ACS Prism/Grism Performance
As of January 23, 2003, the Cycle 11 Interim Calibration derived
aXe configuration files are available from the
ECF.
(Link goes to the aXe User Manual.)
The web version of the November 2002
ST-ECF Newsletter features detailed articles about
the grism mode of the ACS.
Raw HRC grism spectrum
The HRC G800L grism spectrum of the Wolf Rayet star WR45 acquired
at the centre of the field of view. Exposure time is 60 s.
The 0th, 1st and 2nd orders are visible from left to right.
The tilt of the spectrum is 38 degrees to the detector X direction.
A. Pasquali, N. Pirzkal, J. R. Walsh (ST-ECF) 27 Jun 2002 (postscript)
Extracted HRC 1st order grism spectrum
The extracted, wavelength calibrated and background-subtracted
1st order spectrum of the Wolf Rayet star WR45 taken with the HRC
and G800L grism.
A. Pasquali, N. Pirzkal, J. R. Walsh (ST-ECF) 27 Jun 2002 (postscript)
WFC grism sensitivity
The provisional sensitivity for the WFC G800L 1st order derived
from the observations of GD 153 shown in wfc_lam.ps. For
comparison, the theoretical computation of the sensitivity from
the Instrument Handbook is shown.
A. Pasquali, N. Pirzkal, J. R. Walsh (ST-ECF) 27 Jun 2002 (postscript)
Raw WFC grism spectrum
The G800L grism spectrum of the Wolf Rayet star WR45 obtained at the
centre of the WFC field of view. Exposure time is 20 s. The 0th,
1st, and 2nd orders are visible from left to right. Spectrum is
tilted by 2 degrees to the detector X direction.
A. Pasquali, N. Pirzkal and J. R. Walsh (ST-ECF) 27 Jun 2002 (postscript)
Extracted WFC 1st order grism spectrum
The extracted, background subtracted and wavelength calibrated
WFC G800L 1st order spectrum of the Wolf Rayet star WR45 from the
image in wfc_wr45.ps.
A. Pasquali, N. Pirzkal, J. R. Walsh (ST-ECF) 27 Jun 2002 (postscript)
Extracted WFC grism spectrum
The extracted and background-subtracted WFC G800L 1st order spectrum
of the White Dwarf GD153. The wavelength scale is from
ground calibration only. The predicted count rate from the
ACS spectroscopic ETC is shown for comparison.
A. Pasquali, N. Pirzkal, J. R. Walsh (ST-ECF) 27 Jun 2002 (postscript)
HRC prism sensitivity 1
The extracted spectrum of the White Dwarf GD71 was compared with
the tabulated spectrum from Bohlin, Colina & Finlay (1995) to
derive the absolute calibration for the HRC prism PR200L. The
resulting sensitivity (green line) is compared with the theoretical
calculation from the Instrument Handbook (dashed red line).
A. Pasquali, N. Pirzkal, J. R. Walsh (ST-ECF) 27 Jun 2002 (postscript)
HRC prism sensitivity 2
Whilst the in-orbit PR200L sensitivity matches the theoretical
one rather poorly at wavelengths beyond 3500A (where the
prism dispersion is highly non-linear), below 3500A the
match is excellent as shown in this expanded view of prism_sens1.ps.
A. Pasquali, N. Pirzkal, J. R. Walsh (ST-ECF) 27 Jun 2002 (postscript)
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