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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"

22051 results found.

  1. Konus-Wind detection of GRB 230307A
  2. Fermi GRB 230308A: Global MASTER-Net observations report
  3. GRB 230307A: Tiled Swift observations
  4. Fermi-LAT gamma-ray observations of IceCube-230306A
  5. GRB 230307A: GECAM detection of an extremely bright burst
  6. Fermi trigger No 699811746: Global MASTER-Net observations report
  7. IceCube Alert 230306.46: Global MASTER-Net observations report
  8. GRB 230228A: 6 GHz VLA radio upper limit
  9. GRB 230228A: Swift/UVOT Upper Limits
  10. Fermi GRB 230301B: Global MASTER-Net observations report
  11. Fermi trigger No 699294715: Global MASTER-Net observations report
  12. Fermi trigger No 699311646: Global MASTER-Net observations report
  13. GRB 230228A: Mondy optical upper limit
  14. Fermi GRB 230227A: Global MASTER-Net observations report
  15. Fermi trigger No 699029364: Global MASTER-Net observations report
  16. GRB 230217A: VLT/FORS2 optical observations and candidate counterpart
  17. GRB 230216A Mondy Observations
  18. GRB 230205A: VLA radio afterglow confirmation
  19. GRB 230217A: Swift/UVOT Upper Limits
  20. GRB 230216A: Swift/UVOT Upper Limits
  21. GRB 230217A: Continued Gemini Observations
  22. GRB 230217A: Swift-XRT afterglow detection
  23. Fermi-LAT gamma-ray observations of IceCube-230220A
  24. Fermi GRB 230220B: Global MASTER-Net observations report
  25. GRB 230217A: Gemini South optical upper limits
  26. GRB 230217A: 6 GHz VLA observations
  27. GRB 230217A: Gemini-South Optical Observation
  28. IceCube-230217A: BOOTES-4/MET Optical Observations
  29. Fermi-LAT gamma-ray observations of IceCube-230217A
  30. GRB 230217A: Swift-XRT observations
  31. Fermi trigger No 698427992: Global MASTER-Net observations report
  32. IceCube Alert 230217.87: Global MASTER-Net observations report
  33. GRB 230205A: Lowell Discovery Telescope Observations
  34. GRB 230204B: Lowell Discovery Telescope Observations
  35. Swift GRB 230216A: Global MASTER-Net observations report
  36. GRB 230216A: Zadko observatory - Gingin optical observations
  37. Fermi GRB 230215A: Global MASTER-Net observations report
  38. GRB 230204B: ATCA radio detection
  39. Fermi trigger No 697926015: Global MASTER-Net observations report
  40. Fermi trigger No 697904388: Global MASTER-Net observations report
  41. GRB 230209B: Swift/BAT-GUANO detection outside the coded FOV
  42. Fermi trigger No 697678542: Global MASTER-Net observations report
  43. Fermi GRB 230209B: Global MASTER-Net observations report
  44. GRB 230205A: 6 GHz VLA observations
  45. GRB 221009A: Continued Swift Observations
  46. GRB 230205A: possible host galaxy detection with the Schmidt - Asiago telescope
  47. GRB 230204B: MASTER early OT detection
  48. GRB 230207B: Swift/BAT-GUANO detection outside the coded FOV
  49. ZTF23aabmzlp/AT2023azs: Neil Gehrels Swift Observatory X-ray observations
  50. Fermi GRB 230207A: Global MASTER-Net observations report
  51. GRB 230204B: Swift/UVOT Upper Limits
  52. Fermi trigger No 697403223: Global MASTER-Net observations report
  53. Fermi trigger No 697396830: Global MASTER-Net observations report
  54. GRB 230205A: Swift/UVOT Upper Limits
  55. GRB 230204B: Swift-XRT afterglow detection
  56. GRB 230205A: OHP/T193 optical observations
  57. GRB 230204B: VLT/X-shooter redshift
  58. GRB 230204B: ATLAS detection of the optical afterglow and a projected location in a nearby galaxy group
  59. GRB 230204B: Swift ToO observations
  60. GRB 230204B: Detection by GRBAlpha
  61. GRB 230204B: GIT discovery of the likely optical afterglow
  62. GRB 230204B: Swift/BAT-GUANO detection outside the coded FOV
  63. GRB 230204A: Swift/UVOT Upper Limits
  64. GRB 230204A/Swift J1552.8-5055: LCOGT Optical Counterpart Candidate
  65. Fermi trigger No 697208885: Global MASTER-Net observations report
  66. GRB 230204A: Swift detection of a possible burst (or possible transient Swift J1552.8-5055)
  67. Fermi trigger No 697098930: Global MASTER-Net observations report
  68. ZTF23aabmzlp/AT2023azs: Lulin 1m LOT optical observations
  69. ZTF23aabmzlp/AT2023azs: VLA radio detection
  70. ZTF23aaarlti/AT2023avj: AMI-LA radio detection
  71. ZTF23aabmzlp/AT2023azs: AMI-LA radio upper limit
  72. IceCube Alert 230201.26: Global MASTER-Net observations report
  73. Fermi GRB 230201B: Global MASTER-Net observations report
  74. Fermi-LAT gamma-ray observations of IceCube-230201A
  75. Fermi GRB 230201A: Global MASTER-Net observations report
  76. GRB 221009A: radio afterglow detection with the EVN
  77. ZTF23aabmzlp/AT2023azs: LCOGT Optical Detection
  78. ZTF23aaarlti/AT2023avj: Assy continued optical observations
  79. ZTF23aabmzlp/AT2023azs: Mondy and AbAO optical observations
  80. AT2023avj: X-ray Detection with Swift/XRT
  81. ZTF23aabmzlp/AT2023azs: 1.3m DFOT optical observations
  82. ZTF23aaarlti/AT2023avj: VLA radio detection
  83. ZTF23aabmzlp/AT2023azs: GIT confirmation of the likely afterglow
  84. ZTF23aabmzlp/AT2023azs: Zwicky Transient Facility discovery of a fast optical transient
  85. AT2023avj ZTF Candidate: Assy optical observations
  86. ZTF and LT Observations of AT2023avj, a Candidate Optical Afterglow
  87. Swift-XRT observations of NuEm-230125A
  88. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-230125A
  89. GRB 230124A: Swift/BAT-GUANO detection outside the coded FOV
  90. Fermi GRB 230124A: Global MASTER-Net observations report
  91. GRB 230122A: Swift/BAT-GUANO detection
  92. Fermi-LAT gamma-ray observations of IceCube-230122A
  93. GRB 230123A: Swift/UVOT Upper Limits
  94. GRB 230123A: Zadko observatory - Gingin optical observations
  95. GRB 230116C: Swift-XRT observations
  96. IceCube Alert 230122.16: Global MASTER-Net observations report
  97. Fermi GRB 230118A: Global MASTER-Net observations report
  98. GRB 230116D: SAO RAS further observations
  99. GRB 230116D: SAO RAS photometry
  100. GRB 230116D: KGO RC-25 optical observations

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