SIMBAD references

We have studied the spectral and rapid variations of GS 2023+338 using all Ginga (LAC) data available of this source. We used colour-colour and hardness-intensity diagrams to study the spectral behaviour and for the variability behaviour we used the FFT-technique to obtain power spectra, the energy dependence of the variability and the energy dependence of the phase delays. We find that the spectral behaviour is strongly influenced by changes in the local absorption. These changes also influence the variability at low photon energies and relatively long time scales (>1s). The global shape of the power spectra of GS 2023+338 is similar to that of other black hole candidates in the "low" (hard) state, however, small differences are present in the detailed power spectral shape between those sources.