Mission Overview

WFC3 Infrared Spectroscopic Parallel Survey (WISP)

 

Primary Investigator: Matthew A. Malkan (DR1/DR2), Andrew Battisti (DR3)

HLSP AuthorsHakim Atek, Micaela Bagley, Andrew Battisti, Y. Sophia Dai, Matthew A. Malkan, Marc Rafelski, Harry Teplitz, and the WISP team

Released: 2015-05-20

Updated: 2024-08-23

Primary Reference(s): Atek et al. 2010, Battisti et al. 2024

DOI: 10.17909/T9C302

Citations: See ADS metrics

Read Me 

Source Data:

 

WISP slideshow

Now showing slide 1 of 5

WISP Field of View

Example of how the pure parallel program works. While a nearby quasar is observed by COS, the WFC3 is turned on to collect data on a nearby, random parallel field.

WISP Fields

Locations of the WISP parallel fields. There are 483 fields within the program up to Cycle 23. A total of 390 fields are included in this release.

WISP Filters

Filters used in the WISP survey and follow-up observations separated by (a) space- and (b) ground-based facilities. The WISP survey obtained WFC3/IR imaging together with the grism spectroscopy (dotted black curves) and all WISP fields have either F140W or F160W data, with deep fields also having F110W imaging. Additional photometry is inhomogeneous and comprises WFC3/UVIS, Spitzer, and/or ground-based optical data (ugri) from Magellan, WIYN 3.5m, and Palomar. The F475XF600LP, and IRAC ch2 curves are shown as thinner lines to highlight that they are available for 20 fields (other filters are 20 fields), with a complete breakdown in Table 5 of Battisti et al. (2024)

WISP Emission Line Depths

The 5σ emission-line sensitivities in the individual WISP fields (light grey curves). The blue dashed line indicates the median 5σ field depth. The depth varies significantly field-to-field due to variations in the exposure time and background levels in each field. A complete breakdown is in Table 2 (online version) of Battisti et al. (2024).

WISP Pipeline Example

HST images and segmentation maps are used to perform ‘forced’ photometry on the lower resolution data (ground-based and Spitzer) by combining the PSFs of both HST and the lower resolution data. This animation shows field ‘Par 104’, starting with the HST F110W image, then the Magellan image, and last is the residual of the Magellan image after running through TPHOT. Instances of oversubtracted residuals (black circles) are expected to occur for sources that are saturated in the HST image (mostly foreground stars); for these cases the HST (deeper) light-profile models are less accurate relative to the same sources in the unsaturated (shallower) low-resolution data. The HST WFC3/IR FOV (2.05 arcmin x 2.27 arcmin) is indicated by the green box in all panels. 

 

Overview

WISP is a large HST "pure-parallel" program using the WFC3 G102 and G141 grisms to obtain images, spectra, and catalogs of star-forming galaxies between redshifts 0.5 to 2.5. The primary science goals are to measure the star formation history over the last ~10 billion years, probe galaxy clustering on Mpc scales at redshifts 1 < z < 2, constrain the evolution of dust extinction and metallicity as functions of mass and luminosity, and to conduct a serendipitous search for highly luminous Lyman alpha emitters beyond redshifts z > 6. 

Update 08/23/ 2024

Data release 3 presents reduced images and catalogues of photometric and emission-line data (~230,000 and ~8,000 sources, respectively) for the WISP survey. The data products incorporate the HST data, various ground-based facilities (ugri bands), and Spitzer IRAC (Infrared Array Camera). Coverage in at least one additional filter beyond the WFC3/IR data are available for roughly half of the fields (227 out of 483), with ~20 percent (86) having coverage in six or more filters from u band to IRAC 3.6um (0.35-3.6um). For the lower spatial resolution (and shallower) ground-based and IRAC data, the team performs PSF (point spread function)-matched, prior-based, deconfusion photometry (i.e. forced-photometry) using the TPHOT software to optimally extract measurements or upper limits. The WISP emission-line detection algorithm adopts a continuous wavelet transformation that significantly reduces the number of spurious sources.

Update 05/09/2017

This release (DR2) provides products created using an updated version of the WISP data reduction pipeline (V6.2). Compared to the version used in DR1 (V5.0), V6.2 has improved both the astrometry and the photometry, as described below, and supersedes the DR1 V5.0 data.

  • Astrometry:  The ASTRODRIZZLE (now included in the 'astroconda' package) “tweakreg" procedure was used to improve astrometric accuracy.
  • Photometry:  Source positions were extracted from combined J+H images (instead of a single image), providing higher sensitivity for detection. The aperture based on the J+H images was then fed to aXe for both the G102 and G141 spectra extractions.
  • Other improvements include:
    • a multi-component sky solution
    • an updated Bad Pixel (BP) mask was used in the computation of the uncertainty and contamination

It also increases the number of fields by a factor of 3 (390 fields). It adds 2D spectral cutouts for all objects in the fields and includes several filters in the science images. Multiple spatial resolutions for images are available for some fields too.

Data Products

DR2 (PI: Matthew A. Malkan) includes WFC3 drizzled images of various filters and G102 and G141 gratings, a tarball of 2D extracted cutout stamps,  a tarball of extracted 1D spectra, a source catalog, and the catalog header text file for all objects in each field. The latest data release (DR3, Battisti et al., 2024 ) includes:  1) HST WFC3 imaging data and ancillary images from Hale 5m, Magellan Clay, WIYN 3.5m, and Spitzer, 2) the emission line catalog derived based on the HST grism spectroscopy of the whole WISP fields using the G102 and G141 gratings, and 3) the photometric catalog that contains data of the whole WISP fields from the aforementioned five telescopes and eight instruments (WFC3/UVIS, WFC3/IR, IRAC, LFC, MiniMosaic, ODI, Megacam, WASP).

Data file naming convention:

hlsp_wisp_<telescope>_<instrument>_<field>_<opt-elem>_v6.2_<prodType>.<ext>

where:

  • <telescope> is the telescope used, one of "HST", "Spitzer", "Palomar", "WIYN", or "Magellan"
  •  <instrument> is the instrument used, one of "IRAC, "LFC", "MiniMosaic", "Megacam", "ODI", "WASP", or" WFC3"
  • <field> is the target field, such as "par1-80mas" or "par99"
  • <opt-elem> is the filter or grating used, "f110w", "f140w", "f160w", "f475x", "f600lp", "f606w", "f814w", "g", "g102", or "g141", "I", "IRAC1", "r", "u", or "multi"
  • <prodType> is the data product type, "1dspectra", "2dstamp", "cat", "catalog-header", "drz", "emission-line-cat", "img",  "photometric-cat" , or "seg" 
  • <ext> is the extension of the file, "fits", "png", "tar.gz" or "txt"

Data file types:

_1dspectra.tar.gz

Tarball containing the extracted 1d spectra for all objects in each field. It contains the text files of spectra and spectra header information.

 

These spectra text tables (_spec1d.dat) contain the wavelengths, fluxes, flux errors, flux contaminations, and flux source flags for each target. The "zeroth" column (last column in the file) is a flag that can be one of three integers: 0=no contamination, 1=contamination from the zeroth order, and 2=edge truncation. The source ID is included in the filename, e.g., "hlsp_wisp_hst_wfc3_par1-0025a_g102-g141_v6.2_spec1d.dat" is the spectrum for source #25 in parallel field #1. 

 

This text file (_spectra-header.txt) contains header information for each extracted spectrum, such as the central coordinates for the first exposure, the filters used, and exposure times. It also includes descriptions of what each column represents within the "_spec1d.dat" files. The same header applies for each extracted spectrum in the folder.

_2dstamp.tar.gz

Tarball containing the extracted 2D cutout stamps for all objects in the field. 

 

Its contents are the FITS images (_stamp2d.fits) containing the distortion-corrected 2D aXe-drizzled spectra cutout stamps for each target's first-order beam. The source ID and grism information are included in the filenames, e.g., "hlsp_wisp_hst_wfc3_par11-00001a_g102_v6.2_stamp2d" is the 2D stamp spectrum for source #1 in parallel field #11 in the G102 grism.

_cat.txt Source catalog for the given filter, derived from the direct images using SExtractor. Source IDs between 1000 and 2000 are sources detected only in the bluer filter, while sources with IDs greater than 2000 are detected only in the redder filter.
_catalog-header.txt This text file contains header information for the first exposure taken in the direct imager sequence of observations. Information includes the central coordinates and date/time of the (first) observation.
_drz.fits Drizzled science image for the given filter. The one's that being with "f" (e.g., "f110w", "f140w") are from the imager, the "g101" and "g141" are the 2D spectral images from the grism. Some have different resolutions available, the resolution is included as part of the field name, e.g., "par1-80mas".
_emission-line-cat.fits 8192 sources derived based on the HST grism spectroscopy of the 419 WISP fields using the G102 and G141 gratings. For details on the catalog entries, please refer to Table 10 of Battisti et al. (2024) for the photometric and emission line catalogs, respectively.
_img.fits

Reduced science image for the given filter in the native pixel scale of the instrument. 

 

All images are cropped to approximately a 5arcmin x 5arcmin region centered on the WISP HST pointing. 

_photometric-cat.fits Photometric data catalog (contains ~230,000 sources) of the whole 439 WISP fields from five different telescopes (HST, Spitzer, Palomar, WIYN, Magellan) and eight instruments (WFC3/UVIS, WFC3/IR, IRAC, LFC, MiniMosaic, ODI, Megacam, WASP). For details on the catalog entries, please refer to Table 6 of Battisti et al. (2024) for the photometric and emission line catalogs, respectively.
_seg.fits

Segmentation map produced by SExtractor using the original HST imaging that is used for the forced-aperture photometry in the catalog
                       

The segment numbers correspond 1:1 with the IDs in the photometric and emission line catalogs. Please note, that not all fields have these segmentation maps available due to a loss of some of these files. 

Data Access

While the emission line catalog and the photometric catalog (DR3) are available only via direct download links below, all other observations are available in the MAST Portal and astroquery. Set the 'Provenance Name' filter to WISP in the Portal Advanced Search to match all observations. See the Portal Guide for Advanced Search for detailed information. All observations can be downloaded for each target as a bundle or individually retrieved by selecting the download basket. To access the preview images, uncheck Minimum Recommended Products in the download basket. See the Portal retrieval methods. 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="wisp")
data_products = Observations.get_product_list(all_obs)
Observations.download_products(data_products, curl_flag=True)
  • A web-based interface for cross-mission searches of data at MAST or the Virtual Observatory.
  • Search for and download WISP data products programmatically in Python.

Direct download

Files Size Description
hlsp_wisp_hst_wfc3_all-par_g102-g141_v6.2_emission-line-cat.fits 3.9 MB Emission line catalog

hlsp_wisp_multi_multi_all-par_multi_v6.2_photometric-cat.fits

201 MB

Photometric catalog

 

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