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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"

28053 results found.

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

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