spectral characterization of calibration lamps: stis an improved list of emission lines for stis...
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Spectral Characterization of Spectral Characterization of calibration lamps: STIS calibration lamps: STIS
An improved list of emission lines for STIS Calibration Enhancement
Florian Kerber, ST-ECF
TIPS Meeting Sept 18th, 2003
TIPS Sept 18th, 2003
F. Kerber, ST-ECF
2
Outline Outline
Calibration lamps for HST spectrographs STIS Calibration Enhancement (STIS-CE) ST-ECF Lamp Project Laboratory Work Results and Outlook
TIPS Sept 18th, 2003
F. Kerber, ST-ECF
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Pt/Ne hollow cathode lamp (IUE) 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)
TIPS Sept 18th, 2003
F. Kerber, ST-ECF
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Hollow cathode lamps - HST (1990)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
TIPS Sept 18th, 2003
F. Kerber, ST-ECF
6
Ready for Flight / Operations ?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
TIPS Sept 18th, 2003
F. Kerber, ST-ECF
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HST Spectrograph OperationsHST 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)
TIPS Sept 18th, 2003
F. Kerber, ST-ECF
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STIS OperationsSTIS 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 fitsfor Echelle modes
TIPS Sept 18th, 2003
F. Kerber, ST-ECF
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STIS Calibration EnhancementSTIS Calibration Enhancement
Physical Model of STIS– Spectrograph Model
Laboratory Standards– Good line list is required to realize full potential of
physical model
TIPS Sept 18th, 2003
F. Kerber, ST-ECF
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ST-ECF Lamp Project 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
TIPS Sept 18th, 2003
F. Kerber, ST-ECF
11
Status of the ST-ECF Lamp Project 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
TIPS Sept 18th, 2003
F. Kerber, ST-ECF
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NIST Eagle vacuum spectrographNIST 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
TIPS Sept 18th, 2003
F. Kerber, ST-ECF
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NIST Eagle vacuum spectrographNIST Eagle vacuum spectrograph
TIPS Sept 18th, 2003
F. Kerber, ST-ECF
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Synchrotron UV Facility (SURF III)Synchrotron UV Facility (SURF III)
Fourier Transform Spectrograph (FTS 700)
TIPS Sept 18th, 2003
F. Kerber, ST-ECF
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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
ST-ECF Lamp Project - Status ST-ECF Lamp Project - Status
in progress
TIPS Sept 18th, 2003
F. Kerber, ST-ECF
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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
ST-ECF Lamp Project - Status ST-ECF Lamp Project - Status
1000 h without significant change
in progress
FOS & GHRS lamps
TIPS Sept 18th, 2003
F. Kerber, ST-ECF
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Mystery feature “Clump” ~1430 Mystery feature “Clump” ~1430 ÅÅ
Seen in both in FOS and STIS
TIPS Sept 18th, 2003
F. Kerber, ST-ECF
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Chromium “Clump” ~1430 Chromium “Clump” ~1430 ÅÅ
Pt/Cr-Ne
Cr-Ne
Pt-Ne
TIPS Sept 18th, 2003
F. Kerber, ST-ECF
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FUV Spectra: Pt vs CrFUV Spectra: Pt vs Cr
Faint Pt-Ne: oldNew CrPt-Ne: old & new
TIPS Sept 18th, 2003
F. Kerber, ST-ECF
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NUV Spectra: Pt vs CrNUV Spectra: Pt vs Cr
Pt/Cr-Ne
Cr-Ne
Pt-Ne
TIPS Sept 18th, 2003
F. Kerber, ST-ECF
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Input for STIS-CE Input for STIS-CE
NUV c: 2843 Å Lines seen : ~ 450 Pt: ~ 100 lines Cr: ~ 700 lines
known
TIPS Sept 18th, 2003
F. Kerber, ST-ECF
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Veteran Space LampsVeteran Space Lamps
After seven years of operation in space back to the lab ...
FOS GHRS
they still work perfectly fine
TIPS Sept 18th, 2003
F. Kerber, ST-ECF
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ST-ECF Lamp Project: Future 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)
TIPS Sept 18th, 2003
F. Kerber, ST-ECF
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Lessons learned: Calibration ...Lessons learned: Calibration ...
requires attention to detail …
needs to be an integral part of any science project
requires expertise from different fields
is at the heart of scientific understanding
will give you better results
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