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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"

22060 results found.

  1. GRB 230307A: ATLAS information on the ULTRACAM optical afterglow candidate
  2. GRB 230307A: Erratum of the GCN 33441
  3. GRB 230204B: MASTER detection of an object near NTT Optical Afterglow Candidate
  4. GRB 230307A: Possible optical afterglow
  5. GRB 230228A: NUTTelA-TAO / BSTI Optical Limits
  6. GRB 230217A: ATCA rapid-response radio detection
  7. GRB 230307A: Swift/BAT upper limits on the early afterglow
  8. GRB 230307A: Swift-XRT observations
  9. Fermi GRB 230307A: Global MASTER-Net observations report
  10. Konus-Wind detection of GRB 230307A
  11. Fermi GRB 230308A: Global MASTER-Net observations report
  12. GRB 230307A: Tiled Swift observations
  13. Fermi-LAT gamma-ray observations of IceCube-230306A
  14. GRB 230307A: GECAM detection of an extremely bright burst
  15. Fermi trigger No 699811746: Global MASTER-Net observations report
  16. IceCube Alert 230306.46: Global MASTER-Net observations report
  17. GRB 230228A: 6 GHz VLA radio upper limit
  18. GRB 230228A: Swift/UVOT Upper Limits
  19. Fermi GRB 230301B: Global MASTER-Net observations report
  20. Fermi trigger No 699294715: Global MASTER-Net observations report
  21. Fermi trigger No 699311646: Global MASTER-Net observations report
  22. GRB 230228A: Mondy optical upper limit
  23. Fermi GRB 230227A: Global MASTER-Net observations report
  24. Fermi trigger No 699029364: Global MASTER-Net observations report
  25. GRB 230217A: VLT/FORS2 optical observations and candidate counterpart
  26. GRB 230216A Mondy Observations
  27. GRB 230205A: VLA radio afterglow confirmation
  28. GRB 230217A: Swift/UVOT Upper Limits
  29. GRB 230216A: Swift/UVOT Upper Limits
  30. GRB 230217A: Continued Gemini Observations
  31. GRB 230217A: Swift-XRT afterglow detection
  32. Fermi-LAT gamma-ray observations of IceCube-230220A
  33. Fermi GRB 230220B: Global MASTER-Net observations report
  34. GRB 230217A: Gemini South optical upper limits
  35. GRB 230217A: 6 GHz VLA observations
  36. GRB 230217A: Gemini-South Optical Observation
  37. IceCube-230217A: BOOTES-4/MET Optical Observations
  38. Fermi-LAT gamma-ray observations of IceCube-230217A
  39. GRB 230217A: Swift-XRT observations
  40. Fermi trigger No 698427992: Global MASTER-Net observations report
  41. IceCube Alert 230217.87: Global MASTER-Net observations report
  42. GRB 230205A: Lowell Discovery Telescope Observations
  43. GRB 230204B: Lowell Discovery Telescope Observations
  44. Swift GRB 230216A: Global MASTER-Net observations report
  45. GRB 230216A: Zadko observatory - Gingin optical observations
  46. Fermi GRB 230215A: Global MASTER-Net observations report
  47. GRB 230204B: ATCA radio detection
  48. Fermi trigger No 697926015: Global MASTER-Net observations report
  49. Fermi trigger No 697904388: Global MASTER-Net observations report
  50. GRB 230209B: Swift/BAT-GUANO detection outside the coded FOV
  51. Fermi trigger No 697678542: Global MASTER-Net observations report
  52. Fermi GRB 230209B: Global MASTER-Net observations report
  53. GRB 230205A: 6 GHz VLA observations
  54. GRB 221009A: Continued Swift Observations
  55. GRB 230205A: possible host galaxy detection with the Schmidt - Asiago telescope
  56. GRB 230204B: MASTER early OT detection
  57. GRB 230207B: Swift/BAT-GUANO detection outside the coded FOV
  58. ZTF23aabmzlp/AT2023azs: Neil Gehrels Swift Observatory X-ray observations
  59. Fermi GRB 230207A: Global MASTER-Net observations report
  60. GRB 230204B: Swift/UVOT Upper Limits
  61. Fermi trigger No 697403223: Global MASTER-Net observations report
  62. Fermi trigger No 697396830: Global MASTER-Net observations report
  63. GRB 230205A: Swift/UVOT Upper Limits
  64. GRB 230204B: Swift-XRT afterglow detection
  65. GRB 230205A: OHP/T193 optical observations
  66. GRB 230204B: VLT/X-shooter redshift
  67. GRB 230204B: ATLAS detection of the optical afterglow and a projected location in a nearby galaxy group
  68. GRB 230204B: Swift ToO observations
  69. GRB 230204B: Detection by GRBAlpha
  70. GRB 230204B: GIT discovery of the likely optical afterglow
  71. GRB 230204B: Swift/BAT-GUANO detection outside the coded FOV
  72. GRB 230204A: Swift/UVOT Upper Limits
  73. GRB 230204A/Swift J1552.8-5055: LCOGT Optical Counterpart Candidate
  74. Fermi trigger No 697208885: Global MASTER-Net observations report
  75. GRB 230204A: Swift detection of a possible burst (or possible transient Swift J1552.8-5055)
  76. Fermi trigger No 697098930: Global MASTER-Net observations report
  77. ZTF23aabmzlp/AT2023azs: Lulin 1m LOT optical observations
  78. ZTF23aabmzlp/AT2023azs: VLA radio detection
  79. ZTF23aaarlti/AT2023avj: AMI-LA radio detection
  80. ZTF23aabmzlp/AT2023azs: AMI-LA radio upper limit
  81. IceCube Alert 230201.26: Global MASTER-Net observations report
  82. Fermi GRB 230201B: Global MASTER-Net observations report
  83. Fermi-LAT gamma-ray observations of IceCube-230201A
  84. Fermi GRB 230201A: Global MASTER-Net observations report
  85. GRB 221009A: radio afterglow detection with the EVN
  86. ZTF23aabmzlp/AT2023azs: LCOGT Optical Detection
  87. ZTF23aaarlti/AT2023avj: Assy continued optical observations
  88. ZTF23aabmzlp/AT2023azs: Mondy and AbAO optical observations
  89. AT2023avj: X-ray Detection with Swift/XRT
  90. ZTF23aabmzlp/AT2023azs: 1.3m DFOT optical observations
  91. ZTF23aaarlti/AT2023avj: VLA radio detection
  92. ZTF23aabmzlp/AT2023azs: GIT confirmation of the likely afterglow
  93. ZTF23aabmzlp/AT2023azs: Zwicky Transient Facility discovery of a fast optical transient
  94. AT2023avj ZTF Candidate: Assy optical observations
  95. ZTF and LT Observations of AT2023avj, a Candidate Optical Afterglow
  96. Swift-XRT observations of NuEm-230125A
  97. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-230125A
  98. GRB 230124A: Swift/BAT-GUANO detection outside the coded FOV
  99. Fermi GRB 230124A: Global MASTER-Net observations report
  100. GRB 230122A: Swift/BAT-GUANO detection

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