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Entrance aperture |
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Multi-grid mechanical collimator with
tandem square aperture arrays to provide field restriction |
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Area: 250 cm2 |
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Field of view: 1° FWHM |
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Mechanical obscuration: 26% |
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Losses from diffraction and
scattering:
16% |
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Primary beam throughput: 62% |
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Optical elements |
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Echelle grating |
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Ruled area 200✕400 mm |
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Groove freq 79 mm-1 |
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Blaze angle 63.4° |
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Meas. Efficiency @ 1040Å 24% |
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Angles of α = β = 63.4°± 0.15°, ±0.30° and
diffraction (4 settings) |
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Off-plane angle: γ = 3.5° |
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Cross-disperser grating |
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Ruled area: 190✕143
mm |
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Groove freq: 171 mm-1 |
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Blaze angle: 0.5° (8 ½ partitions) |
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Width of each partition 17 mm |
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Theoretical resolution 0.34Å = 11μm
at focus of each partition |
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Worst efficiency away from 79% blaze maximum |
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Figure Off-axis
paraboloid |
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Focal length 1800 mm |
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Chief ray decenter distance 130 mm |
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Distance from echelle grating 1200 mm |
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Measured efficienty @ 1040Å 25% (incl. coating and blaze
efficiencies |
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Detector |
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Photocathode |
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Material
KBr |
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Quantum efficiencies 83% @ 950Å |
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77% @ 1000Å |
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74% @ 1150Å |
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Permanent Magnet Focus Assembly |
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Field strength 132 gauss |
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Angle between B and E 20° |
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Field uniformity 2 gauss |
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Electrostatic assembly |
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Operating voltage 18.5 kV |
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CCD (RCA type SID-502) |
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Pixel format 320 ✕
256 |
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Active area 9.6 mm ✕ 7.7mm |
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Charge well dimensions 30μm ✕ 30μm |
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Charge well capacity 8.5 ✕ 105 e- |
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Amplifier output 1.5μV/e- |
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Secondary electron yield for 2500 e- for 18.5 kV |
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Lateral spread of secondary 8 – 12 μm electrons (distance
between 1/e points) |
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Output signal characteristics |
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Frame rate 15
Hz |
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Pixel dwell time 0.60 μs |
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Frame transfer time: A→B
register 1.78ms |
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rms noise in each pixel 75e- |
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Dark current: 3000 e- @20°
C |
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( varies by ~30% over the image
format) |
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Image Layout |
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Angles in the sky |
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CCD field of view 18’20” ✕ 14’40” |
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Image scale 115” mm-1 |
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CCD pixel 3.45” |
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Lowest echelle order 197 |
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Order separation 178 μm |
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Central λ 1150
Å |
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Free spectral range 35.5 mm = 5.5 Å |
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Highest useful echelle order 238 |
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Order separation 122 μm |
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Central λ
950 Å |
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Free spectral range 29.0 mm = 3.7 Å |
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Echelle angle settings |
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Number
4 |
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Overlap of adjacent settings 0.42 mm |
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Sample characteristics |
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Mean dispersion: (λ/1000Å)✕ 0.139Å mm-1 |
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Sample size along orders 30 μm |
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Sample size ┴ to orders 30 μm |
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Instrumental profile 60 – 90 μm FWHM (Δλ ≥ λ/2.3 ✕
105) |
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Broad band star images for guidance
corrections (sounding rocket flights only) |
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Location 0.78 mm (90”) from short λ edge |
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Brightness ~ 50 events per 1/15 s frame |
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λ
range
1250 – 1500 Å |
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Scientific articles: |
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E. B. Jenkins, J. F. Lees, E. F. van
Dishoeck, and E. M. Wilcots (1989): "Velocities and Rotational
Excitation of Interstellar H2 toward π Scorpii“ Astrophysical
Journal, 343, pp. 785-810. |
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C. L. Joseph and E. B. Jenkins (1991): "UV
interstellar lines in the spectrum of π Scorpii recorded at 2 kilometers
per second resolution“ Astrophysical Journal, 368, pp. 201-214. |
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F. Bertoldi and E. B. Jenkins (1992): "Dense
Clumps of ionized gas near π Scorpii, as revealed by the fine-structure
excitation of N II" Astrophysical Journal, 388, pp. 495-512. |
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E. B. Jenkins and A. Peimbert (1997): "Molecular
hydrogen in the direction of ζ Ori A" Astrophysical Journal, 477,
pp. 265-280. |
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U. J. Sofia and E. B. Jenkins (1998): "Interstellar
Medium Absorption Profile Spectrograph Observations of Interstellar Neutral
Argon and the Implications for Partially Ionized Gas" Astrophysical
Journal, 499, pp. 951-965. |
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E. B. Jenkins, U. J. Sofia, and G.
Sonneborn (1998): "Observations of interstellar O VI absorption at 3
km/s resolution" in The Hot Universe, K.
Koyama, S. Kitamoto, and M. Itoh,
(Kluwer, Dordrecht) 271-272. |
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S. P. Sarlin (1998): “Ultraviolet
studies on interstellar molecular hydrogen.” Ph.D. Dissertation, University of
Colorado, Boulder. 186 p. |
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E. B. Jenkins, T. M. Tripp, P. R. Wozniak,
U. J. Sofia, and G. Sonneborn (1999): "Spatial Variability in the Ratio
of Interstellar Atomic Deuterium to Hydrogen. I. Observations toward δ
Orionis by the Interstellar Medium Absorption Profile Spectrograph" Astrophysical
Journal, 520, pp. 182-195. |
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G. Sonneborn, E. B. Jenkins, T. Tripp,
P. Wozniak, R. Ferlet, A. Vidal- Madjar, and U. J. Sofia (2000): "Spatial
variations in the atomic D/H ratio in the ISM" in The Light elements and
their Evolution, L. da Silva, M. Spite, and R. de Medeiros, (Astr. Soc. Pacific, San Francisco)
242-243. |
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E. B. Jenkins, P. R. Wozniak, U. J.
Sofia, G. Sonneborn, and T. M. Tripp (2000): "The Properties of
Molecular Hydrogen toward the Orion Belt Stars from Observations by the
Interstellar Medium Absorption Profile Spectrograph“ Astrophysical Journal,
538, pp. 275-288. |
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G. Sonneborn, T. M. Tripp, R. Ferlet,
E. B. Jenkins, U. J. Sofia, A. Vidal-Madjar, and P. R. Wozniak (2000): "Spatial
Variability in the Ratio of Interstellar Atomic Deuterium to Hydrogen. II.
Observations toward γ2
Velorum and ζ Puppis by the Interstellar Medium Absorption Profile
Spectrograph" Astrophysical Journal, 545, pp. 277-289. |
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E. B. Jenkins, C. Gry, and O. Dupin
(2000): "Electron densities, temperatures and ionization rates in two
interstellar clouds in front of β Canis Majoris, as revealed by UV
absorption lines observed with IMAPS“ Astronomy and Astrophysics, 354, pp.
253-260. |
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C. Gry and E. B. Jenkins (2001): "Local
clouds: Ionization, temperatures, electron densities and interfaces, from
GHRS and IMAPS spectra of ε Canis Majoris" Astronomy and
Astrophysics, 367, pp. 617-628. |
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D. E. Welty, E. B. Jenkins, J. C.
Raymond, C. Mallouris, and D. G. York (2002): "Intermediate- and
high-velocity ionized gas toward ζ Orionis“ Astrophysical Journal, 579,
pp. 304-326. |
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Technical or Instrumental articles: |
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E. B. Jenkins, C. L. Joseph, D. Long,
P. M. Zucchino, G. R. Carruthers, M. Bottema, and W. A. Delamere (1988): "IMAPS:
a high-resolution, echelle spectrograph to record far-ultraviolet spectra of
stars from sounding rockets“ in Ultraviolet Technology II R. E. Huffman, (The International Society for Optical
Engineering, Bellingham) 213-229. |
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E. B. Jenkins, C. L. Joseph, M. A.
Reale, P. Zucchino, and T. B. Williams (1990): "Use of a high-density
digital tape drive to improve complex spectroscopic data acquisition"
Spectroscopy, 5, pp. 37-40. |
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M. Reale (1990): “Serial transmission
of digitized video over an RF link using the Advanced Micro Devices TAXI
chipset” in Advanced Devices Article Reprints, 33‑. |
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E. B. Jenkins, M. A. Reale, P. M.
Zucchino, and U. J. Sofia (1996): "High resolution spectroscopy in the
far uv: Observations of the interstellar medium by IMAPS on ORFEUS-SPAS"
Astrophysics and Space Science, 239, pp. 315-360. |
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E. B. Jenkins (1993): "The IMAPS
instrument: A new horizon for recording the real shapes of interstellar
absorption lines in the far UV" in UV and X-ray Spectroscopy of
Astrophysical and Laboratory Plasmas, E. H. Silver and S. M. Kahn, (Cambridge U. Press, Cambridge) 254-269. |
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E. B. Jenkins (1995): "IMAPS
Observations of Interstellar Absorption Lines between 950 and 1150 A at 2
km/s Resolution" in Laboratory and Astronomical High Resolution Spectra, A. J. Sauval, R. Blomme, and N. Grevesse,
(Astronomical Society of the Pacific, San Francisco) 453-458. |
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E. B. Jenkins, M. A. Reale, and P. M.
Zucchino (1999): “Development of a photon‑counting capability for the
electron‑bombarded far‑UV image sensor” in Ultraviolet and X‑Ray Detection,
Spectroscopy, and Polarimetry III, S. Fineschi, B. E. Woodgate, and R. A.
Kimble, (SPIE (Intl. Soc. for Optical
Eng.), Bellingham) 226‑233. |
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Analysis Methodology inspired by IMAPS
results: |
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E. B. Jenkins (1996): "A procedure
for correcting the apparent optical depths of moderately saturated
interstellar absorption lines" Astrophysical Journal, 471, pp. 292-301 |