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We report Cr III ultraviolet (UV) transition wavelengths measured using a high-resolution Fourier transform spectrometer (FTS), for the first time, available for use as wavelength standards. The doubly ionized iron group element spectra dominate the observed opacity of hot B stars in the UV, and improved, accurate, wavelengths are required for the analysis of astronomical spectra. The spectrum was excited using a chromium-neon Penning discharge lamp and measured with the Imperial College vacuum ultraviolet FTS. 140 classified 3d(exp 3)4s- 3d(exp 3)4p Cr III transition lines, in the spectral range 38,000 to 49,000 cm(exp -1) (2632 to 2041 A), the strongest having wavelength uncertainties less than one part in 10(exp 7), are presented.

The indium spectrum emitted from a hollow cathode discharge has been recorded using a Fourier transform spectrometer. Accurate wavelengths have been determined for 54 In II lines, and improved In II energy levels have been derived. The hyperfine structure of 42 lines has been analysed, yielding hyperfine constantsA andB for 23 In II levels. The spin-forbidden In I transition 5s25p 2P–5s5p2 4P has also been analysed and absolute wavelengths, hyperfine constants A and B and improved energy level values are reported.

An investigation has been carried out to determine how effectively a stacked HpGe detector with ultra-thin electrical contacts can be used to improve the spectrum shapes for the detection of monoenergetic γ-rays with energies above 2 MeV. Results are presented which show that almost ideal spectrum shapes with a single photopeak and a low intensity lower energy continuum can be achieved using a stacked HpGe detector that was not specifically designed for γ-detection. It is concluded that the spectrum shape could be improved further by developing stacked HpGe detectors with the new ultra-thin electrical contacts specifically for γ-detection.

We use wavelet transforms to study the characteristic time scales of chromospheric oscillation "wave packets" that are observed in Transition Region and Coronal Explorer (TRACE) ultraviolet continuum image time series. Using several data sets, we investigate the statistical, spatial, and temporal intermittence of the number, duration, mean frequency, and delay ("wait time") between wave packets in the time series data. Further, we demonstrate that these characteristic values are consistent with newly developed pictures of the wave-mode suppression and conversion by the chromospheric magnetic "canopy." We propose that wavelet analysis may be fruitfully used in diagnosing the structure of the chromosphere and in identifying chromospheric oscillation wave packets temporally and spatially with their photospheric sources.

High resolution spectrographs on astronomical telescopes create demands for accurate high resolution UV/VUV atomic data for interpretation of astrophysical spectra. Atomic spectroscopy combining high resolution VUV Fourier Transform and grating spectroscopy is described.

We describe the use of phosphor image plates for recording spectra in the vacuum ultraviolet (VUV) and for determining accurate relative and absolute intensities. We investigated the spatial uniformity, noise, linearity of the response to VUV light, fading characteristics, saturation characteristics, reproducibility of the image when scanned multiple times, and long-term stability and lifetime of the plates. We find that the plates have a linear intensity response with a dynamic range of more than 4 orders of magnitude. We also show that they have potential as an absolute detector for VUV radiation.