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Limits on the short-timescale near-infrared variability of Seyfert 1 nuclei
We present new time-resolved photometric observations and images at 2.2microns of a small sample of X-ray variable Seyfert 1 nuclei. Aftercorrecting for dilution by the host galaxy in the observing aperture, wecompare the fractional variation, over the timescales of theobservations, in the near-infrared (NIR) to that expected in the X rays.We have not detected with confidence any NIR variability on timescalesshort enough to be incompatible with the dust reradiation scenario. Thegalaxy-corrected upper limits which we have obtained for variations onshort timescales, typical of non-thermal processes, imply that the NIRemission is dominated by a slowly varying, presumably reprocessed,component which accounts for no less than 80%-90% of the total.
| Radial-velocity measurements. V - Ground support of the HIPPARCOS satellite observation program
The paper presents data on 1070 radial velocity measurements of starsdistributed in 39 fields measuring 4 deg x 4 deg. The PPO series ofFehrenbach et al. (1987) and Duflot et al. (1990) is continued using theFehrenbach objective prism method.
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Besorolás csoportokba:
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Pozíciós és asztrometriai adatok
| Csillagkép: | Ökörhajcsár |
| Rektaszcenzió: | 14h16m29.06s |
| Deklináció: | +26°37'44.1" |
| Vizuális fényesség: | 8.377 |
| Távolság: | 77.7 parszek |
| RA sajátmozgás: | 29.6 |
| Dec sajátmozgás: | 56.8 |
| B-T magnitude: | 8.908 |
| V-T magnitude: | 8.421 |
Katalógusok és elnevezések:
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