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Multiwavelength Monitoring of the BL Lacertae Object PKS 2155-304 in 1994 May. II. The IUE Campaign
PKS 2155-304, the brightest BL Lac object in the ultraviolet sky, wasmonitored with the International Ultraviolet Explorer satellite at ~1 hrtime resolution for 10 nearly uninterrupted days in 1994 May. Thecampaign, which was coordinated with Extreme Ultraviolet Explorer,ROSAT, and ASCA monitoring, along with optical and radio observationsfrom the ground, yielded the largest set of spectra and the richestshort-timescale variability information ever gathered for a blazar at UVwavelengths. The source flared dramatically during the first day, withan increase by a factor of ~2.2 in an hour and a half. In subsequentdays, the flux maintained a nearly constant level for ~5 days, thenflared with ~35% amplitude for 2 days. The same variability was seen inboth short- and long-wavelength IUE light curves, with zero formal lag(<~2 hr), except during the rapid initial flare, when the variationswere not resolved. Spectral index variations were small and not clearlycorrelated with flux. The flux variability observed in the presentmonitoring is so rapid that, for the first time, based on the UVemission alone, the traditional Delta L/ Delta t limit indicatingrelativistic beaming is exceeded. The most rapid variations, under thelikely assumption of synchrotron radiation, lead to a lower limit of 1 Gon the magnetic field strength in the UV-emitting region. These resultsare compared with earlier intensive monitoring of PKS 2155-304 with IUEin 1991 November, when the UV flux variations had completely differentcharacteristics.
| E. W. Fick Observatory stellar radial velocity measurements. I - 1976-1984
Stellar radial velocity observations made with the large vacuumhigh-dispersion photoelectric radial velocity spectrometer at FickObservatory are reported. This includes nearly 2000 late-type starsobserved during 585 nights. Gradual modifications to this instrumentover its first eight years of operation have reduced the observationalerror for high-quality dip observations to + or - 0.8 km/s.
| Radial velocities of southern stars obtained with the photoelectric scanner CORAVEL. III - 790 late-type bright stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1985A&AS...59...15A&db_key=AST
| Radial velocities of southern HR stars. II
Fick Observatory's second major installment of radial-velocitymeasurements of bright southern stars is presented. This includes 373radial-velocity measurements for 90 stars which were obtained betweenJanuary 1978 and June 1981. Fifteen new possible velocity variables andone new double-line spectroscopic binary (HD 1782) have been detected.Subsequent velocity measurements of stars from the first southern HRstudy (Beavers and Eitter, 1980) found that (1) two stars (HR 0745 andHR 5428), originally classified as possible variables, are actuallyconstant velocity variables, and that (2) HR 0953 is a definite velocityvariable covering a range of at least -1 to +14 km/sec. This study, whencombined with the earlier southern HR observations and those reported byGriffin (1972), result in a total of 280 HR objects with newradial-velocity determinations.
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Gözlemler ve gökölçümü verileri
| Takýmyýldýz: | Guney Baligi |
| Sað Açýklýk: | 21h55m55.60s |
| Yükselim: | -30°36'23.0" |
| Görünürdeki Parlaklýk: | 6.41 |
| Uzaklýk: | 126.263 parsek |
| özdevim Sað Açýklýk: | 52 |
| özdevim Yükselim: | -18.9 |
| B-T magnitude: | 7.591 |
| V-T magnitude: | 6.518 |
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