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General Desciption
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IRAC2b was ESO's 1 to 2.5 micron imager on the ESO 2.2m
telescope until July 1998. It was equipped with a 256x256 NICMOS-3 array.
Imaging could be done through the standard J, H
and K broadband filters, a special K'
filter and several narrow band filters. IRAC2b also had a warm Fabry Perot
coated for the 2 to 2.5 micon range with a resolving power of 1000. Imaging
could be done through four different objectives with scales ranging from 0.15
to 0.71 arc seconds per pixel.
Documentation
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IRAC2b
Users Manual
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Data
Reduction, Calibration Frames and Archive
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Calibration
Plan
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IRAC2b
Technical Reports
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Bad
Pixel Map
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Observing Logs
- 2 formats.
- Normal Spacing --- IRAC2_OL.ps.gz
(1.8 kb)
- Double Spacing --- IRAC2_OL.fat.ps.gz
(1.6 kb)
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Problems
and Solution Page - PostScript File. Version: April, 1997.
Instrument Performance
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Filter |
Zero Point |
Typical Backgrounds (Magnitudes/sq. arc-sec.) |
J
| 21.80
| 15.0 - 16.5 |
H
| 21.64
| 12.8 - 14.3 |
K
| 21.10
| 11.2 - 13.0 |
K'
| 21.01
| 12.0 - 13.5 |
The Zero-Points are a function of the lens used, the cleanliness of the mirror,
the read-out method. The values reported above were obtained during March,
1997. The lens was LC and the read-out method was NDR (Non-Destructive Read).
Array Characteristics
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Detector Material
| HgCdTe |
Pixel Size
| 40 microns |
Number of Elements
| 256 x 256 |
Quantum Efficiency
| 40% at 1.2 microns,
60% at 2.2 microns |
Well Depth
| 100,000 electrons |
Read Out Noise (Double Correlated Read)
| 46 electrons |
Gain(Double Correlated Read)
| 6.6 electrons/ADU
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Filters and Objectives
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To get the ascii file of the transmission curve, click on the wavelength.
The ZPs (DCR) for the broadband filters were measured during March, 1997.
The ZPs (DCR) for the narrow band filters and the FP were measured during
August, 1996. During this time, the external temperature was near zero,
so backgrounds were low. More realistic backgrounds will be 0.5 magnitudes
brighter.
Internal reflections have been detected for BP2, BP10 and BP11.
Lens
| Scale (arc-seconds per pixel)
| Field of View (arc-seconds) |
LA
| 0.151
| 38 x 38 |
LB
| 0.278
| 71 x 71 |
LC
| 0.507
| 129 x 129 |
LD
| 0.708
| A disc of diameter 180 |
LE
| 1.061
| A disc of diameter 180 |
Lens LE is not recommended for general use.
Pictures
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Picture
1
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Picture
2