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MR2251-178: Preliminary results of an X-ray monitoring programme
Pounds, K. A.; Stewart, G. C.; Stanger, V. A.
We present the initial results from an X-ray monitoring programme of the bright QSO MR2251-178.
Search for millisecond rotational periods in some low-mass X-ray binaries observed by EXOSAT
Sztajno, M.; Truemper, J.; Langmeier, A.
We present the results of a search for millisecond rotational pulsations in the X-ray emission of five low-mass X-ray binaries: MXB1728-34, 4U1702-42, 4U1705-44, 4U1755-33 and GX17+2. The data were obtained by the EXOSAT Medium Energy Experiment Argon Counters (1-20 keV) with a time resolution of 7.8125 milliseconds. We searched for periods in the…
EXOSAT Observations of the Bl-Lacertae Object MKN421
McHardy, I.; Warwick, R. S.; Pounds, K. A.
The BL Lac object Mkn 421 was observed by EXOSAT four times over a period of six days in February 1984. Significant X-ray variability was apparent on a timescale of less than a day, but with no accompanying spectral change. The source exhibited a very soft power law X-ray spectrum with an extremely low intrinsic column density (NH≲10
Observations of Comet Crommelin. V - Anomalous hydrogen source
Wallis, M. K.; Carey, W. C.
Lyman-alpha intensities measured by IUE at various positions in the coma of Comet Crommelin are interpreted on the basis of H2O model calculations. However, the H-production on dates in March and April 1984 was significantly higher than implied by OH measurements by IUE and from the ground. Simultaneous data from the two apertures on March 30 excl…
X-Ray Optical and Ultraviolet Observations of the Am-Herculis System E2003+225
Mukai, K.; Maraschi, L.; Chiappetti, L. +13 more
The AM Her type object E2003+225 was observed with EXOSAT, IUE and ground-based telescopes on 1983 Oct. 12. The brightness of the ultrasoft X-ray component allowed the Objective Grating Spectrometer (OGS) to be used, which gave a model-independent determination of the temperature of the blackbody spectrum. The star was observed again on 1984 July …
The Discovery of a 25-MIN Regular Modulation in the X-Ray Flux from 2S0142+61
Parmar, A. N.; White, N. E.; Giommi, P. +2 more
A 13 hr observation of 2S0142+61 on 1984 August 27 by EXOSAT shows the X-ray flux of 2S0142+61 to be modulated with a period of 1456+/-6 s. The 1 10 keV spectrum is two component with a ∼0.7 keV thermal and 0.0 energy index power law, with 30% of the total luminosity in the thermal component. The spectrum is absorbed by ∼1 × 1022 H cm
Simultaneous EXOSAT-IUE observations of NGC 4151
Tarenghi, M.; Piro, L.; Perola, G. C. +9 more
NGC 4151 was observed four times in Nov. 83. The results indicate that: a) there exists a correlation between the X-ray and UV fluxes on the long term; b) the soft X-ray excess between 0.1 and 1 keV is probably steeper than expected from the leaky absorber model by Holt et al (1980); c)the spectral fit to the ME data, after correction for a soft c…
More on theλ2800 Å `interstellar extinction' feature
Nandy, K.; McLachlan, A.
We respond to comments made in a recent letter by Karimet al. (1984), and show that the examples of interstellar absorption atλ2800 Å that they have presented so far can all be attributed to overexposure of the IUE detectors.
High and medium resolution spectroscopy of the X-ray transient 4U1543-47
Chiappetti, L.; White, N. E.; Kahn, S. M. +1 more
Preliminary results of an EXOSAT observation of the transient X-ray source 4U1543-47 are presented. The source was observed in August 1983, during a high state, following a Tenma alert that the source was again active. Results from the GSPC and the LE 1000 l/mm grating are presented. The spectrum is complex, but in the 2 10 keV energy range can be…
EXOSAT PSD and CMA observations of the SNR PKS 1209-52
Kellett, B. J.
EXOSAT PSD images and spectra are presented of the supernova remnant (SNR) PKS 1209-52 (G296.5+9.7. Milne 23). This source was observed for 8.5 hours in June, 1983. PSD images constructed in different energy intervals reveal that the spatial structure of the SNR is energy dependent. Comparison of the PSD and CMA images with the latest radio map of…