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Procedure: NGS Spectroscopy
Contents
- Acquisition
- Execution
- Calibration: Arcs
- Calibration: Dome Flats
- Calibration: Darks
- Modifications
Acquisition:
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In ShARCS wheel control GUI: Ensure Aperture is
set to Open.
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In ShARCS wheel control GUI: Ensure there are
no dispersive elements (i.e. CaF-Kgrism,
HGrism) in beam path.
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In Fieldsteer.tcl GUI: From on-axis position, field steer:
7.125 arcseconds South
and
0.165 arcseconds East.
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Acquire single short exposure image of field.
Approximate slit centre corresponds to pixel coordinate
(1324, 1102).
Therefore, target should fall on, or near, this position.
If necessary, use Move Tel option (Imahe Browser GUI)
to refine positioning.
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In ShARCS wheel control GUI: Set Aperture to
Slit-100um-H.
Ensure there are no dispersion
elements (i.e. CaF-Kgrism, HGrism) in
beam path.
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Acquire single short exposure through-slit image to confirm target
is satisfactorily positioned near slit centre.
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In ShARCS wheel control GUI: Install dispersion element.
Execution:
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For exposure times greater than circa 300 s, consider selecting
the FlexureCompensation.
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In scriptproc.tcl GUI, select spect.
This script acquires 3 images of spectra (one spectrum
approximately on slit centre, and two further spectra dithered
either side of slit centre).
Calibration: Arcs
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Due to poor reproducibilty in positioning the slit aperture wheel,
it is recommended that accompanying arc spectra are acquired at
the same on-sky position, immediately before and/or after observing
the science object.
Optionally, general purpose/diagnostic arc spectra may be acquired
with the telescope parked at zenith during the afternoon.
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In ShARCS wheel control GUI:
Ensure Aperture remains set to Slit-100um-H.
Select appropriate dispersion element.
Select corresponding order-sorting filter (H or K, not Ks).
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In ShaneAO motor control GUI:
Set Cal X to White Light.
Set Cal Y to Red Light.
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In ShaneAO Power Controls GUI:
Set Argon Lamp (C4) to ON.
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Sample exposure times (may vary as calibration lamp ages):
| Kgrism + K |
6 seconds |
| H + Hgrism |
3 seconds |
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Ensure lamp (C4) is set to OFF when arc calibrations completed.
Calibration: Dome Flats
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Due to poor reproducibilty in positioning the slit aperture wheel,
it is recommended that accompanying spectroscopic flat fields are acquired at
the same on-sky position, immediately before and/or after observing
the science object.
Optionally, general purpose/diagnostic spectroscopic flat fields may be acquired
with the telescope parked at zenith during the afternoon.
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In sdiagmir_fe GUI:
Ensure diagonal mirror in position 3.
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Ensure Shane primary mirror cover is open and enclosure ambient lighting
is extinguished.
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In ShARCS wheel control GUI: Ensure aperture wheel set to Slit-100um-H.
Select appropriate dispersion element.
Select corresponding order-sorting filter (H or K, not Ks).
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Activate SuperBlue flat field lamp, with output set to 100.
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Sample exposure times (may vary as calibration lamp ages):
| Kgrism + K |
15 seconds |
| H + Hgrism |
12 seconds |
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Ensure lamp is set to OFF when flat calibrations completed.
Calibration: Darks
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In sharcs_fe GUI, from the Windows menu item, select
Take Darks option.
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Configure for the required number of dark frames.
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Select Set Filters.
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Select Start.
Modifications:
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2022-01-11:
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First version.
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