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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

36311 results found.

  1. GRB 250702F: Swift-XRT refined Analysis
  2. GRB 250702F: Fermi GBM Observation
  3. GRB 250702F: Leavitt Observatory optical observations
  4. GRB 250702F: AKO Optical Afterglow Detection
  5. GRBs 250702B,C,D,E / EP250702a: VLT/HAWK-I NIR candidate
  6. GRBs 250702B,C,D,E / EP250702a: SVOM/GRM observation
  7. GRB 250702A: GECAM-B detection
  8. GRB 250702F: Skynet Optical Observations
  9. GRB 250424A: VIRT Optical Upper Limit
  10. GRB 250702B,C,D,E/EP250702a: COLIBRÍ optical upper limit
  11. EP250702a/GRB 250702B, C, D, E: EP-FXT follow-up observation
  12. GRB 250702F: TRT Optical Observation
  13. GRB 250703A: DDOTI Optical Upper Limit
  14. GRB 250702F: REM optical afterglow detection
  15. GRB 250702F: DDOTI Optical Observation
  16. GRB 250702B,C,D,E / EP 250702a: MAXI/GSC detection
  17. GRB 250703A: Fermi GBM Final Real-time Localization
  18. EP250702a/GRB 250702B,C,D,E: GOTO optical upper limits
  19. GRB 250702F: COLIBRÍ Observations of the Afterglow
  20. EP250702a : an X-ray transient detected by Einstein Probe likely associated with GRB 250702B,C,D,E
  21. Fermi GRB 250702E: Global MASTER-Net observations report
  22. Fermi GRB 250702B: Global MASTER-Net observations report
  23. GRB 250702D, C, E: Swift/BAT-GUANO localization skymap of a burst or galactic transient
  24. GRB 250702F: Enhanced Swift-XRT position
  25. GRB 250702F: GTC/OSIRIS+ spectroscopic redshift z = 1.520
  26. GRB 250702F: NOT observations of the optical afterglow
  27. GRB 250702F: MASTER optical afterglow observation
  28. Fermi GRB 250702F: Global MASTER-Net observations report
  29. Fermi GRB 250702C: Global MASTER-Net observations report
  30. GRB 250702F: GOTO optical counterpart detection
  31. GRB 250702F: Ondrejov D50 optical afterglow detection
  32. GRB 250702F: Swift detection of a burst with an optical counterpart
  33. Swift GRB 250702F: Global MASTER-Net observations report
  34. GRB 250702F: Fermi GBM Final Real-time Localization
  35. Fermi GBM Triggers 250702B, C, D and E are likely from the same source
  36. GRB 250702E: Fermi GBM Final Real-time Localization
  37. Konus-Wind detection of GRB 250627A
  38. IPN triangulation of GRB 250627A (short)
  39. GRB 250702A: Fermi GBM Detection
  40. GRB 250702D: Fermi GBM Final Localization Correction
  41. GRB 250702C: Fermi GBM Final Real-time Localization
  42. GRB 250702B: Fermi GBM Final Real-time Localization
  43. GRB 250702A: BALROG localization (Fermi Trigger 773142852 / GRB 250702413)
  44. GRB 250702A: Fermi GBM Final Real-time Localization
  45. Fermi Gamma-ray Burst Monitor trigger 772838080/250628885 is not a GRB
  46. GRB 250628B: Swift-XRT observations
  47. Fermi Gamma-ray Burst Monitor trigger 772981768/250630548 is not a GRB
  48. GRB 250628B: SVOM/VT optical upper limit
  49. GRB 250628B: EP-FXT counterpart detection
  50. GRB 250627A: Insight-HXMT detection
  51. GRB 250627A: SVOM/GRM detection of a short burst
  52. LIGO/Virgo/KAGRA S250628am: Identification of a GW compact binary merger candidate (duplicate submission)
  53. GRB 250628A: REM optical/NIR upper limits
  54. GRB 250628C: Fermi GBM Final Real-time Localization
  55. GRB 250628B: SVOM detection of a long burst
  56. Fermi Gamma-ray Burst Monitor trigger 772811638/250628579 is not a GRB
  57. GRB 250625A: VLT/X-shooter spectroscopic observations at the afterglow position
  58. GRB 250628A: VLT/X-shooter upper limits
  59. GRB 250628A: Swift/UVOT Upper Limits
  60. GRB 250628A: Swift-XRT refined Analysis
  61. Fermi GRB 250626A: Global MASTER-Net observations report
  62. Swift GRB 250628A: Global MASTER-Net observations report
  63. GRB 250628A: Enhanced Swift-XRT position
  64. GRB 250628A: Swift detection of a burst
  65. GRB 250625A: Swift-BAT refined analysis
  66. GRB 250625A: Leavitt Observatory afterglow detection
  67. Fermi Gamma-ray Burst Monitor trigger 772732642/250627665 is not a GRB
  68. Fermi Gamma-ray Burst Monitor trigger 772720540/250627525 is not a GRB
  69. GRB 250625A: AbAO and INASAN Kislovodsk Optical Observations
  70. GRB 250625A: GTC/OSIRIS+ spectroscopic observations of the potential host galaxy
  71. GRB 250626A: Fermi GBM Final Real-time Localization
  72. Fermi Gamma-ray Burst Monitor trigger 772647532/250626680 is not a GRB
  73. GRB 250625A: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
  74. GRB 250625A: SVOM/C-GFT upper limit in early phase
  75. GRB 250625A: GECAM-B detection
  76. GRB 250625A: Swift/UVOT Upper Limits
  77. GRB 250625A: ABObservatory afterglow detection
  78. GRB 250625A: OHP/T193 optical detection
  79. GRB 250625A: COLIBRÍ optical observations
  80. GRB 250625A: Fermi-LAT detection
  81. GRB 250625A: Swift-XRT refined Analysis
  82. GRB 250625A: JinShan optical observations
  83. GRB250625A: Fermi GBM Observation
  84. Swift GRB 250625A: Global MASTER-Net observations report
  85. GRB 250625A: NOT z-band upper limit
  86. GRB 250625A: SVOM/VT optical confirmation
  87. GRB 250620B: Fermi GBM Observation
  88. GRB 250625A: SAO RAS possible optical afterglow
  89. GRB 250625A: Enhanced Swift-XRT position
  90. Fermi GRB 250625A: Global MASTER-Net observations report
  91. GRB 250625A: Swift detection of a burst
  92. GRB 250625A: Fermi GBM Final Real-time Localization
  93. GRB 250617B: Mondy and SAO RAS optical observations on 2025-06-23, 2025-06-24
  94. GRB 250620A: AstroSat CZTI detection
  95. GRB 241018A: Maidanak optical observations
  96. GRB 250620C: AstroSat CZTI detection
  97. Fermi GRB 250624A: Global MASTER-Net observations report
  98. GRB 250624A: Fermi GBM Final Real-time Localization
  99. sb25061207/GRB 250612D - SVOM/ECLAIRs refined analysis
  100. Fermi GRB 250623A: Global MASTER-Net observations report

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