... Changing Programs & Resolving Problems . ... Several factors first came to mind that might explain what was seen. ... However, such changes cannot also explain the changes seen in the stellar spectra, and again this hypothesis was initially rejected. A drift of the spectrum on the diode array could lead to a decrease in observed flux over time. ... As mentioned previously, a significant change should also lead to a drop in the spectrum at one end relative to the other, and that is not seen. ...

... The J, H and K bands are characterized by a bright background, such a background is mainly due to the emission of atmospheric lines and of thermal radiation. ... If the source cover a large fraction of the slit, spectra off-source must be observed to adequately sample the sky background. ... The on chip integration time (time spent in each position of the slit) must not exceed 40 seconds in J and H bands and 60 seconds in K band. ... We suggest a sequence of 10 for each elementary integration time. ...

RELATIVE SUNSPOT NUMBERS Description of Data from SGD Explanation of Data Reports: Relative Sunspot Numbers -- The relative sunspot number is an index of the activity of the entire visible disk of the Sun. ... The provisional daily Zurich relative sunspot numbers, Rz, were based upon observations made at Zurich and its two branch stations in Arosa and Locarno and communicated by M. Waldmeier of the Swiss Federal Observatory. ... This indicates the uncertainty above and below the predicted number. ...

... 2.3 Establishing the Extragalactic Distance Scale . ... 2.3.2 The Second Rung: Distances to stellar clusters . ... 2.3.4 Distances to Local Group Galaxies . ... The Luminosity Function of Planetary Nebulae . ... 3.2.2 Clusters of Galaxies . ... 4.2 Evidence for Dark Matter as a Function of Scale Size . ... 4.3 Other Dark Matter Indicators for Galaxies . ... What is the nature of the large-scale distribution of matter in the universe as traced by the three-dimensional galaxy distribution? ...

... 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. ...

Next: ATCA Spectral Line Correlator Up: Spectral Line Data Reduction Previous: Spectral Line Data Reduction . Because of the Doppler effect, the observed frequency of a spectral line can be related to the radial velocity between the observer and the source. ... where v is the radial velocity, the observed frequency, the rest frequency, and c is the speed of light. ... Next: ATCA Spectral Line Correlator Up: Spectral Line Data Reduction Previous: Spectral Line Data Reduction Miriad manager . ...

... They are concerned with Attitude Control System of the spacecraft, satellite visibility from tracking stations, limits on the satellite autonomous operations during the orbit, and needs for auxiliary operations with the spacecraft. ... Among the operational constraints the most important one is the number of programmed slews per orbit, which determines the maximum number of radio sources to be observed during one orbit. ... System temperature (K) . ... Progress of the RadioAstron Project in Pictures...

... This thread contains a step-by-step recipe to extract MOS spectra of a point-like source observed in Imaging mode and to create associated response matrices, starting from a calibrated, concatenated event list (either produced with emproc or available as PPS product; here it has the assumed file name MOS.fits ). ... The users should note that the SAS metatask xmmselect allows them to interactively define source and background regions (via ds9) and to run backscale on the fly. ...

... Editor's note: This activity is both on the Astrocappella web site and the CD-ROM featured in this article. ... Every student can demonstrate the Doppler effect! ... splash out' ball** . ... Twist the 'splash out' ball open. ... This effect can occur with both sound and light, because both sound and light reveal wave- like behavior. ... The number of waves reaching an observer in one second is called the frequency. ... What has the Doppler shift told astronomers about the expansion of the universe? ...

Next: Retrieving demonstration and Up: Echelle Reduction Method Previous: Echelle Reduction Method . ... User data is a set of echelle images, observed with the same instrument configuration, including a wavelength calibration image ( WLC ), a flat field image ( FLAT ) and astronomical objects OBJ . Optionally, this set will include standard stars ( STD ) to be used in the absolute or relative flux calibration, and dark images ( DARK ). ... Rotation of input frames. ...

Astronomy Discussion Forums . Forums: . ... TIME DILATION . ... Time dilation is what we take to be the disagreement in the total time of an event as measured by a moving frame and stationary frame. ... Imagine a car 100km from a stationary observer and which is positioned such that it would travel 200km on a straight line in a direction away from the stationary observer. ... Therefore the total time of motion of the car as measured by the stationary observer is T= t- 100km/C + (100km+200km/C). ...

... The OH line strength, which dep ends critically on the relative motion of the comet and the sun, is greatest b efore March 12, and after March 24. ... However, we observed comet LINEAR 2001/WM1 at near zero inversion, and saw the line in absorption when red-shifted, and in emission when blue-shifted, since the gas outflow velo city is a significant fraction of the total radial velo city with resp ect to the sun. ... The remaining 2 days we will attempt to observe the formaldehyde line at 4.83 GHz. ...

... The choice of the spectrograph design (Fig.2) is determined by the quantity R, the overall dimensions of the PF cage and the restrictions on the rigidity of the structure of the device. ... As the camera's objective a fast 4-lens aplanat is used having a focal distance F cam =140 mm and a relative aperture of 1:1.8, the resolution at the centre is no less than 80 gr/mm, that over the field at a distance of 3 mm from the edge along the frame ( ) diagonal is 35 gr/mm. ...

Next: Identifications and Efficiency Up: THE DEEP X-RAY RADIO Previous: Source Classification . ... For some sources which did not have NVSS positions before the time of optical observations, arcsecond positions from the Texas survey (Douglas et al. 1996) and NED (typically based on VLA data) were used. ... All X-ray/radio sources without counterparts on the survey plates were imaged at either the KPNO 0.9m or the CTIO 0.9m telescopes. ... Previously Identified Sources . Sample Properties . ...

... The experience of determination of the link between radio sources and dynamical reference frames is presented. To obtain this connection we used a series of very long baseline interferometry (VLBI) observations of the spacecraft Phobos-2 and angularly nearby quasars. ... The dynamical reference frame is determined by equator and equinox of these ephemerides. ... References . ... The relative orientation of the radio and dynamical reference frames can be described by a sequence of three rotations . ...

... solve : find optimum fit in a grid of model spectra . ... It initiates an optimisation by starting with a grid of theoretical spectra, defined by model or read_grid , a set of starting parameters and an observed spectrum. ... The parameters to be optimised include: T eff , log g , n A , v sin i , v rad being effective temperature, surface gravity, an abundance variable, rotation velocity and radial velocity for one or two stars, and R 2 / R 1 being the relative radius of the second star, if present....

... Series 4000 filters thread into the barrels of virtually all 1.25" eyepiece brands. Meade Series 4000 filters are a large 26mm in clear aperture and are manufactured from the purest crown optical glass, dyed-in-the-mass ( not "color coated"); there are no finer filters available for telescopic applications. ... For visual applications Series 4000 filters thread into the barrels of all Meade 1.25" eyepieces, and into the barrels of virtually all other 1.25" eyepiece brands as well. ... Meade 4M | ...

... 1996RMxAC___4__118V Informations. relative to: 5-Jupiter reference frame: astrometric centre of frame: topocentre epoch of equinox: J2000.0 time scale: UTC-3h reduction: no information coordinates: X, Y diff. refraction: no information receptor: CCD telescope: Ritchey-Chretien reflector, D=1.6 m, F=15.8 m observers: Veiga C. H., Vieira Martins R. data included in standard data file: no Comments. ... X observed, arcsec 11. ... X calculated, arcsec 13. ... O-C) X observed - X calculated, arcsec 15. ...

Irregular phenomena in the Earth Pole oscillation process and temporal variations of geopotential Valery Bondarenko, Vadim Perepelkin s The observed irregular phenomena in the Earth Pole oscillation process are very variety. ... These phenomena indicated in the IERS data are the "abnormal" fluctuation of the Earth Pole coordinates which owing to changing of the geodynamical parameters gives negative result in interpolation and forecast of the first approximation mathematical model. ... Fig. ...

... The concept of continuous solar wind developed in 1950's. First, Biermann (1951, 1957) observed comet tails as they passed close to the Sun , and explained the observed tail deflection by a continuous flux of protons from the Sun. Then Parker (1959) showed that the solar corona must expand, and called the outward streaming coronal gas 'solar wind'. ... The expanding solar wind drags also the solar magnetic field outward, forming what is called the interplanetary magnetic field (IMF) . ...