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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"

12334 results found.

  1. GRB 251106A: Swift-XRT afterglow detection
  2. GRB 251106A: Kilonova-Catcher optical upper limit
  3. GRB 251106A: MASTER optical observations
  4. Fermi trigger No 784034269: Global MASTER-Net observations report
  5. GRB 251104A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  6. GRB 251103B: Swift/UVOT Upper Limits
  7. Fermi GRB 251105A: Global MASTER-Net observations report
  8. GRB 251103A: Optical afterglow detection by ZTF’s public survey
  9. GRB 251103B: Nanshan/HMT optical upper limit
  10. GRB 251103B: MITSuME Akeno optical upper limits
  11. Fermi GRB 251103A: Global MASTER-Net observations report
  12. EP251102a: NIR observations with WINTER
  13. GRB 251103A: J-band detection with WINTER
  14. Swift GRB 251103B: Global MASTER-Net observations report
  15. GRB 251103B: GROWTH-India Telescope optical upper limits
  16. GRB 251103B: Swift detection of a burst
  17. GRB 251103A: Swift-XRT afterglow detection
  18. GRB 251025B: OHP/T193 optical upper limit
  19. Fermi GRB 251102A: Global MASTER-Net observations report
  20. GRB 251026B: LBT near-infrared observations
  21. Fermi GRB 251028B: Global MASTER-Net observations report
  22. GRB251026B: PRIME H-band upper limit
  23. GRB 251028A: MAXI/GSC detection
  24. IceCube-251025A: Upper limits from a search for additional neutrino events in IceCube
  25. GRB 251026B: Swift-XRT observations of GOTO25jgl/AT2025absf
  26. Fermi-LAT Gamma-ray Observations of IceCube-251025A
  27. GRB 251023B: Swift-UVOT Upper Limits
  28. GRB 251027A: Swift-XRT observations
  29. EP251027.145: COLIBRÍ optical upper limits
  30. GRB 251027A: LCO optical upper limit
  31. GRB 251027A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  32. GRB 251023B / EP251023b: Mondy optical upper limit
  33. GRB 251026A: Mondy optical upper limit
  34. GRB 251026B: Tentative GOTO optical counterpart candidate
  35. Fermi GRB 251026B: Global MASTER-Net observations report
  36. Fermi GRB 251025C: Global MASTER-Net observations report
  37. GRB 251026A: Swift-XRT observations
  38. GRB 251026A: SVOM/C-GFT upper limit
  39. IceCube-251025A: DDOTI Optical Upper Limit
  40. GRB 251026A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  41. GRB 251024A: Swift/UVOT Upper Limits
  42. GRB 251025B: Swift-XRT afterglow detection
  43. IceCube Alert 251025.57: Global MASTER-Net observations report
  44. GRB 251025A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  45. GRB 251025A: SVOM/VT VHF optical upper limit
  46. GRB 251024A: Swift detection of a burst
  47. Swift GRB 251024A: Global MASTER-Net observations report
  48. GRB 251022A: COLIBRÍ Further Multi-frequency Optical Observations
  49. GRB 251023B: OHP/T193 optical observations
  50. GRB 251022A: Swift-XRT detection of GOTO25iym
  51. EP251023b: Global MASTER-Net observations report
  52. EP251023a: Global MASTER-Net observations report
  53. EP#01709247298: Swift-XRT counterpart detection
  54. GRB 251023B / MAXI J0451+122: MAXI/GSC detection
  55. Fermi GRB 251023A: Global MASTER-Net observations report
  56. LAT GRB251022A: Global MASTER-Net observations report
  57. EP251021b: BOOTES-7 optical upper limit
  58. GRB 250911A: MAXI/GSC detection
  59. Fermi-LAT gamma-ray observations of IceCube-251018A
  60. GRB 251017A : RAPAS follow-up observations
  61. IceCube-251018A: Upper limits from a search for additional neutrino events in IceCube
  62. IceCube-251018A: DDOTI Optical Upper Limit
  63. Fermi trigger No 782500909: Global MASTER-Net observations report
  64. IceCube-251018A: Global MASTER-Net observations report
  65. GRB 251017A: Swift/UVOT Detection
  66. GRB 251016A: Swift/UVOT Detection
  67. Swift GRB 251018A: Global MASTER-Net observations report
  68. Fermi GRB 251016B: Global MASTER-Net observations report
  69. Swift GRB 251017A: Global MASTER-Net observations report
  70. GRB 251016A: BOOTES-6/DPRT optical upper limit
  71. sb25101602: Swift-XRT counterpart detection
  72. Fermi GRB 251016A: Global MASTER-Net observations report
  73. GRB 251014A: Swift-XRT observations
  74. GRB 251014B: PRIME J-band upper limit
  75. Upper limits from a search for additional neutrino events in IceCube
  76. IceCube Alert 251014.77: Global MASTER-Net observations report
  77. Swift GRB251015.60: Global MASTER-Net observations report
  78. Fermi-LAT Gamma-ray Observations of IceCube-251014A
  79. GRB 251013D: Swift/UVOT Observations
  80. GRB 251013C: Swift/UVOT Detection
  81. Konus-Wind detection of GRB 251007A
  82. GRB 251013D: Swift-XRT observations
  83. Swift Trigger 1404295: possible GRB 251015A
  84. GRB 251014B: Swift-XRT observations
  85. GRB 251014B: Swift/UVOT Upper Limits
  86. GRB 251014D: Swift/UVOT Upper Limits
  87. GRB 251014D: BOOTES-6/DPRT optical upper limit
  88. GRB 251011B: SVOM/VT optical upper limit
  89. GRB 251014D: Swift detection of a burst
  90. GRB 251014A: PRIME near-infrared upper limits
  91. GRB 251013D: LAST optical upper limit on Swift/BAT-GUANO localization
  92. GRB 251014A: DDOTI Upper Limit
  93. GRB 251014A: SAO RAS optical upper limit
  94. Swift GRB 251014A: Global MASTER-Net observations report
  95. Fermi trigger No 782044789: Global MASTER-Net observations report
  96. Fermi GRB 251013C: Global MASTER-Net observations report
  97. Fermi GRB 251013B: Global MASTER-Net observations report
  98. Fermi GRB 251013D: Global MASTER-Net observations report
  99. GRB 251013C: Swift-XRT counterpart detection
  100. GRB 251003A: Mondy optical upper limit

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