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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"

35427 results found.

  1. GRB 250702B / EP2050702a: FTW optical and NIR observations
  2. Konus-Wind detection of GRB 250702F
  3. EP250704a / GRB 250704B - REM observations
  4. GRB 250702F: GROWTH-India Telescope optical observations
  5. EP250704a / GRB 250704B: VLT/FORS2 optical afterglow detection
  6. GRB 250704A: REM retraction of optical afterglow detection and updated limit
  7. EP250704a: Einstein Probe detection of an X-ray transient
  8. GRB 250704B: SVOM/GRM observation of a short burst
  9. GRB 250702F: optical photometry from Konkoly
  10. GRB 250704A: REM detection of the optical afterglow
  11. GRB 250702F: SVOM/VT optical observation
  12. GRB 250704A: SVOM detection of a burst
  13. GRB 250702F: Swift/UVOT Detection
  14. GRB 250702A: CALET Gamma-Ray Burst Monitor detection
  15. Fermi GBM Analysis of GRB 250702B (formerly B,D,E); dissociation of C burst
  16. Fermi GRB 250703A: Global MASTER-Net observations report
  17. GRBs 250702B,C,D,E / EP250702a: 2.2m CAHA optical upper limit
  18. GRB 250702F: Swift-XRT refined Analysis
  19. GRB 250702F: Fermi GBM Observation
  20. GRB 250702F: Leavitt Observatory optical observations
  21. GRB 250702F: AKO Optical Afterglow Detection
  22. GRBs 250702B,C,D,E / EP250702a: VLT/HAWK-I NIR candidate
  23. GRBs 250702B,C,D,E / EP250702a: SVOM/GRM observation
  24. GRB 250702A: GECAM-B detection
  25. GRB 250702F: Skynet Optical Observations
  26. GRB 250424A: VIRT Optical Upper Limit
  27. GRB 250702B,C,D,E/EP250702a: COLIBRÍ optical upper limit
  28. EP250702a/GRB 250702B, C, D, E: EP-FXT follow-up observation
  29. GRB 250702F: TRT Optical Observation
  30. GRB 250703A: DDOTI Optical Upper Limit
  31. GRB 250702F: REM optical afterglow detection
  32. GRB 250702F: DDOTI Optical Observation
  33. GRB 250702B,C,D,E / EP 250702a: MAXI/GSC detection
  34. GRB 250703A: Fermi GBM Final Real-time Localization
  35. EP250702a/GRB 250702B,C,D,E: GOTO optical upper limits
  36. GRB 250702F: COLIBRÍ Observations of the Afterglow
  37. EP250702a : an X-ray transient detected by Einstein Probe likely associated with GRB 250702B,C,D,E
  38. Fermi GRB 250702E: Global MASTER-Net observations report
  39. Fermi GRB 250702B: Global MASTER-Net observations report
  40. GRB 250702D, C, E: Swift/BAT-GUANO localization skymap of a burst or galactic transient
  41. GRB 250702F: Enhanced Swift-XRT position
  42. GRB 250702F: GTC/OSIRIS+ spectroscopic redshift z = 1.520
  43. GRB 250702F: NOT observations of the optical afterglow
  44. GRB 250702F: MASTER optical afterglow observation
  45. Fermi GRB 250702F: Global MASTER-Net observations report
  46. Fermi GRB 250702C: Global MASTER-Net observations report
  47. GRB 250702F: GOTO optical counterpart detection
  48. GRB 250702F: Ondrejov D50 optical afterglow detection
  49. GRB 250702F: Swift detection of a burst with an optical counterpart
  50. Swift GRB 250702F: Global MASTER-Net observations report
  51. GRB 250702F: Fermi GBM Final Real-time Localization
  52. Fermi GBM Triggers 250702B, C, D and E are likely from the same source
  53. GRB 250702E: Fermi GBM Final Real-time Localization
  54. Konus-Wind detection of GRB 250627A
  55. IPN triangulation of GRB 250627A (short)
  56. GRB 250702A: Fermi GBM Detection
  57. GRB 250702D: Fermi GBM Final Localization Correction
  58. GRB 250702C: Fermi GBM Final Real-time Localization
  59. GRB 250702B: Fermi GBM Final Real-time Localization
  60. GRB 250702A: BALROG localization (Fermi Trigger 773142852 / GRB 250702413)
  61. GRB 250702A: Fermi GBM Final Real-time Localization
  62. Fermi Gamma-ray Burst Monitor trigger 772838080/250628885 is not a GRB
  63. GRB 250628B: Swift-XRT observations
  64. Fermi Gamma-ray Burst Monitor trigger 772981768/250630548 is not a GRB
  65. GRB 250628B: SVOM/VT optical upper limit
  66. GRB 250628B: EP-FXT counterpart detection
  67. GRB 250627A: Insight-HXMT detection
  68. GRB 250627A: SVOM/GRM detection of a short burst
  69. LIGO/Virgo/KAGRA S250628am: Identification of a GW compact binary merger candidate (duplicate submission)
  70. GRB 250628A: REM optical/NIR upper limits
  71. GRB 250628C: Fermi GBM Final Real-time Localization
  72. GRB 250628B: SVOM detection of a long burst
  73. Fermi Gamma-ray Burst Monitor trigger 772811638/250628579 is not a GRB
  74. GRB 250625A: VLT/X-shooter spectroscopic observations at the afterglow position
  75. GRB 250628A: VLT/X-shooter upper limits
  76. GRB 250628A: Swift/UVOT Upper Limits
  77. GRB 250628A: Swift-XRT refined Analysis
  78. Fermi GRB 250626A: Global MASTER-Net observations report
  79. Swift GRB 250628A: Global MASTER-Net observations report
  80. GRB 250628A: Enhanced Swift-XRT position
  81. GRB 250628A: Swift detection of a burst
  82. GRB 250625A: Swift-BAT refined analysis
  83. GRB 250625A: Leavitt Observatory afterglow detection
  84. Fermi Gamma-ray Burst Monitor trigger 772732642/250627665 is not a GRB
  85. Fermi Gamma-ray Burst Monitor trigger 772720540/250627525 is not a GRB
  86. GRB 250625A: AbAO and INASAN Kislovodsk Optical Observations
  87. GRB 250625A: GTC/OSIRIS+ spectroscopic observations of the potential host galaxy
  88. GRB 250626A: Fermi GBM Final Real-time Localization
  89. Fermi Gamma-ray Burst Monitor trigger 772647532/250626680 is not a GRB
  90. GRB 250625A: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
  91. GRB 250625A: SVOM/C-GFT upper limit in early phase
  92. GRB 250625A: GECAM-B detection
  93. GRB 250625A: Swift/UVOT Upper Limits
  94. GRB 250625A: ABObservatory afterglow detection
  95. GRB 250625A: OHP/T193 optical detection
  96. GRB 250625A: COLIBRÍ optical observations
  97. GRB 250625A: Fermi-LAT detection
  98. GRB 250625A: Swift-XRT refined Analysis
  99. GRB 250625A: JinShan optical observations
  100. GRB250625A: Fermi GBM Observation

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