Mission Overview

The NIRSpec WIDE GTO Survey ("WIDE")

 

Primary Investigator: Michael Maseda

HLSP Authors: Michael Maseda, Anna de Graaff, Stefano Carniani, Eleonora Parlanti

Released: 2024-09-09

Updated: 2024-09-09

Primary Reference(s): Maseda et al. 2024

DOI: 10.17909/57km-j134

Citations: View ADS Metrics

Read Me

Source Data:

 
The top panel shows a plot of the 1D spectrum of one of the WIDE galaxies. The bottom panel shows the 2D spectrum of the same galaxy.
Characteristic 1D (top panel) and 2D (bottom panel) PRISM spectrum for an object from the NIRSpec Wide survey.

Overview

The NIRSpec Wide Survey, part of the NIRSpec Guaranteed Time Observations (GTO), consists of 31 pointings covering approximately 320 square arcminutes in the five CANDELS extragalactic fields with exquisite ancillary Hubble Space Telescope photometry.  Each pointing utilizes NIRSpec’s microshutter array (MSA) to simultaneously obtain spectra for an average of 135 galaxies each.  Observations are performed with the low-resolution PRISM (2451s), the high-resolution G235H grating (1634s), and the high-resolution G395H grating (1780s).  Pointing centers are determined to maximize the observability of the rarest, high-value sources.  Subsequently, the microshutter configurations are optimized to observe the maximum number of "census" galaxies with a selection function based primarily on HST/F160W magnitude, photometric/slitless grism redshift, and predicted Halpha flux tracing the bulk of the galaxy population at cosmic noon (z=2).


Here the team releases the reduced 2D and 1D extracted spectra.  To mitigate self-subtraction when performing nodded background subtraction for very extended objects, the team releases the PRISM data with a two-point nodding pattern in addition to the default three-point pattern; only two-point nodding is available for the high-resolution gratings.  Various 1D boxcar extraction apertures are released, which can be chosen to optimize a source’s signal-to-noise ratio.  In total the team produces three-nod, 3 pixel extraction and three-nod 5 pixel extraction for the PRISM exposures and two-nod 5 pixel extraction and two-nod 15 pixel extraction for PRISM, G235H, and G395H exposures.

The current release (September 2024) consists of the data for the five pointings in the CANDELS/AEGIS field (pointings 2017-2021).  Future releases will contain data from the other Wide pointings.

Data Products

Both 1D and 2D extracted spectra are available.

1D spectra are available for each grating/filter combination according to the following convention:

hlsp_wide_jwst_nirspec_<field>-<pointing><ID>_<filter>-<grating>_v1.0_<nnod>-spec1d.fits

where:

  • <field> is the name of the CANDELS field, e.g. “aegis”
  • <pointing> is the pointing number, e.g. “2021” (see Maseda et al. 2024 for a list of the 31 pointings)
  • <ID> is the ID number for a particular object in that pointing
  • <filter> and <grating> are the specified observing setup, namely “clear/prism,” “f170lp/g235h,” and “f290lp/g395h”
  • <nnod> is the nodding pattern used in the reduction, “2nod” is available for all exposures and “3nod” is only available for the PRISM exposures

2D spectra follow the same convention, but have the extension “spec2d.fits”

 

Data file types:

-spec1d.fits 1D spectra files
-spec2d.fits 2D spectra files

 

Within the 1D files, there are extensions corresponding to the number of pixels used in the extraction (3, 5, or 15).  Each of these extensions consists of a table with “WAVELENGTH,” “FLUX,” and “FLUX_ERR” values: wavelengths are in microns, fluxes and errors are in units of erg/s/cm2/Angstrom.

The 2D files have extensions “FLUX,” “FLUX_ERR,” “WAVELENGTH,” “RA,” and “DEC.”  These are 2D arrays with the same units as the 1D data products.

 

Data Access

MAST Portal and Astroquery

All observations are available in the MAST Portal and astroquery. Set the 'Provenance Name' filter to WIDE in the Portal Advanced Search to match all observations. The spectra can be downloaded for each target as a bundle or individually retrieved by selecting the download basket. The observations can also be retrieved programmatically using the astroquery.mast module. The code example below retrieves all products.

from astroquery.mast import Observations
all_obs = Observations.query_criteria(provenance_name="wide")
data_products = Observations.get_product_list(all_obs)
Observations.download_products(data_products)
  • A web-based interface for cross-mission searches of data at MAST or the Virtual Observatory.
  • Search for and download WIDE data products programmatically in Python.

Direct Download Links

The data products can also be downloaded directly using the cURL script linked below: 

cURL Script for All WIDE Spectra

 

Citations

Please remember to cite the appropriate paper(s) below and the DOI if you use these data in a published work. 

Note: These HLSP data products are licensed for use under CC BY 4.0.

References