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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. See the documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
Advanced Search

To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

4055 results found.

  1. IceCube-260919A: Upper limits from a search for additional neutrino events in IceCube
  2. IceCube-260919A - IceCube observation of a high-energy neutrino candidate track-like event
  3. Fermi GBM Sub-Threshold Detection of GRB 260918A
  4. GRB 260918A: SVOM detection of a burst
  5. IceCube-260916A: Upper limits from a search for additional neutrino events in IceCube
  6. IceCube-260916A - IceCube observation of a high-energy neutrino candidate track-like event
  7. GRB 260913A: SVOM trigger sb26091302 is not an astrophysical event
  8. IceCube-260827A: Upper limits from a search for additional neutrino events in IceCube
  9. IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube
  10. IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube
  11. IceCube-260827A - IceCube observation of a high-energy neutrino candidate track-like event
  12. IceCube-260825A - IceCube observation of a high-energy neutrino candidate track-like event
  13. IceCube-260821A: Upper limits from a search for additional neutrino events in IceCube
  14. IceCube-260821A - IceCube observation of a high-energy neutrino candidate track-like event
  15. IceCube-260807A: Upper limits from a search for additional neutrino events in IceCube
  16. IceCube-260805A: Upper limits from a search for additional neutrino events in IceCube
  17. IceCube-260807A - IceCube observation of a high-energy neutrino candidate track-like event
  18. IceCube-260805A - IceCube observation of a high-energy neutrino candidate track-like event
  19. IceCube-260722A: Upper limits from a search for additional neutrino events in IceCube
  20. IceCube-260722A - IceCube observation of a high-energy neutrino candidate track-like event
  21. GRB 260718A: SVOM detection of a burst
  22. IceCube-260708A: Follow-up studies of cosmic-ray origin of high-energy neutrino alert
  23. IceCube-260712A: Upper limits from a search for additional neutrino events in IceCube
  24. IceCube-260708A: Upper limits from a search for additional neutrino events in IceCube
  25. IceCube-260712A - IceCube observation of a high-energy neutrino candidate track-like event
  26. IceCube-260708A - IceCube observation of a high-energy neutrino candidate track-like event
  27. IceCube-260704A: Upper limits from a search for additional neutrino events in IceCube
  28. IceCube-260704A - IceCube observation of a high-energy neutrino candidate track-like event
  29. IceCube-260622A: Upper limits from a search for additional neutrino events in IceCube
  30. IceCube-260622A - IceCube observation of a high-energy neutrino candidate track-like event
  31. GRB 260618C: SVOM/ECLAIRs detection of a possible burst through on-ground search
  32. IceCube-260610A: Upper limits from a search for additional neutrino events in IceCube
  33. IceCube-260610A - IceCube observation of a high-energy neutrino candidate track-like event
  34. GRB 260511A: UTGO H50 optical afterglow observation
  35. Fermi GBM Sub-Threshold Detection of GRB 260510B
  36. GRB 260510B: SVOM detection of a burst
  37. GRB 260509A: SVOM detection of a burst
  38. IceCube-260504A: Upper limits from a search for additional neutrino events in IceCube
  39. IceCube-260504A - IceCube observation of a high-energy neutrino candidate track-like event
  40. IPN triangulation of a bright burst from SGR 1E1841-045
  41. IceCube-260425A: Upper limits from a search for additional neutrino events in IceCube
  42. IceCube-260425A - IceCube observation of a high-energy neutrino candidate track-like event
  43. GRB 260410B: SVOM/GRM detection of a short faint burst
  44. EP260321a: Upper limits from a neutrino search with IceCube
  45. IceCube-260315A: Upper limits from a search for additional neutrino events in IceCube
  46. IceCube-260315A - IceCube observation of a high-energy neutrino candidate track-like event
  47. IceCube-260217A: Upper limits from a search for additional neutrino events in IceCube
  48. IceCube-260125A: Upper limits from a search for additional neutrino events in IceCube
  49. Trigger 1442421: Swift detection of HMXB 1A 1118-61
  50. IceCube-260115A: Upper limits from a search for additional neutrino events in IceCube
  51. IceCube-260115A - IceCube observation of a high-energy neutrino candidate track-like event
  52. IceCube-260111A: Upper limits from a search for additional neutrino events in IceCube
  53. GRB 260111A: Swift/BAT-GUANO arcminute localization of a burst
  54. LIGO/Virgo/KAGRA S251112cm: Candidates from the NSF-DOE Vera C. Rubin Observatory
  55. IceCube-251225A: Upper limits from a search for additional neutrino events in IceCube
  56. IceCube-251218A: Upper limits from a search for additional neutrino events in IceCube
  57. GRB 251215A: Swift/BAT-GUANO arcminute localization of a burst
  58. IceCube-251210A: Upper limits from a search for additional neutrino events in IceCube
  59. GRB 251208B: Swift/BAT-GUANO arcminute localization of a burst
  60. GRB 251208D: SVOM possible detection of a faint burst
  61. GRB 251203B : SVOM trigger sb25120304 is not a GRB
  62. IceCube-251130A: Upper limits from a search for additional neutrino events in IceCube
  63. LIGO/Virgo/KAGRA S251112cm: GECKO/KMTNet tiling observations and transient candidates
  64. LIGO/Virgo/KAGRA S251112cm: AT 2025adht Kinder follow-up observations
  65. LIGO/Virgo/KAGRA S251105aj: SVOM/VT optical observations and preliminary results on SVOM J2320.0-2901
  66. LIGO/Virgo/KAGRA S251105aj: EP-FXT follow-up observations and preliminary results on SVOM J2320.0-2901
  67. LIGO/Virgo/KAGRA S251105aj: SVOM/ECLAIRs detection of a high-energy transient SVOM J2320.0-2901 through targeted search
  68. LIGO/Virgo/KAGRA S251112cm: SOAR spectroscopy of three TROVE TNS candidates
  69. LIGO/Virgo/KAGRA S251112cm: SVOM/VT optical observations and preliminary results
  70. EP251118a: preliminary result of EP-FXT follow-up observation
  71. LIGO/Virgo/KAGRA S251112cm: Upper limits from Glowbug gamma-ray observations
  72. LIGO/Virgo/KAGRA S251117dq: Updated Sky localization
  73. LIGO/Virgo/KAGRA S251117dq: Identification of a GW compact binary merger candidate
  74. LIGO/Virgo/KAGRA S251112cm: J-GEM follow-up observations
  75. LIGO/Virgo/KAGRA S251112cm: Classification of reported candidates with SOAR/Goodman
  76. LIGO/Virgo/KAGRA S251112cm: WFST follow-up observations and preliminary results
  77. LIGO/Virgo/KAGRA S251116en: Updated Sky localization
  78. LIGO/Virgo/KAGRA S251112cm: EP-FXT follow-up observations
  79. LIGO/Virgo/KAGRA S251116en: Identification of a GW compact binary merger candidate
  80. LIGO/Virgo/KAGRA S251112cm: Observations with the NSF-DOE Vera C. Rubin Observatory
  81. LIGO/Virgo/KAGRA S251112cm: GRANDMA observations of the skymap
  82. LIGO/Virgo/KAGRA S251112cm: AT2025adht follow-up at Maidanak observatory by GRANDMA
  83. LIGO/Virgo/KAGRA S251112cm: NED Galaxies in the 4-Update Localization Volume
  84. LIGO/Virgo/KAGRA S251112cm: DECam GW-MMADS candidates
  85. LIGO/Virgo/KAGRA S251112cm: Updated Sky localization and false alarm rate estimate
  86. LIGO/Virgo/KAGRA S251112cm: ATLAS targeted observations of the skymap
  87. LIGO/Virgo/KAGRA S251112cm: Swift XRT observations, 20 X-ray sources
  88. LIGO/Virgo/KAGRA S251112cm: Candidates from the Zwicky Transient Facility
  89. LIGO/Virgo/KAGRA S251112cm: TROVE Vetting of TNS Candidates
  90. LIGO/Virgo/KAGRA S251112cm: FTW observations of galaxies within localization region
  91. LIGO/Virgo/KAGRA S251112cm: ATLAS pre-detections of AT2025adgp and AT2025adgq
  92. LIGO/Virgo/KAGRA S251112cm: Detection of two young transients by BlackGEM/MeerLICHT: AT2025adgp and AT2025adgq
  93. LIGO/Virgo/KAGRA S251112cm: Coverage and upper limits from MAXI/GSC observations
  94. LIGO/Virgo/KAGRA S251112cm: Initial GOTO-South observations
  95. LIGO/Virgo/KAGRA S251112cm: Upper limits from Fermi-GBM Observations
  96. LIGO/Virgo/KAGRA S251112cm: NED Galaxies in the 3-Initial Localization Volume
  97. LIGO/Virgo/KAGRA S251112cm: Identification of a GW compact binary merger candidate
  98. LIGO/Virgo/KAGRA S251108fi: DDOTI Optical Candidate
  99. LIGO/Virgo/KAGRA S251108fi: One counterpart neutrino candidate from IceCube neutrino searches
  100. LIGO/Virgo/KAGRA S251108fi: Updated Sky localization

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