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Nancy Grace Roman Space Telescope Wide Field Instrument: Bright Point Source Saturation Response and Persistence Properties from Thermal-Vacuum Testing

T0 review · 3 major / 7 minor · reviewed 2026-08-01 · deepseek-v4-flash

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Pith's one-line read Deeply saturated bright stars in Roman survey fields will create large masked regions and short-lived persistence, with a 4th-magnitude source engulfing ~150 pixels in a ~170 s exposure and persistence fading to background within ~20 minute

desk verdict A careful, much-needed measurement of Roman WFI deep point-source saturation and persistence; the 20-minute persistence decay is solid, but the 150-pixel saturation diameter carries an unquantified SORC-to-flight transfer caveat. read the letter →

arxiv 2607.18419 v1 pith:O2KDZ7HW submitted 2026-07-20 astro-ph.IM astro-ph.EPastro-ph.GAastro-ph.SR

Dana R. Louie , Robert F. Wilson , Thomas Barclay , Joshua E. Schlieder , Nicholas Bond , Evan Bray , Mario Cabrera , Stephanie Cheung
show 14 more authors
Ami Choi Analia Cillis Nicholas Collins Tyler D. Groff Robert J. Hill Jeffrey Kruk Gregory Mosby Jennie Paine Bernard J. Rauscher Timothy A. Reichard Maxime Rizzo Scott Rohrbach Nicole Schanche Eric R. Switzer
This is my paper · ORCID
classification astro-ph.IMastro-ph.EPastro-ph.GAastro-ph.SR
keywords saturationpersistenceHgCdTedetectorsH4RG-10RomanSpaceTelescopethermalvacuumtestingchargeleakageband-edgeemission
verification ladder T0 review T1 audit T2 compute T3 formal

The pith

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The reading

Roman's surveys will point at hundreds of thousands of stars bright enough to saturate the WFI detectors, yet prior ground characterization never pushed a point source deep into saturation. This paper reports a dedicated thermal-vacuum test in which nine point sources from ~4th to ~18th magnitude were projected onto two of the flight-like sensor chips. The central measurements: a ~4th-magnitude source saturates a region roughly 150 pixels in diameter after ~170 s (versus ~15 pixels at ~12th magnitude), pixels at the expanding saturation front show a dynamic charge-leakage non-linearity, and the persistence signal left after illumination decays to the detector background (≲0.05 e−/s) within about 20 minutes, largely independent of source brightness. If these numbers hold on orbit, survey planners can mask bright-star cores with known sizes and schedule repeat observations knowing that persistence will not linger beyond roughly one visitor.

What carries the argument

The analysis rests on a 56-frame up-the-ramp exposure sequence (reset frame plus 55 science frames) corrected with the IRRC reference correction, superbias subtraction, and per-pixel gain maps. A saturation mask flags pixels reaching 100,000–130,000 e− in the final frame; the saturation front is characterized by the ratio of instantaneous slope (difference between consecutive frames) to mean slope (average of pre-saturation frames) per pixel. Persistence is measured as the slope of interleaved dark exposures after subtracting a thermal dark-current frame and empirically constructed fiber-contamination masks, and the decay curves are the median persistence within each saturation mask versus t

What would settle it

Measure, on orbit, the saturated-region diameter and persistence decay for a known ~4th-magnitude star observed through F146: if the saturated region differs substantially from ~150 pixels at ~170 s (beyond PSF differences) or if persistence remains above the detector background for more than ~20–30 minutes at the flight operating temperature, the central claims would be refuted. On the ground, repeating the test with the full F146 spectrum (extending the projector's cut-on from 1.2 µm down to 0.927 µm) would show whether the narrower test bandpass altered the saturation growth or the persiste

Watch

Extended reading notes

Core claim

We measured the saturation response and persistence of two Roman WFI sensor chip assemblies by projecting nine in-focus point sources through the F146 filter with the SORC telescope simulator, at fluxes approximating stellar magnitudes ~4 to ~18, in ~170 s up-the-ramp exposures. The saturated region grows to ~150 pixels in diameter for a ~4 mag source versus ~15 pixels for ~12 mag, and pixels adjacent to the advancing saturation front exhibit a dynamic increase in instantaneous slope relative to their pre-saturation mean slope, consistent with charge leakage from saturated neighbors. In interleaved dark exposures, the median persistence within the saturated pixels is broadly consistent acros

Load-bearing premise

The quantitative results transfer to orbit only if the projector's point spread function, spectral passband (1.2–1.9 µm versus the F146 band 0.927–2.0 µm), and stray light faithfully mimic how the flight telescope will illuminate the detectors.

Editorial extensions

If this is right

  • A ~4 mag star in a ~170 s exposure will saturate a ~150-pixel-diameter region, so masking tools for GBTDS and other surveys can use this as a first-order footprint for the brightest targets.
  • Persistence from deeply saturated point sources decays to the detector background within about 20 minutes, so repeat visits to dense stellar fields can be planned with roughly that recovery timescale in mind.
  • Because the first post-illumination persistence is nearly independent of source magnitude, a single persistence correction curve may apply across a wide brightness range.
  • The charge leakage at the saturation front is time-dependent and scales with the pixel's own brightness, so photometry of pixels bordering saturated cores requires a model with a time-varying count-rate boost.
  • The band-edge halo redistributes flux laterally across the detector and casts defect shadows, so high-accuracy photometry of the brightest saturated sources must account for internal radiative emission.

Reading between the lines

Editorial extensions of the paper, not claims the author makes directly.

  • If the trap population responsible for persistence is already filled at the fluxes tested, even deeper saturation (say a mag 2–3 source or a ~400 s exposure) should leave the ~20-minute recovery unchanged; a follow-up test could check that directly.
  • The near-magnitude independence of persistence suggests a simple scheduling rule for Roman operations: after any exposure containing a saturated star, wait roughly 25–30 minutes before using the same detector region for faint science, making persistence a fixed overhead.
  • The observed dynamic charge leakage could be modeled as a spreading-front wave triggered by neighbor saturation; if such a model were developed, it might recover reliable photometry for pixels that are currently discarded in crowded fields.
  • The flux halo may be mistaken for telescope stray light or PSF wings in ground test data; on-orbit observations of bright stars in touchstone fields should separate the internal band-edge halo from the flight telescope's scattered light.
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Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, and a circularity audit.

Referee Report

3 major / 7 minor

Summary. This paper reports a bright point-source saturation and persistence test performed during the Roman WFI Thermal Vacuum campaign TVAC2. Using the SORC telescope simulator, nine in-focus point sources approximating stellar magnitudes 4–18 were projected through the F146 filter onto SCAs 4 and 11. The authors analyze up-the-ramp data to measure the growth of saturated regions, characterize non-linear slope behavior near the saturation front, and derive persistence decay curves from interleaved darks. The headline results are that a ~4 mag source produces a saturated region ~150 pixels in diameter after ~170 s (vs. ~15 pixels for ~12 mag), and that persistence from all tested sources decays to detector background levels (≲0.05 e− s−1) within about 20 minutes. The paper also reports a flux halo with defect shadows around the brightest source and makes its analysis products available via Zenodo and STScI repositories.

Significance. If correct, these measurements provide the first direct pre-flight characterization of deep point-source saturation and persistence for Roman WFI, with immediate value for survey planning, masking, and scheduling in the GBTDS and other bright-star fields. The paper is unusually detailed in its data processing: IRRC reference correction, superbias subtraction, per-pixel gains, classical non-linearity correction, explicit saturation-mask definitions, bad-pixel masks, dark-current subtraction, and a documented fiber-contamination subtraction procedure. The persistence comparison with flat-field illumination from the same TVAC2 campaign is a strong internal consistency check, and the public data products will enable further analysis. The principal weakness is the transferability of SORC-based measurements, especially the saturation-region diameter, to the flight telescope.

major comments (3)
  1. [§2.1, Fig. 4, §3.1] The headline saturation-region diameter (~150 px for mag 4, ~15 px for mag 12) is measured under SORC illumination whose spectrum (SPLIT-IR, 1.2–1.9 µm) is markedly narrower than F146 (0.927–2.0 µm) and whose optics produce stray-light arcs (Fig. 6) that are acknowledged to be absent in flight. The diameter is reported without error bars or a comparison with a modeled PSF (e.g., stpsf) that would support transfer to flight conditions. Since the saturation mask is defined by a 100,000–130,000 e− threshold in the final frame, any PSF broadening or spectral shift could change the measured diameter. Please provide a PSF-fidelity assessment (e.g., comparing a sub-saturated SORC PSF to stpsf predictions and propagating the uncertainty) or explicitly frame the 150-pixel value as a SORC-specific measurement with a corresponding caveat in the abstract and conclusions.
  2. [§2.2.3, §3.2] The central persistence claim — decay to ≲0.05 e− s−1 within ~20 min — is not supported by a quantitative criterion. The abstract quotes ≲0.05 e− s−1, but the text does not show how this background threshold is derived, nor is it overlaid on the decay curves in Figs. 19 and 21. Several data points are explicitly labeled as oversubtracted or biased by stray light (mag 4 first three points; last points for SCA 4), and the first interleaved dark values for SCA 4 do not agree within the error bars. Please define 'detector background level,' show the threshold on the decay curves, and fit or tabulate the time at which each magnitude/SCA reaches the threshold (or provide another statistical summary). Without this, the 20-minute claim is not crisply evidenced.
  3. [§2.2.3, steps 1–4] The fiber-contamination subtraction uses an empirical flux threshold (0.62 e−/s for SCA 11, 0.75 e−/s for SCA 4) and a scaling factor for the 'lower' component that is tuned to force the lowest residual in the mask to zero. These are free parameters, and the paper itself reports oversubtraction for the mag 4 source in the first three interleaved darks. The sensitivity of the persistence decay curves to reasonable variations in the threshold and scaling factor should be quantified, or the correction validated using a source geometry where the fiber leak lies outside the ROI. This would establish that the persistence-decay conclusion is robust to the correction.
minor comments (7)
  1. [§2.1] The SORC characterization reference (Wake and Lyons et al., in prep) is not public. If possible, include additional details of the SORC PSF and its measured quality, or a preprint/technical note.
  2. [§2.2.1] The IRRC algorithm is cited as 'Rauscher et al., in prep' in addition to the STScI report; a public reference or more algorithmic detail would help reproducibility.
  3. [§3.1] The statement that the saturation region 'grows to about 150 pixels in diameter' should specify how the diameter is defined (e.g., equivalent circular diameter from the mask area) and should include an uncertainty estimate.
  4. [§3.2] The error bars are described as 'the average of the persistence interquartile range for all pixels within a given saturation mask.' This is unusual; clarify the statistical choice (e.g., why not the median absolute deviation or bootstrap uncertainty).
  5. [Fig. 20 caption] For mag 17, only 6 pixels are in the saturation mask and all are affected by fiber contamination. This context should be stated in the figure caption or main text when interpreting the mag 17 point.
  6. [§4.1] The flux-halo/defect-shadow explanation rests on 'internal discussions with detector experts' and a private communication with T. Brandt. This is speculative; label it clearly as a hypothesis rather than an established mechanism, and cite the NIRCam in-flight observation once the analysis is public.
  7. [§4.2] The statement 'We make our analysis products publicly available' is qualified by 'the Zenodo repository will be published after paper acceptance.' Please clarify the current availability status in the submitted version.

Circularity Check

0 steps flagged · score 0.0 of 10

No circularity: TVAC2 bright-star saturation and persistence results are direct measurements with independent internal and external anchors.

full rationale

This is a measurement/characterization paper, not a derivation. The headline numbers—~150-pixel saturated-region diameter for a ~4 mag source, ~15 pixels for ~12 mag, and persistence decaying to ≲0.05 e−/s within ~20 minutes—are read directly from up-the-ramp detector frames and interleaved darks. The saturation mask definition (pixels reaching 100,000–130,000 e− in the final illuminated frame) is an operational threshold chosen from the observed flat-top well-depth structure, not a parameter fitted to the reported diameters or persistence levels. The simulated magnitudes were calibrated independently via a published time-to-saturation, magnitude scaling, and the STScI stpsf PSF model; they are approximate inputs but are not derived from the measured saturated-region size, so the magnitude-dependent diameter is not circular. Persistence values are computed as slopes in post-illumination darks with dark-current subtraction, and the comparison with flat-field persistence from the same TVAC2 campaign is a cross-check between two independent measurements, not an input. The paper does cite prior work by overlapping authors (e.g., Betti et al. 2024 for IRRC, Mosby et al. 2020/2025, Schlieder et al. 2024, Wilson et al. 2023), but none of these citations supplies or constrains the central saturation/persistence results; they provide calibration, detector context, and instrument description. The load-bearing caveat, acknowledged in the manuscript itself, is that the SORC projector's spectrum and PSF/stray light (Figs. 4 and 6) must faithfully represent flight illumination for the quantitative values to transfer to orbit; this is an external-validity/correctness risk, not a circularity. No step in the paper's chain equates a prediction with a fitted input or an imported self-citation.

Assumptions & free parameters 5 free parameters · 5 assumptions · 0 invented entities

The paper's quantitative claims rest on calibrated test inputs (source fluxes, saturation thresholds, fiber-correction parameters) and on the fidelity of the SORC stimulus as a proxy for flight point sources. No new physical entities are postulated; the halo mechanism is an existing semiconductor explanation applied to the data. The most fragile inputs are the empirically fitted fiber subtraction and the assumed full-well range used for masks.

free parameters (5)
  • SORC source flux calibration for each simulated magnitude = Mag 4: 4.7e10 e−; 7: 2.9e9; 10: 1.9e8; 12: 2.9e7; 14: 4.7e6; 15: 1.9e6; 16: 7.4e5; 17: 2.9e5; 18: 1.17e5 e− per ~170 s a
    Chosen in test planning from an assumed 80,000 e− full well and stpsf brightest-pixel fractions (Table 1, §2.1). Actual measured full well is 100,000–130,000 e−, so effective magnitudes may differ from the labels; this calibrates all magnitude-dependent claims.
  • Saturation mask electron range = 100,000–130,000 e−
    Hand-selected to bracket full-well variation (§2.2.3, Fig 7). Defines the saturated region used for both saturation-size and persistence analysis, so the central numbers inherit this choice.
  • Fiber contamination threshold = 0.62 e−/s (SCA 11); 0.75 e−/s (SCA 4)
    Empirically set to the maximum background fluctuation in interleaved darks (§2.2.3, Figs 10, 12). Determines the 70- and 46-pixel fiber masks used for contamination subtraction.
  • Lower fiber subtraction scaling factor = Not stated numerically (per-pixel constant enforced to give a zero minimum)
    Computed from the data so that the lowest background-subtracted value inside the fiber mask is zero (§2.2.3 step 3). Fit to the persistence frame itself and acknowledged to cause oversubtraction at mag 4.
  • Saturation definition for slope analysis = Signal constant in subsequent frame and uncorrected signal > 63,500 DN; only first 54 of 55 science frames used
    Convenient definition adopted in §2.2.2 to assign pixels to saturation regimes; affects the slope-ratio analysis in Figs 16–18.
assumptions (5)
  • domain assumption SORC projector reproduces the Roman telescope optical prescription (≈f/8) and its SPLIT-IR spectrum adequately represents F146 stellar illumination
    §2.1: the stimulus PSF, stray-light arcs, and spectral cut-on at 1.2 µm mean the illumination is not exactly stellar; all quantitative conclusions (saturation diameter, persistence) inherit this assumption.
  • domain assumption Classical non-linearity coefficients from TVAC2 are correct for the deeply saturated regime
    §2.2.2 applies classical non-linearity correction before slope analysis; inaccurate coefficients would distort the slope-ratio diagnostics and the interpretation of charge leakage.
  • domain assumption The slope enhancement near saturated pixels is caused by charge leakage from saturated neighbors
    §3.1 cites prior H2RG observations (Brandt et al. 2017) but does not rule out optical cross-talk or projector focus drift; this is an interpretation of the observed non-linearity.
  • ad hoc to paper The flux halo and defect shadows originate from internal radiative recombination near the HgCdTe bandgap edge
    §4.1 asserts this on the basis of internal discussions and a private communication (T. Brandt); no quantitative model, independent laboratory measurement, or public reference is provided in the paper.
  • domain assumption The flat-field persistence measured in the same TVAC2 campaign is a valid baseline for point-source persistence comparison
    §3.2 compares point-source persistence to flat-field persistence from the same campaign; both share detector state and environment, making it a reasonable internal benchmark, but any shared systematic would affect both.

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Pith. "Pith review of Nancy Grace Roman Space Telescope Wide Field Instrument: Bright Point Source Saturation Response and Persistence Properties from Thermal-Vacuum Testing." pith.science (2026). https://pith.science/paper/O2KDZ7HW

@misc{pith2026260718419,
  author       = {Pith},
  title        = {Pith review of: Nancy Grace Roman Space Telescope Wide Field Instrument: Bright Point Source Saturation Response and Persistence Properties from Thermal-Vacuum Testing},
  year         = {2026},
  howpublished = {\url{https://pith.science/paper/O2KDZ7HW}},
  note         = {Machine review of arXiv:2607.18419}
}
abstract

The Nancy Grace Roman Space Telescope's Wide Field Instrument (WFI) will observe hundreds of thousands of bright stars across its Core Community Surveys, particularly in the dense stellar fields of the Galactic Bulge Time Domain Survey (GBTDS). Sources brighter than ~17th magnitude will saturate WFI detector pixels in typical survey exposures, with the brightest stars deeply saturating large pixel regions and potentially producing persistence signals that may impact subsequent observations. Prior detector characterization did not explore the regime of deep point source saturation. To address this gap, we conducted a bright star saturation test during WFI's second Thermal Vacuum test campaign (TVAC2) at BAE Space & Mission Systems in Boulder, CO. Using the Stimulus of Ray Cones (SORC) telescope simulator, we projected nine in-focus point sources through the F146 filter onto two Sensor Chip Assemblies (SCAs), with fluxes tuned to approximate stellar magnitudes ranging from ~4 to ~18 in ~170 s exposures. We present analyses of the saturation response and persistence properties of these detectors. We find that the saturated region of a ~4 mag source grows to ~150 pixels in diameter after ~170 s of illumination, compared to ~15 pixels for a ~12 mag source. Pixels adjacent to the expanding saturation front exhibit pronounced non-linear behavior consistent with charge leakage from saturated neighbors. For persistence, we find that the median signal in the first post-illumination dark exposure is broadly consistent across source magnitudes spanning ~4 to ~17, and that persistence decays to detector background levels ($\lesssim$0.05 e$^{-}$ s$^{-1}$) within approximately 20 minutes, consistent with flat field persistence measurements from the same TVAC2 campaign. These pre-flight characterization results inform community understanding of WFI detector response to prepare for Roman science.

Figures

Figures reproduced from arXiv: 2607.18419 by the authors.

Figure 1
Figure 1. Wide Field Instrument (WFI) Focal Plane Array (FPA). Sensor Chip Assemblies (SCAs), or detectors, are referred to by number. Our test analyzed the saturation response and persistence properties of detectors 4 and 11 to nine different bright point sources designed to approximate stars ranging in magnitude from ∼4 to ∼18. F087 F062 Prism (P127) F106 F129 F184 Grism (G150) F146 F213 Dark F158 [PITH_FULL_IMAGE:figures/… view at source ↗
Figure 2
Figure 2. Wide Field Instrument (WFI) Element Wheel Assembly (EWA). The EWA is equipped with 8 filters, the G150 grism (1.0 – 1.93 µm), and the P127 prism (0.75 – 1.80 µm). eral Astrophysics Surveys defined by the community5 . Sky locations and integration times vary widely across each of the three CCSs, leading to a large diversity of source fluxes. When combined with the high sensitivity resulting from Roman’s 2.4m aperture… view at source ↗
Figure 3
Figure 3. The approximate number and distribution of saturated stars in the GBTDS based on archival 2MASS data. The shading shows the number of expected stars with F146 < 10 magAB (top left), F146 < 12.5 magAB (top right), and F146 < 15 magAB (bottom left) in 0.0025 deg2 bins. The blue points denote the locations of stars with F146 < 7.5 magAB, with the size of the points indicative of their brightness. The red outlines denot… view at source ↗
Figures from the paper (31 more)
Figure 4
Figure 4. Figure 4: Comparison of the F146 Filter bandpass for SCAs 4 and 11 with the SORC SPLIT-IR input spectrum used in the TVAC2 Bright Star test. The F146 filter spans wavelengths from 0.927 to 2.0 µm and The SORC SPLIT-IR spectrum fits within the F146 bandpass. The spectrum has a cu…
Figure 5
Figure 5. Figure 5: Locations of projected SORC PSFs upon the SCA, with approximate saturated region sizes indicated us￾ing red circles. SORC PSFs were projected in sequence from 1 to 9 as tabulated in column 1 of [PITH_FULL_IMAGE:figures/full_fig_p006_5.png]
Figure 6
Figure 6. Figure 6: SCA 4 first science frame (after reset-read frame) for the ∼4 mag source. We show the raw data at left, and the IRRC-corrected and superbias-subtracted frame on the right, showing significant improvement. The arcs surrounding the central bright source in the right-hand…
Figure 7
Figure 7. Figure 7: Regions of Interest (ROIs) for SCA 4 (left) and 11 (right) magnitude ∼4 sources. The top panels show the final illuminated frames for the bright sources upon each SCA, while the bottom panels depict the counts in electrons through each row of the saturation region. Our…
Figure 8
Figure 8. Figure 8: Region of Interest (ROI) for the SCA 11 mag￾nitude 4 source overplotted with the saturation mask used in our persistence analysis. Those pixels that are part of the saturation mask are colored purple. Our saturation mask flagged those pixels with electron counts betwee…
Figure 9
Figure 9. Figure 9: SCA 11 First interleaved dark persistence frame. The diffuse, PSF shaped signal region in the center of the ROI is persistence caused by the ∼4 mag projected source. The two bright spots near the center of the persistence dis￾tribution are caused by SORC fiber light co…
Figure 10
Figure 10. Figure 10: ROI for the SCA 11 ∼18 mag first interleaved dark persistence frame. The top panel shows the image of the fiber contamination upon SCA 11, with pink squares showing the 70 pixels contained within our light fiber mask. Fiber light contamination is the primary cause of …
Figure 12
Figure 12. Figure 12: ROI for the SCA 4 ∼17 mag first interleaved dark persistence frame. The top panel shows the image of the fiber contamination upon SCA 4, with pink squares show￾ing the 46 pixels contained within our light fiber mask. Fiber light contamination is the primary cause of t…
Figure 14
Figure 14. Figure 14: ROI for SCA 11 magnitude ∼7 interleaved dark persistence frame. The upper left panel shows the persistence image, where the 2 bright spots caused by SORC light fiber contamination are clearly visible. In the upper right panel we overplot the saturation mask in pink. I…
Figure 15
Figure 15. Figure 15: ROI for SCA 11 magnitude ∼15 interleaved dark persistence frame. The upper left panel shows the persistence image, which contains a large component of SORC light fiber contamination. In the upper right panel we overplot the saturation mask in pink. Note that the brigh…
Figure 16
Figure 16. Figure 16: Pixels adjacent to saturated regions show pronounced non-linear behavior. The saturation response for an ap￾proximately 12 mag source on SCA 11 is shown here. Top row: total accumulated signal in the indicated frame. Middle row: instantaneous slope, computed as the di…
Figure 17
Figure 17. Figure 17: The accumulated signal for specific pixels of an approximately 12 mag source on SCA 11 is shown here across all frames. Each line corresponds to a pixel from [PITH_FULL_IMAGE:figures/full_fig_p016_17.png]
Figure 18
Figure 18. Figure 18: The ratio of the instantaneous slope to the mean slope measured for all pixels for which a neighboring pixel saturates during an exposure. Each line is the time-series of one pixel, with the frame number shifted so that the frame immediately before the neighboring pix…
Figure 19
Figure 19. Figure 19: SCA 11 Persistence Decay Curves for magnitudes ∼4 through ∼17. The first interleaved dark persistence values largely agree within the errors bars. However, we note that the mag ∼4 persistence value is slightly lower than the value for other magnitudes, while the value…
Figure 20
Figure 20. Figure 20: SCA 11 comparison of persistence in first interleaved dark exposures, which suffered from SORC light fiber contamination. We show the first interleaved dark frames after subtracting the fiber contamination (see §2.2.3). Although the Mag ∼4 source persistence appears s…
Figure 21
Figure 21. Figure 21: SCA 4 Persistence Decay Curves for magnitudes ∼4 through ∼17. The first interleaved dark values do not agree within the error bars. Underlying persistence performance varies spatially across SCA 4, and thus persistence values in the first interleaved dark exposure wer…
Figure 22
Figure 22. Figure 22: SCA 4 comparison of persistence in first interleaved dark, showing that the values do not agree within the error bars. Underlying persistence performance varies spatially across SCA 4, and thus persistence values in the first interleaved dark exposure were impacted by…
Figure 23
Figure 23. Figure 23: SCA 4 persistence measured from a dark exposure following flat field illumination during TVAC2. The bright point source saturation masks for each magnitude are overplotted in white, with the accompanying ROIs outlined using gray boxes. The spatial variation of persist…
Figure 24
Figure 24. Figure 24: Comparison of SCA 4 persistence measurements in subsequent dark frames following two separate TVAC2 tests: 1.) flat field illumination and 2.) bright point source projection. Flat field persistence shown was computed within the ROIs designated in [PITH_FULL_IMAGE:fig…
Figure 25
Figure 25. Figure 25: SCA 4 (left) and 11 (right) superbias frames subtracted during our IRRC correction [PITH_FULL_IMAGE:figures/full_fig_p025_25.png]
Figure 26
Figure 26. Figure 26: Frames for SCA 4 (left) and 11 (right) pixel-level photon transfer gains applied following IRRC correction and superbias subtraction [PITH_FULL_IMAGE:figures/full_fig_p025_26.png]
Figure 27
Figure 27. Figure 27: Final frame of SCA 4 illuminated data overplotted with saturation masks for each source magnitude. Those pixels that are part of the saturation mask are colored purple. Sources appear from brightest to dimmest, going from left to right and top to bottom. Our saturatio…
Figure 28
Figure 28. Figure 28: Final frame of SCA 11 illuminated data overplotted with saturation masks for each source magnitude. Those pixels that are part of the saturation mask are colored purple. Sources appear from brightest to dimmest, going from left to right and top to bottom. Our saturati…
Figure 29
Figure 29. Figure 29: SCA 4 (left) and 11 (right) dark current frames used in persistence analysis [PITH_FULL_IMAGE:figures/full_fig_p028_29.png]
Figure 30
Figure 30. Figure 30: SCA 4 Persistence Frames produced from interleaved dark exposures and the three post-test final darks, as explained in Section 2.2.3. As compared to SCA 11, stray light artifacts from the SORC telescope simulator appear more diffuse and less structured on SCA 4. Howev…
Figure 31
Figure 31. Figure 31: SCA 11 Persistence Frames produced from interleaved dark exposures and the three post-test final darks, as explained in Section 2.2.3. The SORC telescope simulator produced stray light artifacts that our team dealt with to produce our final persistence decay curves […
Figure 32
Figure 32. Figure 32: SCA 11 Persistence Decay Curves for the 4 brightest magnitude sources in our study. The first interleaved dark persistence values largely agree within the errors bars. However, we note that the mag ∼4 persistence value is slightly lower than the value for other magnit…
Figure 33
Figure 33. Figure 33: SCA 11 Persistence Decay Curves for magnitudes 7, 12, 14, and 15 [PITH_FULL_IMAGE:figures/full_fig_p031_33.png]
Figure 34
Figure 34. Figure 34: SCA 4 Persistence Decay Curves for the 4 brightest magnitude sources in our study. The first interleaved dark values do not agree within the error bars. Underlying persistence performance varies spatially across SCA 4, and thus persistence values in the first interlea…
Figure 35
Figure 35. Figure 35: SCA 11 persistence measured from a dark exposure following flat field illumination during TVAC2. The bright point source saturation masks for each magnitude are overplotted in white, with the accompanying ROIs outlined using gray boxes. The spatial variation of persis…
Figure 36
Figure 36. Figure 36: Comparison of SCA 11 persistence measurements in subsequent dark frames following two separate TVAC2 tests: 1.) flat field illumination and 2.) bright point source projection. Flat field persistence shown was computed within the ROIs designated in [PITH_FULL_IMAGE:fi…

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Forward citations

Cited by 1 Pith paper

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score. Full citation record

  1. Persistence characteristics of H4RG-15 detectors for ESO instruments

    astro-ph.IM 2026-07 conditional novelty 4.0 of 10

    Persistence in H4RG-15 detectors varies widely between detectors and with temperature; only 2 of 15 show the previously reported 65 K persistence peak.

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