FIFI LS SITR April 2009

1. FIFI LSSITRApril 2009 Randolf Klein (UCB)‏

2. Quick Summary

3. Schedule Issues • Blue Spectrometer • We are making good progress, but not as much as originally hoped. The main efforts are focussed on characterizing the red spectrometer.

4. Schedule Issues • Documentation • Not much real progress, yet, but preparations to get the airworthiness efforts re-started are very promising. • A TIM on FIFI LS Airworthiness will be held at the MPE on June 2nd, 2009.

5. FIFI LS Team F. Fumi - electronics design - 1FTE N. Geis – FP guider + operations - 0.1 FTE R. Hönle - detector design and testing – 0.5 FTE R. Klein – project scientist & S/W (UCB) – 0.75 FTE L. Looney - system & optics (UIUC) – 0.1 FTE K. Nishikida – EOOP S/W - 1 FTE A. Poglitsch – PI and interface for CREs – 0.1 FTE W. Raab - cryo-mechanical systems & optics – 0.5 FTE USRA contact: Murad Hamidouche

6. Schedule

7. Budget EOOP: Guider camera planned for last year was bought in November. Otherwise, the monthly spending is below the budget plan as we estimated a faster ramp up to flight activities than is needed now. FIFI LS itself is funded by the MPE.

8. Progress

9. Progress Summary • Extensive Performance tests of the Red Spectrometer • Alignment verification • CO spectra to verify spectral resolution • 399 out 400 red detector pixels working • Blue detector is finished + two spare modules

10. Alignment verification HD [N II] [O I] [C II] CO 14-13 [N II] The point spread function has been measured at 6 wavelengths; consistent with the optical design simulations of last November (from last SITR). There was one under-illuminated column before the re-alignment.

11. Alignment verification • Before: Modules 5, 10, 15, 20, 25 (blue dots) got ~1/2 the light of the other modules (red squares). The data is not corrected for responsivity variations and thus the scatter. • After re-alignment, no obvious decrease on the pixels in the “rightmost” column of the slicer. Only pixel 25 looks a bit weak, but not weaker than pixel 3. Could just be detectors.

12. Alignment verification The pixel positions are the same after the re-alignment. And the relative pixel positions do not change with wavelength. The measurements show that the alignment is repeatable and the spatial calibration is stable.

13. Spectral Resolution • The spectral resolution of FIFI LS was measured with 6 CO lines throughout the red spectrometer’s wavelength range (J=23->22 @113µm to J=14->13 @186µm) with a gas cell pressure of 1.2 mbar and ~1/4 pixel step size. • Due to the low line intensity, all 399 working pixels had to be stacked. We first took the same scans at ~20 mbar to derive accurate center positions on all pixels individually. • These center positions were used to shift the individual low-pressure profiles before stacking.

14. Spectral Resolution A broadened CO line at “high pressure” of 20mbar to get an exact wavelength calibration for each pixel. Lorentz Gauß R=λ/Δλ1/21241 1363

15. Spectral Resolution "J=15->14", 173.631, 1.2 mbar Hardly broadened CO line at 1.2mbar all 399 pixels stacked together. The stacking was actually done by drizzling the individual signals on a 1/8 pixel grid. The result of this procedure is shown as blue line. The Lorentz/Gauß fits were done to the full set of individual, shifted data directly. LorentzGauß R=λ/Δλ1/216101560

16. Spectral Resolution Another example for a low pressure CO line. "J=23->22", 113.458, 1.2 mbar LorentzGauß R=λ/Δλ1/2695 704

17. Spectral Resolution Spectral resolution vs wavelength Prediction vs Measurements The red curve shows simple model: Rectangular (rather than the elliptical geometrical beam), flat illumination of grating with borders determined by geometrical diameters of collimated beam. The resulting LSF is convolved with square pixel and FWHM calculated. Diffraction effects give a larger illumination at longer wavelengths; thus a higher spectral resolution and vice versa. R µm

18. Blue Detector Blue detector is finished! 25 detector modules plus CREs + 2 spares

19. FIFI LSEOOPExtended Observing Opportunity Program Allowing the US community to use FIFI LS as if it were a facility instrument.

20. Progress • The main focus lies on the data reduction pipeline. • Raw data format has been changed to FITS standard which will be compliant with SOFIA DCS requirements • A simple data base has been created for calibration parameters • Data gets calibrated with the latest calibration parameters respective the observing date

21. Data Reduction Pipeline 3D cube

22. Data Reduction Pipeline • We developed an IDL GUI to visualize the FIFI LS data, especially the intermediate steps in the pipeline. • This is what the raw data looks like.

23. Data Reduction Pipeline • Here you see the effectiveness of the correlated noise removal. • Displayed are the residuals of the linear fit to the ramps for both the raw and the cleaned data.

24. Data Reduction Pipeline After the demodulation the data can be displayed as a cube. The GUI allows three different views: 5x5 “narrow band” maps The whole detector Map of Spectra (different data set)

25. Next steps • Interface to DCS and test data ingestion. • Refine observing modes • Define FIFI LS API so that SOFIA can schedule FIFI LS observation