Space Telescope Science Institute   3.4.3 Data Storage and Transfer Chapter 4:  Detector Performance

3.5 ACS Quick Reference Guide



Table 3.1: Instrument characteristics.

WFC
HRC
SBC
Field-of-View
202"× 202"
29"× 26"
34.6"× 30.8"
Plate Scale
~0.05"/pixel
~0.028 × 0.025"/pixel
~0.034 × 0.030"/pixel
Pixel Size
15 × 15 µm
21 × 21 µm
25 × 25 µm
Image Format
2 × 2048 × 4096 pixels
1024 × 1024 pixel
1024 × 1024 pixel
Spectral Response
~3500 Å to 11,000 Å
~1700 Å to 11,000 Å
~1150 Å to 1700 Å
Detector
SITe CCDs
SITe CCD
CsI MCP with MAMA readout
Detector
Efficiency
~77% at 4000 Å
~83% at 6000 Å
~67% at 8000 Å
~33% at 2500 Å
~69% at 6000 Å
~53% at 8000 Å
~19.2% @ 1216 Å
Peak Efficiency
48% at ~7000 Å
29% at ~6500 Å
7.5% at ~1250 Å
Read Noise
5.0 e-
4.7 e-
0 counts
Dark Current
0.0032 e-/s/pixel
0.0036 e-/s/pixel
1.241 × 10-5e-/s/pixel
Full Well
84,700 e-
155,000 e-
1Detector count rate linearity limit: 200,000 counts/second
Pixel count-rate linearity limit: ~22 counts/second/pixel
Gain
1,2,4 and 8 e-/DN
(Max 65,535 DN)
1,2,4 and 8 e-/DN
(Max 65,535 DN)
n/a
1Loss of linearity occurs at count rates larger than these values. For more information, please see Section 4.5.6.

Table 3.2: Calibration accuracies.
Attribute
WFC
HRC
SBC
Limiting factor
Distortion Solution Accuracy
0.1 pixel
0.1 pixel
0.25 pixel

Calibration & stability of
geometric distortion1
Absolute Astrometry
0.5" to 1"
1"
1"
Guide Star Catalog uncertainties2
Absolute Photometry
3%
2%
5%
Absolute calibration, standards
Relative Photometry
within an Image
1%
1%
2%
Flat-field characterization or
characterization of geometric distortion.
Repeated Photometry of
Same Star
0.3%
0.3%
1%
Stability of flat field
Transformation to
Standard
Magnitude Systems
0.02 mag SDSS
0.025 mag WFPC2
0.03 mag BVRI
0.02 mag SDSS
0.025 mag WFPC2
0.03 mag BVRI
n/a
DQE curve determination
Color terms
Polarimetry
1%
1%
n/a

Wavelength Calibration
20 Å grism
12 Å grism
1 pixel prisms
Accuracy of dispersion solution
Spectrophotometry
6% (Grism)
10% (Grism)
20% (Prism)

1Anderson & King, ISR 04-15 (http://www.stsci.edu/hst/acs/documents/isrs/isr0415.pdf)
2Koekemoe, et. al., ISR 05-06 (http://www.stsci.edu/hst/acs/documents/isrs/isr0506.pdf)

Table 3.3: ACS filters.
Filter type
Filter description
Camera
Broadband
Sloan Digital Sky Survey (SDSS): F475W, F625W, F775W, F850LP
WFC/HRC

B, V, Medium V, Wide V, I: F435W, F555W, F550M, F606W, F814W
WFC/HRC

Near-UV: F220W, F250W, F330W
HRC

No Filter: CLEAR
WFC/HRC
Narrowband
H (2%), [OIII] (1%), [NII] (1%): F658N, F502N, F660N
WFC/HRC

NeV (3440 Å): F344N
HRC

Methane (8920 Å): F892N
HRC/[WFC 1]
Ramp filters
2% bandpass (3700-10,700 Å): FR388N, FR505N, FR656N
WFC/HRC

2% bandpass (3700-10,700 Å): FR423N, FR462N, FR716N, FR782N, FR853N, FR931N, FR1016N, FR551N, FR601N
WFC

9% bandpass (3700-10,700 Å): FR459M, FR914M
WFC/HRC

9% bandpass (3700-10,700 Å): FR647M
WFC
Spectroscopic
Grism: G800L
WFC/HRC

Prism: PR200L
HRC
Polarizers
Visible (0º, 60º,120º): POL0V, POL60V, POL120V
HRC/[WFC1]

Near-UV (0º, 60º, 120º): POL0UV, POL60UV, POL120UV
HRC/[WFC 1]
Medium Band
Lyman-Alpha: F122M
SBC
Long Pass
MgF2, CaF2, BaF2, Quartz, Fused Silica: F115LP, F125LP, F140LP, F150LP, F165LP
SBC
Prisms
LiF, CaF2: PR110L, PR130L
SBC
1Limited field of view (72" x 72") for these filters using WFC

Table 3.4: ACS polarizers.
Polarizer set
Filters
Filter comments
POL0UV, POL60UV, POL120UV
F220W
F250W
F330W
F435W
F814W
HRC NUV short
HRC NUV long
HRC U
Johnson B
Broad I
POL0V, POL60V, POL120V
F475W
F606W
F625W
F658N
F775W
SDSS g
Johnson V
SDSS r
H
SDSS i

Table 3.5: ACS dispersers.
Disperser
Channel
Wavelength range (Å)
Resolving power
G800L
WFC
1st order: 5500 to 10,500
100 @8000 Å
G800L
WFC
2nd order: 5000 to 8500
200 @8000 Å
G800L
HRC
1st order: 5500 to 10,500
140 @8000 Å
G800L
HRC
2nd order: 5500 to 8500
280 @8000 Å
PR200L
HRC
1700 to 3900
59 @2500 Å
PR110L
SBC
1150 to 1800
79 @1500 Å
PR130L
SBC
1250 to 1800
96 @1500 Å

Table 3.6: Useful tables and figures list.
Topics
Tables
Proposal
Preparation
Tips
Overheads
Autoparallels
Aperture
Parameters
Detector
Characteristics
SBC Bright
Object
Protection
Limits
Hot and
Warm
Pixels
Charge
Transfer
Efficiency
Geometric
Distortion
Encircled
Energy
PSF
Plate Scale
Filters
Polarizers:
Photometry
Limiting
Magnitudes
for Direct
Imaging
Spectroscopy
Sky
Backgrounds
Calibration
Accuracies


 3.4.3 Data Storage and Transfer Chapter 4:  Detector Performance
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