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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"

14825 results found.

  1. GRB 250516B: NuSTAR Detection of the Prompt Emission
  2. EP-WXT trigger (ID: 01709176312): a new X-ray outburst of HMXB RX J0111.2-7317
  3. GRB 250515A: 1.6m Mephisto optical detection
  4. GRB 250516A: AstroSat CZTI detection
  5. GRB 250516A: Swift/UVOT Detection
  6. GRB 250516B: GECAM-B detection of a bright long burst
  7. GRB 250516A: Swift detection of a burst
  8. GRB 250516A: Fermi GBM Final Real-time Localization
  9. GRB 250515A: Fermi GBM Final Localization
  10. GRB 250424A: COLIBRÍ detection of the associated supernova
  11. Konus-Wind detection of GRB 250512B / EP250512a
  12. GRB 250502A: TESS observations
  13. GRB 250511A: GECAM-A detection of a short burst
  14. LIGO/Virgo/KAGRA S250328ae: DECam DESGW Candidates (Final Epochs)
  15. Konus-Wind detection of GRB 250506A
  16. GRB 250507B: AstroSat CZTI detection
  17. GRB 250507B: GRBAlpha detection
  18. GRB 250506A: GRBAlpha detection
  19. GRB 250512B: SVOM detection of a burst
  20. EP250512a: Einstein Probe detection of an X-ray transient
  21. GRB 250512A: Fermi GBM Final Real-time Localization
  22. EP250511a: BOOTES-5 optical upper limit
  23. EP250511a: Einstein Probe detection of an X-ray transient
  24. GRB 250510C: Fermi GBM Final Real-time Localization
  25. GRB 250510A: follow-up observation with EP-FXT
  26. GRB 250510B: Fermi GBM Final Localization
  27. GRB 250510A: SVOM possible detection of a burst
  28. GRB 250509A: Swift detection of a burst
  29. GRB 250509A: Fermi GBM Final Real-time Localization
  30. EP250508a: Liverpool Telescope optical upper limits
  31. EP250508a: follow-up observation with EP-FXT
  32. GRB 250506A: GECAM detection
  33. GRB 250506A: Swift-XRT afterglow detection
  34. EP250508a: Einstein Probe detection of an X-ray transient
  35. GRB 250427B : SVOM detection of a burst through offline search
  36. GRB 250430A / EP250430a: AstroSat CZTI detection
  37. EP#01709175213/IGR J19566+0326: Swift-XRT detection
  38. EP-WXT trigger 01709175213: a new X-ray outburst of LMXB MAXI J1957+032
  39. GRB 250507A: SVOM detection of a long burst
  40. GRB 250504A: EIRSAT-1 GMOD Detection
  41. IceCube-250506A - IceCube observation of a high-energy neutrino candidate track-like event
  42. GRB 250430A: Konus-Wind detection and joint Konus-Wind+Swift-BAT spectral analysis
  43. GRB 250506A: SVOM improved position and MXT detection of a fading X-ray afterglow
  44. GRB 250506A: Swift XRT observations and possible counterpart detection
  45. GRB 250506A: SVOM detection of a burst
  46. GRB 250506A: Fermi GBM Final Real-time Localization
  47. GRB 250504A: SVOM/VT upper limit
  48. GRB 250505A: Fermi GBM Final Real-time Localization
  49. GRB 250504A: MeerLICHT optical afterglow detection
  50. GRB 250504A: Swift detection of a burst
  51. GRB 250504A: Fermi GBM Final Real-time Localization
  52. GRB 250502A: Montarrenti Observatory optical detection
  53. GRB 250502A: Swift-XRT afterglow detection
  54. GRB 250502a: Liverpool Telescope optical follow-up
  55. GRB 250502B: AstroSat CZTI detection
  56. GRB 250502A: AKO Optical Afterglow Detection
  57. GRB 250502A: LCO optical counterpart detection
  58. GRB 250502C: Fermi GBM Final Localization
  59. GRB 250407A: VZLUSAT-2 detection
  60. GRB 250502A: Early optical counterpart detection by LCO.
  61. GRB 250430A: Swift/UVOT Detection
  62. GRB 250430A: Optical Observations via Virtual Telescope Project, Italy
  63. GRB 250502A: SVOM/COLIBRÍ (FM-GFT) Detection of a Bright Optical Counterpart Candidate
  64. GRB 250502B: Fermi GBM Final Real-time Localization
  65. GRB 250502A: SVOM detection of a burst
  66. EP250428b: Pan-STARRS follow-up, upper limit on the optical counterpart, and possible host galaxy.
  67. EP250427a / GRB 250427A: OHP/T193 photometric observations: third visit
  68. EP250430a/GRB 250430A: Einstein Probe WXT detection of the X-ray prompt emission
  69. GRB 250424A: CALET Gamma-Ray Burst Monitor detection
  70. GRB 250430A: AKO Optical Afterglow Detection
  71. EP 250427A: Optical counterpart detection by LCO.
  72. GRB 250430A: Swift detection of a burst with optical counterpart
  73. SVOM/sb25043004: SVOM detection of a X-ray transient
  74. EP250428b: refined analysis of the EP-FXT follow-up observation
  75. IceCube-250429A - IceCube observation of a high-energy neutrino candidate track-like event
  76. GRB 250427A: Swift/UVOT Detection
  77. EP250428b: Einstein Probe detection of a fast X-ray transient
  78. EP250427a: EP-FXT follow-up observations
  79. EP250427a: Lesedi optical counterpart detection
  80. GRB250427A/EP250427a GIT optical afterglow detection:
  81. EP250427a: LT optical counterpart detection
  82. EP250427a / GRB 250427A: LCO optical counterpart detection
  83. EP250427a / GRB 250427A: VLT/X-shooter redshift confirmation z = 1.520
  84. EP250427a: REM optical/NIR afterglow detection
  85. GRB 250427A/ EP250427a: Fermi-GBM Sub-Threshold Detection
  86. EP250427A: COLIBRÍ Optical Detection
  87. EP250427a: TRT optical counterpart detection
  88. EP 250427a: BOOTES-7 optical afterglow candidate
  89. EP250427a: Einstein Probe detection of a fast X-ray transient
  90. IceCube-250426A - IceCube observation of a high-energy neutrino candidate track-like event
  91. GRB 250424A: PRIME near-infrared detection
  92. GRB 250424A: WINTER J-band detection
  93. GRB 250424A: EIRSAT-1 GMOD Detection
  94. GRB 250424A: Swift/UVOT Detection
  95. Konus-Wind detection of GRB 250424A
  96. GRB 250424A: Kilonova-Catcher optical afterglow detection
  97. GRB 250419a: Continued Liverpool Telescope observations
  98. GRB 250407A: GRBAlpha detection
  99. GRB 250404A / EP250404a: GRBAlpha detection
  100. GRB 250330B: GRBAlpha detection

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