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New HST ACS and WFC3 Imaging of the Veil Nebula

September 24, 2015

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Fig. 1: WFC3/UVIS multi-color image of Veil Nebula.
Fig. 2: Heritage Veil Nebula H-alpha Mosaic. WFC3/UVIS H-alpha (main observations) are married with ACS/WFC H-alpha (parallel observations).

New observations of the Veil Nebula (Cygnus Loop) were obtained in April 2015 by the Hubble Heritage Team. These include 6 tiles in a 3x2 mosaic with the WFC3/UVIS channel in three narrowband and two broadband filters (Fig. 1). Parallel observations with the ACS/WFC were also obtained to create an H-alpha mosaic adjacent to and overlapping the WFC3 H-alpha mosaic (Fig. 2). A summary of the observations is given in Table 1, while the footprints are labeled in Figure 3. For more details on the observing strategy, see the proposal 14056, PI: Zolt Levay and the README file.

The wider field of view, higher resolution, and broader wavelength coverage of the new images highlight the improved capabilities of HST over its long-lasting operation, made possible by the upgraded instrumentation installed during Space Shuttle servicing missions. Since these new mosaics represent a significant investment of expert processing beyond the standard archival products, these AstroDrizzle-combined FITS images have now been released as High-Level Science Products via the B. Mikulski Archive for Space Telescopes (MAST). We provide a list of downloadable FITS files which include both the drizzled science (sci) and weight (wht) images, where the latter provide an effective exposure time map for each filter.

The FITS files and their PNG previews follow the naming convention:



ii-ii - instrument used ("acs-wfc" or "wfc3-uvis")

fffff - filter (e.g., "f502n" or "f658n")

ttt - the file type: "drc" (science-grade, drizzled images), or "wht" (weights)

Table 1: Observing Summary
Click on the links in the Filter column to visit the Interactive Display for that filter.
You can also click here to visit the multi-filter Interactive Display.
Dataset Name Detector Filter Exposure
per Image
# images
per Tile
per Tile
# tiles Total Exposure
_acs-wfc_veil_f658n_v1_drc.fits ACS/WFC F658N 750 sec 9 6750 sec 6 40500 sec
_wfc3-uvis_veil_f502n_v1_drc.fits WFC3/UVIS F502N 950 sec 3 2850 sec 6 17100 sec
_wfc3-uvis_veil_f555w_v1_drc.fits WFC3/UVIS F555W 60 sec 3 180 sec 6 1080 sec
_wfc3-uvis_veil_f657n_v1_drc.fits WFC3/UVIS F657N 400 sec 3 1200 sec 6 7200 sec
_wfc3-uvis_veil_f673n_v1_drc.fits WFC3/UVIS F673N 665 sec 3 1995 sec 6 11970 sec
_wfc3-uvis_veil_f814w_v1_drc.fits WFC3/UVIS F814W 40 sec 3 120 sec 6 720 sec
Figure 3: Veil Nebula - Hubble Heritage Footprint Geometry
Fig. 3: Footprints of the Heritage program's observations. The blue footprints to the northeast are the WFC3-UVIS observations. The pink footprints to the southwest are the parallel observations with ACS-WFC that were taken at the time of the main observations.