Scott Burles, Ian Thompson, Steve Shectman, Jennifer Marshall, Bruce Bigelow, Matt Smith, Christoph Birk, Patricio Jones, Greg Burley, Jorge Estrada, Vince Kowal, Robert Storts, Jerson Castillo
Data Reduction Software
The MagE (Magellan Echellette) Spectrograph is a moderate-resolution single-object optical echellette spectrograph
for the Clay (Magellan II) telescope. It will be mounted on the center folded port (FP2).
MagE has been designed to have exceptional throughput in the blue, with a goal of 30% total throughput (including the telescope).
MagE has eight available slit widths to give various resolutions: 0.5, 0.7, 0.85, 1.0, 1.2, 1.5, 2.0, and 5.0".
All slits are 10" long.
The platescale at the detectore is 0.3" per pixel.
There is currently one grating available that gives a resolution for the 1" slit of R=4200.
MagE has very few moving parts. Slitmask, flip mirror, shutter, collimator focus.
The control of these mechanisms are described below.
The figure below shows the optical layout of MagE. The design is a simple echelle spectrograph design: science light is collimated by a collimator mirror,
dispersed by a reflection grating, and is separated into echelle orders by a double-pass and single-pass prism. The camera is a
typical Schmidt camera design, with the CCD mounted to the inside of the dewar window.
The spectrum below shows a solar spectrum taken with MagE, with the order number and central wavelength of each order indicated.
MagE currently has only one available grating, 175 lines/mm blazed at 32.3 Å.
This grating gives a resolution of R=4200 for a 1 arcsec slit.
MagE has eight available slit widths to give various resolutions: 0.5, 0.7, 0.85, 1.0, 1.2, 1.5, 2.0, and 5.0".
All slits are 10" long.
The MagE CCD is an e2v 42-20, which has a 2048x1024 format with 13.5 micron pixels.
The plate scale at the detector is 0.3 arcsec/pixel.
The CCD may be read out at three speeds: Slow, Fast, and Turbo.
The characteristics of these speeds are described in the table below.
MagE readout options
| Readout Speed |
Time to read (s) |
Gain |
RMS noise (e-) |
| Slow |
33 |
1.13 |
3.2 |
| Fast |
21 |
0.91 |
3.4 |
| Turbo |
14 |
1.65 |
4.5 |
The dewar vacuum is maintained with a Varian Ion pump.
This pump remains on during normal operations.
The MagE control gui should be familiar to Magellan observers: it is similar to the MIKE and B&C guis.
A screencapture of the gui is shown below.
Begin the MagE CCD control program by typing "mage" in an xterm on the observer computer.
The gui will appear.
The user may select Object, Bias, Dark, Flat, HC-Lamp, or Xe-Flash lamp under the "ExpType" pulldown window.
See below for instructions on using the flask lamp.
Flat field frames are enabled under the "Xe-Flash" pulldown menu.
The flat field source is a flash lamp; it flashes pulses of light instead of a constant source.
The user may select how many flashes are desired, at 10 flashes per second.
To take flat field frames, the user selects "Xe-Flash" in the
ExpType pulldown menu.
When the user clicks "Start", a flipper mirror will move into the beam,
directing light from the flat lamp onto the detector. Once the exposure is complete,
the mirror will be removed from the beam.
Comparison lamp frames are enabled under the "HC-Lamp" pulldown menu.
The comparison source is a ThAr hollow cathode tube, which provides suitable lines
over nearly the entire wavelength range.
The user selects "HC-Lamp" in the ExpType pulldown menu to enable comparison lamp frames.
When the user clicks "Start", a flipper mirror will move into the beam,
directing light from the ThAr source onto the detector. Once the exposure is complete,
the mirror will be removed from the beam.
Several different binning options are available.
The pulldown menu labeled "Slitmask" allows selection of the slit. Simply click on the desired slit width to be used.
There is a Quicklook tool, located under Options >> QL-Tool. This tool will display data in real time as it is being read from the detector.
MagE has been designed to have exceptional throughput in the blue.
The table below shows the expected throughput at various wavelengths.
Expected MagE Sensitivity
| lambda |
Dlambda |
Zeropoint |
Minutes to reach S/N=10 per pixela |
| (Å) |
(Å) |
(1 ct/s/Å) |
18th |
19th |
20th |
21st |
22nd |
| 3200 |
0.241 |
19.21 |
3.11 |
8.19 |
23.04 |
74.27 |
296.65 |
| 3600 |
0.271 |
19.64 |
1.85 |
4.80 |
13.07 |
39.54 |
144.29 |
| 4000 |
0.301 |
19.89 |
1.31 |
3.39 |
9.08 |
26.56 |
91.78 |
| 5000 |
0.377 |
19.74 |
1.22 |
3.20 |
8.91 |
28.10 |
108.93 |
| 6000 |
0.452 |
19.35 |
1.48 |
3.98 |
11.71 |
40.95 |
179.83 |
| 7000 |
0.527 |
19.00 |
1.82 |
5.15 |
16.77 |
67.93 |
340.09 |
| 8000 |
0.603 |
18.64 |
2.27 |
6.56 |
22.24 |
94.40 |
488.74 |
| 9000 |
0.678 |
18.29 |
2.86 |
8.58 |
30.95 |
140.26 |
757.29 |
| 10000 |
0.753 |
17.54 |
5.54 |
18.07 |
73.30 |
367.42 |
2096.27 |
- Note:
- (a) AB magnitude after slit losses, ~23 km/s pixel.
MagE has only four simple mechanisms: a slitmask (decker), a flip mirror, a shutter, and a collimator focus mechanism.
The slitmask has eight slits (0.5, 0.7, 0.85, 1.0, 1.2, 1.5, 2.0, and 5.0") for observations, each 10" long, as well as
a mask position that has three 0.1 mm (0.3") square pinholes for diagnostic and focus tests.
The flip mirror moves into the beam to direct light from the comparison lamps into the instrument,
blocking the light from the telescope.
The mirror moves in automatically when a comparison lamp image is taken;
no action by the user is necessary.
The shutter is a simple Uniblitz iris shutter design.
The collimator mirror can be focused remotely using the collimator focus motor.
Include a linelist and wavelength solution here.
Need some!
Last modified: Thur Sept 06 2007