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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"

28062 results found.

  1. GRB 260114A: VLT/HAWK-I further near-infrared upper limits
  2. IceCube Alert 260115.73: Global MASTER-Net observations report
  3. GRB 260115A: BALROG localization (Fermi Trigger 790192010 / GRB 260115741)
  4. IceCube: GCN Notices for high-energy track alerts now streamed via Kafka
  5. Fermi GRB 260115A: Global MASTER-Net observations report
  6. GRB 251222A: radio detection with the VLA
  7. GRB 260114A: VLT/HAWK-I near-infrared upper limits
  8. GRB 260114A: Swift-XRT refined Analysis
  9. GRB 260114A: VLT/X-shooter redshift of the putative host galaxy
  10. GRB 260114A : MITSuME Akeno optical upper limits
  11. GRB 260114A: COLIBRÍ optical upper limits
  12. GRB 260114A: TNG NIR upper limit
  13. GRB 260114A: NOT optical observations
  14. GRB 260114A: SVOM/GRM observation of a short burst
  15. Swift GRB 260114A: Global MASTER-Net observations report
  16. GRB 260114A: Mondy optical observations
  17. GRB 260114A: GMG Optical Observation
  18. Fermi-LAT Gamma-ray Observations of IceCube-260111A
  19. GRB 260114A: Swift detection of a short burst
  20. EP-WXT trigger 01709251266: SVOM/C-GFT confirmation of a stellar flare
  21. IceCube-260111A: Upper limits from a search for additional neutrino events in IceCube
  22. Swift GRB260113.43: Global MASTER-Net observations report
  23. EP260110a: NOT and GTC Optical and Near-Infrared Observations
  24. EP260110a: TRT optical upper limits
  25. Konus-Wind detection of GRB 260101A
  26. GRB 260111A: Swift-XRT observations
  27. Swift Trigger 1439093: is probably not GRB 260113A
  28. GRB 260111A: COLIBRÍ optical afterglow candidate
  29. GRB 260111A: Fermi GBM Observation
  30. GRB 251230A: Mondy Optical Observations
  31. GRB 260111A: Swift/BAT-GUANO arcminute localization of a burst
  32. IceCube Alert 260111A: Global MASTER-Net observations report
  33. EP260110a: Global MASTER-Net observations report
  34. Fermi GRB 260111A: Global MASTER-Net observations report
  35. Swift trigger 1436759 is not an astrophysical event
  36. EP260110a: KAIT optical upper limit
  37. EP260110a: refined analysis of the EP-WXT and EP-FXT observations
  38. EP 260110a: COLIBRÍ optical observations
  39. EP260110a: SVOM/C-GFT upper limit
  40. EP260110a: Einstein Probe detection of an X-ray transient
  41. GRB 260109C: LCO optical upper limits
  42. GRB 260109C: Kilonova-Catcher optical upper limit
  43. EP260105b / GRB 260105C : Fermi-GBM Sub-Threshold Detection
  44. Swift Trigger 1434591: possible GRB 260109C
  45. GRB 260102A: Swift-XRT afterglow detection
  46. GRB 260104A: Swift-BAT refined analysis
  47. GRB 260101A: Swift-BAT refined analysis
  48. Swift GRB 251230A: Global MASTER-Net OT detection
  49. Fermi GRB 260107A: Global MASTER-Net observations report
  50. GRB 260102A: AbAO optical observations
  51. EP260105b/EP-WXT trigger 01709251028: Einstein Probe detection of an X-ray transient
  52. Fermi GRB 260105A: Global MASTER-Net observations report
  53. GRB 260105B: Fermi GBM Detection
  54. GRB 260105B: BALROG localization (Fermi Trigger 789348101 / GRB 260105973)
  55. GRB 260105A: SVOM/GRM observation
  56. GRB 260105B: SVOM/GRM observation
  57. FRB 20251229A: COLIBRÍ optical upper limits
  58. Fermi GRB 260105B: Global MASTER-Net observations report
  59. FRB 20251229A: A potentially hyperactive repeating fast radio burst source
  60. EP260105a: refined analysis of the EP-WXT and EP-FXT observations
  61. EP260105a: LCO Optical Upper limit
  62. EP260104a: Global MASTER-Net observations report
  63. EP260104a: Einstein Probe detection of a fast X-ray transient
  64. GRB 260101A: COLIBRÍ optical upper limits
  65. EP260105a: Global MASTER-Net observations report
  66. EP260105a: Einstein Probe detection of an X-ray transient
  67. GRB 260104A: COLIBRÍ optical upper limits
  68. Fermi GRB 260104B: Global MASTER-Net observations report
  69. Swift GRB 260104A: Global MASTER-Net observations report
  70. GRB 251230A/EP-WXT trigger 01709250693: Mephisto optical upper limits
  71. GRB 260104A: Swift-XRT refined Analysis
  72. GRB 260104A: Enhanced Swift-XRT position
  73. GRB 260101A: Swift/UVOT Detection
  74. GRB 260103A: GECAM-B observation of a burst
  75. GRB 260104A: Swift detection of a burst
  76. Fermi-LAT Gamma-ray Observations of IceCube-251225A
  77. GRB 260101A: COLIBRÍ optical observations
  78. SVOM GRB260103.08: Global MASTER-Net observations report
  79. SVOM GRB260102A: Global MASTER-Net observations report
  80. Fermi GBM Sub-Threshold Detection of GRB 260102A
  81. GRB 260102A: EP-FXT follow-up observation
  82. EP260101a: Global MASTER-Net observations report
  83. GRB 260102A: LCO optical upper limits
  84. GRB 260102A: Swift-XRT observations
  85. GRB 260102A: SVOM/COLIBRÍ (FM-GFT) optical observations
  86. GRB 260101A: Fermi GBM Observation
  87. EP260101a: refined analysis of the EP-WXT and EP-FXT observations
  88. GRB 260102A: SVOM detection of a burst
  89. GRB 260101A: NOT spectroscopic observations
  90. GRB 260101A: SVOM/GRM observation
  91. GRB 260101A: Swift-XRT refined Analysis
  92. Swift GRB 260101A: Global MASTER-Net observations report
  93. GRB 260101A: Enhanced Swift-XRT position
  94. EP260101a: Einstein Probe detection of an X-ray transient
  95. GRB 260101A: LCO detection of the optical counterpart
  96. GRB 260101A: Swift detection of a burst with an optical counterpart
  97. GRB 260101A: Fermi GBM Final Real-time Localization
  98. SVOM GRB251231.57: Global MASTER-Net observations report
  99. GRB 251230A: GRANDMA/TAROT Early Detection
  100. GRB 251230A/EP251230a: Optical upper limit with Kinder observations

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