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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"

28055 results found.

  1. IceCube: GCN Notices for high-energy track alerts now streamed via Kafka
  2. Fermi GRB 260115A: Global MASTER-Net observations report
  3. GRB 251222A: radio detection with the VLA
  4. GRB 260114A: VLT/HAWK-I near-infrared upper limits
  5. GRB 260114A: Swift-XRT refined Analysis
  6. GRB 260114A: VLT/X-shooter redshift of the putative host galaxy
  7. GRB 260114A : MITSuME Akeno optical upper limits
  8. GRB 260114A: COLIBRÍ optical upper limits
  9. GRB 260114A: TNG NIR upper limit
  10. GRB 260114A: NOT optical observations
  11. GRB 260114A: SVOM/GRM observation of a short burst
  12. Swift GRB 260114A: Global MASTER-Net observations report
  13. GRB 260114A: Mondy optical observations
  14. GRB 260114A: GMG Optical Observation
  15. Fermi-LAT Gamma-ray Observations of IceCube-260111A
  16. GRB 260114A: Swift detection of a short burst
  17. EP-WXT trigger 01709251266: SVOM/C-GFT confirmation of a stellar flare
  18. IceCube-260111A: Upper limits from a search for additional neutrino events in IceCube
  19. Swift GRB260113.43: Global MASTER-Net observations report
  20. EP260110a: NOT and GTC Optical and Near-Infrared Observations
  21. EP260110a: TRT optical upper limits
  22. Konus-Wind detection of GRB 260101A
  23. GRB 260111A: Swift-XRT observations
  24. Swift Trigger 1439093: is probably not GRB 260113A
  25. GRB 260111A: COLIBRÍ optical afterglow candidate
  26. GRB 260111A: Fermi GBM Observation
  27. GRB 251230A: Mondy Optical Observations
  28. GRB 260111A: Swift/BAT-GUANO arcminute localization of a burst
  29. IceCube Alert 260111A: Global MASTER-Net observations report
  30. EP260110a: Global MASTER-Net observations report
  31. Fermi GRB 260111A: Global MASTER-Net observations report
  32. Swift trigger 1436759 is not an astrophysical event
  33. EP260110a: KAIT optical upper limit
  34. EP260110a: refined analysis of the EP-WXT and EP-FXT observations
  35. EP 260110a: COLIBRÍ optical observations
  36. EP260110a: SVOM/C-GFT upper limit
  37. EP260110a: Einstein Probe detection of an X-ray transient
  38. GRB 260109C: LCO optical upper limits
  39. GRB 260109C: Kilonova-Catcher optical upper limit
  40. EP260105b / GRB 260105C : Fermi-GBM Sub-Threshold Detection
  41. Swift Trigger 1434591: possible GRB 260109C
  42. GRB 260102A: Swift-XRT afterglow detection
  43. GRB 260104A: Swift-BAT refined analysis
  44. GRB 260101A: Swift-BAT refined analysis
  45. Swift GRB 251230A: Global MASTER-Net OT detection
  46. Fermi GRB 260107A: Global MASTER-Net observations report
  47. GRB 260102A: AbAO optical observations
  48. EP260105b/EP-WXT trigger 01709251028: Einstein Probe detection of an X-ray transient
  49. Fermi GRB 260105A: Global MASTER-Net observations report
  50. GRB 260105B: Fermi GBM Detection
  51. GRB 260105B: BALROG localization (Fermi Trigger 789348101 / GRB 260105973)
  52. GRB 260105A: SVOM/GRM observation
  53. GRB 260105B: SVOM/GRM observation
  54. FRB 20251229A: COLIBRÍ optical upper limits
  55. Fermi GRB 260105B: Global MASTER-Net observations report
  56. FRB 20251229A: A potentially hyperactive repeating fast radio burst source
  57. EP260105a: refined analysis of the EP-WXT and EP-FXT observations
  58. EP260105a: LCO Optical Upper limit
  59. EP260104a: Global MASTER-Net observations report
  60. EP260104a: Einstein Probe detection of a fast X-ray transient
  61. GRB 260101A: COLIBRÍ optical upper limits
  62. EP260105a: Global MASTER-Net observations report
  63. EP260105a: Einstein Probe detection of an X-ray transient
  64. GRB 260104A: COLIBRÍ optical upper limits
  65. Fermi GRB 260104B: Global MASTER-Net observations report
  66. Swift GRB 260104A: Global MASTER-Net observations report
  67. GRB 251230A/EP-WXT trigger 01709250693: Mephisto optical upper limits
  68. GRB 260104A: Swift-XRT refined Analysis
  69. GRB 260104A: Enhanced Swift-XRT position
  70. GRB 260101A: Swift/UVOT Detection
  71. GRB 260103A: GECAM-B observation of a burst
  72. GRB 260104A: Swift detection of a burst
  73. Fermi-LAT Gamma-ray Observations of IceCube-251225A
  74. GRB 260101A: COLIBRÍ optical observations
  75. SVOM GRB260103.08: Global MASTER-Net observations report
  76. SVOM GRB260102A: Global MASTER-Net observations report
  77. Fermi GBM Sub-Threshold Detection of GRB 260102A
  78. GRB 260102A: EP-FXT follow-up observation
  79. EP260101a: Global MASTER-Net observations report
  80. GRB 260102A: LCO optical upper limits
  81. GRB 260102A: Swift-XRT observations
  82. GRB 260102A: SVOM/COLIBRÍ (FM-GFT) optical observations
  83. GRB 260101A: Fermi GBM Observation
  84. EP260101a: refined analysis of the EP-WXT and EP-FXT observations
  85. GRB 260102A: SVOM detection of a burst
  86. GRB 260101A: NOT spectroscopic observations
  87. GRB 260101A: SVOM/GRM observation
  88. GRB 260101A: Swift-XRT refined Analysis
  89. Swift GRB 260101A: Global MASTER-Net observations report
  90. GRB 260101A: Enhanced Swift-XRT position
  91. EP260101a: Einstein Probe detection of an X-ray transient
  92. GRB 260101A: LCO detection of the optical counterpart
  93. GRB 260101A: Swift detection of a burst with an optical counterpart
  94. GRB 260101A: Fermi GBM Final Real-time Localization
  95. SVOM GRB251231.57: Global MASTER-Net observations report
  96. GRB 251230A: GRANDMA/TAROT Early Detection
  97. GRB 251230A/EP251230a: Optical upper limit with Kinder observations
  98. EP251229a: Optical upper limit with Kinder observations
  99. GRB 251230A: 1.3m DFOT optical upper limit
  100. GRB 251230A: Swift-XRT refined Analysis

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