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ISAAC data reduction:
calibration LW-arm spectroscopy

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LW-arm spectroscopy darks

See section on data reduction of Aladdin array dark calibrations

LW-arm spectroscopic flat

For Recipe and Purpose see section on data reduction of SW-arm spectroscopic flats

Here some example spectroscopic flat products of the Aladdin detector:


LW-arm, LR-grating, J+Block-filter, 1.25 micron LW-arm, LR-grating, SH-filter, 1.64 micron
[std.gif 10K]
LW-arm, LR-grating, SK-filter, 2.20 micron LW-arm, LR-grating, SL-filter, 3.55 micron



LW-arm, MR-grating, SL-filter, 3.50 micron LW-arm, MR-grating, M-filter, 4.72 micron



LW-arm arc lamp calibrations

For Recipe and Purpose see section on data reduction of SW-arm arc frames

Here some example arc frames:

LR-grating Arcs:

LW-arm, LR-grating, SL-filter 3.55 micron, Xe+Ar lamp LW-arm, LR-grating, SH-filter, 4.80 micron, Xe+Ar lamp, (used for science in M-band)


MR-grating Arcs

[std.gif 10K]
LW MR SL 4.08 (1rst order) LW MR J+Block (2nd order)


The Xenon and Argon lamp spectra in the L and M band suffer from the low number of arc lines. To overcome these calibration problems and to provide better optimized arc frames for the calibration the arc frames taken a) with the spectroscopic setup and b) with a distinct broad band filter to sample the spectrum in a higher order. The calibration plan and the association is explained in the following: The INS.FILT.ASSOCNAM key has to be used to associate arcs with science frames or standard star frames. The following table shows the higher order arc settings used


science setting arc setting higher order arc
LR J+Block 1.25 LR J+Block 1.25  

LR SH 1.65

LR SH 1.65

LR SK 2.20 LR SK 2.20  
LR SL 3.55 LR SL 3.55  
LR M 4.80 LR M 4.80 LR SH 4.80 (3rd order)
MR M {any} MR M {any} MR SH {any} (3rd order)
MR SL (>3.55) MR SL MR J+Block (>3.55) (3rd order)
MR SL (<=3.55) MR SL MR SH (<=3.55) (2rd order)

*) For a science OB with setup LW-arm, MR-grating, SL-filter and central wavelength < 3.55 micron, arc calibrations are taken with the same setup (LR, MR, SL) and in addition an arc with the SH filter corresponding to the second order. Both arc calibrations are delivered.


LW-arm spectroscopy startrace

For Recipe and Purpose see section on data reduction of SW-arm startrace frames

[std.gif 10K] A combination of 11 stellar raw spectra and the 11 star images subtracted, to demonstrate the Y-shift of the spectrum versus the target position in imaging. The MR grating is used.


[std.gif 10K]

As above for the LR grating.



LW-arm telluric standard stars

For Recipe and Purpose see section on data reduction of SW-arm telluric standard stars

Telluric standard star product frame. The spectroscopic setting is LW-arm, MR-grating, SL-filter, 3.30 micron.
Both telluric standard star raw frames summed up.
Extracted standard star spectrum.

The --wavecal=std option is an important operational change, but only for SW-arm spectra. The LW-arm spectra are still reduced using the day-time calibration arc frames. There is no air glow sky emission line atlas available for the L and M band.