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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"

39039 results found.

  1. GRB 250515A: 1.6m Mephisto optical detection
  2. GRB 250516A: AstroSat CZTI detection
  3. GRB 250515A/GOTO25cqo: SVOM/VT optical blue color
  4. GRB 250516A: Fermi GBM Observation
  5. GRB 250516A: Swift-XRT refined Analysis
  6. GRB 250516A: Swift/UVOT Detection
  7. GRB 250515A: Swift ToO observations
  8. GRB 250516B: GECAM-B detection of a bright long burst
  9. GRB 250516A: Enhanced Swift-XRT position
  10. GRB 250516A: Swift detection of a burst
  11. GRB 250516A: Fermi GBM Final Real-time Localization
  12. GRB 250512B / EP250512a: SVOM/GRM analysis
  13. GRB 250515A: GOTO candidate optical counterpart
  14. MAXI GRB250515.65: Global MASTER-Net observations report
  15. GRB 250515A: Fermi GBM Final Localization
  16. GRB 250424A: COLIBRÍ detection of the associated supernova
  17. Konus-Wind detection of GRB 250512B / EP250512a
  18. GRB 250502A: TESS observations
  19. Fermi trigger No 768922089: Global MASTER-Net observations report
  20. GRB 250511A: GECAM-A detection of a short burst
  21. GRB 250509A: Swift-BAT refined analysis
  22. Fermi GRB 250512A: Global MASTER-Net observations report
  23. Konus-Wind detection of GRB 250506A
  24. EP250512a/GRB 250512B: REM optical/NIR observations
  25. EP250511a: Koshka Zeiss-1000 Optical Upper Limit
  26. GRB 250507B: AstroSat CZTI detection
  27. EP250512a/GRB 250512B refined analysis of the EP-WXT and EP-FXT observations
  28. EP250512a/GRB 250512B: FTW optical and NIR observations of the counterpart
  29. EP250512a: Global MASTER-Net observations report
  30. GRB 250512B/EP250512a: SVOM/VT optical fading
  31. GRB 250512B/EP250512a:SVOM/VT bright optical counterpart
  32. EP250511a: Mephisto optical upper limits
  33. GRB 250507B: GRBAlpha detection
  34. GRB 250506A: GRBAlpha detection
  35. GRB 250512B: SVOM detection of a burst
  36. GRB 250507B: SVOM/GRM observation of a burst
  37. GRB 250512A: Fermi GBM Final Real-time Localization
  38. EP250511a: REM optical/NIR observations
  39. EP250511a: Global MASTER-Net observations report
  40. EP250511a: COLIBRÍ optical counterpart candidate
  41. GRB 250510B: Fermi GBM Observation
  42. Fermi GRB 250510C: Global MASTER-Net observations report
  43. Fermi GRB 250510B: Global MASTER-Net observations report
  44. GRB 250510C: Fermi GBM Final Real-time Localization
  45. GRB 250510A: Swift-XRT observations
  46. GRB 250509A: Fermi GBM Observation
  47. GRB 250510A: follow-up observation with EP-FXT
  48. GRB 250510B: Swift/BAT-GUANO localization skymap of a burst
  49. GRB 250510B: Fermi GBM Final Localization
  50. GRB 250510A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  51. GRB 250509A: Swift-XRT refined Analysis
  52. GRB 250510A: SVOM possible detection of a burst
  53. GRB 250507A: J-band observations with WINTER (duplicate submission)
  54. GRB 250507A: J-band observations with WINTER
  55. GRB 250509A: Enhanced Swift-XRT position
  56. GRB 250509A: Prompt enhanced Swift-XRT position
  57. Fermi GRB 250509A: Global MASTER-Net observations report
  58. Swift GRB 250509A: Global MASTER-Net observations report
  59. GRB 250509A: Swift detection of a burst
  60. GRB 250509A: Fermi GBM Final Real-time Localization
  61. GRB 250506A: NOT optical upper limits
  62. EP250508a: KAIT optical upper limit
  63. GRB 250507A: KAIT optical upper limit
  64. GRB 250505B: SVOM/GRM observation of a short burst
  65. GRB 250502A: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  66. GRB 250506A: GECAM detection
  67. EP250508a: REM optical/NIR observations
  68. GRB 250506A: Swift-XRT afterglow detection
  69. EP250508a: Global MASTER-Net observations report
  70. GRB 250506A: SVOM/VT optical upper limit
  71. EP250508a: COLIBRÍ Optical Limit
  72. GRB 250507A: Swift-XRT refined Analysis
  73. GRB 250506A: Swift/UVOT Upper Limits
  74. GRB 250427B : SVOM detection of a burst through offline search
  75. GRB 250507A: follow-up observation with EP-FXT
  76. GRB 250430A / EP250430a: AstroSat CZTI detection
  77. GRB 250506A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  78. GRB 250507A: refined SVOM/MXT data analysis
  79. GRB 250507A: REM optical/NIR observations
  80. GRB 250507A: SVOM/VT optical upper limit
  81. GRB 250506A: Swift-XRT observations
  82. GRB 250507A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  83. GRB 250507A: SVOM detection of a long burst
  84. GRB 250506A: Mephisto optical upper limits
  85. GRB 250504A: EIRSAT-1 GMOD Detection
  86. GRB 250506A: Swift ToO observations
  87. GRB 250502A: Bassano Bresciano Observatory upper limit
  88. IceCube-250506A - IceCube observation of a high-energy neutrino candidate track-like event
  89. IceCube Alert 250506.59: Global MASTER-Net observations report
  90. GRB 250430A: Konus-Wind detection and joint Konus-Wind+Swift-BAT spectral analysis
  91. GRB 250506A: Xinglong 2.16m optical upper limit
  92. GRB 250506A: SVOM improved position and MXT detection of a fading X-ray afterglow
  93. GRB 250506A: REM optical/NIR upper limits
  94. GRB 250506A: Fermi GBM Observation
  95. GRB 250506A: Swift XRT observations and possible counterpart detection
  96. GRB 250506A: TRT optical observations
  97. GRB 250506A: SVOM/COLIBRÍ (FM-GFT) Upper Limits on the Optical Counterpart
  98. GRB 250506A: SVOM detection of a burst
  99. GRB 250504A: Swift-BAT refined analysis
  100. GRB 250430A: Swift-BAT refined analysis

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