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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"

27183 results found.

  1. GRB 250520A: GOTO optical upper limit
  2. GRB 250520A: Swift detection of a burst
  3. Swift GRB 250520A: Global MASTER-Net observations report
  4. GRB 250516A: Swift-BAT refined analysis
  5. GRB 250516A: COLIBRÍ optical upper limit
  6. EP-WXT trigger (ID: 01709176312): a new X-ray outburst of HMXB RX J0111.2-7317
  7. Fermi GRB 250516A: Global MASTER-Net observations report
  8. GRB 250515A: NOT classification of GOTO25cqo as a type-Ia SN
  9. Fermi Gamma-ray Burst Monitor trigger 769160489/250517320 is not a GRB
  10. GRB 250515A:COLIBRÍ optical observations of the GOTO candidate
  11. Swift GRB 250516A: Global MASTER-Net observations report
  12. GRB 250515A/GOTO25cqo: SVOM/VT optical blue color
  13. GRB 250516A: Fermi GBM Observation
  14. GRB 250516A: Swift-XRT refined Analysis
  15. GRB 250516A: Swift/UVOT Detection
  16. GRB 250516B: GECAM-B detection of a bright long burst
  17. GRB 250516A: Swift detection of a burst
  18. GRB 250516A: Fermi GBM Final Real-time Localization
  19. GRB 250512B / EP250512a: SVOM/GRM analysis
  20. GRB 250515A: GOTO candidate optical counterpart
  21. MAXI GRB250515.65: Global MASTER-Net observations report
  22. GRB 250515A: Fermi GBM Final Localization
  23. GRB 250424A: COLIBRÍ detection of the associated supernova
  24. GRB 250502A: TESS observations
  25. Fermi trigger No 768922089: Global MASTER-Net observations report
  26. GRB 250511A: GECAM-A detection of a short burst
  27. GRB 250509A: Swift-BAT refined analysis
  28. Fermi GRB 250512A: Global MASTER-Net observations report
  29. EP250512a/GRB 250512B: REM optical/NIR observations
  30. EP250511a: Koshka Zeiss-1000 Optical Upper Limit
  31. EP250511a: Gemini optical counterpart observation
  32. EP250512a/GRB 250512B refined analysis of the EP-WXT and EP-FXT observations
  33. EP250512a/GRB 250512B: FTW optical and NIR observations of the counterpart
  34. EP250512a: Global MASTER-Net observations report
  35. EP250511a: FTW optical and NIR observations
  36. GRB 250512B/EP250512a: SVOM/VT optical fading
  37. GRB 250512B/EP250512a：SVOM/VT bright optical counterpart
  38. EP250511a: Mephisto optical upper limits
  39. GRB 250507B: GRBAlpha detection
  40. GRB 250512B: SVOM detection of a burst
  41. GRB 250507B: SVOM/GRM observation of a burst
  42. EP250512a: Einstein Probe detection of an X-ray transient
  43. GRB 250512A: Fermi GBM Final Real-time Localization
  44. EP250511a: REM optical/NIR observations
  45. EP250511a: Einstein Probe follow-up obsevation and refined analysis
  46. EP250511a: SVOM/VT optical candidate comfirmation
  47. EP250511a: Global MASTER-Net observations report
  48. EP250511a: COLIBRÍ optical counterpart candidate
  49. EP250511a: Einstein Probe detection of an X-ray transient
  50. EP250508a: Gemini NIR upper limits
  51. GRB 250510B: Fermi GBM Observation
  52. Fermi GRB 250510C: Global MASTER-Net observations report
  53. Fermi GRB 250510B: Global MASTER-Net observations report
  54. GRB 250510C: Fermi GBM Final Real-time Localization
  55. GRB 250510A: Swift-XRT observations
  56. GRB 250509A: Fermi GBM Observation
  57. GRB 250510A: follow-up observation with EP-FXT
  58. GRB 250510B: Swift/BAT-GUANO localization skymap of a burst
  59. GRB 250510B: Fermi GBM Final Localization
  60. GRB 250510A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  61. GRB 250509A: Swift-XRT refined Analysis
  62. GRB 250510A: SVOM possible detection of a burst
  63. EP250508a: SVOM/VT optical candidate fading
  64. Fermi GRB 250509A: Global MASTER-Net observations report
  65. Swift GRB 250509A: Global MASTER-Net observations report
  66. GRB 250509A: Swift detection of a burst
  67. GRB 250509A: Fermi GBM Final Real-time Localization
  68. GRB 250506A: NOT optical upper limits
  69. EP250508a: follow-up observation with EP-FXT
  70. EP250508a: SVOM/VT optical candidate
  71. EP250508a: refined analysis of the EP-WXT and EP-FXT observations
  72. GRB 250505B: SVOM/GRM observation of a short burst
  73. GRB 250506A: GECAM detection
  74. EP250508a: REM optical/NIR observations
  75. EP250508a: Global MASTER-Net observations report
  76. GRB 250506A: SVOM/VT optical upper limit
  77. EP250508a: COLIBRÍ Optical Limit
  78. EP250508a: Einstein Probe detection of an X-ray transient
  79. GRB 250507A: Swift-XRT refined Analysis
  80. GRB 250427B : SVOM detection of a burst through offline search
  81. GRB 250507A: follow-up observation with EP-FXT
  82. EP#01709175213/IGR J19566+0326: Swift-XRT detection
  83. GRB 250506A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  84. GRB 250507A: refined SVOM/MXT data analysis
  85. GRB 250507A: REM optical/NIR observations
  86. GRB 250507A: SVOM/VT optical upper limit
  87. GRB 250507A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  88. EP-WXT trigger 01709175213: a new X-ray outburst of LMXB MAXI J1957+032
  89. GRB 250507A: SVOM detection of a long burst
  90. GRB 250506A: Mephisto optical upper limits
  91. GRB 250502A: Bassano Bresciano Observatory upper limit
  92. IceCube Alert 250506.59: Global MASTER-Net observations report
  93. GRB 250506A: Xinglong 2.16m optical upper limit
  94. SVOM/sb25050601: EP-FXT observations
  95. GRB 250506A: SVOM improved position and MXT detection of a fading X-ray afterglow
  96. GRB 250506A: REM optical/NIR upper limits
  97. GRB 250506A: Fermi GBM Observation
  98. GRB 250506A: Swift XRT observations and possible counterpart detection
  99. GRB 250506A: TRT optical observations
  100. GRB 250506A: SVOM/COLIBRÍ (FM-GFT) Upper Limits on the Optical Counterpart

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