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Ýlgili Makaleler
Visual polarization measurements in the Cepheus flare
We present polarization measurements on a stellar sample located in alarge area in Cepheus. The observations were made with the 2-m telescopeat the Pic du Midi (France), around 4350 A and with an accuracy of thepolarization degree of the order of 0.0001. At large scales, we findthat the galactic magnetic field as given by the direction of thepolarization (alignment of the dust) is, roughly speaking, parallel tothe galactic plane in the Cassiopeia cloud, with a scale size of theorder of 100 pc, while it is turned by about 90 in the Cepheus cloud. Atsmall scales, in both the Cepheus and the Cassiopeia clouds, the COcontent has little correlation with the degree of polarization.
| X-ray observations of flat spectrum radio sources with the HEAO-A, Einstein and EXOSAT observatories
Most of the flat spectrum radio sources for which X-ray data collectedby three different satellites are given here are from a complete sampleof the high declination 5 GHz survey. Attention is given to tabulationsof the imaging proportional counter, low energy, and medium energyobservations.
| The EXOSAT high Galactic latitude survey
This study presents a survey of serendipitous sources performed in thevery soft X-ray band (0.05-2.0 keV) using the Exosat imaging telescopes.It covers 783 sq deg of high Galactic latitude sky and includes 210serendipitous sources which define a complete (flux-limited) sample. Twohundred of the 210 detected sources are identified via extensive opticaland radio observations together with cross-correlations with catalogs ofknown objects. The log N-log S relation was found to be consistent withthat of the Einstein extended Medium-Sensitivity Survey (EMSS) and withthe 'Euclidean' value of 1.5. The normalization of the relation is astrong function of the assumed spectral slope of AGN. It is inferredfrom the consistency with the EMSS results that the average (energy)slope of extragalactic sources in the soft X-ray band is very steep(approximately 1.5). An analysis of the association between AGNdetection and Galactic N(H) also shows that the average slope is steepand inconsistent with the canonical value of 0.7.
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Gözlemler ve gökölçümü verileri
| Takýmyýldýz: | Ejderha |
| Sað Açýklýk: | 20h04m53.23s |
| Yükselim: | +72°46'57.0" |
| Görünürdeki Parlaklýk: | 7.541 |
| Uzaklýk: | 229.885 parsek |
| özdevim Sað Açýklýk: | 16.9 |
| özdevim Yükselim: | 24.6 |
| B-T magnitude: | 7.563 |
| V-T magnitude: | 7.543 |
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