Transcript Operational Issues for the FGS-TFI

Hubble Science Briefing
Delivering JWST Science, from Exoplanets to First Light:
The Near-InfraRed Imager and Slitless Spectrograph
(NIRISS)
March 6, 2014
Alex Fullerton (STScI)
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Agenda for Today
The Science Themes of JWST
What is NIRISS and How Can It Help?
Hardware
Observing Modes
What’s happening next ?
Your Questions!
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James Webb Space Telescope
Maryland Science Center, Baltimore’s Inner Harbor (2011 October 23)
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James Webb Space Telescope
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The Frontiers of Knowledge: Science Themes of JWST
1.) Seek the first stars and
galaxies that formed in the
early Universe
3.) Solve the mysteries of star formation
and birth of protoplanetary systems
2.) Determine how galaxies evolve from
the early Universe to the present day
4.) Probe the chemistry of solar systems
(including our own) to constrain the building
blocks of life
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JWST: Four Instruments
NIRCam
Near Infrared Camera
NIRSpec
Near Infrared Spectrograph
MIRI
Mid-Infrared Instrument
NIRISS
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What’s in a Name?
NIRISS
NIR:
Near Infrared
Wavelengths 0.6 to 5.0 microns*
I:
Imager
Normal people say “camera”
SS:
Slitless Spectrograph
This takes some explaining
*1 micron = 1000th of a millimeter.
An average human hair is about 100 microns thick.
Recall: The Discovery of Infrared Radiation
Sir William Herschel’s Experiment
1800 Feb. 11
From: “Infrared Beyond the Visible”
http://webbtelescope.org/webb_telescope/science_on_the_edge/beyond_the_visible/
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“Slitless” Spectroscopy
Spectrographs typically use an entrance aperture
(“slit”) to improve the resolving power (especially
for spectrographs on ground-based telescopes) and
to limit the region of the sky that enters the
instrument.
Objective Prism Spectroscopy
For example:
A technological marvel developed for NIRSpec is
the Multi-Shutter Array (MSA), which allows many
slits to be configured “on the fly.”
An objective prism spectrogram of a region near Gamma Cygni,
taken October 16 – 17, 1950 with the 24-inch Schmidt telescope of
the Warner and Swasey Observatory. The exposure was 4 minutes
on Eastman IIa-O blue-sensitive emulsion by Daniel L. Harris.
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FGS / NIRISS
Fine Guidance Sensor (FGS)
The camera to acquire targets and guide
on them during observations. Used for
purely functional purposes.
Supplied by CSA.
Prime Contractor: COM DEV International
Optical Bench
NIRISS
A science instrument.
Supplied by CSA.
Prime Contractor:
COM DEV International
Principal Investigator:
René Doyon, Université de Montréal
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Schematic: Optical Layout
Image from Telescope
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Enabling Elements
Pupil Wheel
Filter Wheel
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Enabling Elements
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NIRISS Observing Modes
Name
Acronym*
What It’s Good For
Wide-Field Slitless Spectroscopy
WFSS
Getting spectra of everything in the field of view**
Single Object Slitless Spectroscopy
SOSS
Getting very precise spectra of bright objects, for
example to extract information about exoplanets.
Aperture Masking Interferometry
Imaging
AMI
Imaging
Finding and measuring the properties of faint
things that are very close to bright things; for
example exoplanets.
Taking pictures at different wavelengths (through
different filters).
* To give you a fighting chance of following me in case I slip up later and start talking in acronyms!
** The field of view of NIRISS is about 1/10th the area of the full moon.
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JWST Science Themes vs. NIRISS Capabilities
NIRISS Observing Mode
JWST Science Theme
The End of the Dark Ages: First Light and
Reionization
The Assembly of Galaxies
The Birth of Stars and Protoplanetary Systems
Wide-Field Slitless Spectroscopy (WFSS)
Single Object Slitless Spectroscopy (SOSS)
Aperture Masking Interferometry (AMI)
Imaging
Planetary Systems and the Origins of Life
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Exoplanet Transit and Eclipse Science
Seager & Deming (2010, ARAA, 48, 631)
Precision needed: 1 part in 1,000
Transit
Learn about atmospheric
from thermal
Measure size of planet. Precision needed: 1 part incirculation
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phase curves
See starlight transmitted
through planet atmosphere. Precision needed: 1 part in 10,000
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Single Object Slitless Spectroscopy
[SOSS]
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GR700XD Grism
weak
cylindrical
surface (lens)
Weak Lens + Prism Side
Weird Stuff!
Prism: ZnS (Zinc Sulfide)
Grism: ZnSe (Zinc Selenide)
Grism Side
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Real Data vs Simulations
ISIM CV1 (October 2013)
2.5 microns
0.5 microns
Simulation (U. de Montréal)
2nd Order
1st Order
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Spectroscopy of the “Water World” GJ1214b
Input spectrum
Simulated NIRISS spectrum
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JWST: First Light, First Galaxies
JWST will Study the First Galaxies
Simulation (U. de Montréal)
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The First Galaxies
HST can already see galaxies formed
within 500 Myr of the Big Bang
(redshift, z = 11).
But neither Hubble nor JWST
imaging will be able to measure
the star formation rate or chemical
evolution of these early galaxies.
Instead: we need spectroscopy to
detect spectral lines of hydrogen
and oxygen to measure the
detailed properties of the very first
galaxies assembling from the
products of the first stars, and to
confirm their redshifts.
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Wide-Field Slitless Spectroscopy
[WFSS]
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MACS J0647+7015: Image in NIRISS F200W
HST Image: Composite of ACS and WFC3 exposures.
Credit: NASA, ESA, M. Postman and D. Coe (STScI), and the
CLASH Team.
Simulation of the CLASH field through the NIRISS
F200W filter by Chris Willott (NRC) and Van Dixon
(STScI).
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MACS J0647+7015: GR150R Grism
F200W
GR150R Disperses Along Rows
Simulations by Willott and Dixon
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MACS J0647+7015: GR150C Grism
F200W
GR150C Disperses Along Columns
Simulations by Willott and Dixon
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Extract Spectra From Both Orientations
And Identify Spectral Features
Filter
Image
GR150R
GR150C
Hydrogen Emission
at redshift of 9.25
Brightness
GR150R
GR150C
Simulations by Willott and Dixon
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2013 March: Integration
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Hanging Out
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What’s Happening Now?
NIRCam
is being worked
on back here.
ISIM
Structure
NIRSpec
MIRI
Stand for NIRCam
http://www.jwst.nasa.gov/webcam.html
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What’s Happening Next?
Space Environment Simulator
Cryogenic Vacuum (CV) Testing at Goddard
One down, two to go
ISIM being lowered into the SES chamber before CV1
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Then: Testing at Johnson
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Then: the Fun Really Begins!
When
Where
What
2014
Goddard Space Flight Center
ISIM Test Campaign 2
2015
Goddard Space Flight Center
ISIM Test Campaign 3
2016
Johnson Space Center
Telescope + ISIM Testing
2017
Johnson Space Center
Telescope + ISIM Testing
2018
French Guiana … and beyond!
Launch!
2019
An astronomy center near you
Amazing results from NIRISS,
NIRCam, NIRSpec, and MIRI !
Thanks for your continued interest and support !
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For More Information
About NIRISS:
http://www.stsci.edu/jwst/instruments/niriss
(with links to the Pocket Guide and multimedia presentations)
About JWST:
http://webbtelescope.org/webb_telescope/
http://www.stsci.edu/jwst/
Arrival at Goddard Space Flight Center
2012 July 30
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