Download Slide 1

The Prime Focus Imaging Spectrograph for the
Southern African Large Telescope:
Operational Modes
Chip Kobulnicky – Instrument Scientist, University of Wisconsin
PFIS Team
Kenneth Nordsieck
Eric Burgh
Darragh O’Donoghue
Michael Smith
Jeffrey Percival
Ted Williams
PI – University of Wisconsin
Instrument Scientist – University of Wisconsin
Detector PI - South African Astrophysical Observatory
Instrument Engineer – University of Wisconsin
Project Manager – University of Wisconsin
Fabry-Perot PI – Rutgers University
PFIS Overview



First-generation, all-purpose
spectrograph on the Southern African
Large Telescope (SALT).
Commissioning in fall 2004.
Optical imaging spectrograph
3200Å - 9000Å
8’ Field of view
All-refractive collimator & camera
(see 4841-164, Burgh et al., for
optical design of PFIS)
PFIS Schematic
Planned Future Upgrade
Subsystems:
1. Focal Plane
open
longslit
custom slitmask
2. Polarization Optics
open (quartz block)
½ wave plate
¼ wave plate
½ & ¼ wave plates
+ polarizing beamsplitter
3. Dispersive Elements
none (unarticulated)
5 VPH gratings
Fabry-Perot etalon(s)
4. CCD Detector
normal readout
frame transfer
charge shuffle
PFIS Operational Modes
Imaging
Waveplat
Charge Shuffle
(very fast;
up to 20 Hz)
Focal
Plane
Unit
Field
Frame Transfer
(fast; ~1 Hz)
Waveplat
Normal
Readout
(<0.25 Hz)
Focal
Plane
Unit
Field
CCD Readout
Mode
Grating Spectroscopy
Filter Imaging
none
8’
N
Longslit Spectroscopy
slits 1-6
8’
N
Fabry-Perot Imaging
none
8’
N
Multi-slit Spectroscopy
mask
8’
N
Imaging Polarimetry
Mask 2
4’
Y
Longslit Spectropolarimetry
slit 7
4’
Y
Fabry-Perot Polarimetry
Mask 2
4’
Y
Multi-slit Spectropolarimetry
mask
4’
Y
Fast Filter Imaging
Mask 1
4’
N
Fast longslit Spectroscopy
slit 8
4’
N
Fast Fabry-Perot Imaging
Mask 1
4’
N
Fast multi-slit Spectroscopy
mask
4’
N
Fast Imaging Polarimetry
-
-
-
Fast Longslit Polarimetry
-
-
-
Fast Fabry-Perot Polarimetry
-
-
-
Fast Longslit Spectropolarimetry
-
-
-
V. Fast Filter Imaging
mask
”
N
V. Fast Longslit Spectroscopy
slits 1-8
”
N
V. Fast Fabry-Perot Imaging
mask
”
N
V. Fast Multi-slit Spectroscopy
mask
”
N
V. Fast Imaging Polarimetry
mask
”
Y
V. Fast Longslit Spectropolar.
slit 7
”
Y
V. Fast Fabry-Perot Polarimetry
mask
”
Y
V. Fast Multi-slit Spectropolar.
mask
”
Y
Observing Mode
Forbidden modes
Observing Mode
λ Coverage & Spectral Resolution
Contours at 90%, 70%, 50% efficiency. Assumes 1.25” slit, αmax=45 deg
Ca H&K, [O II] kinematics
4500
z = 1.6 Ly α
z = 1-2 restframe UV
Bowen florescence
R
3000
Planetary nebula
kinematics & abundances
Ca II stellar kinematics1500
Redshift surveys
Nebular abundances
Spectral Resolution vs. Throughput
0.7” seeing
1.2” seeing
780 l/mm VPH grating: efficiency and
wavelength coverage
-2’ field angle
Field center
+2’ field angle
Readout Modes and Times
Normal readouts: 4096 x 6044 pixels – 3.6 s with 5e- read noise
2048
2048
2048
Image field
4’
Frame Transfer: 2048 x 6044 pixels –
1.8 s with 5 e- readnoise
Charge transfer buffer
High Time Resolution
Image Height
(arcmin)
Image Height
(pixels)
Readout Time
(s)
4.0
2048
1.595
2.0
1024
0.797
0.5
256
0.199
0.125
64
0.050
See 4841-052, O’Donoghue et al. for detector details
Fabry-Perot Spectroscopy
(PI - Ted Williams, Rutgers)

3 F-P Etalons
 R=500 tunable filter
 R=2500 (dual etalon)
 R=12000 (dual etalon)
4300 Å – 8600 Å
Star cluster kinematics
Galaxy cluster kinematics (z>0.4)
Flows in SF regions & galaxies
F-P imaging polarimetry of reflection nebulae
Polarimetry
(See 4843-24 - Nordsieck et al.)
Linear polarimetry – ½ wave plate, 8 positions
Imaging polarimetry, 4’ FOV – polarimetric surveys
Longslit spectropolarimetry – novae, magnetic stars, AGN
Time-resolved polarimetry or spectropolarimetry –
accreting binaries, AGN, GRB
Circular polarimetry – ½ wave plate (8 positions), ¼ wave plates (2 positions)
Focal Plane
2048
4’
mask
4096
mask
Detector
2048
2048
PFIS Science & Summary
Fabry-Perot
X
Wide-field polarimetric imaging (e.g., Magellanic Cloud surveys)
X
Extreme blue λ galaxy kinematics & populations (z=1-2)
X
High time resolution spectroscopy (CVs, GRB, AGN)
X
High time resolution spectropolarimetry (CVs, GRB, AGN)
X
Imaging spectropolarimetry (novae, PNe, active galaxies)
X
?????
Rapid Readout
Polarimetry
Multi-object
Multi-slit spectral surveys (e.g., redshift surveys, stellar surveys)
X
X
Signal-to-noise vs. Magnitude
Efficiency
Spectral Resolution vs. Throughput