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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"

12335 results found.

  1. GRB 251003A: Mondy optical upper limit
  2. Fermi GRB 251013A: Global MASTER-Net observations report
  3. GRB 251011B: Swift/UVOT Upper Limits
  4. Fermi GRB 251011A: Global MASTER-Net observations report
  5. GRB 251007B: Swift/UVOT Upper Limits
  6. EP251006a: Global MASTER-Net observations report
  7. IceCube Alert 251008A: Global MASTER-Net observations report
  8. GRB 251007B: COLIBRÍ optical upper limit
  9. GRB 250917B: iTelescope T-26 upper limit
  10. EP250911a: Koshka Zeiss-1000 Optical Upper Limit
  11. GRB 251007A: AKO Optical Upper Limit
  12. GRB 251005C: PRIME J-band upper limit
  13. Swift GRB 251007B: Global MASTER-Net observations report
  14. GRB 251007B: SVOM/C-GFT upper limit
  15. Swift GRB 251007A: Global MASTER-Net observations report
  16. GRB 250702B/EP250702a: JWST/NIRCam Observations
  17. GRB 251006B: COLIBRÍ optical upper limit
  18. Fermi GRB 251006B: Global MASTER-Net observations report
  19. Fermi GRB 251006A: Global MASTER-Net observations report
  20. GRB 251005C: Swift/UVOT Upper Limits
  21. Swift GRB 251005A: Global MASTER-Net observations report
  22. GRB 251005C: GOTO optical upper limits
  23. Fermi trigger No 781367244: Global MASTER-Net observations report
  24. GRB 251005C: Swift detection of a burst
  25. GRB 251002A: NIR observations with WINTER
  26. GRB 251001B: NIR observations with WINTER
  27. GRB 251003A: Swift/UVOT Upper Limits
  28. EP250821a: iTelescope T-59 possible detection of the optical counterpart
  29. GRB 251002A: Swift-XRT afterglow detection
  30. GRB 251001B: AbAO optical upper limit
  31. GRB 251003A: Swift detection of a burst
  32. Swift GRB251003A: Global MASTER-Net observations report
  33. Fermi GRB 251002A: Global MASTER-Net observations report
  34. Swift GRB 251001B: Global MASTER-Net observations report
  35. Fermi GRB 250929A: Global MASTER-Net observations report
  36. Fermi-LAT Gamma-ray Observations of IceCube-250926A
  37. IceCube-250926A: Upper limits from a search for additional neutrino events in IceCube
  38. Fermi trigger No 780609036: Global MASTER-Net observations report
  39. IceCube Alert 250926.52: Global MASTER-Net observations report
  40. GRB 250925A: Swift/UVOT Upper Limits
  41. GRB 250925A: COLIBRÍ photometric redshift
  42. GRB 250925A: SVOM/GWAC-F60A upper limit
  43. GRB 250925A : MITSuME Akeno optical upper limits
  44. Fermi GRB 250926A: Global MASTER-Net observations report
  45. GRB 250925A: Leavitt Observatory optical upper limit
  46. GRB 250925A: GROWTH-India Telescope Upper Limits
  47. Swift GRB 250925A: Global MASTER-Net observations report
  48. GRB 250924A: 1.6m Mephisto optical upper limits
  49. GRB 250924A: Swift/UVOT Detection
  50. GRB 250924A: GROWTH-India Telescope Upper Limits
  51. Swift GRB 250924A: Global MASTER-Net observations report
  52. GRB 250920B: AbAO optical upper limits
  53. Konus-Wind detection of GRB 250920C
  54. EP250911a: e-MERLIN radio observations
  55. Fermi GRB 250922B: Global MASTER-Net observations report
  56. GRB 250920C: NIR observations with WINTER
  57. GRB 250920B: NIR observations with WINTER
  58. Fermi trigger No 780156732: Global MASTER-Net observations report
  59. GRB 250916A: Swift/UVOT Detection
  60. GRB 250920B: Kitab-ISON optical upper limit
  61. GRB 250917B: KAIT optical upper limit
  62. GRB 250920C: Swift/UVOT Detection
  63. Swift GRB 250920C: Global MASTER-Net observations report
  64. GRB 250920B: Swift/UVOT Detection
  65. LIGO/Virgo/KAGRA S250920bq: Coverage and upper limits from MAXI/GSC observations
  66. Swift GRB 250920B: Global MASTER-Net observations report
  67. Fermi GRB 250918A: Global MASTER-Net observations report
  68. GRB 250919A: Swift-XRT afterglow detection
  69. EP250919a: Global MASTER-Net observations report
  70. Fermi GRB 250919A: Global MASTER-Net observations report
  71. GRB 250917B: Swift/UVOT Upper Limits
  72. GRB 250916A: Swift-XRT observations
  73. GRB 250917B: Swift-XRT observations
  74. Fermi GRB 250917B: Global MASTER-Net observations report
  75. GRB 250917B: Swift detection of a short burst
  76. GRB 250916A: GOTO optical counterpart candidate
  77. Fermi GRB 250916A: Global MASTER-Net observations report
  78. GRB 250912A: Swift-XRT observations
  79. GRB 250912A: VLT observations
  80. GRB 250912A:SVOM/VT optical upper limit
  81. GRB 250912A: LCO optical upper limit
  82. Fermi GRB 250912A: Global MASTER-Net observations report
  83. EP250911a: Global MASTER-Net observations report
  84. IceCube-Cascade 250911A: Upper limits from a search for additional neutrino events in IceCube
  85. EP250911a: Upper limit from Fermi-GBM Observations
  86. EP250911a: Swift-XRT observations
  87. GRB 250911A: Swift/UVOT Detection
  88. Fermi GRB 250910B: Global MASTER-Net observations report
  89. EP250910a: Global MASTER-Net observations report
  90. GRB 250910A: SVOM/VT optical upper limit
  91. GRB 250910A: LCO optical upper limit
  92. EP#01709240653: Swift-XRT observations
  93. EP250908c: Global MASTER-Net observations report
  94. Fermi GRB 250909A: Global MASTER-Net observations report
  95. Fermi-LAT Gamma-ray Observations of IceCube-250905A
  96. IceCube-250905A: Upper limits from a search for additional neutrino events in IceCube
  97. EP250905a: Liverpool Telescope i-band upper limits
  98. EP250905a: Liverpool Telescope observations
  99. EP250905b: Global MASTER-Net observations report
  100. IceCube Alert 250905.84: Global MASTER-Net observations report

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