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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"

41209 results found.

  1. GRB 260115A: BALROG localization (Fermi Trigger 790192010 / GRB 260115741)
  2. IceCube: GCN Notices for high-energy track alerts now streamed via Kafka
  3. Fermi GRB 260115A: Global MASTER-Net observations report
  4. GRB 260115A: Fermi GBM Final Real-time Localization
  5. GRB260114A: STEP/T80S optical limits
  6. GRB 251222A: radio detection with the VLA
  7. GRB 260114A: VLT/HAWK-I near-infrared upper limits
  8. Konus-Wind detection of GRB 260114A
  9. GRB 260114A: Swift-XRT refined Analysis
  10. GRB 260114A: 6 GHz VLA observations
  11. GRB 260114A: VLT/X-shooter redshift of the putative host galaxy
  12. GRB 260114A : MITSuME Akeno optical upper limits
  13. GRB 260114A: COLIBRÍ optical upper limits
  14. GRB 260114A: TNG NIR upper limit
  15. GRB 260114A: NOT optical observations
  16. Konus-Wind detection of GRB 251230A / EP251230a
  17. GRB 260114A: SVOM/GRM observation of a short burst
  18. Swift GRB 260114A: Global MASTER-Net observations report
  19. GRB 260114A: GECAM-B observation of a short burst
  20. GRB 260114A: Mondy optical observations
  21. GRB 260114A: Fermi GBM observation
  22. GRB 260112B: GECAM-B observation
  23. GRB 260114A: GMG Optical Observation
  24. Fermi-LAT Gamma-ray Observations of IceCube-260111A
  25. GRB 260114A: Swift detection of a short burst
  26. GRB 260114A: Fermi GBM Final Real-time Localization
  27. EP-WXT trigger 01709251266: SVOM/C-GFT confirmation of a stellar flare
  28. IceCube-260111A: Upper limits from a search for additional neutrino events in IceCube
  29. Swift GRB260113.43: Global MASTER-Net observations report
  30. EP260110a: NOT and GTC Optical and Near-Infrared Observations
  31. EP260110a: TRT optical upper limits
  32. Konus-Wind detection of GRB 260101A
  33. GRB 260111A: Swift-XRT observations
  34. Swift Trigger 1439093: is probably not GRB 260113A
  35. GRB 260111A: COLIBRÍ optical afterglow candidate
  36. GRB 260111A: GECAM-B observation of a burst
  37. GRB 260111A: Fermi GBM Observation
  38. The EP-WXT trigger 01709251266 is likely a flaring star
  39. Swift Trigger 1434591 is not a GRB
  40. GRB 260111A: GOTO optical upper limits
  41. GRB 260112B: Fermi GBM Final Real-time Localization
  42. GRB 260111A: Swift ToO observations
  43. GRB 251230A: Mondy Optical Observations
  44. GRB 260111A: Swift/BAT-GUANO arcminute localization of a burst
  45. GRB 260112A: Fermi GBM Final Real-time Localization
  46. EP260110a: SVOM/VT optical upper limits
  47. IceCube-260111A - IceCube observation of a high-energy neutrino candidate track-like event
  48. IceCube Alert 260111A: Global MASTER-Net observations report
  49. EP260110a: Global MASTER-Net observations report
  50. Fermi GRB 260111A: Global MASTER-Net observations report
  51. GRB 260111A: Fermi GBM Final Real-time Localization
  52. Swift trigger 1436759 is not an astrophysical event
  53. EP260110a: KAIT optical upper limit
  54. EP260110a: refined analysis of the EP-WXT and EP-FXT observations
  55. EP 260110a: COLIBRÍ optical observations
  56. EP260110a: SVOM/C-GFT upper limit
  57. EP260110a: BOOTES-5/JGU optical upper limit
  58. EP260110a: Einstein Probe detection of an X-ray transient
  59. GRB 260109C: LCO optical upper limits
  60. GRB 260109C: Kilonova-Catcher optical upper limit
  61. EP260105b / GRB 260105C : Fermi-GBM Sub-Threshold Detection
  62. Swift Trigger 1434591: possible GRB 260109C
  63. GRB 260109B: Fermi GBM Final Real-time Localization
  64. GRB 260102A: Swift-XRT afterglow detection
  65. GRB 260109A: Fermi GBM Final Real-time Localization
  66. GRB 260104A: Swift-BAT refined analysis
  67. GRB 260101A: Swift-BAT refined analysis
  68. Swift GRB 251230A: Global MASTER-Net OT detection
  69. Fermi GRB 260107A: Global MASTER-Net observations report
  70. GRB 260102A: AbAO optical observations
  71. GRB 260107A: Fermi GBM Final Real-time Localization
  72. EP260105b/EP-WXT trigger 01709251028: Einstein Probe detection of an X-ray transient
  73. The EP-WXT trigger 01709251112 is likely a flaring star
  74. Fermi GRB 260105A: Global MASTER-Net observations report
  75. GRB 260105B: Fermi GBM Detection
  76. EP260105a: FTW optical observations
  77. EP260104a: FTW optical observations
  78. GRB 260105B: BALROG localization (Fermi Trigger 789348101 / GRB 260105973)
  79. GRB 260105A: SVOM/GRM observation
  80. GRB 260105B: SVOM/GRM observation
  81. The EP-WXT trigger 01709251028 is likely a flaring star
  82. FRB 20251229A: COLIBRÍ optical upper limits
  83. Fermi GRB 260105B: Global MASTER-Net observations report
  84. EP260105a: SVOM/VT optical upperlimit
  85. GRB 260105B: Fermi GBM Final Real-time Localization
  86. GRB 260105A: Fermi GBM Final Real-time Localization
  87. FRB 20251229A: A potentially hyperactive repeating fast radio burst source
  88. EP260105a: refined analysis of the EP-WXT and EP-FXT observations
  89. EP260105a: LCO Optical Upper limit
  90. EP260104a: Global MASTER-Net observations report
  91. EP260104a: Einstein Probe detection of a fast X-ray transient
  92. GRB 260101A: COLIBRÍ optical upper limits
  93. EP260105a: Global MASTER-Net observations report
  94. EP260105a: Einstein Probe detection of an X-ray transient
  95. GRB 260103A: Insight-HXMT/HE detection
  96. GRB 260104A: COLIBRÍ optical upper limits
  97. GRB 260104C: Fermi GBM Final Real-time Localization
  98. Fermi GRB 260104B: Global MASTER-Net observations report
  99. Swift GRB 260104A: Global MASTER-Net observations report
  100. GRB 251230A/EP-WXT trigger 01709250693: Mephisto optical upper limits

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