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Extreme color-magnitude variability efficiently identifies changing-look AGNs by selecting candidates with strong bluer-when-brighter behavior and large amplitudes.

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2026-06-29 21:41 UTC pith:4VHZ7UGY

load-bearing objection The paper's main value is the spectroscopic confirmation of seven new turn-on CL-AGNs from a photometric CM-variability selection of 12 SDSS Type-2 candidates, with direct follow-up spectra and flare timing. the 2 major comments →

arxiv 2605.25689 v1 pith:4VHZ7UGY submitted 2026-05-25 astro-ph.GA

Extreme color-magnitude variability: connection to changing-look AGNs

Litao Zhu , Zhongxiang Wang (1) , Alok C. Gupta , P. U. Devanand (2) , Ruoheng Yang , Qiangmeng Huang , Man Lang , Jiawen Li (1) ((1) Yunnan University
show 3 more authors
China (2) ARIES India)
This is my paper
classification astro-ph.GA
keywords changing-look AGNscolor-magnitude variabilityactive galactic nucleiturn-on transitionsaccretion processesphotometric selectionSDSS catalogmid-infrared variability
verification ladder T0 review T1 audit T2 compute T3 formal T4 reserved

The pith

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

The paper applies a photometric color-magnitude variability method to Type-2 AGNs from the SDSS catalog, selecting candidates based on the slope k of color-magnitude changes plus optical and mid-infrared amplitudes. Spectroscopic follow-up with the 3.6-m DOT and 2-m HCT telescopes confirms seven turn-on changing-look AGNs out of twelve candidates. These objects exhibit larger optical and MIR variations and higher k values than general AGN populations, with extreme magnitude changes exceeding 0.9 occurring recently and sometimes linked to flare-like episodes 3-7 years earlier. The method is presented as a highly efficient way to find objects likely experiencing enhanced accretion activity that drives the type transitions.

Core claim

We confirm seven turn-on CL-AGNs among 12 candidates selected via extreme CM variability from SDSS Type-2 AGNs. The confirmed sources display larger optical and MIR variations and k values than both general AGN populations and previously known spectroscopically identified CL-AGNs, with optical magnitude changes greater than 0.9 that occurred recently; for four sources, flare-like brightening episodes are temporally associated with the turn-on transitions within 3-7 years, indicating that these flares may trace short-timescale accretion enhancement, central brightening, and BLR re-illumination.

What carries the argument

The colour-magnitude (CM) variability method, which identifies strong bluer-when-brighter behavior through the slope k of CM variations while also requiring large variation amplitudes in optical and mid-infrared bands.

Load-bearing premise

The combination of CM slope k, optical amplitude, and MIR amplitude reliably selects objects undergoing a true spectroscopic type transition rather than other forms of AGN variability.

What would settle it

A large sample of additional candidates selected by the same CM criteria that show no spectroscopic type changes upon follow-up observation, or a substantial population of confirmed CL-AGNs lacking extreme CM variability.

Watch this falsifier — get emailed when new claim-graph text bears on it.

If this is right

  • CL-AGNs found this way occur at a pivotal state driven by enhanced accretion activity on timescales of several years.
  • The recent extreme CM variabilities and associated flares suggest short-timescale accretion enhancements that re-illuminate the broad line region.
  • Photometric CM selection provides an efficient alternative to systematic spectroscopic comparisons for building larger CL-AGN samples.
  • The properties of these CL-AGNs differ from general AGN populations in both amplitude and color behavior.
  • The cause of the accretion activity enhancement remains open but operates on multi-year timescales.

Where Pith is reading between the lines

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

  • The method could reduce the need for initial spectroscopic screening in large surveys by prioritizing photometric candidates for follow-up.
  • Association between flares and transitions points to testable links between short-term accretion events and longer-term type changes.
  • If the selection criteria hold, similar CM analysis on other photometric surveys could map how common such pivotal states are across the AGN population.

Editorial analysis

A structured set of objections, weighed in public.

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

Referee Report

2 major / 2 minor

Summary. The paper claims that extreme color-magnitude (CM) variability—identified via the slope k of CM variations combined with large optical and mid-infrared amplitudes—provides a highly efficient photometric criterion for selecting changing-look AGNs (CL-AGNs). From the SDSS Type-2 AGN catalog, 12 candidates were chosen and followed up spectroscopically with the 3.6-m DOT and 2-m HCT telescopes, confirming 7 as turn-on CL-AGNs. These objects exhibit larger optical/MIR variations and more extreme k values than the general AGN population and existing spectroscopic CL-AGN samples; four show flare-like brightening temporally linked to the transitions on 3–7 year timescales, interpreted as tracing enhanced accretion and BLR re-illumination.

Significance. If the spectroscopic results hold, the work supplies direct empirical validation that the CM-variability selection recovers true type transitions at a 7/12 rate, offering a practical alternative to purely spectroscopic searches for CL-AGNs. The quantitative comparison to control samples and the reported association with short-timescale flares strengthen the interpretation that these objects occupy a pivotal accretion state. The direct follow-up on every photometrically selected candidate is a clear methodological strength that reduces reliance on untested assumptions.

major comments (2)
  1. [Results] Results section: the claim that the confirmed CL-AGNs 'showed larger optical and MIR variations and k values' than the general AGN population and the spectroscopic CL-AGN sample is presented without mean values, standard deviations, error bars, or statistical tests (e.g., Kolmogorov–Smirnov probabilities). This quantitative detail is load-bearing for the assertion that the selected objects occupy the 'extreme tail' and for the efficiency conclusion.
  2. [Methods] Methods section: exact numerical thresholds for the CM slope k, the optical amplitude criterion (abstract states >0.9 mag but does not specify measurement or uncertainty), MIR amplitude cuts, and data-exclusion rules are not reported. Without these, independent reproduction of the 12-candidate list and assessment of the 7/12 confirmation rate cannot be performed.
minor comments (2)
  1. A table listing the 12 candidates with their measured k, optical/MIR amplitudes, redshifts, and final spectroscopic classifications would improve clarity and allow readers to assess the selection directly.
  2. [Conclusions] The abstract and conclusions use 'highly efficient' without a baseline false-positive rate from a control sample of non-CM-variable Type-2 AGNs; a brief quantitative comparison would strengthen the wording.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for the constructive comments and positive assessment of our work. We address each major comment below and will revise the manuscript to improve quantitative support and reproducibility.

read point-by-point responses

  1. Referee: [Results] Results section: the claim that the confirmed CL-AGNs 'showed larger optical and MIR variations and k values' than the general AGN population and the spectroscopic CL-AGN sample is presented without mean values, standard deviations, error bars, or statistical tests (e.g., Kolmogorov–Smirnov probabilities). This quantitative detail is load-bearing for the assertion that the selected objects occupy the 'extreme tail' and for the efficiency conclusion.

    Authors: We agree that the quantitative details are important for supporting the claims. In the revised manuscript, we will add mean values, standard deviations, and error bars for the optical/MIR amplitudes and k values across our confirmed sample, the general AGN population, and the spectroscopic CL-AGN sample. We will also include statistical tests such as Kolmogorov-Smirnov probabilities to demonstrate that our objects occupy the extreme tail. revision: yes

  2. Referee: [Methods] Methods section: exact numerical thresholds for the CM slope k, the optical amplitude criterion (abstract states >0.9 mag but does not specify measurement or uncertainty), MIR amplitude cuts, and data-exclusion rules are not reported. Without these, independent reproduction of the 12-candidate list and assessment of the 7/12 confirmation rate cannot be performed.

    Authors: We acknowledge that the exact selection thresholds were not explicitly detailed. In the revision, we will specify the precise numerical thresholds for the CM slope k, the optical amplitude criterion (including measurement method and uncertainties), MIR amplitude cuts, and data-exclusion rules used to select the 12 candidates from the SDSS Type-2 AGN catalog. revision: yes

Circularity Check

0 steps flagged

No significant circularity

full rationale

The paper applies a photometric color-magnitude selection (slope k plus amplitude cuts) to SDSS Type-2 AGN candidates, then obtains independent spectra for all 12 selected objects and reports that 7 are confirmed turn-on CL-AGNs. The efficiency claim rests on this spectroscopic verification rather than on any equation, fitted parameter, or self-citation that reduces the identifications to quantities defined by the selection itself. No self-definitional, fitted-input, or ansatz-smuggling steps appear in the derivation chain.

Axiom & Free-Parameter Ledger

0 free parameters · 0 axioms · 0 invented entities

No free parameters, axioms beyond standard observational astronomy, or invented entities are introduced; the work rests on existing SDSS catalogs and telescope data.

pith-pipeline@v0.9.1-grok · 5914 in / 1063 out tokens · 25769 ms · 2026-06-29T21:41:43.400687+00:00 · methodology

0 comments
read the original abstract

Context. Changing-look active galactic nuclei (CL-AGNs) challenge the unified model of AGNs and offer key insights into the physics of the accretion processes of super-massive black holes. While systematic spectroscopic comparisons have successfully identified large samples of CL-AGNs, photometric selection based on variability features provides an efficient alternative. Methods. We use the colour--magnitude (CM) variability method to continue our identification of the CL transition in AGNs, which utilizes the slope ($k$) of the CM variations to identify strong bluer-when-brighter behavior, while the variation amplitudes in optical and mid-infrared bands are also considered. The candidates thus selected from the Type-2 AGNs given in the Sloan Digital Sky Survey catalog are spectroscopically observed using the 3.6-m DOT and the 2-m HCT. Results. We confirm seven turn-on CL-AGNs among 12 candidates. Comparing them with both the general AGN populations and the spectroscopically identified CL-AGN sample, the CL-AGNs showed larger optical and MIR variations and $k$ values. The extreme CM variabilities of these sources (with optical magnitude changes $>$ 0.9) occurred recently. For four sources, flare-like brightening episodes were temporally associated with the turn-on transitions within 3--7 years, suggesting that these flares may trace short-timescale accretion enhancement, central brightening, and BLR re-illumination. Conclusions. The extreme CM variability serves as a highly efficient criterion for finding CL-AGNs. The properties of the CL-AGNs thus found suggest that they may represent AGNs at a pivotal state, which likely occur CL transitions due to enhanced accretion activity, while the cause of the accretion activity, determined to have a time scale of several years, remains to be investigated.

Figures

Figures reproduced from arXiv: 2605.25689 by (2) ARIES, Alok C. Gupta, China, India), Jiawen Li (1) ((1) Yunnan University, Litao Zhu, Man Lang, P. U. Devanand (2), Qiangmeng Huang, Ruoheng Yang, Zhongxiang Wang (1).

Figure 1
Figure 1. Figure 1: Light curves and spectra for J160626+044802. The left panel displays the optical and MIR light curves, where a flare determined from the zg-band data is marked red with its time duration marked by the grey region. The right top panel shows the spectra obtained from SDSS, DESI, and HCT (whose epochs are marked by the vertical dashed lines in the left panel), and the right bottom panel shows the difference s… view at source ↗
Figure 2
Figure 2. Figure 2: Same as Fig [PITH_FULL_IMAGE:figures/full_fig_p003_2.png] view at source ↗
Figure 3
Figure 3. Figure 3: Example of spectral fitting using PyQSOFit for the DOT spectrum of J115953+051330. The spectrum was corrected for redshift and Galactic extinction, and the host galaxy contribu￾tion was subtracted to model the pure quasar emission compo￾nents and to derive the corresponding parameters. The parame￾ters MBH and λEdd for this AGN calculated from the fitting pa￾rameters are given in [PITH_FULL_IMAGE:figures/f… view at source ↗
Figure 4
Figure 4. Figure 4: Distributions of variability amplitudes ( [PITH_FULL_IMAGE:figures/full_fig_p005_4.png] view at source ↗
Figure 5
Figure 5. Figure 5: Distribution of black hole masses (MBH) versus Edding￾ton ratios (λEdd) for the CL-AGNs identified via the CM variabil￾ity method. The data points comprise six confirmed sources from this work and the four sources previously reported in Zhu et al. (2025). The background data points are those CL-AGNs re￾ported by Guo et al. (2025). 4. Discussion Following our CM variability method established in Zhu et al. … view at source ↗

discussion (0)

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Works this paper leans on

68 extracted references · 7 canonical work pages · 3 internal anchors

  1. [1]

    N., Adelman-McCarthy, J

    Abazajian, K. N., Adelman-McCarthy, J. K., Agüeros, M. A., e t al. 2009, ApJS, 182, 543

    2009

  2. [2]

    A., Almeida, A., et al

    Ahumada, R., Prieto, C. A., Almeida, A., et al. 2020, The Astr ophysical Journal Supplement Series, 249, 3

    2020

  3. [3]

    2020, ApJ, 890, L29

    Ai, Y ., Dou, L., Y ang, C., et al. 2020, ApJ, 890, L29

    2020

  4. [4]

    1993, ARA&A, 31, 473

    Antonucci, R. 1993, ARA&A, 31, 473

    1993

  5. [5]

    Aretxaga, I., Joguet, B., Kunth, D., Melnick, J., & Terlevic h, R. J. 1999, ApJ, 519, L123

    1999

  6. [6]

    Fermi Large Area Telescope Fourth Source Catalog Data Release 4 (4FGL-DR4)

    Ballet, J., Bruel, P ., Burnett, T. H., Lott, B., & The Fermi-L A T collaboration. 2023, arXiv e-prints, arXiv:2307.12546

    work page internal anchor Pith review Pith/arXiv arXiv 2023

  7. [7]

    C., Kulkarni, S

    Bellm, E. C., Kulkarni, S. R., Graham, M. J., et al. 2019, PASP , 131, 018002

    2019

  8. [8]

    C., Denney, K

    Bentz, M. C., Denney, K. D., Grier, C. J., et al. 2013, ApJ, 767 , 149

    2013

  9. [9]

    K., Nicholl, M., Berger, E., et al

    Blanchard, P . K., Nicholl, M., Berger, E., et al. 2017, ApJ, 8 43, 106

    2017

  10. [10]

    2025, arXiv e-pri nts, arXiv:2511.15359

    Chen, Z.-Q., Jin, J.-J., Guo, W.-J., et al. 2025, arXiv e-pri nts, arXiv:2511.15359

    work page arXiv 2025

  11. [11]

    D., Rudy, R

    Cohen, R. D., Rudy, R. J., Puetter, R. C., Ake, T. B., & Foltz, C . B. 1986, ApJ, 311, 135

    1986

  12. [12]

    Cowsik, R., Srinivasan, R., & Prabhu, T. P . 2002, Bulletin of the Astronomical Society of India, 30, 105

    2002

  13. [13]

    2012, Research in Astronomy and Astrophysics, 12, 1197

    Cui, X.-Q., Zhao, Y .-H., Chu, Y .-Q., et al. 2012, Research in Astronomy and Astrophysics, 12, 1197

    2012

  14. [14]

    The DESI Experiment Part I: Science,Targeting, and Survey Design

    Denney, K. D., De Rosa, G., Croxall, K., et al. 2014, ApJ, 796, 134 DESI Collaboration, Aghamousa, A., Aguilar, J., et al. 2016 , arXiv e-prints, arXiv:1611.00036

    work page internal anchor Pith review Pith/arXiv arXiv 2014

  15. [15]

    & Agol, E

    Dexter, J. & Agol, E. 2011, ApJ, 727, L24

    2011

  16. [16]

    & Begelman, M

    Dexter, J. & Begelman, M. C. 2019, MNRAS, 483, L17

    2019

  17. [17]

    J., Djorgovski, S

    Drake, A. J., Djorgovski, S. G., Mahabal, A., et al. 2009, ApJ , 696, 870

    2009

  18. [18]

    2012, ApJ, 747, L33

    Elitzur, M. 2012, ApJ, 747, L33

    2012

  19. [19]

    & Halpern, J

    Eracleous, M. & Halpern, J. P . 2001, ApJ, 554, 240

    2001

  20. [20]

    J., et al

    Frederick, S., Gezari, S., Graham, M. J., et al. 2019, ApJ, 88 3, 31

    2019

  21. [21]

    Gaskell, C. M. & Harrington, P . Z. 2018, MNRAS, 478, 1660

    2018

  22. [22]

    B., et al

    Gezari, S., Hung, T., Cenko, S. B., et al. 2017, ApJ, 835, 144

    2017

  23. [23]

    J., Du ffy, L., et al

    Gilbert, O., Ruan, J. J., Du ffy, L., et al. 2025, arXiv e-prints, arXiv:2508.01933

    work page arXiv 2025

  24. [24]

    Goad, M. R. & Korista, K. T. 2014, MNRAS, 444, 43

    2014

  25. [25]

    J., Ross, N

    Graham, M. J., Ross, N. P ., Stern, D., et al. 2020, MNRAS, 491, 4925

    2020

  26. [26]

    J., Pulgarin-Duque, L., Anderson, S

    Green, P . J., Pulgarin-Duque, L., Anderson, S. F., et al. 2022, ApJ, 933, 180

    2022

  27. [27]

    2018, PyQSOFit: Python code to fit the spectrum of quasars, Astrophysics Source Code Library, record ascl: 1809.008

    Guo, H., Shen, Y ., & Wang, S. 2018, PyQSOFit: Python code to fit the spectrum of quasars, Astrophysics Source Code Library, record ascl: 1809.008

    2018

  28. [28]

    A., et al

    Guo, W.-J., Zou, H., Fawcett, V . A., et al. 2024, ApJS, 270, 26 Article number, page 7 of 15 A&A proofs: manuscript no. cl3

    2024

  29. [29]

    L., et al

    Guo, W.-J., Zou, H., Greenwell, C. L., et al. 2025, ApJS, 278, 28

    2025

  30. [30]

    J., et al

    Jana, A., Ricci, C., Temple, M. J., et al. 2025, A&A, 693, A35

    2025

  31. [31]

    Changing-Look AGN Powered By Disk Tearing

    Kaaz, N., Liska, M., Ward, C., & Davelaar, J. 2025, arXiv e-pr ints, arXiv:2511.09626

    work page internal anchor Pith review Pith/arXiv arXiv 2025

  32. [32]

    M., Cales, S., Moran, E

    LaMassa, S. M., Cales, S., Moran, E. C., et al. 2015, ApJ, 800, 144

    2015

  33. [33]

    M., Y aqoob, T., Ptak, A

    LaMassa, S. M., Y aqoob, T., Ptak, A. F., et al. 2014, ApJ, 787, 61

    2014

  34. [34]

    1987, PASP , 99, 309

    Lawrence, A. 1987, PASP , 99, 309

    1987

  35. [35]

    2018, Nature Astronomy, 2, 102 liu, H., Wu, Q., Lyu, B., & Y an, Z

    Lawrence, A. 2018, Nature Astronomy, 2, 102 liu, H., Wu, Q., Lyu, B., & Y an, Z. 2019, arXiv e-prints, arXiv :1912.03972 López-Navas, E., Martínez-Aldama, M. L., Bernal, S., et al. 2022, MNRAS, 513, L57 López-Navas, E., Sánchez-Sáez, P ., Arévalo, P ., et al. 2023, MNRAS, 524, 188

    work page arXiv 2018

  36. [36]

    L., Green, P

    MacLeod, C. L., Green, P . J., Anderson, S. F., et al. 2019, ApJ , 874, 8

    2019

  37. [37]

    L., Ross, N

    MacLeod, C. L., Ross, N. P ., Lawrence, A., et al. 2016, MNRAS, 457, 389

    2016

  38. [38]

    2011, ApJ, 731, 53

    Mainzer, A., Bauer, J., Grav, T., et al. 2011, ApJ, 731, 53

    2011

  39. [39]

    & Done, C

    Noda, H. & Done, C. 2018, MNRAS, 480, 3898

    2018

  40. [40]

    S., Krishna Reddy, B., Pant, J., & Mahto, M

    Omar, A., Kumar, T. S., Krishna Reddy, B., Pant, J., & Mahto, M . 2019, arXiv e-prints, arXiv:1902.05857

    work page arXiv 2019

  41. [41]

    Osterbrock, D. E. 1981, ApJ, 249, 462

    1981

  42. [42]

    & ´Sniegowska, M

    Panda, S. & ´Sniegowska, M. 2024, ApJS, 272, 13 Planck Collaboration, Aghanim, N., Akrami, Y ., et al. 2020, A&A, 641, A6

    2024

  43. [43]

    2022, ApJ, 925, 50

    Ren, W., Wang, J., Cai, Z., & Guo, H. 2022, ApJ, 925, 50

    2022

  44. [44]

    P ., Ford, K

    Ross, N. P ., Ford, K. E. S., Graham, M., et al. 2018, MNRAS, 480 , 4468

    2018

  45. [45]

    P ., Graham, M

    Ross, N. P ., Graham, M. J., Calderone, G., et al. 2020, MNRAS, 498, 2339

    2020

  46. [46]

    J., Anderson, S

    Ruan, J. J., Anderson, S. F., Cales, S. L., et al. 2016, ApJ, 82 6, 188

    2016

  47. [47]

    J., Anderson, S

    Ruan, J. J., Anderson, S. F., Eracleous, M., et al. 2019, ApJ, 883, 76

    2019

  48. [48]

    2018, ApJ, 854, 160

    Rumbaugh, N., Shen, Y ., Morganson, E., et al. 2018, ApJ, 854, 160

    2018

  49. [49]

    C., Cales, S., Ruan, J

    Runnoe, J. C., Cales, S., Ruan, J. J., et al. 2016, MNRAS, 455, 1691

    2016

  50. [50]

    D., Norris, J

    Scargle, J. D., Norris, J. P ., Jackson, B., & Chiang, J. 2013, ApJ, 764, 167

    2013

  51. [51]

    J., Prieto, J

    Shappee, B. J., Prieto, J. L., Grupe, D., et al. 2014, ApJ, 788 , 48

    2014

  52. [52]

    2020, ApJ, 889, 46

    Sheng, Z., Wang, T., Jiang, N., et al. 2020, ApJ, 889, 46

    2020

  53. [53]

    2020, A&A, 641, A167

    Sniegowska, M., Czerny, B., Bon, E., & Bon, N. 2020, A&A, 641, A167

    2020

  54. [54]

    A., & Wilson, A

    Storchi-Bergmann, T., Baldwin, J. A., & Wilson, A. S. 1993, A pJ, 410, L11

    1993

  55. [55]

    2008, New A Rev., 52, 227

    Tadhunter, C. 2008, New A Rev., 52, 227

    2008

  56. [56]

    Tohline, J. E. & Osterbrock, D. E. 1976, ApJ, 210, L117

    1976

  57. [57]

    L., Denneau, L., Heinze, A

    Tonry, J. L., Denneau, L., Heinze, A. N., et al. 2018, PASP , 13 0, 064505

    2018

  58. [58]

    L., et al

    Trakhtenbrot, B., Arcavi, I., MacLeod, C. L., et al. 2019, Ap J, 883, 94

    2019

  59. [59]

    Urry, C. M. & Padovani, P . 1995, PASP , 107, 803 V estergaard, M. & Peterson, B. M. 2006, ApJ, 641, 689

    1995

  60. [60]

    K., Brink, T

    Wang, J., Zheng, W. K., Brink, T. G., et al. 2023, ApJ, 956, 137

    2023

  61. [61]

    & Bon, E

    Wang, J.-M. & Bon, E. 2020, A&A, 643, L9

    2020

  62. [62]

    2024, ApJ, 966, 128

    Wang, S., Woo, J.-H., Gallo, E., et al. 2024, ApJ, 966, 128

    2024

  63. [63]

    1992, MNRAS, 257, 677 WISE Team

    Winkler, H. 1992, MNRAS, 257, 677 WISE Team. 2020, NEOWISE 2-Band Post-Cryo Single Exposure (L1b) Source Table

    1992

  64. [64]

    L., Eisenhardt, P

    Wright, E. L., Eisenhardt, P . R. M., Mainzer, A. K., et al. 201 0, AJ, 140, 1868 Y ang, Q., Green, P ., Wu, X.-B., et al. 2025, in American Astro nomical Society Meeting Abstracts, V ol. 245, American Astronomical Societ y Meeting Ab- stracts #245, 221.06 Y ang, Q., Green, P . J., MacLeod, C. L., et al. 2023, ApJ, 953, 61 Y ang, Q., Wu, X.-B., Fan, X., e...

    2025

  65. [65]

    2024, Ap J, 966, 85

    Zeltyn, G., Trakhtenbrot, B., Eracleous, M., et al. 2024, Ap J, 966, 85

    2024

  66. [66]

    2024, MNRAS, 530, 3538

    Zhu, L.-T., Li, J., Wang, Z., & Zhang, J.-J. 2024, MNRAS, 530, 3538

    2024

  67. [67]

    U., et al

    Zhu, L.-T., Wang, Z., Devanand, P . U., et al. 2025, MNRAS, 536, 2715 1 Department of Astronomy, School of Physics and Astronomy, K ey Laboratory of Astroparticle Physics of Y unnan Province, Y u nnan

    2025

  68. [68]

    University, Kunming 650091, China e-mail: zhulitao@mail.ynu.edu.cn, wangzx20@ynu.edu.cn 2 Aryabhatta Research Institute of Observational Sciences ( ARIES), Manora Peak, Nainital - 263 001, India Article number, page 8 of 15 Litao Zhu et al.: Extreme colour–magnitude variability: connection to changing-look AGNs Appendix A: Information for the DOT and HCT ...

    2024