SKYSURF: Constraints on Zodiacal Light and Extragalactic Background Light through Panchromatic HST All-Sky Surface-Brightness Measurements: I. Survey Overview and Methods. (arXiv:2205.06214v1 [astro-ph.CO])
<a href="http://arxiv.org/find/astro-ph/1/au:+Windhorst_R/0/1/0/all/0/1">Rogier A. Windhorst</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Carleton_T/0/1/0/all/0/1">Timothy Carleton</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+OBrien_R/0/1/0/all/0/1">Rosalia O&#x27;Brien</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Cohen_S/0/1/0/all/0/1">Seth H. Cohen</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Carter_D/0/1/0/all/0/1">Delondrae Carter</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Jansen_R/0/1/0/all/0/1">Rolf Jansen</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Tompkins_S/0/1/0/all/0/1">Scott Tompkins</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Arendt_R/0/1/0/all/0/1">Richard G. Arendt</a> (2), <a href="http://arxiv.org/find/astro-ph/1/au:+Caddy_S/0/1/0/all/0/1">Sarah Caddy</a> (3), <a href="http://arxiv.org/find/astro-ph/1/au:+Grogin_N/0/1/0/all/0/1">Norman Grogin</a> (4), <a href="http://arxiv.org/find/astro-ph/1/au:+Koekemoer_A/0/1/0/all/0/1">Anton Koekemoer</a> (4), <a href="http://arxiv.org/find/astro-ph/1/au:+MacKenty_J/0/1/0/all/0/1">John MacKenty</a> (4), <a href="http://arxiv.org/find/astro-ph/1/au:+Casertano_S/0/1/0/all/0/1">Stefano Casertano</a> (4), <a href="http://arxiv.org/find/astro-ph/1/au:+Davies_L/0/1/0/all/0/1">Luke J. M. Davies</a> (6), <a href="http://arxiv.org/find/astro-ph/1/au:+Driver_S/0/1/0/all/0/1">Simon P. Driver</a> (7), <a href="http://arxiv.org/find/astro-ph/1/au:+Dwek_E/0/1/0/all/0/1">Eli Dwek</a> (2), <a href="http://arxiv.org/find/astro-ph/1/au:+Kashlinsky_A/0/1/0/all/0/1">Alexander Kashlinsky</a> (2), <a href="http://arxiv.org/find/astro-ph/1/au:+Kenyon_S/0/1/0/all/0/1">Scott J. Kenyon</a> (5), <a href="http://arxiv.org/find/astro-ph/1/au:+Miles_N/0/1/0/all/0/1">Nathan Miles</a> (4), <a href="http://arxiv.org/find/astro-ph/1/au:+Pirzkal_N/0/1/0/all/0/1">Nor Pirzkal</a> (4), <a href="http://arxiv.org/find/astro-ph/1/au:+Robotham_A/0/1/0/all/0/1">Aaron Robotham</a> (7), <a href="http://arxiv.org/find/astro-ph/1/au:+Ryan_R/0/1/0/all/0/1">Russell Ryan</a> (4), <a href="http://arxiv.org/find/astro-ph/1/au:+Abate_H/0/1/0/all/0/1">Haley Abate</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Andras_Letanovszky_H/0/1/0/all/0/1">Hanga Andras-Letanovszky</a> (8), <a href="http://arxiv.org/find/astro-ph/1/au:+Berkheimer_J/0/1/0/all/0/1">Jessica Berkheimer</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Chambers_J/0/1/0/all/0/1">John Chambers</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Gelb_C/0/1/0/all/0/1">Connor Gelb</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Goisman_Z/0/1/0/all/0/1">Zak Goisman</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Henningsen_D/0/1/0/all/0/1">Daniel Henningsen</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Huckabe_I/0/1/0/all/0/1">Isabela Huckabe</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Kramer_D/0/1/0/all/0/1">Darby Kramer</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Patel_T/0/1/0/all/0/1">Teerthal Patel</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Pawnikar_R/0/1/0/all/0/1">Rushabh Pawnikar</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Pringle_E/0/1/0/all/0/1">Ewan Pringle</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Rogers_C/0/1/0/all/0/1">Ci&#x27;mone Rogers</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Sherman_S/0/1/0/all/0/1">Steven Sherman</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Swirbul_A/0/1/0/all/0/1">Andi Swirbul</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Webber_K/0/1/0/all/0/1">Kaitlin Webber</a> (1) ((1) Arizona State University, (2) NASA Goddard Space Flight Center, (3) Macquarie University, (4) Space Telescope Science Institute, (5) Smithsonian Astrophysical Observatory, (6) The University of Western Australia, (7) International Centre for Radio Astronomy Research, (8) Steward Observatory)

We give an overview and describe the rationale, methods, and testing of the
Hubble Space Telescope (HST) Archival Legacy project “SKYSURF.” SKYSURF uses
HST’s unique capability as an absolute photometer to measure the ~0.2-1.7
$mu$m sky surface brightness (SB) from 249,861 WFPC2, ACS, and WFC3 exposures
in ~1400 independent HST fields. SKYSURF’s panchromatic dataset is designed to
constrain the discrete and diffuse UV to near-IR sky components: Zodiacal Light
(ZL; inner Solar System), Kuiper Belt Objects (KBOs; outer Solar System),
Diffuse Galactic Light (DGL), and the discrete plus diffuse Extragalactic
Background Light (EBL). We outline SKYSURF’s methods to: (1) measure sky-SB
levels between its detected objects; (2) measure the integrated discrete EBL,
most of which comes from AB$simeq$17-22 mag galaxies; and (3) estimate how
much diffuse light may exist in addition to the extrapolated discrete galaxy
counts. Simulations of HST WFC3/IR images with known sky-values and gradients,
realistic cosmic ray (CR) distributions, and star plus galaxy counts were
processed with nine different algorithms to measure the “Lowest Estimated
Sky-SB” (LES) in each image between the discrete objects. The best algorithms
recover the inserted LES values within 0.2% when there are no image gradients,
and within 0.2-0.4% when there are 5-10% gradients. SKYSURF requires
non-standard re-processing of these HST images that includes restoring the
lowest sky-level from each visit into each drizzled image. We provide a proof
of concept of our methods from the WFC3/IR F125W images, where any residual
diffuse light that HST sees in excess of the Kelsall et al. (1998) Zodiacal
model prediction does not depend on the total object flux that each image
contains. This enables us to present our first SKYSURF results on diffuse light
in Carleton et al. (2022).

We give an overview and describe the rationale, methods, and testing of the
Hubble Space Telescope (HST) Archival Legacy project “SKYSURF.” SKYSURF uses
HST’s unique capability as an absolute photometer to measure the ~0.2-1.7
$mu$m sky surface brightness (SB) from 249,861 WFPC2, ACS, and WFC3 exposures
in ~1400 independent HST fields. SKYSURF’s panchromatic dataset is designed to
constrain the discrete and diffuse UV to near-IR sky components: Zodiacal Light
(ZL; inner Solar System), Kuiper Belt Objects (KBOs; outer Solar System),
Diffuse Galactic Light (DGL), and the discrete plus diffuse Extragalactic
Background Light (EBL). We outline SKYSURF’s methods to: (1) measure sky-SB
levels between its detected objects; (2) measure the integrated discrete EBL,
most of which comes from AB$simeq$17-22 mag galaxies; and (3) estimate how
much diffuse light may exist in addition to the extrapolated discrete galaxy
counts. Simulations of HST WFC3/IR images with known sky-values and gradients,
realistic cosmic ray (CR) distributions, and star plus galaxy counts were
processed with nine different algorithms to measure the “Lowest Estimated
Sky-SB” (LES) in each image between the discrete objects. The best algorithms
recover the inserted LES values within 0.2% when there are no image gradients,
and within 0.2-0.4% when there are 5-10% gradients. SKYSURF requires
non-standard re-processing of these HST images that includes restoring the
lowest sky-level from each visit into each drizzled image. We provide a proof
of concept of our methods from the WFC3/IR F125W images, where any residual
diffuse light that HST sees in excess of the Kelsall et al. (1998) Zodiacal
model prediction does not depend on the total object flux that each image
contains. This enables us to present our first SKYSURF results on diffuse light
in Carleton et al. (2022).

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