The STIS NUV-MAMA objective prism and looking beyond for HST UV - - PowerPoint PPT Presentation
The STIS NUV-MAMA objective prism and looking beyond for HST UV slitless spectroscopy Jes s Ma z Apell niz HST Calibration worskhop 26 October 2005 Outline The STIS objective prism Description Calibration problems
FUV NUV
1200 2125
– Difficulty of wavelength calibration – Lack of “repeatability” (~10%)
– Coupling between wavelength and flux calibration: positioning and geometric distortion are crucial – Strong count gradient @ 3300 Å: PSF effects – TDS effects
– Flux recalibration and geometric distortion solution – Ad-hoc solution for λ > 3000 Å – TDS correction
– Difficulty of wavelength calibration – Lack of “repeatability” (~10%)
– Coupling between wavelength and flux calibration: positioning and geometric distortion are crucial – Strong count gradient @ 3300 Å: PSF effects – TDS effects
– Flux recalibration, separation by settings (1200 and 2125), and geometric distortion solution – Ad-hoc solution for λ > 3000 Å (low precision) – TDS correction
– Spectral exposure (objective prism, grism, grating) – Image of the field (two filters) – Image photometry (using e.g. DAOPHOT) – Optional multiple orientations – Calibration files (ready for STIS objective prism)
– Slitless and 52x2 datasets in the archive (prism, G140L, G230L) – Will STIS become a born-again instrument?
– HRC (1 objective prism): PR200L – SBC (2 objective prisms): PR110L + PR130L
– Wavelength and flux calibration: yes for prisms (especially PR200L) – Strong count gradient: minor issue for PR200L – TDS effects: yes for SBC, not for HRC (but CTE)
– Observations of standard stars with very different spectral slopes and emission line objects (10391,10743) – Observations of crowded, UV-bright clusters (10722, 10736)