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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"

12320 results found.

  1. Swift GRB 260101A: Global MASTER-Net observations report
  2. SVOM GRB251231.57: Global MASTER-Net observations report
  3. GRB 251230A / EP251230a: SVOM/VT optical continued observations and upper limit
  4. GRB 251230A / EP251230a: further NOT optical observations revealing shallower decay or possible rebrightening
  5. GRB 251230A/EP251230a: Optical upper limit with Kinder observations
  6. EP251229a: Optical upper limit with Kinder observations
  7. GRB 251230A: 1.3m DFOT optical upper limit
  8. GRB251230A: 7DT optical upper limits
  9. GRB 251230A / EP251230a: NOT observations and spectroscopic redshift upper limit z < 2.2
  10. EP251229a: BOOTES-2 early optical upper limit
  11. GRB 251230A: GOTO optical upper limit
  12. EP251229a: NOT optical upper limits
  13. Swift GRB 251230A: Global MASTER-Net observations report
  14. EP251229a: Global MASTER-Net observations report
  15. Fermi GRB 251228A: Global MASTER-Net observations report
  16. SVOM GRB251227.07: Global MASTER-Net observations report
  17. IceCube-251225A: Upper limits from a search for additional neutrino events in IceCube
  18. IceCube Alert 251225.84: Global MASTER-Net observations report
  19. EP251222a: Optical upper limit with Kinder observations
  20. GRB 251129A / EP251129a: VLA detection of a radio counterpart
  21. EP251221a: PRIME upper limit
  22. EP251222a: Global MASTER-Net observations report
  23. EP251221a: Liverpool Telescope upper limits
  24. GRB 251222A: Swift-XRT afterglow detection
  25. EP251222a: GOTO optical upper limit
  26. GRB251221A: 7DT optical upper limits
  27. EP251221a: Global MASTER-Net observations report
  28. EP251221a: NOT optical upper limit
  29. IceCube-251218A: No Candidate Transients from the Zwicky Transient Facility
  30. SVOM GRB251222A: Global MASTER-Net observations report
  31. EP251220a: PRIME upper limit
  32. EP251220a: VLT/FORS2 spectroscopic redshift z = 2.375
  33. GRB 251221A: UAFO and Mondy optical upper limit
  34. GRB 251221A: Swift/UVOT Upper Limits
  35. EP251220a: COLIBRÍ confirmation of fading and photometric redshift upper limit of z < 3.4
  36. GRB 251221A: Swift detection of a burst
  37. Swift GRB251221A: Global MASTER-Net observations report
  38. EP251220a: Global MASTER-Net observations report
  39. SVOM GRB251220.98: Global MASTER-Net observations report
  40. Fermi-LAT Gamma-ray Observations of IceCube-251218A
  41. GRB 251220A: MAXI/GSC detection
  42. IceCube-251218A: Upper limits from a search for additional neutrino events in IceCube
  43. IceCube-251218A: COLIBRÍ optical upper limits
  44. SVOM GRB251219.11: Global MASTER-Net observations report
  45. IceCube Alert 251218.85: Global MASTER-Net observations report
  46. GRB 251214B: VIRT Optical Upper Limit
  47. Fermi trigger No 787736968: Global MASTER-Net observations report
  48. Fermi GRB 251217A: Global MASTER-Net observations report
  49. GRB 251215A: Swift/UVOT Upper LImits
  50. Fermi GRB 251216A: Global MASTER-Net observations report
  51. GRB 251202A/EP251202a: Koshka optical upper limit
  52. GRB 251214B: Mondy optical upper limit
  53. GRB 251215A: COLIBRÍ optical upper limit
  54. EP251214b: KAIT optical upper limit
  55. GRB 251215A: Swift-XRT observations
  56. Fermi GRB 251215A: Global MASTER-Net observations report
  57. EP251214a: Optical upper limit with Kinder observations
  58. GRB 251214B: 1.6m Mephisto observations with newly installed mosaic cameras
  59. GRB 251214B: UAFO optical upper limit
  60. EP251214b: Global MASTER-Net observations report
  61. EP251214a: KAIT optical upper limit
  62. GRB 251214B: Swift/UVOT Detection
  63. EP251214a: EP-FXT non-detection and upper limit
  64. EP251214a: Global MASTER-Net observations report
  65. Fermi trigger No 787396657: Global MASTER-Net observations report
  66. EP251214a: COLIBRÍ optical upper limit
  67. Swift GRB 251214B: Global MASTER-Net observations report
  68. EP251214.305: COLIBRÍ optical upper limit
  69. Fermi GRB 251214A: Global MASTER-Net observations report
  70. EP251212a: Global MASTER-Net observations report
  71. EP251212a: KAIT optical upper limit
  72. EP251212a : COLIBRÍ optical upper limit
  73. Fermi-LAT Gamma-ray Observations of IceCube-251210A
  74. IceCube-251210A: Upper limits from a search for additional neutrino events in IceCube
  75. Fermi GRB 251211B: Global MASTER-Net observations report
  76. IceCube-251210A: DDOTI Optical Upper Limit
  77. SVOM GRB251211.12: Global MASTER-Net observations report
  78. GRB 251205A: 1.3m DFOT optical upper limit
  79. IceCube Alert 251210.46: Global MASTER-Net observations report
  80. EP251124a: Mondy optical upper limit
  81. GRB 251208B: COLIBRÍ optical upper limits
  82. Fermi GRB 251209A: Global MASTER-Net observations report
  83. Fermi GRB 251208C: Global MASTER-Net observations report
  84. GRB 251206A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  85. GRB 251208D: LAST optical upper limit
  86. GRB 251208B: GROWTH-India Telescope optical upper limits
  87. GRB 251208D: Swift-XRT observations
  88. GRB 251129A: e-MERLIN C-band observations
  89. LAT GRB251208.43: Global MASTER-Net observations report
  90. GRB 251208D: LCO optical upper limits
  91. SVOM GRB251208D: Global MASTER-Net observations report
  92. SVOM GRB251206.86: Global MASTER-Net observations report
  93. GRB 251203C: Swift/UVOT Upper Limit
  94. Konus-Wind detection of GRB 251118A
  95. Swift GRB251205A: Global MASTER-Net observations report
  96. GRB 251203C: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  97. GRB 251201B: SALT spectroscopic redshift z = 1.599
  98. GRB 251203C: J-band observations with WINTER
  99. GRB 251203C: LCO optical afterglow confirmation
  100. GRB 251203B: Swift-XRT observations

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