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7.6 Wavelength calibration accuracy

 

The goal was to achieve an accuracy of between 10 and 20% of a resolution   element for the two gratings. An accuracy of 10% was hoped for the LW grating as this is used by the FP wavelength calibration.

The errors expected on the wavelength calibration of the grating  are shown in Table 7.4. It lists the requirements on ISO, what has been achieved in ground tests and during operations.

 

SW LW
tex2html_wrap_inline7608 tex2html_wrap_inline7610
Requirements tex2html_wrap_inline7612 tex2html_wrap_inline7612 tex2html_wrap_inline7612
Obtained on ;SPMlt;1 LVDT ;SPMlt;0.5 - 1.0 LVDT 2.0 LVDT
ground tex2html_wrap_inline7622 tex2html_wrap_inline7624 tex2html_wrap_inline7626
Flight Achieved 1 LVDT 0.5 - 1 LVDT
tex2html_wrap_inline7628 tex2html_wrap_inline7630
Table 7.4: Grating Wavelength calibration errors.

 

The limitation on the grating wavelength calibration accuracy appear to come from pointing, see section 5.7.

The wavelength calibration stabilisation is very good. A slight shift was seen in the wavelength calibration between PV and rev 450 of about 1 LVDT  which was corrected by an update of the calibration files.

For the two FPs the relevant information is shown in Table 7.5.

 

SW-FP1 LW-FP1
Requirements tex2html_wrap_inline7632 tex2html_wrap_inline7632
Obtained on ground tex2html_wrap_inline7636 tex2html_wrap_inline7638
Flight Achieved tex2html_wrap_inline7640 tex2html_wrap_inline7640
Table 7.5: FP Wavelength calibration errors.

 

next up previous contents index
Next: 8 The Pipeline and Up: 7 SWS Calibration Previous: 7.5 Wavelength calibration

K. Leech with contributions from
the SWS Instrument Dedicated Team (SIDT)
and the SWS Instrument Support Team (SIST)