Publications

First-Author Publications

  • PyLongslit: a simple manual Python pipeline for processing of astronomical long-slit spectra recorded with CCD detectors
    K. Valeckas, J. P. U. Fynbo, J.-K. Krogager, K. E. Heintz
    Journal of Open Source Software 10(116), 9264 (2025).
    DOI

  • Introducing the data-reduction pipeline for the Nordic Optical Telescope Transient Explorer spectrograph
    Valeckas, Kostas, Kadela, Arthur M., Viuho, Joonas K. M., Christensen, Lise B., Fynbo, Johan P. U., Andersen, Michael I., Sørensen, Anton N., Milvang-Jensen, Bo, and Heintz, Kasper E.
    In Software and Cyberinfrastructure for Astronomy IX (SPIE Proceedings), Paper 14155-15, 2026.

Non-First Author Publications

  • Phase-resolved optical spectroscopy of the rapidly varying white dwarf ZTF 1851+1714
    C. C. Pedersen, M. R. M. Knudsen, K. Valeckas, L. Izzo, T. M. Tauris, J. P. U. Fynbo
    Astronomy & Astrophysics 703, A87 (2025).
    DOI

Preprints in Review

  • SN 2025aico: Early observations of a faint Type IIb supernova with a low-mass envelope
    J.-W. Zhao, A. Pastorello, B. Kumar, Y.-Z. Cai, A. Dutta, D. K. Sahu, A. Reguitti, R. S. Teja, H. Das, T. J. Moriya, N. Pyykkinen, K. Valeckas, et al.
    arXiv e-prints (2026).
    arXiv:2607.10671 · DOI

  • A remarkable Gaia-assisted discovery of a temporally varying, triple-lensed quasar at z = 2.67
    C. Lind-Thomsen, K. E. Heintz, A. Sneppen, K. Valeckas, S. Geier, J.-K. Krogager, J. Richard, J. P. U. Fynbo
    arXiv (2025).
    arXiv:2512.10811 · DOI

Transient GCN Reports

  • GRB 260509A: NOT spectroscopic redshift upper limit z < 1.95
    G. Corcoran, A. Saccardi, B. Schneider, D. B. Malesani, N. R. Tanvir, K. Valeckas, V. Vuolteenaho
    GRB Coordinates Network 44514 (2026).
    ADS

  • EP260329a: NOT optical counterpart candidate
    L. B. He, S. Q. Jiang, Z. P. Zhu, J. An, X. Liu, D. Xu, S. Y. Fu, J. P. U. Fynbo, K. Valeckas
    GRB Coordinates Network 44152 (2026).
    ADS

  • EP260214a: NOT optical upper limits
    L. B. He, S. Y. Fu, J. An, X. Liu, S. Q. Jiang, Z. P. Zhu, D. Xu, J. P. U. Fynbo, K. Valeckas
    GRB Coordinates Network 43754 (2026).
    ADS

  • EP260214b: NOT optical counterpart detection
    L. B. He, Z. P. Zhu, J. An, X. Liu, S. Q. Jiang, D. Xu, S. Y. Fu, J. P. U. Fynbo, K. Valeckas
    GRB Coordinates Network 43745 (2026).
    ADS

  • GRB 260131A: NOT spectroscopic redshift z = 1.434
    A. Saccardi, J. An, G. Corcoran, B. Gompertz, L. Izzo, D. B. Malesani, A. Martin-Carrillo, B. Schneider, A. de Ugarte Postigo, K. Valeckas
    GRB Coordinates Network 43595 (2026).
    ADS

  • EP260119a: NOT optical observations
    X. Liu, S. Q. Jiang, J. An, L. B. He, Z. P. Zhu, D. Xu, S. Y. Fu, J. P. U. Fynbo, K. Valeckas
    GRB Coordinates Network 43464 (2026).
    ADS

  • EP260131a: NOT early detection of the counterpart in “rapid response mode”
    D. B. Malesani, J. N. D. van Dalen, J. A. Quirola-Vasquez, P. G. Jonker, K. Valeckas
    GRB Coordinates Network 43581 (2026).
    ADS

  • GRB 260101A: NOT spectroscopic observations
    A. Saccardi, L. Izzo, A. Martin-Carrillo, G. Corcoran, D. B. Malesani, K. Valeckas
    GRB Coordinates Network 43293 (2026).
    ADS

  • GRB 260114A: NOT optical observations
    G. Corcoran, A. Martin-Carrillo, A. Saccardi, D. B. Malesani, K. Valeckas
    GRB Coordinates Network 43406 (2026).
    ADS

  • GRB 260127A: NOT optical observations
    D. B. Malesani, J. An, L. B. He, G. Corcoran, K. Valeckas, L. Izzo, A. Martin-Carrillo, A. Saccardi, B. Schneider
    GRB Coordinates Network 43543 (2026).
    ADS

  • GRB 251230A / EP251230a: further NOT optical observations revealing shallower decay or possible rebrightening
    L. He, L. Izzo, A. Martin-Carrillo, A. Saccardi, K. Valeckas
    GRB Coordinates Network 43280 (2025).
    ADS

  • GRB 251013C: NOT spectroscopic redshift z = 0.572
    A. Martin-Carrillo, L. Izzo, D. B. Malesani, G. Corcoran, B. Schneider, A. de Ugarte Postigo, A. Saccardi, B. P. Gompertz, K. Valeckas
    GRB Coordinates Network 42227 (2025).
    ADS

  • GRB 250924A: NOT optical observations
    L. Cotter, D. B. Malesani, A. Martin-Carrillo, A. de Ugarte Postigo, B. Schneider, G. Corcoran, K. Valeckas
    GRB Coordinates Network 41980 (2025).
    ADS

  • GRB 250925A: NOT optical afterglow candidate
    G. Corcoran, L. Cotter, D. B. Malesani, A. Martin-Carrillo, A. de Ugarte Postigo, B. Schneider, K. Valeckas
    GRB Coordinates Network 41990 (2025).
    ADS

  • GRB 250818B: NOT optical observations
    J. Broe Bendtsen, J. Hein Pedersen, I. A. Koch, S. L. Wagner, J. Magaard Knudsen, R. Holmberg Rasmussen, K. Valeckas, J. P. U. Fynbo, D. B. Malesani, A. de Ugarte Postigo
    GRB Coordinates Network 41426 (2025).
    ADS

  • GRB 250821A: NOT z-band upper limit
    M. Beyer Stjerne, K. A. Grimstrup, W. K. Krarup Mirsal, C. Lind-Thomsen, F. Hjorth Gammelgaard, I. L. Róbertsdóttir, J. P. U. Fynbo, K. Valeckas, R. Holmberg Rasmussen, D. B. Malesani
    GRB Coordinates Network 41483 (2025).
    ADS

  • LIGO/Virgo/KAGRA S250818k: NOT optical observations of AT2025ulz
    D. B. Malesani, A. Boye, L. Izzo, G. Leloudas, J. An, X. Liu, D. Xu, M. Fraser, S. J. Brennan, J. Broe Bendsten, I. A. Koch, S. L. Wagner, J. Magaard Knudsen, J. Hein Pedersen, J. P. U. Fynbo, R. Holmberg Rasmussen, K. Valeckas, M. De Pasquale
    GRB Coordinates Network 41492 (2025).
    ADS

  • GRB 250713A: NOT optical upper limits
    A. Saccardi, A. Martin-Carrillo, D. B. Malesani, A. de Ugarte Postigo, G. Corcoran, J. T. Palmerio, L. Izzo, B. P. Gompertz, N. Pyykkinen, K. Valeckas
    GRB Coordinates Network 41091 (2025).
    ADS

  • GRB 250103A: NOT optical observations
    D. Xu, Z. P. Zhu, D. B. Malesani, L. Izzo, A. de Ugarte Postigo, A. Saccardi, K. Valeckas
    GRB Coordinates Network 38808 (2025).
    ADS

  • GRB 250103A: NOT spectroscopic redshift
    Z. P. Zhu, D. Xu, D. B. Malesani, A. Saccardi, K. Valeckas
    GRB Coordinates Network 38814 (2025).
    ADS

  • EP240804a (GRB 240804B): NOT optical observations
    D. B. Malesani, J. P. U. Fynbo, J. Verwohlt, K. Valeckas, T. Bach Johannessen, J. K. Mogensen, D. Xu, S. Grund
    GRB Coordinates Network 37081 (2024).
    ADS

Supernova Classifications

  • Classification of SN 2026naq as a Type IIb supernova
    L. Izzo, G. Leloudas, D. B. Malesani, K. Valeckas, O. B. T. E. Collaboration
    Transient Name Server AstroNote 150 (2026).
    ADS

  • ENGRAVE Transient Classification Report for 2026-05-23 (SN 2026naq)
    L. Izzo, G. Leloudas, D. B. Malesani, K. Valeckas
    Transient Name Server Classification Report 2026-2251 (2026).
    ADS

  • Transient Classification Report for 2026-02-09 (SN 2026bkp)
    N. Pyykkinen, S. B. Seshashayana, H. Kuncarayakti, K. Valeckas
    Transient Name Server Classification Report 2026-564 (2026).
    ADS

  • Transient Classification Report for 2026-01-31 (SN 2026bhr)
    N. Pyykkinen, K. Valeckas
    Transient Name Server Classification Report 2026-422 (2026).
    ADS

  • Transient Classification Report for 2025-10-14 (SN 2025yer)
    N. Pyykkinen, K. Valeckas, H. Kuncarayakti
    Transient Name Server Classification Report 2025-4121 (2025).
    ADS ```