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Thus, the absorption line in both cell spectra can be balanced so that the peak absorbance is still in the linear regime for a large [L.sub.OPC] and well above the noise level for a much smaller [L.sub.ref].
When greater measurement resolution is required (as it does in the case of multiple line integrated spectroscopy), single absorption lines (rotational lines) are considered.
The team is able to discern such a tiny discrepancy thanks to a combination of factors including better instruments and a focus on elements that have many absorption lines, says Christopher W.
If so, it could be possible to observe an absorption line at 3.5 keV when observing at angles close to the direction of the black hole, and an emission line when looking at the cluster hot gas at large angles away from the black hole.
The emission line shows large variation in its interferogram while they fade quickly for the absorption line. In this example, only a [square root of N] photon noise is applied and, since the mean flux is the same for both lines, the average level of noise is about the same.
Each of the four sample spectra which are shown in Figure 1 were calibrated using water absorption lines as discussed above.
This isotopic species has numerous absorption lines at longer wavelengths, ranging from 1595 nm to 1630 nm.
By placing a gas cell between their spectrograph and the Canada-France-Hawaii Telescope, they superimpose narrow absorption lines onto the observed stellar spectra.
Scientists at the VU University of Amsterdam and the Max Planck Institute for Radio Astronomy in Bonn used the 100-metre radio telescope in Effelsberg to measure absorption lines of the methanol molecule at a number of characteristic frequencies.
Previous studies had found a few examples of quasars whose broad absorption lines seemed to have disappeared between one observation and the next.