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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"

24373 results found.

  1. GRB 250516A: Swift-XRT refined Analysis
  2. GRB 250516B: GECAM-B detection of a bright long burst
  3. GRB 250516A: Fermi GBM Final Real-time Localization
  4. GRB 250512B / EP250512a: SVOM/GRM analysis
  5. GRB 250515A: GOTO candidate optical counterpart
  6. MAXI GRB250515.65: Global MASTER-Net observations report
  7. GRB 250515A: Fermi GBM Final Localization
  8. Konus-Wind detection of GRB 250512B / EP250512a
  9. Fermi trigger No 768922089: Global MASTER-Net observations report
  10. GRB 250509A: Swift-BAT refined analysis
  11. LIGO/Virgo/KAGRA S250328ae: DECam DESGW Candidates (Final Epochs)
  12. Fermi GRB 250512A: Global MASTER-Net observations report
  13. Konus-Wind detection of GRB 250506A
  14. EP250512a/GRB 250512B: REM optical/NIR observations
  15. EP250512a/GRB 250512B refined analysis of the EP-WXT and EP-FXT observations
  16. EP250512a: Global MASTER-Net observations report
  17. EP250511a: FTW optical and NIR observations
  18. GRB 250512B/EP250512a: SVOM/VT optical fading
  19. GRB 250512B/EP250512a:SVOM/VT bright optical counterpart
  20. EP250511a: Mephisto optical upper limits
  21. GRB 250507B: GRBAlpha detection
  22. GRB 250506A: GRBAlpha detection
  23. GRB 250512B: SVOM detection of a burst
  24. GRB 250507B: SVOM/GRM observation of a burst
  25. GRB 250512A: Fermi GBM Final Real-time Localization
  26. EP250511a: REM optical/NIR observations
  27. EP250511a: SVOM/VT optical candidate comfirmation
  28. EP250511a: Global MASTER-Net observations report
  29. GRB 250510B: Fermi GBM Observation
  30. Fermi GRB 250510C: Global MASTER-Net observations report
  31. Fermi GRB 250510B: Global MASTER-Net observations report
  32. GRB 250510C: Fermi GBM Final Real-time Localization
  33. GRB 250509A: Fermi GBM Observation
  34. IceCube-250506A: No Transient Candidates from the Zwicky Transient Facility
  35. GRB 250510A: follow-up observation with EP-FXT
  36. GRB 250510B: Swift/BAT-GUANO localization skymap of a burst
  37. GRB 250510B: Fermi GBM Final Localization
  38. GRB 250510A: SVOM possible detection of a burst
  39. EP250508a: SVOM/VT optical candidate fading
  40. Fermi GRB 250509A: Global MASTER-Net observations report
  41. Swift GRB 250509A: Global MASTER-Net observations report
  42. GRB 250509A: Swift detection of a burst
  43. GRB 250509A: Fermi GBM Final Real-time Localization
  44. EP250508a: follow-up observation with EP-FXT
  45. EP250508a: SVOM/VT optical candidate
  46. GRB 250507A: KAIT optical upper limit
  47. GRB 250505B: SVOM/GRM observation of a short burst
  48. GRB 250502A: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  49. GRB 250506A: GECAM detection
  50. EP250508a: REM optical/NIR observations
  51. GRB 250506A: Swift-XRT afterglow detection
  52. EP250508a: Global MASTER-Net observations report
  53. GRB 250506A: SVOM/VT optical upper limit
  54. GRB 250507A: Swift-XRT refined Analysis
  55. IceCube-250506A: Upper limits from a search for additional neutrino events in IceCube
  56. GRB 250427B : SVOM detection of a burst through offline search
  57. GRB 250507A: refined SVOM/MXT data analysis
  58. GRB 250507A: REM optical/NIR observations
  59. GRB 250507A: SVOM/VT optical upper limit
  60. GRB 250506A: Swift-XRT observations
  61. Fermi-LAT Gamma-ray Observations of IceCube-250506A
  62. GRB 250507A: SVOM detection of a long burst
  63. GRB 250506A: Mephisto optical upper limits
  64. GRB 250504A: EIRSAT-1 GMOD Detection
  65. IceCube-250506A - IceCube observation of a high-energy neutrino candidate track-like event
  66. IceCube Alert 250506.59: Global MASTER-Net observations report
  67. GRB 250430A: Konus-Wind detection and joint Konus-Wind+Swift-BAT spectral analysis
  68. GRB 250506A: SVOM improved position and MXT detection of a fading X-ray afterglow
  69. GRB 250506A: REM optical/NIR upper limits
  70. GRB 250506A: Fermi GBM Observation
  71. GRB 250506A: TRT optical observations
  72. GRB 250506A: SVOM detection of a burst
  73. GRB 250504A: Swift-BAT refined analysis
  74. GRB 250430A: Swift-BAT refined analysis
  75. GRB 250506A: Fermi GBM Final Real-time Localization
  76. Fermi GRB 250505A: Global MASTER-Net observations report
  77. GRB 250504A: REM optical/NIR observations
  78. GRB 250502A: REM optical/NIR observations
  79. GRB 250505A: Fermi GBM Final Real-time Localization
  80. GRB 250504A: Fermi GBM Observation
  81. Fermi GRB 250504A: Global MASTER-Net observations report
  82. GRB 250504A: Fermi GBM Final Real-time Localization
  83. Swift GRB250504.98: Global MASTER-Net observations report
  84. GRB 250502A: Montarrenti Observatory optical detection
  85. GRB 250502A: Swift-XRT afterglow detection
  86. Fermi trigger No 767975731: Global MASTER-Net observations report
  87. GRB 250502A: NOT optical observations
  88. GRB 250502A: LCO optical counterpart detection
  89. GRB 250502C: Fermi GBM Final Localization
  90. GRB 250407A: VZLUSAT-2 detection
  91. Fermi-LAT Gamma-ray Observations of IceCube-250429A
  92. Fermi GRB 250502B: Global MASTER-Net observations report
  93. GRB 250430A: Optical Observations via Virtual Telescope Project, Italy
  94. GRB 250502B: Fermi GBM Final Real-time Localization
  95. GRB 250502A: SVOM detection of a burst
  96. GRB 250430A: SVOM/VT optical observations
  97. GRB 250430A: KAIT optical observations
  98. GRB 250430A: NUTTelA-TAO Early Measurements
  99. EP250427a / GRB 250427A: OHP/T193 photometric observations: third visit
  100. GRB 250430A: Leavitt Observatory optical upper limit

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