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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"

12390 results found.

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

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