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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

12391 results found.

  1. GRB 250925A: Leavitt Observatory optical upper limit
  2. GRB 250925A: GROWTH-India Telescope Upper Limits
  3. Swift GRB 250925A: Global MASTER-Net observations report
  4. GRB 250924A: 1.6m Mephisto optical upper limits
  5. GRB 250924A: Swift/UVOT Detection
  6. GRB 250924A: GROWTH-India Telescope Upper Limits
  7. Swift GRB 250924A: Global MASTER-Net observations report
  8. GRB 250920B: AbAO optical upper limits
  9. Konus-Wind detection of GRB 250920C
  10. EP250911a: e-MERLIN radio observations
  11. Fermi GRB 250922B: Global MASTER-Net observations report
  12. GRB 250920C: NIR observations with WINTER
  13. GRB 250920B: NIR observations with WINTER
  14. Fermi trigger No 780156732: Global MASTER-Net observations report
  15. GRB 250916A: Swift/UVOT Detection
  16. GRB 250920B: Kitab-ISON optical upper limit
  17. GRB 250917B: KAIT optical upper limit
  18. GRB 250920C: Swift/UVOT Detection
  19. Swift GRB 250920C: Global MASTER-Net observations report
  20. GRB 250920B: Swift/UVOT Detection
  21. LIGO/Virgo/KAGRA S250920bq: Coverage and upper limits from MAXI/GSC observations
  22. Swift GRB 250920B: Global MASTER-Net observations report
  23. Fermi GRB 250918A: Global MASTER-Net observations report
  24. GRB 250919A: Swift-XRT afterglow detection
  25. EP250919a: Global MASTER-Net observations report
  26. Fermi GRB 250919A: Global MASTER-Net observations report
  27. GRB 250917B: Swift/UVOT Upper Limits
  28. GRB 250916A: Swift-XRT observations
  29. GRB 250917B: Swift-XRT observations
  30. Fermi GRB 250917B: Global MASTER-Net observations report
  31. GRB 250917B: Swift detection of a short burst
  32. GRB 250916A: GOTO optical counterpart candidate
  33. Fermi GRB 250916A: Global MASTER-Net observations report
  34. GRB 250912A: Swift-XRT observations
  35. GRB 250912A: VLT observations
  36. GRB 250912A:SVOM/VT optical upper limit
  37. GRB 250912A: LCO optical upper limit
  38. Fermi GRB 250912A: Global MASTER-Net observations report
  39. EP250911a: Global MASTER-Net observations report
  40. IceCube-Cascade 250911A: Upper limits from a search for additional neutrino events in IceCube
  41. EP250911a: Upper limit from Fermi-GBM Observations
  42. EP250911a: Swift-XRT observations
  43. GRB 250911A: Swift/UVOT Detection
  44. Fermi GRB 250910B: Global MASTER-Net observations report
  45. EP250910a: Global MASTER-Net observations report
  46. GRB 250910A: SVOM/VT optical upper limit
  47. GRB 250910A: LCO optical upper limit
  48. EP#01709240653: Swift-XRT observations
  49. EP250908c: Global MASTER-Net observations report
  50. Fermi GRB 250909A: Global MASTER-Net observations report
  51. Fermi-LAT Gamma-ray Observations of IceCube-250905A
  52. IceCube-250905A: Upper limits from a search for additional neutrino events in IceCube
  53. EP250905a: Liverpool Telescope i-band upper limits
  54. EP250905a: Liverpool Telescope observations
  55. EP250905b: Global MASTER-Net observations report
  56. IceCube Alert 250905.84: Global MASTER-Net observations report
  57. GRB 250905A: Swift/UVOT Upper Limits
  58. EP250905a: Global MASTER-Net observations report
  59. GRB250904A: Liverpool Telescope upper limits
  60. GRB 250904A: Swift/UVOT Detection
  61. GRB 250905A: KAIT optical upper limit
  62. Swift GRB250905.09: Global MASTER-Net observations report
  63. Swift GRB 250904A: Global MASTER-Net observations report
  64. IceCube-Cascade 250903A: Upper limits from a search for additional neutrino events in IceCube
  65. EP250827a and EP250827b: Upper limit from Fermi-GBM Observations
  66. GRB 250904A: Swift detection of a burst
  67. GRB 250903A: Swift-XRT observations
  68. EP250903a: Swift-XRT observations
  69. EP#01709201209: Swift-XRT observations
  70. EP-WXT trigger 01709201209: Liverpool Telescope upper limits
  71. GRB 250903A: VLT X-shooter spectroscopic redshift z = 1.590
  72. EP250903a: Global MASTER-Net observations report
  73. Fermi GRB 250902B: Global MASTER-Net observations report
  74. Fermi-LAT Gamma-ray Observations of IceCube-250831A
  75. GRB 250901A: Swift/UVOT Upper Limit
  76. IceCube-250831A: Upper limits from a search for additional neutrino events in IceCube
  77. IceCube-Cascade 250828A: Upper limits from a search for additional neutrino events in IceCube
  78. GRB 250901A: Swift-XRT afterglow detection
  79. EP250901a: Swift-XRT observations
  80. GRB 250901A: LCO optical upper limit
  81. EP250827b: Swift observations of AT 2025wkm
  82. EP250827b: Contemporaneous detection of EP X-ray flare EP250827b and ZTF transient ZTF25abmpngy/AT2025wkm
  83. EP250901a: Mephisto optical upper limits
  84. EP250901a: Global MASTER-Net observations report
  85. EP250831a: Swift-XRT observations
  86. LIGO/Virgo/KAGRA S250831cc: Coverage and upper limits from MAXI/GSC observations
  87. IceCube Alert 250831.75: Global MASTER-Net observations report
  88. EP250831a: Global MASTER-Net observations report
  89. GRB 250831A: Swift-XRT counterpart detection
  90. GRB 250831A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  91. GRB 250831A: SVOM/VT upper limit with VHF data
  92. GRB 250830B: Swift-XRT observations
  93. EP250830a: Global MASTER-Net observations report
  94. LIGO/Virgo/KAGRA S250830bp: Coverage and upper limits from MAXI/GSC observations
  95. EP-WXT trigger 01709200994: Liverpool Telescope upper limits
  96. GRB 250830B: MAXI/GSC detection
  97. GRB 250830A / MAXI J0853+337: MAXI/GSC detection
  98. EP250821a: SOAR observations
  99. EP250828a: Liverpool Telescope upper limits
  100. Swift GRB 250828B: Global MASTER-Net observations report

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