spectra of IRAS04296 we have discovered strong emission in the (0;0) and (0;1) bands of the Swan system of the molecule. ... Now consider the case of IRAS04296. ...

Next: The derived luminosity and Up: The galactic population of Previous: The galactic population of . Figure 16: The observed distribution of pulsar dispersion measures. Dotted curve is the total known population, solid curve is the Parkes survey. Figure 17: The observed distribution of pulsar distances above the galactic plane. ... Figure 18: The observed distribution of pulsar flux densities. ...

... Bojan Nikolic web pages (r. 329) . ALMA . ... These errors are due to the refractive effects of the Earth?s atmosphere, specifically due to the (tropospheric) water vapour. ... Making use of information on baselines this long will require very accurate calibration and correction of atmospheric phase errors. ... The design of the ALMA phase correction system is summarised in Nikolic et al 2013 . Introduction to phase correction for ALMA . ALMA Goals . ALMA Phase correction strategy . ...

... 12c. Venus transit (1) . 12d. Venus transit (2) . 12e. Venus transit (3) . ... 1 The 2004 Venus transit . ... Kepler's third law allows one to evaluate the dimensions of the solar system in relative units, e.g. in " astronomical units " (AUs), where 1 AU is the mean Sun-Earth distance. ... Edmond Halley suggested using the transit of Venus across the Sun's disk, when it appears as a dark round spot --or to quote one observer of the 2004 transit, "like a blueberry in front of an orange." ...

... A theory suggests that a certain sub-class of gamma-ray bursts all have the same absolute magnitude. ... The author claims that this absolute magnitude is so different from that in the previous sample that this must belong to a new sub-class of gamma-ray bursts. ... To do this, there needs to be some feature in their spectra which correlates with their absolute magnitude. ... Consider a telescope which is continually monitoring a star, looking for transits due to planets orbiting this star. ...

... A star was observed at different zenith distances during one night at the Engelgardt's Astronomical Observatory in the program of atmospheric extinction study at blue. ... The determination of the star's brightness was performed with the method of photon counting. ... Variable star. ... The brightness of the variable star was measured occasionally during the other nights, and moments of maximal values of brightness (15.59m) were received on nights 2­5, the 2nd table. ... JD 2452805. ...

... In order to compare the number of different evolutionary stages obtained and X-ray luminosity of the chosen X-ray sources with the observed galactic values we use the sum of C/O+O/C , where C and O are the calculated and observed values of a given binary type, respectively. If we make comparison for a number of different binary species (for example, we compare the number of CV, number of X-ray pulsars,   total X-ray luminosity of LMXB, etc.), we write this criterion in the form: . ...

M. ( / DIAS, Ireland), A. (ISDC, Switzerland) 1 - Key Question Only 3 binary systems regularly observed in TeV: PSR B1259-63 (young pulsar +Be star, P=3.4 y) LSI +61 303 (comp. source + Be star, P=26.42 d) LS 5039 (comp. source + O star, P=3.9 d) Origin of the high-energy emission? ... 2006; Neronov &Chernyakova 2007 4 3.4 years orbital period. e~0.87 Correlated variability with a sharp rise ( "two bumps structure" ) is seen in radio, X-ray (and TeV?) bands. ...

... Home Education Classes AAA Winter Astronomy Class: Measuring Distances in Space тАУ Dec 2015 тАУ Feb 2016 . ... Classes . AAA Fall Astronomy Class: Astronomy Basics тАУ October-November 2015 . AAA Winter Astronomy Class: Measuring Distances in Space тАУ Dec 2015 тАУ Feb 2016 . AAA Spring Astronomy Class: The Physics of Astronomy тАУ February - March 2016 . ... This MonthтАЩs Sky тАУ April 2016 . ... Dec. ... Observing Resources for Amateur Astronomers - Part 1: Beginning Observers . ...

... Kashyap, V., Drake, J., Smith, R., & Wargelin, B., 2014, 15 Years of Science with Chandra Symposium, Spectrum Ultimum Capellae: XV Years of Chandra Observations of Capella . ... Kashyap, V.L., Connors, A., Drake, J., Lee, T., Posson-Brown, J., Saar, S., Scargle, J., van Dyk, D., & Wong, R., 2014, AAS/HEAD 14, 119.05 TANAGRA: Timing Analysis of Grating Data . ... Audard, M., G del, M., Drake, J.J., & Kashyap, V.L., 2000, ApJ, 541, 396 . Audard, M., G del, M., & Guinan, E.F., 1999, ApJ, 513, L53 . ...

Next: C.S. Jeffery, Research Astronomer Up: Research Previous: J.E. Chambers, Research Astronomer Contents . During 1998 Dr Gerry Doyle was involved with three PPARC PDRA research grants, and was also a co-organiser of two international conferences (the COSPAR Symposium `Activity Observed in the Sun and in Similar Stars', and the Armagh Cool Star Workshop `Solar and Stellar Activity: Similarities and Differences'). He was Associate Scientist with the CDS and SUMER instruments on SOHO. ...

... Within SAS, a tool is available to check the pile-up fraction in the pn data: epatplot . This tool compares the observed pattern distributions (derived from a pn calibrated and concatenated even list) with the calibrated models. ... The lower panel is the key element for the evaluation of the pile-up fraction: it shows the observed distribution of pattern as a function of energy (PI channel in Analog-Digital Units ), using the same color code. ... Pages maintained by SAS librarian . ...

... Assured of a reliable method of solving the normal equations, we now consider the equations of condition. The observed magnitude m of a star at M air masses with true instrumental magnitude is modelled as ([ 10 ], [ 28 ]) . ... The effective extinction coefficient depends on the effective spectral gradient [ 29 ] of the star, for which we use some color index, affected by half the atmospheric reddening ([ 26 ], [ 10 ]): . ... Thus, for the B band of UBV, we use the (U-V) color. ...