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Figure 1: Simplified view of how the CCD chip is illuminated and shuffled. The mask aperture size controls the amount of the CCD exposed and therefore the number of different images fit on to an individual frame. Charge can be shuffled in both up and down the chip.

  
Figure 2: (a) Charge shuffled image of the planetary nebula NGC 2438 in [SII]6371 (top) and [SII]6717 (bottom). The TTF was frequency-switched 18 times during the 12 min exposure and the charge shuffled back and forth in concert. A 10 Å bandpass was used. (b) Charge shuffle time-series imaging of V2116 Oph, an x-ray pulsar in orbit around a red giant. V2116 Oph is to the right, reference stars are at the centre and left. TTF was tuned to a 7 Å bandpass centred on the [OI]8446 line, which is suspected to vary with the pulsar period of 120 s. Each exposure was 12 s. (c) Charge shuffling either side of an emission-line to average out the effect of a steeply sloping continuum. Equal time is spent collecting continuum from both sides of the emission-line (left). The line only contributes to the top portion of the shuffle frame while both sides of the continuum contribute to the bottom (right).

  
Figure 3: Images showing the removal of the atmospheric OH emission lines from a raw TTF image before (a) and after (b) cleaning. Only half the full TTF field is shown in each case.

© Copyright Astronomical Society of Australia 1997