Future Instruments
SCORPIO: Spectrograph and Camera for Observation of Rapid Phenomena in the Infrared and Optical
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IGRINS-2: Immersion GRating INfrared Spectrograph
IGRINS-2 will be a high-resolution near-infrared spectrograph (R ~ 45,000; 1.45 - 2.50 μm), closely based on the original IGRINS (Immersion GRating INfrared Spectrograph). Unlike IGRINS, being used as a visiting instrument at Gemini South, IGRINS-2 will be a full facility instrument when it comes to Gemini North.
The Telescopes
Instrument Support Structure
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Acquisition Hardware and Techniques
Dedicated to the Acquisition and Guidance Unit (A&G), this section includes descriptions of the instruments on Gemini that are used to acquire the science target after the telescope has been slewed to the approximate coordinate of the target. It also describes the commonly used methods for accurate placement of the target with respect to the field of view of the science instrument.
Guiding and Wavefront Sensors
Essentially all observations with the Gemini telescopes require the use of either a peripheral wavefront sensor (PWFS) or an on-instrument wavefront sensor (OIWFS) assigned to a star near the science target, and in some cases an adaptive optics wavefront sensor (AOWFS) assigned to a star or artificial laser guide star, in order to:
(1) remove low order aberrations of the primary mirror;
Adaptive Optics
![[M2-9 with AO]](http://www.gemini.edu/images/pio/20080825_m2-9_0001.jpg "M2-9 with Adaptive Optics. Click to view larger image.") |
Adaptive optics (AO) forms an integral part of the Gemini telescopes' current and future suite of instrumentation.
Calibration Unit (GCAL)
A Gemini Facility Calibration Unit (GCAL) is available on each Gemini telescope, providing continuum and line emission light sources for wavelength and flat-field calibrations. Each GCAL is located permanently on one port of the instrument support structure and light is directed into an instrument by the science fold mirror. The GCAL optics simulate the f/16 telescope beam, illuminating the instrument pupil in the same way as light from an astronomical source.
The basic performance requirements are defined in the Science Requirements Document that guided overall telescope design and construction (frozen at SRD 3.0; 130k PDF) e.g., pointing, tracking, guiding, chopping, intrinsic image quality in the absence of atmosphere, etc.
Science Community questions from the impact of COVID-19 shutdown
Regularly updated Google Doc: Science community FAQ on telescope shutdown
Data reduction
Wide-field data will be provided as raw FITS cubes via the Gemini Observatory Archive which can be processed with most standard image reduction software.
Speckle data will be processed by the 'Alopeke & Zorro team and the reduced data will be distributed 1-2 months after the end of the run and uploaded to the Misc Files section of the Gemini Observatory Archive. The speckle data products include:
Observation preparation
Phase II observations should be set up using the Template Observations included in your program. These will be filled in with the targets and observing conditions from the Phase I proposal and will include blank observations for the point source standards for speckle observations.
Observing Strategies (Phase II Set-up)
Speckle:
Speckle imaging at Gemini traditionally consists of 1-minute integrations comprised of 1000 images of 60 msec each using a 256x256 pixel (2.5") subarray which closely matches the isoplanatic patch size.
Overheads
Every group of speckle targets within 15 degrees and/or every hour must include a point source standard. A photometric standard must be included once/night when doing photometry.
Acquisition overheads associated with setting up on each new target include time for slewing the telescope, configuring the guiding, and centering the target. This is already included in the OT calculation and is added to every observation.
`Alopeke and Zorro OT Details
This page explains how to configure the Gemini "Visitor Instrument" component for use with 'Alopeke and Zorro
Name
The Visitor Instrument name should be set to "Alopeke" in the case of 'Alopeke, and "Zorro" for Zorro
Exposure Time
The "Exp Time" field should be filled in with the total desired integration time for each target.
Phase II Checklist
Instrument Configuration
- The Instrument Name should be "Alopeke" for GN and "Zorro" for GS
- The Observing Tool has no mechanism to specify the instrument configuration (dichroic & filters), so please include a note with this information.
- The "Exp Time" should be the total desired integration time
- The Wavelength should be between the two imaging filters, typically ~0.66um
Target Coordinates
Calibrations
Point Source Standards
Point source standards (bright stars known to be single) will be observed at each sky location with a minimum of one per hour. PIs should select the closest single (not binary) 5-6th magnitude star from the Yale Bright Star Catalog for each science target, and a search utility is provided here.
Photometric Standards
Components
EMCCDs
'Alopeke & Zorro have two iXon Ultra 888 back-illuminated Electron Multiplying CCDs (EMCCDs).
Filters
'Alopeke and Zorro use a dichroic beam splitter to simultaneously image in two filters. The incident light is split at 674 nm, reflecting blue light through the blue filter wheel and transmitting red light through the red filter wheel.
Data Reduction
These pages present the most up-to-date information about the data format and the data reduction.
Data format
This page describes:
Data Format
How to get the data from Gemini Observatory Archive (GOA)
- Access the GOA search form and either Login to GOA or Request an Account
- Search for your program ID
- Follow the instructions to download your data
How to get associated calibrations
Data Reduction
Two pipelines were developed completely independently for GRACES data. One is called OPERA, the other DRAGraces. Both are open source, and are described further down on this page.
Old GRACES Exposure Time Estimation
This page describes the deprecated GRACES ITC written in IDL for reference only. The new ITC written in Python should now be used instead.
List of critical bugs identified in the IDL ITC script:
Observation preparation
This section mainly describes how to prepare and check GRACES observations. Setting up acquisition and observing sequences at Phase II is not intuitive until one is quite experienced (and maybe even not then). An important key to successful observation preparation is to start from the template observations generated by the Observing Tool from the configuration specified in your observing proposal.
Observing Strategies
This page contains information that might affect decisions on observing strategy in various GRACES observing modes, and provides guidelines/tips to maximize observing efficiency and avoid some common errors. For information about actually setting up observations in the Observing Tool, please see the OT details section of these pages. If you discover errors or inconsistencies, please contact us at graces_science@gemini.edu.
Overheads
For Phase I observing proposals, you can use the telescope setup times given below, plus 2 min per exposure to cover readout, GRACES cassette motion, etc. This is a rough approximation.
For more exact calculation of the overheads, the detailed listings on this page may be used. The detailed overhead information is also useful for the Phase II planning of your observing program.
Telescope setup (acquisition) time
Acquisition
GRACES acquisition is entirely performed using GMOS-N. Once the target is placed over a pre-determined GMOS-N CCD pixel, the GRACES cassette containing the pick-off mirror and the fiber injectors is moved into the beam. The whole acquisition sequence takes in average 10 min, inclluding the time required to move from any coordinate in the sky to the requested position. The sequence is as follows:
GRACES OT Details (2016A and after)
This page explains how to configure the Gemini Remote Access to CFHT ESPaDOnS Spectrograph (GRACES) in the Observing Tool. There is only a small number of steps to follow, as they consist on a SINGLE sequence using GMOS-N combiing both Acquisition and Science sequences.
Phase II Checklist
Checklist for GRACES Phase II (OT) programs
- General
- Have you selected appropriate templates from the GRACES OT library? Have you gone through the checklist in the Top-level Program Overview note and included relevant standardized notes? Add notes with information about the program and acquisition that will make it easier for the observer.