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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"

24375 results found.

  1. GRB 250515A/GOTO25cqo: SVOM/VT optical blue color
  2. GRB 250516A: Fermi GBM Observation
  3. GRB 250516A: Swift-XRT refined Analysis
  4. GRB 250516B: GECAM-B detection of a bright long burst
  5. GRB 250516A: Fermi GBM Final Real-time Localization
  6. GRB 250512B / EP250512a: SVOM/GRM analysis
  7. GRB 250515A: GOTO candidate optical counterpart
  8. MAXI GRB250515.65: Global MASTER-Net observations report
  9. GRB 250515A: Fermi GBM Final Localization
  10. Konus-Wind detection of GRB 250512B / EP250512a
  11. Fermi trigger No 768922089: Global MASTER-Net observations report
  12. GRB 250509A: Swift-BAT refined analysis
  13. LIGO/Virgo/KAGRA S250328ae: DECam DESGW Candidates (Final Epochs)
  14. Fermi GRB 250512A: Global MASTER-Net observations report
  15. Konus-Wind detection of GRB 250506A
  16. EP250512a/GRB 250512B: REM optical/NIR observations
  17. EP250512a/GRB 250512B refined analysis of the EP-WXT and EP-FXT observations
  18. EP250512a: Global MASTER-Net observations report
  19. EP250511a: FTW optical and NIR observations
  20. GRB 250512B/EP250512a: SVOM/VT optical fading
  21. GRB 250512B/EP250512a:SVOM/VT bright optical counterpart
  22. EP250511a: Mephisto optical upper limits
  23. GRB 250507B: GRBAlpha detection
  24. GRB 250506A: GRBAlpha detection
  25. GRB 250512B: SVOM detection of a burst
  26. GRB 250507B: SVOM/GRM observation of a burst
  27. GRB 250512A: Fermi GBM Final Real-time Localization
  28. EP250511a: REM optical/NIR observations
  29. EP250511a: SVOM/VT optical candidate comfirmation
  30. EP250511a: Global MASTER-Net observations report
  31. GRB 250510B: Fermi GBM Observation
  32. Fermi GRB 250510C: Global MASTER-Net observations report
  33. Fermi GRB 250510B: Global MASTER-Net observations report
  34. GRB 250510C: Fermi GBM Final Real-time Localization
  35. GRB 250509A: Fermi GBM Observation
  36. IceCube-250506A: No Transient Candidates from the Zwicky Transient Facility
  37. GRB 250510A: follow-up observation with EP-FXT
  38. GRB 250510B: Swift/BAT-GUANO localization skymap of a burst
  39. GRB 250510B: Fermi GBM Final Localization
  40. GRB 250510A: SVOM possible detection of a burst
  41. EP250508a: SVOM/VT optical candidate fading
  42. Fermi GRB 250509A: Global MASTER-Net observations report
  43. Swift GRB 250509A: Global MASTER-Net observations report
  44. GRB 250509A: Swift detection of a burst
  45. GRB 250509A: Fermi GBM Final Real-time Localization
  46. EP250508a: follow-up observation with EP-FXT
  47. EP250508a: SVOM/VT optical candidate
  48. GRB 250507A: KAIT optical upper limit
  49. GRB 250505B: SVOM/GRM observation of a short burst
  50. GRB 250502A: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  51. GRB 250506A: GECAM detection
  52. EP250508a: REM optical/NIR observations
  53. GRB 250506A: Swift-XRT afterglow detection
  54. EP250508a: Global MASTER-Net observations report
  55. GRB 250506A: SVOM/VT optical upper limit
  56. GRB 250507A: Swift-XRT refined Analysis
  57. IceCube-250506A: Upper limits from a search for additional neutrino events in IceCube
  58. GRB 250427B : SVOM detection of a burst through offline search
  59. GRB 250507A: refined SVOM/MXT data analysis
  60. GRB 250507A: REM optical/NIR observations
  61. GRB 250507A: SVOM/VT optical upper limit
  62. GRB 250506A: Swift-XRT observations
  63. Fermi-LAT Gamma-ray Observations of IceCube-250506A
  64. GRB 250507A: SVOM detection of a long burst
  65. GRB 250506A: Mephisto optical upper limits
  66. GRB 250504A: EIRSAT-1 GMOD Detection
  67. IceCube-250506A - IceCube observation of a high-energy neutrino candidate track-like event
  68. IceCube Alert 250506.59: Global MASTER-Net observations report
  69. GRB 250430A: Konus-Wind detection and joint Konus-Wind+Swift-BAT spectral analysis
  70. GRB 250506A: SVOM improved position and MXT detection of a fading X-ray afterglow
  71. GRB 250506A: REM optical/NIR upper limits
  72. GRB 250506A: Fermi GBM Observation
  73. GRB 250506A: TRT optical observations
  74. GRB 250506A: SVOM detection of a burst
  75. GRB 250504A: Swift-BAT refined analysis
  76. GRB 250430A: Swift-BAT refined analysis
  77. GRB 250506A: Fermi GBM Final Real-time Localization
  78. Fermi GRB 250505A: Global MASTER-Net observations report
  79. GRB 250504A: REM optical/NIR observations
  80. GRB 250502A: REM optical/NIR observations
  81. GRB 250505A: Fermi GBM Final Real-time Localization
  82. GRB 250504A: Fermi GBM Observation
  83. Fermi GRB 250504A: Global MASTER-Net observations report
  84. GRB 250504A: Fermi GBM Final Real-time Localization
  85. Swift GRB250504.98: Global MASTER-Net observations report
  86. GRB 250502A: Montarrenti Observatory optical detection
  87. GRB 250502A: Swift-XRT afterglow detection
  88. Fermi trigger No 767975731: Global MASTER-Net observations report
  89. GRB 250502A: NOT optical observations
  90. GRB 250502A: LCO optical counterpart detection
  91. GRB 250502C: Fermi GBM Final Localization
  92. GRB 250407A: VZLUSAT-2 detection
  93. Fermi-LAT Gamma-ray Observations of IceCube-250429A
  94. Fermi GRB 250502B: Global MASTER-Net observations report
  95. GRB 250430A: Optical Observations via Virtual Telescope Project, Italy
  96. GRB 250502B: Fermi GBM Final Real-time Localization
  97. GRB 250502A: SVOM detection of a burst
  98. GRB 250430A: SVOM/VT optical observations
  99. GRB 250430A: KAIT optical observations
  100. GRB 250430A: NUTTelA-TAO Early Measurements

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