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Spectral Characterization of calibration lamps: STIS

Spectral Characterization of calibration lamps: STIS. An improved list of emission lines for STIS Calibration Enhancement Florian Kerber, ST-ECF TIPS Meeting Sept 18th, 2003. Outline. Calibration lamps for HST spectrographs STIS Calibration Enhancement (STIS-CE) ST-ECF Lamp Project

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Spectral Characterization of calibration lamps: STIS

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  1. Spectral Characterization of calibration lamps: STIS An improved list of emission lines for STIS Calibration Enhancement Florian Kerber, ST-ECF TIPS Meeting Sept 18th, 2003

  2. Outline • Calibration lamps for HST spectrographs • STIS Calibration Enhancement (STIS-CE) • ST-ECF Lamp Project • Laboratory Work • Results and Outlook F. Kerber, ST-ECF

  3. Hollow cathode lamp • Schematic drawing F. Kerber, ST-ECF

  4. Pt/Ne hollow cathode lamp (IUE) • Parameters of operation • starting voltage: 300 V; operating voltage: 185 V; current: 10 - 60 mA, power consumption: 2 W @ 10 mA • dimensions: 19.7 by 4.5 cm; weight: 71 (285) g • Lifetime: > 750 h or 3 - 5 years of operation on IUE • Source brightness stability: ~ 5 % after 5 - 10 min • Rich emission line spectrum: 115 to 310 nm • Wavelengths for 585 lines; Shenstone (1939) F. Kerber, ST-ECF

  5. Hollow cathode lamps - HST (1990) • Goddard High Resolution Spectrograph (GHRS): 115 - 320 nm; Pt-Ne ok • Faint Object Spectrograph (FOS): 115 - 895 nm • Addition of ~ 10% Cr to cathode extends coverage to 540 nm and Ne has lines up to 800 nm • Space Telescope Imaging Spectrograph (STIS): 115 - 1000 nm F. Kerber, ST-ECF

  6. Ready for Flight / Operations ? • Engineering • for both Pt-Ne and Pt/Cr-Ne thorough characterization of lamps in terms of hardware performance • Science Operations • information on spectral output incomplete and crucial wavelength information based on measurements done in the 1930s (Pt) or absent (Cr) • no spectral characterization of flight hardware F. Kerber, ST-ECF

  7. HST Spectrograph Operations • National Institute of Standards and Technology • Pt-Ne lamp atlas 110 - 400 nm with ~ 3000 lines (Reader et al., 1990, ApJS 72, 831) F. Kerber, ST-ECF

  8. STIS Operations • Pt line list from NIST • Cr lines can not be used because of lack of lab data • 1st order long-slit modes have many Pt/Cr blends • wavelengths assigned should be average weighted by line intensity ratios, which are not known • Empirical approach using 2-D polynomial fits for Echelle modes F. Kerber, ST-ECF

  9. STIS Calibration Enhancement • Physical Model of STIS • Spectrograph Model • Laboratory Standards • Good line list is required to realize full potential of physical model F. Kerber, ST-ECF

  10. ST-ECF Lamp Project • Dedicated ESA funding • Measure spectrum of Pt/Cr-Ne lamp at NIST: 110 - 320 nm • Derive an accurate ( < 1/1000 nm) list of wavelengths as input for STIS-CE • Quantify differences between Pt-Ne and Pt/Cr-Ne spectrum • Look into aging effects of hollow cathode lamps F. Kerber, ST-ECF

  11. Status of the ST-ECF Lamp Project • First memorandum May 2001 • Approved & funded in spring 2002 • Contracts to NIST and IST (lamps) issued June 2002 • FUV: 5 week measurement campaign Sep/Oct 2002 • Intermediate results delivered Nov & Dec 2002 • NUV: 6 week campaign in Apr/May 2003 • Use within STIS-CE in progress F. Kerber, ST-ECF

  12. NIST Eagle vacuum spectrograph • 10.7 m focal length, Vacuum UV (VUV) coverage • 1.25 m/1 m diameter • 13 m long, 15 m3 • 3 chambers • Two 16 in. UV sensitive photographic plates • 750 Å coverage • 0.78 Å/mm resolution F. Kerber, ST-ECF

  13. NIST Eagle vacuum spectrograph

  14. Synchrotron UV Facility (SURF III) • Fourier Transform Spectrograph (FTS 700)

  15. Hollow cathode lamp

  16. ST-ECF Lamp Project - Status • Measure spectrum of Pt/Cr-Ne lamp at NIST • 10.7 m vacuum spectrograph: 113 - 183 nm • FTS: 165 - 350 nm • Derive an accurate ( < 1/1000 nm) list of wavelengths as input for STIS-CEs • FUV: > 1100 lines total - 95% identified; 235 Cr • NUV: > 3500 lines; ca 50% Cr    in progress F. Kerber, ST-ECF

  17. ST-ECF Lamp Project - Status • Quantify differences between Pt-Ne and Pt/Cr-Ne spectrum • addition of Cr changes of line ratios • metal vs gas change as a function of operating current • Aging of lamps • accelerated aging test: 30s on/30s off cycle • vintage flight hardware in progress 1000 h without significant change FOS & GHRS lamps F. Kerber, ST-ECF

  18. Mystery feature “Clump” ~1430 Å • Seen in both in FOS and STIS F. Kerber, ST-ECF

  19. Chromium “Clump” ~1430 Å Cr-Ne Pt/Cr-Ne Pt-Ne F. Kerber, ST-ECF

  20. FUV Spectra: Pt vs Cr Pt-Ne: old & new New Cr Faint Pt-Ne: old F. Kerber, ST-ECF

  21. NUV Spectra: Pt vs Cr Pt/Cr-Ne Cr-Ne Pt-Ne F. Kerber, ST-ECF

  22. Input for STIS-CE • NUV c: 2843 Å • Lines seen : ~ 450 • Pt: ~ 100 lines • Cr: ~ 700 lines known F. Kerber, ST-ECF

  23. Open Instrument Surgery F. Kerber, ST-ECF

  24. Veteran Space Lamps • After seven years of operation in space back to the lab ... FOS GHRS they still work perfectly fine F. Kerber, ST-ECF

  25. ST-ECF Lamp Project: Future • NUV FTS data reduction, fall 2003 • Return of FOS lamps to museum, Sept 23rd • Paper I, ApJS, Sept 2003 (FUV results) • STIS-CE new dispersion solutions, end 2003 • Incorporate into calstis pipeline • STIS calibration proposal #10031 (PI: B. Mobasher) F. Kerber, ST-ECF

  26. Lessons learned: Calibration ... • requires attention to detail … • requires expertise from different fields • will give you better results • is at the heart of scientific understanding needs to be an integral part of any science project F. Kerber, ST-ECF

  27. Lessons learned ...

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