pith. sign in

arxiv: 2606.26796 · v1 · pith:JAET5YJ2new · submitted 2026-06-25 · 🌌 astro-ph.GA

Validating the ICCF-Cut Method with Simultaneous Photometric and Spectroscopic Hα Reverberation Mapping of NGC 4151 and UGC 3374

Chi-Zhuo Wang , Hai-Cheng Feng , Sha-Sha Li , Xue-Bing Wu , Qinchun Ma This is my paper

Pith reviewed 2026-06-26 04:08 UTC · model grok-4.3

classification 🌌 astro-ph.GA
keywords reverberation mappingphotometric RMH-alphaICCF-Cut methodNGC 4151UGC 3374broad line regionAGN
0
0 comments X

The pith

The ICCF-Cut method extracts Hα light curves from photometry that closely match spectroscopic results and yield consistent lags in two Seyfert galaxies.

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

This paper validates the ICCF-Cut method by running simultaneous photometric and spectroscopic monitoring of NGC 4151 and UGC 3374 across multiple seasons. The photometric Hα light curves produced by the method closely resemble the spectroscopic versions. The resulting photometric lags agree with spectroscopic lags within uncertainties in most cases. Where photometric lags come out slightly low, the paper attributes the gap to residual He I contamination and shows that correcting for it improves the match. Simulations with different filter bandwidths further confirm that the method recovers emission-line variability and lags in line with spectroscopic expectations.

Core claim

By directly comparing the photometric and spectroscopic RM results in each season, the extracted Hα light curves using the ICCF-Cut method closely resemble those derived from spectroscopy. The photometric Hα lags are also generally consistent with the spectroscopic Hα lags within the uncertainties. For several seasons where the photometric Hα lags are slightly underestimated, residual He I contamination in the extracted Hα light curves is identified as the cause, and correcting for this contamination brings the photometric lag measurements into closer agreement with the spectroscopic results. The method recovers the emission-line variability and lag measurements broadly consistent with the s

What carries the argument

The ICCF-Cut method, which isolates Hα emission-line variability from broadband photometric light curves to measure time lags.

If this is right

  • The ICCF-Cut method can serve as a reliable alternative to full spectroscopic monitoring for estimating broad-line region sizes in active galaxies.
  • Photometric reverberation mapping produces usable Hα light curves and lags across multiple observing seasons for nearby Seyfert galaxies.
  • Accounting for residual He I contamination resolves underestimates in some photometric lag measurements.
  • The method recovers expected variability and lags in simulations that vary filter bandwidth.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • This validation could support using photometry alone to monitor larger samples of AGNs than spectroscopy permits.
  • The approach might extend to other emission lines if similar contamination corrections can be developed.
  • Routine adoption would lower the telescope resources needed for reverberation mapping campaigns on additional objects.

Load-bearing premise

That any remaining discrepancies after ICCF-Cut extraction can be fully attributed to and corrected for residual He I contamination without introducing new systematic bias into the lag measurements.

What would settle it

A season in which photometric and spectroscopic Hα lags remain significantly different even after the He I correction step, or a simulation in which the input lag is not recovered within uncertainties.

Figures

Figures reproduced from arXiv: 2606.26796 by Chi-Zhuo Wang, Hai-Cheng Feng, Qinchun Ma, Sha-Sha Li, Xue-Bing Wu.

Figure 1
Figure 1. Figure 1: Multicomponent fitting of the mean spectrum of NGC 4151 (2022–2023). The black solid line shows the observed spectrum. The blue solid line and gray shaded region depict the best-fit model and its uncertainties. The orange solid line denotes the AGN power-law continuum component, which is extrapolated toward the blue (blue shaded region) and red (red shaded region) ends. The cyan solid line represents the F… view at source ↗
Figure 2
Figure 2. Figure 2: Photometric light curves of NGC 4151 and UGC 3374 obtained from the LJT. Top panel: Photometric light curves of NGC 4151 during 2022–2025, where the red and blue points represent the R and B bands, respectively. Bottom panel: Photometric light curves of UGC 3374 during 2023–2025, with the same color scheme as the top panel. seasons for NGC 4151 and the 2023–2025 seasons for UGC 3374, we obtained spectrosco… view at source ↗
Figure 3
Figure 3. Figure 3: Light curves and lag distributions for NGC 4151 (LJT 2022-2023). The top left panel shows the light curves of the continuum-band (B) and the line-band (R). The bottom left panel shows the extracted Hα light curve compared with the lagged continuum-band light curve. The three right panels show the lag distributions between the continuum-band and extracted Hα light curves with the ICCF-Cut, JAVELIN, and χ 2 … view at source ↗
Figure 4
Figure 4. Figure 4: Comparison between Hα lags derived from the ICCF-Cut method and the reference lags reported in the literature. The solid points in different colors correspond to lags measured for NGC 4151 and UGC 3374 in different observing seasons, while the hollow points show the corrected ICCF-Cut lags accounting for He i contamination. may be caused by the residual continuum contamination arising from the conservative… view at source ↗
Figure 5
Figure 5. Figure 5: Simulation results for NGC 4151 (LJT 2022–2023) illustrating the influence of the continuum lag and Hα ratio on the ICCF-Cut measurements. Left panel: Heat map of the derived ICCF-Cut lag τcut, with colors denoting lag values and the corresponding numerical values labeled in white within each parameter cell. Right panel: Heat map of the maximum correlation coefficient rmax, with colors indicating the corre… view at source ↗
Figure 6
Figure 6. Figure 6: Left panel: Search for quasi-periodic variability in the LJT R-band light curve of NGC 4151 during 2022-2023. The top left subpanel shows the observed LJT R-band light curve (black points), the long-term trend fitted by a second-order polynomial (blue dashed line), and the fitted light curve considering the quasi-periodic component and the long-term trend (red solid line). The bottom left subpanel displays… view at source ↗
Figure 7
Figure 7. Figure 7: Top panel: Decomposition of the Hα light curves and corresponding lag measurements for NGC 4151 (2022–2023). The left subpanel shows the ICCF-Cut photometric Hα light curve (green points), the spectroscopic He i light curve from H.-C. Feng et al. (2024) (orange points), and the pure Hα light curve after subtracting the He i contamination (green points). The middle subpanel presents the corrected ICCF-Cut l… view at source ↗
Figure 8
Figure 8. Figure 8: Simulated light curves of NGC 4151 (2022–2023) across different photometric filter systems. Top panels: Broadband simulations for ZTF g/r (left), WFST g/r (middle), and LSST g/r (right). Bottom panels: Narrow-band light curve simulations for INT MR661 (left), GTC F657 (middle), and NAOC Hα C2/C12 filters (right). where LHα(t) and LHe i(t) denote the pure Hα and He i light curves, respectively. Due to poten… view at source ↗
Figure 9
Figure 9. Figure 9: PRM results for NGC 4151 (2022–2023) across different bandwidth filters. Top panel: Blue solid circles represent the inter-band lags measured directly from the continuum-band and line-band light curves without ICCF-Cut processing. Orange solid squares show Hα lags measured from the ICCF-Cut method, while orange hollow squares denote ICCF-Cut lags corrected for potential He i contamination. Middle panel: Pu… view at source ↗
Figure 10
Figure 10. Figure 10: Same as [PITH_FULL_IMAGE:figures/full_fig_p016_10.png] view at source ↗
read the original abstract

Photometric reverberation mapping (RM) provides an efficient alternative to spectroscopic RM for probing the broad-line region (BLR) sizes in AGNs. In our previous work, we proposed the ICCF-Cut method, which extracts H$\alpha$ emission-line variability from broadband photometric light curves and measures the lags to estimate the BLR sizes. To further assess the reliability of this method, we conduct simultaneous photometric and spectroscopic monitoring of two nearby Seyfert galaxies, NGC 4151 and UGC 3374, over multiple observing seasons using the Lijiang 2.4 m telescope. By directly comparing the photometric and spectroscopic RM results in each season, we find that the extracted H$\alpha$ light curves using the ICCF-Cut method closely resemble those derived from spectroscopy. The photometric H$\alpha$ lags are also generally consistent with the spectroscopic H$\alpha$ lags within the uncertainties. For several seasons where the photometric H$\alpha$ lags are slightly underestimated, we find that the discrepancy may be caused by residual He\,\textsc{i} contamination in the extracted H$\alpha$ light curves. After correcting for this contamination, the photometric lag measurements become more consistent with the spectroscopic results. We further explore the performance of the ICCF-Cut method using the simulated light curves with different filter bandwidths. For our observational and simulated cases, the method can successfully recover the emission-line variability and lag measurements broadly consistent with the spectroscopic results. This provides further support for the applicability of the ICCF-Cut method in photometric RM.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

1 major / 2 minor

Summary. The paper claims to validate the ICCF-Cut method for extracting Hα light curves from photometric data by comparing it to simultaneous spectroscopic RM observations of NGC 4151 and UGC 3374 across multiple seasons. The extracted photometric light curves resemble spectroscopic ones, and the lags are generally consistent within uncertainties. Discrepancies are attributed to He I contamination and corrected to achieve better agreement, with simulations further supporting the method.

Significance. If the central claims hold, the work offers a direct empirical validation of a photometric RM technique against spectroscopic benchmarks, which could facilitate larger-scale studies of AGN broad-line regions. The season-by-season comparison is a positive aspect of the experimental design.

major comments (1)
  1. [He I contamination correction (Results/Discussion)] The identification and correction for residual He I contamination, used to explain and resolve underestimates in photometric lags for several seasons, is presented without quantitative details on the procedure or tests for systematic bias in the lag measurements. This step is load-bearing for the claim that the method produces results consistent with spectroscopy after correction.
minor comments (2)
  1. [Abstract] The abstract states that the correction makes the measurements 'more consistent' but does not provide any quantitative information on the correction method or its impact.
  2. [Simulations section] Details on the specific filter bandwidths used in the simulations and how they compare to the observational setup would improve clarity.

Simulated Author's Rebuttal

1 responses · 0 unresolved

We thank the referee for their careful reading and for highlighting the potential significance of our empirical validation of the ICCF-Cut method. We address the single major comment below and will revise the manuscript to strengthen the presentation of the He I correction.

read point-by-point responses

  1. Referee: [He I contamination correction (Results/Discussion)] The identification and correction for residual He I contamination, used to explain and resolve underestimates in photometric lags for several seasons, is presented without quantitative details on the procedure or tests for systematic bias in the lag measurements. This step is load-bearing for the claim that the method produces results consistent with spectroscopy after correction.

    Authors: We agree that the current manuscript lacks sufficient quantitative detail on the He I correction procedure and its validation. In the revised version we will expand the Results/Discussion section with: (1) a step-by-step description of how residual He I contamination was identified and quantified (using the available simultaneous spectra and filter transmission curves); (2) the explicit correction formula or scaling applied to the photometric light curves; (3) the numerical changes in lag values before and after correction for each affected season; and (4) Monte Carlo tests that inject varying levels of He I contamination into simulated light curves to quantify any systematic bias introduced into the ICCF-Cut lag recovery. These additions will make the correction transparent and will directly address the concern that this step is load-bearing for the consistency claim. revision: yes

Circularity Check

0 steps flagged

Minor self-citation to prior ICCF-Cut proposal; validation uses independent spectroscopic benchmark

full rationale

The paper validates ICCF-Cut by direct season-by-season comparison of photometric Hα light curves and lags to simultaneous spectroscopic RM results on NGC 4151 and UGC 3374. This benchmark is external to any fit performed on the photometric data alone. The sole self-citation is the reference to 'our previous work' proposing the method; it is not load-bearing for the consistency claim, which rests on the new simultaneous observations. No equations, fitted parameters, or corrections are shown to reduce the reported lags to quantities defined by the same photometric fit. The He I correction is invoked post-hoc to address specific discrepancies but does not redefine the primary results or create a self-referential loop.

Axiom & Free-Parameter Ledger

0 free parameters · 2 axioms · 0 invented entities

The validation rests on standard reverberation-mapping assumptions that measured lags trace light-travel time across the BLR and that the two observing modes can be directly compared when taken simultaneously; no new free parameters or invented entities are introduced in the abstract.

axioms (2)
  • domain assumption Spectroscopic RM provides an unbiased reference measurement of the true Hα lag against which photometric results can be judged.
    Invoked when the paper states that photometric lags are 'generally consistent' with spectroscopic ones.
  • ad hoc to paper Residual He I contamination is the dominant source of any observed lag discrepancy and can be corrected without new systematic error.
    Invoked to explain and resolve underestimates in several seasons.

pith-pipeline@v0.9.1-grok · 5843 in / 1522 out tokens · 60407 ms · 2026-06-26T04:08:42.902367+00:00 · methodology

discussion (0)

Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.

Reference graph

Works this paper leans on

99 extracted references · 96 canonical work pages · 43 internal anchors

  1. [1]

    , keywords =

    Reverberation Mapping of Two Variable Active Galactic Nuclei: Probing the Distinct Characteristics of the Inner and Outer Broad-line Regions. , keywords =. doi:10.3847/1538-4357/ad9c71 , archivePrefix =. 2412.02204 , primaryClass =

    work page doi:10.3847/1538-4357/ad9c71

  2. [2]

    F., & Finkbeiner, D

    Measuring Reddening with Sloan Digital Sky Survey Stellar Spectra and Recalibrating SFD. , keywords =. doi:10.1088/0004-637X/737/2/103 , archivePrefix =. 1012.4804 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1088/0004-637x/737/2/103

  3. [3]

    , keywords =

    The Most Luminous H Reverberation Mapping of E1821+643 Indicates the Lower Boundary of the Radius─Luminosity Relation. , keywords =. doi:10.3847/1538-4357/ae3de1 , archivePrefix =. 2601.18269 , primaryClass =

    work page doi:10.3847/1538-4357/ae3de1

  4. [4]

    The Lick AGN Monitoring Project: Reverberation Mapping of Optical Hydrogen and Helium Recombination Lines

    The Lick AGN Monitoring Project: Reverberation Mapping of Optical Hydrogen and Helium Recombination Lines. , keywords =. doi:10.1088/0004-637X/716/2/993 , archivePrefix =. 1004.2922 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1088/0004-637x/716/2/993

  5. [5]

    , keywords =

    Discovery of a Luminosity-dependent Continuum Lag in NGC 4151 from Photometric and Spectroscopic Continuum Reverberation Mapping. , keywords =. doi:10.3847/1538-4357/ae30db , archivePrefix =. 2512.18276 , primaryClass =

    work page doi:10.3847/1538-4357/ae30db

  6. [6]

    The First Swift Intensive AGN Accretion Disk Reverberation Mapping Survey

    The First Swift Intensive AGN Accretion Disk Reverberation Mapping Survey. , keywords =. doi:10.3847/1538-4357/aaf3b4 , archivePrefix =. 1811.07956 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.3847/1538-4357/aaf3b4

  7. [7]

    Quantifying the Diffuse Continuum Contribution of BLR Clouds to AGN Continuum Inter-band Delays

    Quantifying the diffuse continuum contribution of BLR Clouds to AGN Continuum Inter-band Delays. , keywords =. doi:10.1093/mnras/sty2242 , archivePrefix =. 1808.04798 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1093/mnras/sty2242

  8. [8]

    Accretion disk reverberation with Hubble Space Telescope observations of NGC 4593: evidence for diffuse continuum lags

    Accretion Disk Reverberation with Hubble Space Telescope Observations of NGC 4593: Evidence for Diffuse Continuum Lags. , keywords =. doi:10.3847/1538-4357/aab4f7 , archivePrefix =. 1712.04025 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.3847/1538-4357/aab4f7

  9. [9]

    Nature Astronomy , year = 2019, month = jan, volume =

    Direct evidence of non-disk optical continuum emission around an active black hole. Nature Astronomy , year = 2019, month = jan, volume =. doi:10.1038/s41550-018-0659-x , adsurl =

    work page doi:10.1038/s41550-018-0659-x 2019

  10. [10]

    Non-Blackbody Disks Can Help Explain Inferred AGN Accretion Disk Sizes

    Non-blackbody Disks Can Help Explain Inferred AGN Accretion Disk Sizes. , keywords =. doi:10.3847/1538-4357/aaa768 , archivePrefix =. 1705.05467 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.3847/1538-4357/aaa768

  11. [11]

    S., Dov c iak, M., Papadakis, I

    UV/Optical Disk Thermal Reverberation in Active Galactic Nuclei: An In-depth Study with an Analytic Prescription for Time-lag Spectra. , keywords =. doi:10.3847/1538-4357/abcb93 , archivePrefix =. 2011.08563 , primaryClass =

    work page doi:10.3847/1538-4357/abcb93 2011

  12. [12]

    N., et al.\ 2020a, , 891, 2, 178

    Corona-heated Accretion-disk Reprocessing: A Physical Model to Decipher the Melody of AGN UV/Optical Twinkling. , keywords =. doi:10.3847/1538-4357/ab789e , archivePrefix =. 2002.08564 , primaryClass =

    work page doi:10.3847/1538-4357/ab789e 2002

  13. [13]

    , keywords =

    Quantifying the impact of variable BLR diffuse continuum contributions on measured continuum interband delays. , keywords =. doi:10.1093/mnras/stz2330 , archivePrefix =. 1908.07757 , primaryClass =

    work page doi:10.1093/mnras/stz2330 1908

  14. [14]

    , keywords =

    Unprecedented Continuum Time Delay Variation Phenomenon in an Active Supermassive Black Hole. , keywords =. doi:10.3847/1538-4357/add468 , archivePrefix =. 2408.11292 , primaryClass =

    work page doi:10.3847/1538-4357/add468

  15. [15]

    , keywords =

    Velocity-resolved Reverberation Mapping of Changing-look AGN NGC 2617. , keywords =. doi:10.3847/1538-4357/abefe0 , archivePrefix =. 2103.03508 , primaryClass =

    work page doi:10.3847/1538-4357/abefe0

  16. [16]

    Velocity-resolved Reverberation Mapping of Changing-look Active Galactic Nucleus NGC 4151 during Outburst Stage. II. Results of Four Seasons of Observation. , keywords =. doi:10.3847/1538-4357/ad8568 , archivePrefix =. 2409.01637 , primaryClass =

    work page doi:10.3847/1538-4357/ad8568

  17. [17]

    , keywords =

    H reverberation mapping from broad-band photometry of dwarf type 1 Seyfert galaxy NGC 4395. , keywords =. doi:10.1093/mnras/stae1063 , archivePrefix =. 2404.11495 , primaryClass =

    work page doi:10.1093/mnras/stae1063

  18. [18]

    , keywords =

    H Time Delays of Active Galactic Nuclei from the Zwicky Transient Facility Broadband Photometry. , keywords =. doi:10.3847/1538-4357/ad34d6 , archivePrefix =. 2403.10223 , primaryClass =

    work page doi:10.3847/1538-4357/ad34d6

  19. [19]

    , keywords =

    The H Broadband Photometric Reverberation Mapping of Four Seyfert 1 Galaxies. , keywords =. doi:10.3847/1538-4357/acc4c1 , archivePrefix =. 2303.10362 , primaryClass =

    work page doi:10.3847/1538-4357/acc4c1

  20. [20]

    , keywords =

    The Emission-Line Properties of Low-Redshift Quasi-stellar Objects. , keywords =. doi:10.1086/191661 , adsurl =

    work page doi:10.1086/191661

  21. [21]

    PyQSOFit: Python code to fit the spectrum of quasars

  22. [22]

    , keywords =

    Prior-informed Active Galactic Nucleus Host Spectral Decomposition Using PyQSOFit. , keywords =. doi:10.3847/1538-4357/ad6e76 , archivePrefix =. 2406.17598 , primaryClass =

    work page doi:10.3847/1538-4357/ad6e76

  23. [23]

    Maps of Dust IR Emission for Use in Estimation of Reddening and CMBR Foregrounds

    Maps of Dust Infrared Emission for Use in Estimation of Reddening and Cosmic Microwave Background Radiation Foregrounds. , keywords =. doi:10.1086/305772 , archivePrefix =. astro-ph/9710327 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1086/305772

  24. [24]

    An Analysis of the Shapes of Ultraviolet Extinction Curves. III. an Atlas of Ultraviolet Extinction Curves. , keywords =. doi:10.1086/191413 , adsurl =

    work page doi:10.1086/191413

  25. [25]

    Polar Dust, Nuclear Obscuration and IR SED Diversity in Type-1 AGNs

    Polar Dust, Nuclear Obscuration, and IR SED Diversity in Type-1 AGNs. , keywords =. doi:10.3847/1538-4357/aae075 , archivePrefix =. 1809.03080 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.3847/1538-4357/aae075

  26. [26]

    , keywords =

    Quasi-simultaneous Spectroscopic and Multiband Photometric Observations of Blazar S5 0716+714 During 2018-2019. , keywords =. doi:10.3847/1538-4357/ab594b , archivePrefix =. 1911.08667 , primaryClass =

    work page doi:10.3847/1538-4357/ab594b 2018

  27. [27]

    , keywords =

    Velocity-resolved Reverberation Mapping of Changing-look Active Galactic Nucleus NGC 4151 during Outburst Stage: Evidence for Kinematics Evolution of Broad-line Region. , keywords =. doi:10.3847/1538-4357/ac8745 , archivePrefix =. 2208.02966 , primaryClass =

    work page doi:10.3847/1538-4357/ac8745

  28. [28]

    Quasar Cartography: from Black Hole to Broad Line Region Scales

    Quasar Cartography: From Black Hole to Broad-line Region Scales. , keywords =. doi:10.1088/0004-637X/769/2/124 , archivePrefix =. 1305.6499 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1088/0004-637x/769/2/124

  29. [29]

    Photometric Reverberation Mapping of the Broad Emission Line Region in Quasars

    Photometric Reverberation Mapping of the Broad Emission Line Region in Quasars. , keywords =. doi:10.1088/0004-637X/747/1/62 , archivePrefix =. 1105.5312 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1088/0004-637x/747/1/62

  30. [30]

    On Uncertainties in Cross-Correlation Lags and the Reality of Wavelength-Dependent Continuum Lags in Active Galactic Nuclei

    On Uncertainties in Cross-Correlation Lags and the Reality of Wavelength-dependent Continuum Lags in Active Galactic Nuclei. , keywords =. doi:10.1086/316177 , archivePrefix =. astro-ph/9802103 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1086/316177

  31. [31]

    , keywords =

    The Accuracy of Cross-Correlation Estimates of Quasar Emission-Line Region Sizes. , keywords =. doi:10.1086/191216 , adsurl =

    work page doi:10.1086/191216

  32. [32]

    , keywords =

    Comments on Cross-Correlation Methodology in Variability Studies of Active Galactic Nuclei. , keywords =. doi:10.1086/133456 , adsurl =

    work page doi:10.1086/133456

  33. [33]

    , year = 1981, month = jan, volume =

    The Shape and Variability of the Nonthermal Component of the Optical Spectra of Active Galaxies. , year = 1981, month = jan, volume =

    1981

  34. [34]

    Photometric reverberation mapping of 3C120

    Photometric reverberation mapping of 3C 120. , keywords =. doi:10.1051/0004-6361/201219107 , archivePrefix =. 1303.3506 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1051/0004-6361/201219107

  35. [35]

    S., van Wyk, F., et al

    Variability studies of seyfert galaxies - I. Broad-band optical photometry. , keywords =. doi:10.1093/mnras/257.4.659 , adsurl =

    work page doi:10.1093/mnras/257.4.659

  36. [36]

    Central Masses and Broad-Line Region Sizes of Active Galactic Nuclei. II. A Homogeneous Analysis of a Large Reverberation-Mapping Database. , keywords =. doi:10.1086/423269 , archivePrefix =. astro-ph/0407299 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1086/423269

  37. [37]

    An Alternative Approach To Measuring Reverberation Lags in Active Galactic Nuclei

    An Alternative Approach to Measuring Reverberation Lags in Active Galactic Nuclei. , keywords =. doi:10.1088/0004-637X/735/2/80 , archivePrefix =. 1008.0641 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1088/0004-637x/735/2/80

  38. [38]

    Is Quasar Optical Variability a Damped Random Walk?

    Is Quasar Optical Variability a Damped Random Walk?. , keywords =. doi:10.1088/0004-637X/765/2/106 , archivePrefix =. 1202.3783 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1088/0004-637x/765/2/106

  39. [39]

    Application of Stochastic Modeling to Analysis of Photometric Reverberation Mapping Data

    Application of Stochastic Modeling to Analysis of Photometric Reverberation Mapping Data. , keywords =. doi:10.3847/0004-637X/819/2/122 , archivePrefix =. 1310.6774 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.3847/0004-637x/819/2/122

  40. [40]

    Towards equation of state of dark energy from quasar monitoring: Reverberation strategy

    Towards equation of state of dark energy from quasar monitoring: Reverberation strategy. , keywords =. doi:10.1051/0004-6361/201220832 , archivePrefix =. 1212.0472 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1051/0004-6361/201220832

  41. [41]

    The Sloan Digital Sky Survey Reverberation Mapping Project: H$\alpha$ and H$\beta$ Reverberation Measurements From First-year Spectroscopy and Photometry

    The Sloan Digital Sky Survey Reverberation Mapping Project: H and H Reverberation Measurements from First-year Spectroscopy and Photometry. , keywords =. doi:10.3847/1538-4357/aa98dc , archivePrefix =. 1711.03114 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.3847/1538-4357/aa98dc

  42. [42]

    , keywords =

    The Sloan Digital Sky Survey Reverberation Mapping Project: Mg II Lag Results from Four Years of Monitoring. , keywords =. doi:10.3847/1538-4357/ababa9 , archivePrefix =. 2005.03663 , primaryClass =

    work page doi:10.3847/1538-4357/ababa9 2005

  43. [43]

    Space Telescope and Optical Reverberation Mapping Project. III. Optical Continuum Emission and Broadband Time Delays in NGC 5548. , keywords =. doi:10.3847/0004-637X/821/1/56 , archivePrefix =. 1510.05648 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.3847/0004-637x/821/1/56

  44. [44]

    , keywords =

    The Ultraviolet/Optical Continuum Reverberation Mapping of Eight Active Galactic Nuclei with Swift: Further Evidence for the Outer Component. , keywords =. doi:10.3847/1538-4357/ae1034 , archivePrefix =. 2511.05792 , primaryClass =

    work page doi:10.3847/1538-4357/ae1034

  45. [45]

    , keywords =

    Least-Squares Frequency Analysis of Unequally Spaced Data. , keywords =. doi:10.1007/BF00648343 , adsurl =

    work page doi:10.1007/bf00648343

  46. [46]

    Studies in astronomical time series analysis. II. Statistical aspects of spectral analysis of unevenly spaced data. , keywords =. doi:10.1086/160554 , adsurl =

    work page doi:10.1086/160554

  47. [47]

    , keywords =

    Wavelets for period analysis of unevenly sampled time series. , keywords =. doi:10.1086/118137 , adsurl =

    work page doi:10.1086/118137

  48. [48]

    , keywords =

    A Method of Computing Periods of Cyclic Phenomena. , keywords =. doi:10.1007/BF00656321 , adsurl =

    work page doi:10.1007/bf00656321

  49. [49]

    Measuring the rotation period distribution of field M-dwarfs with Kepler

    Measuring the rotation period distribution of field M dwarfs with Kepler. , keywords =. doi:10.1093/mnras/stt536 , archivePrefix =. 1303.6787 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1093/mnras/stt536

  50. [50]

    wwz: Weighted wavelet z-transform code

  51. [51]

    , keywords =

    Quasi-periodic oscillation analysis for a sample of blazars at the optical band. , keywords =. doi:10.1051/0004-6361/202347593 , adsurl =

    work page doi:10.1051/0004-6361/202347593

  52. [52]

    Generating artificial light curves: Revisited and updated

    Generating artificial light curves: revisited and updated. , keywords =. doi:10.1093/mnras/stt764 , archivePrefix =. 1305.0304 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1093/mnras/stt764

  53. [53]

    , keywords =

    Broad-line Region Characterization in Dozens of Active Galactic Nuclei Using Small-aperture Telescopes. , keywords =. doi:10.3847/1538-4365/ad9474 , archivePrefix =. 2411.07847 , primaryClass =

    work page doi:10.3847/1538-4365/ad9474

  54. [54]

    , keywords =

    Medium-band Photometry Reverberation Mapping of Nearby Active Galactic Nuclei. , keywords =. doi:10.3847/1538-4357/ab40cd , archivePrefix =. 1910.01061 , primaryClass =

    work page doi:10.3847/1538-4357/ab40cd 1910

  55. [55]

    Automatized photometric monitoring of active galactic nuclei with the 46 cm telescope of the Wise observatory

    Automatized Photometric Monitoring of Active Galactic Nuclei with the 46cm Telescope of the Wise Observatory. , keywords =. doi:10.1088/1538-3873/aa7a55 , archivePrefix =. 1706.05463 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1088/1538-3873/aa7a55

  56. [56]

    Photometric AGN reverberation mapping - an efficient tool for BLR sizes, black hole masses and host-subtracted AGN luminosities

    Photometric AGN reverberation mapping - an efficient tool for BLR sizes, black hole masses, and host-subtracted AGN luminosities. , keywords =. doi:10.1051/0004-6361/201117325 , archivePrefix =. 1109.1848 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1051/0004-6361/201117325

  57. [57]

    M., Bentz, M

    Reverberation mapping of active galactic nuclei: from X-ray corona to dusty torus. iScience , keywords =. doi:10.1016/j.isci.2021.102557 , archivePrefix =. 2105.06926 , primaryClass =

    work page doi:10.1016/j.isci.2021.102557 2021

  58. [58]

    , year = 1969, month = aug, volume =

    Galactic Nuclei as Collapsed Old Quasars. , year = 1969, month = aug, volume =. doi:10.1038/223690a0 , adsurl =

    work page doi:10.1038/223690a0 1969

  59. [59]

    , keywords =

    Reverberation Mapping of Active Galactic Nuclei. , keywords =. doi:10.1086/133140 , adsurl =

    work page doi:10.1086/133140

  60. [60]

    , keywords =

    Reverberation mapping of the emission line regions of Seyfert galaxies and quasars. , keywords =. doi:10.1086/159843 , adsurl =

    work page doi:10.1086/159843

  61. [61]

    The Radius-Luminosity Relationship for Active Galactic Nuclei: The Effect of Host-Galaxy Starlight on Luminosity Measurements. II. The Full Sample of Reverberation-Mapped AGNs. , keywords =. doi:10.1088/0004-637X/697/1/160 , archivePrefix =. 0812.2283 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1088/0004-637x/697/1/160

  62. [62]

    The Low-Luminosity End of the Radius-Luminosity Relationship for Active Galactic Nuclei

    The Low-luminosity End of the Radius-Luminosity Relationship for Active Galactic Nuclei. , keywords =. doi:10.1088/0004-637X/767/2/149 , archivePrefix =. 1303.1742 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1088/0004-637x/767/2/149

  63. [63]

    The Lick AGN Monitoring Project: Broad-Line Region Radii and Black Hole Masses from Reverberation Mapping of Hbeta

    The Lick AGN Monitoring Project: Broad-line Region Radii and Black Hole Masses from Reverberation Mapping of H. , keywords =. doi:10.1088/0004-637X/705/1/199 , archivePrefix =. 0908.0003 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1088/0004-637x/705/1/199

  64. [64]

    The Lick AGN Monitoring Project 2011: Spectroscopic Campaign and Emission-Line Light Curves

    The Lick AGN Monitoring Project 2011: Spectroscopic Campaign and Emission-line Light Curves. , keywords =. doi:10.1088/0067-0049/217/2/26 , archivePrefix =. 1503.01146 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1088/0067-0049/217/2/26 2011

  65. [65]

    , keywords =

    The Lick AGN Monitoring Project 2016: Velocity-resolved H Lags in Luminous Seyfert Galaxies. , keywords =. doi:10.3847/1538-4357/ac3d26 , archivePrefix =. 2111.14849 , primaryClass =

    work page doi:10.3847/1538-4357/ac3d26 2016

  66. [66]

    Supermassive Black Holes with High Accretion Rates in Active Galactic Nuclei. IX. 10 New Observations of Reverberation Mapping and Shortened H Lags. , keywords =. doi:10.3847/1538-4357/aaae6b , archivePrefix =. 1802.03022 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.3847/1538-4357/aaae6b

  67. [67]

    Supermassive Black Holes with High Accretion Rates in Active Galactic Nuclei. V. A New Size-Luminosity Scaling Relation for the Broad-line Region. , keywords =. doi:10.3847/0004-637X/825/2/126 , archivePrefix =. 1604.06218 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.3847/0004-637x/825/2/126

  68. [68]

    Supermassive Black Holes with High Accretion Rates in Active Galactic Nuclei. IV. H Time Lags and Implications for Super-Eddington Accretion. , keywords =. doi:10.1088/0004-637X/806/1/22 , archivePrefix =. 1504.01844 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1088/0004-637x/806/1/22

  69. [69]

    Supermassive Black Holes with High Accretion Rates in Active Galactic Nuclei. I. First Results from a New Reverberation Mapping Campaign. , keywords =. doi:10.1088/0004-637X/782/1/45 , archivePrefix =. 1310.4107 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1088/0004-637x/782/1/45

  70. [70]

    Monitoring AGNs with H Asymmetry. I. First Results: Velocity-resolved Reverberation Mapping. , keywords =. doi:10.3847/1538-4357/aaed2c , archivePrefix =. 1810.11996 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.3847/1538-4357/aaed2c

  71. [71]

    Monitoring AGNs with H Asymmetry. III. Long-term Reverberation Mapping Results of 15 Palomar-Green Quasars. , keywords =. doi:10.3847/1538-4365/ac7beb , archivePrefix =. 2207.00297 , primaryClass =

    work page doi:10.3847/1538-4365/ac7beb

  72. [72]

    Monitoring AGNs with H Asymmetry. II. Reverberation Mapping of Three Seyfert Galaxies Historically Displaying H Profiles with Changing Asymmetry: Mrk 79, NGC 3227, and Mrk 841. , keywords =. doi:10.3847/1538-4357/abc2d2 , archivePrefix =. 2011.05902 , primaryClass =

    work page doi:10.3847/1538-4357/abc2d2 2011

  73. [73]

    Monitoring AGNs with H Asymmetry. IV. First Reverberation Mapping Results of 14 Active Galactic Nuclei. , keywords =. doi:10.3847/1538-4365/ad3bad , archivePrefix =. 2404.07343 , primaryClass =

    work page doi:10.3847/1538-4365/ad3bad

  74. [74]

    The Sloan Digital Sky Survey Reverberation Mapping Project: Technical Overview

    The Sloan Digital Sky Survey Reverberation Mapping Project: Technical Overview. , keywords =. doi:10.1088/0067-0049/216/1/4 , archivePrefix =. 1408.5970 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1088/0067-0049/216/1/4

  75. [75]

    The Sloan Digital Sky Survey Reverberation Mapping Project: Sample Characterization

    The Sloan Digital Sky Survey Reverberation Mapping Project: Sample Characterization. , keywords =. doi:10.3847/1538-4365/ab074f , archivePrefix =. 1810.01447 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.3847/1538-4365/ab074f

  76. [76]

    The Sloan Digital Sky Survey Reverberation Mapping Project: First Broad-line Hbeta and MgII Lags at z>~0.3 from six-Month Spectroscopy

    The Sloan Digital Sky Survey Reverberation Mapping Project: First Broad-line H and Mg II Lags at z 0.3 from Six-month Spectroscopy. , keywords =. doi:10.3847/0004-637X/818/1/30 , archivePrefix =. 1510.02802 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.3847/0004-637x/818/1/30

  77. [77]

    , keywords =

    The Sloan Digital Sky Survey Reverberation Mapping Project: Key Results. , keywords =. doi:10.3847/1538-4365/ad3936 , archivePrefix =. 2305.01014 , primaryClass =

    work page doi:10.3847/1538-4365/ad3936

  78. [78]

    , keywords =

    The Sloan Digital Sky Survey Reverberation Mapping Project: Initial C IV Lag Results from Four Years of Data. , keywords =. doi:10.3847/1538-4357/ab4ea5 , archivePrefix =. 1904.03199 , primaryClass =

    work page doi:10.3847/1538-4357/ab4ea5 1904

  79. [79]

    , keywords =

    The Sloan Digital Sky Survey Reverberation Mapping Project: Accretion Disk Sizes from Continuum Lags. , keywords =. doi:10.3847/1538-4357/ab2638 , archivePrefix =. 1806.08360 , primaryClass =

    work page doi:10.3847/1538-4357/ab2638

  80. [80]

    OzDES Reverberation Mapping of Active Galactic Nuclei: Final Data Release, Black-Hole Mass Results, & Scaling Relations

    OzDES Reverberation Mapping of Active Galactic Nuclei: Final Data Release, Black-Hole Mass Results, & Scaling Relations. arXiv e-prints , keywords =. doi:10.48550/arXiv.2512.01261 , archivePrefix =. 2512.01261 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.48550/arxiv.2512.01261

Showing first 80 references.