Space Telescope Science Institute   6.3.1 WFC G800L  6.3.3 HRC PR200L

6.3.2 HRC G800L


When used with the HRC, the G800L grism provides higher spatial resolution (0.028 arcseconds) pixels than the WFC and also higher spectral resolution. However, the spectra are tilted at -38º to the detector X axis. Figure 6.18 shows the wavelength extent and sensitivity in the zero, first and second orders, with the pixel extent shown in Figure 6.19. Figure 6.20 shows the observed spectrum of the standard star GD153. Again there is contamination of the first order spectrum by the second order beyond 9500 Å. The total extent of the spectrum (orders -1 and +2) in Figure 6.20 covers about 70% of the 1024 detector pixels. In addition, a much greater number of spectra will be formed by objects situated outside the HRC direct image, or will have their spectra truncated by the chip edges, than for the WFC. The variation of the grism dispersion over the HRC field is about ±2% from center to corner and has been calibrated.

Figure 6.18: Sensitivity versus wavelength for HRC G800L.

 
Figure 6.19: Sensitivity versus pixel position for HRC G800L.

 
Figure 6.20: Full dispersed spectrum of white dwarf GD153 with HRC/G800L.

 
The numbers indicate the different grism orders.
 

 6.3.1 WFC G800L  6.3.3 HRC PR200L
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