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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"

11612 results found.

  1. GRB 250625A: AbAO and INASAN Kislovodsk Optical Observations
  2. GRB 250625A: GTC/OSIRIS+ spectroscopic observations of the potential host galaxy
  3. GRB 250626A: Fermi GBM Final Real-time Localization
  4. Fermi Gamma-ray Burst Monitor trigger 772647532/250626680 is not a GRB
  5. GRB 250625A: SVOM/C-GFT upper limit in early phase
  6. GRB 250625A: GECAM-B detection
  7. GRB 250625A: ABObservatory afterglow detection
  8. GRB 250625A: OHP/T193 optical detection
  9. GRB 250625A: COLIBRÍ optical observations
  10. GRB 250625A: Fermi-LAT detection
  11. GRB 250625A: JinShan optical observations
  12. GRB250625A: Fermi GBM Observation
  13. GRB 250625A: NOT z-band upper limit
  14. GRB 250625A: SVOM/VT optical confirmation
  15. GRB 250620B: Fermi GBM Observation
  16. GRB 250625A: SAO RAS possible optical afterglow
  17. Fermi GRB 250625A: Global MASTER-Net observations report
  18. GRB 250625A: Swift detection of a burst
  19. GRB 250625A: Fermi GBM Final Real-time Localization
  20. GRB 250617B: Mondy and SAO RAS optical observations on 2025-06-23, 2025-06-24
  21. GRB 250620A: AstroSat CZTI detection
  22. GRB 250620C: AstroSat CZTI detection
  23. Fermi GRB 250624A: Global MASTER-Net observations report
  24. GRB 250624A: Fermi GBM Final Real-time Localization
  25. Fermi GRB 250623A: Global MASTER-Net observations report
  26. GRB 250623A: Fermi GBM Final Real-time Localization
  27. GRB 250521A: VZLUSAT-2 detection
  28. Fermi trigger No 772190032: Global MASTER-Net observations report
  29. Konus-Wind detection of GRB 250620C
  30. IPN triangulation of GRB 250620C (long/bright)
  31. GRB 250621B: SVOM/GRM detection of a possible magnetar X-ray burst
  32. GRB 250620C: SVOM/GRM observation
  33. GRB 250620A: SVOM/GRM observation of a short burst
  34. GRB250620A: Fermi GBM Observation
  35. Fermi GRB 250621A: Global MASTER-Net observations report
  36. GRB 250619B: Fermi GBM Observation
  37. GRB 250621A: Fermi GBM Final Real-time Localization
  38. GRB 250620B: Swift/BAT-GUANO localization skymap of a burst
  39. GRB250620C: Fermi GBM Observation
  40. GRB 250506A - SVOM/ECLAIRs Refined analysis
  41. GRB 250620A: Swift/BAT-GUANO subthreshold detection of a possibly short burst
  42. GRB 250619B: Swift/BAT-GUANO localization skymap of a burst
  43. GRB 250620C: Fermi GBM Final Real-time Localization
  44. Fermi trigger No 772128434: Global MASTER-Net observations report
  45. GRB 250620B: Fermi GBM Final Real-time Localization
  46. GRB 250620A: Fermi GBM Final Real-time Localization
  47. GRB 250617B: Nickel telescope optical observations
  48. GRB 250619B: Fermi GBM Final Real-time Localization
  49. Fermi trigger No 772058337: Global MASTER-Net observations report
  50. Fermi Gamma-ray Burst Monitor trigger 772058337/250619860 is not a GRB
  51. GRB 250619A: Fermi GBM Final Real-time Localization
  52. GRB 250617B: Assy AZT-20 Optical Observations
  53. Fermi GRB 250617A: Global MASTER-Net observations report
  54. GRB 250617B: VLT/X-shooter spectroscopic redshift z = 1.396
  55. GRB 250617B: COLIBRÍ optical observations
  56. GRB 250617B: NOT NIR observations of the afterglow
  57. GRB 250617B: SVOM/VT optical observation
  58. Fermi trigger No 771886893: Global MASTER-Net observations report
  59. GRB 250617B: GOTO optical upper limit
  60. GRB 250617B: Fermi GBM Observation
  61. GRB 250617B: Fermi GBM Final Localization
  62. GRB 250617A: Fermi GBM Final Real-time Localization
  63. IPN triangulation of GRB 250612C (short/hard)
  64. Fermi Gamma-ray Burst Monitor trigger 771803204/250616907 is not a GRB
  65. Konus-Wind detection of GRB 250612C (short/hard with extended emission)
  66. Fermi trigger No 771752663: Global MASTER-Net observations report
  67. Fermi Gamma-ray Burst Monitor trigger 771718064/250615922 is not a GRB
  68. Fermi trigger No 771718064: Global MASTER-Net observations report
  69. Fermi Gamma-ray Burst Monitor trigger 771704505/250615765 is not a GRB
  70. GRID detection of GRB 250612C
  71. Fermi Gamma-ray Burst Monitor trigger 771596290/250614513 is not a GRB
  72. GRB 250614A: Fermi GBM Final Real-time Localization
  73. EP250612a / GRB 250612B: NOT optical observations of the afterglow candidate
  74. Fermi Gamma-ray Burst Monitor trigger 771547945/250613953 is not a GRB
  75. Fermi Gamma-ray Burst Monitor trigger 771541927/250613883 is not a GRB
  76. Fermi trigger No 771494087: Global MASTER-Net observations report
  77. EP250612a: refined analysis of the EP-WXT and EP-FXT observations
  78. GRB 250612B: Fermi GBM Observation
  79. EP250612a / GRB 250612B: SVOM/VT optical candidate
  80. Fermi trigger No 771424081: Global MASTER-Net observations report
  81. GRB 250612C: Fermi GBM Observation
  82. EP250612a/GRB 250612B: JinShan optical upper limit
  83. EP 250612a: AST3-3 Yaoan Optical Observation
  84. GRB 250612C: SVOM/GRM observation an intermedium duration burst
  85. GRB 250612C: BALROG localization (Fermi Trigger 771432801 / GRB 250612620)
  86. GRB 250612C: Fermi GBM Final Real-time Localization
  87. EP250610a: Upper limit from Fermi-GBM Observations
  88. GRB 250612B (250612519/771424081): Fermi GBM Final Localization
  89. GRB 250612B: BALROG localization (Fermi Trigger 771424081 / GRB 250612519)
  90. Fermi GBM Sub-Threshold Detection of GRB 250610B
  91. GRB 250610B: SVOM/GRM analysis
  92. GRB 250610B: Fermi/GBM sub-threshold detection of a possibly hard burst
  93. Fermi Gamma-ray Burst Monitor trigger 771286888/250610932 is not a GRB
  94. GRB 250610C: Fermi GBM Final Real-time Localization
  95. Fermi Gamma-ray Burst Monitor trigger 771256110/250610575 is not a GRB
  96. GRB 250610A: Fermi GBM Final Real-time Localization
  97. GRB 250609A: Fermi GBM Observation
  98. Fermi trigger No 771072240: Global MASTER-Net observations report
  99. GRB 250609A: Swift/BAT-GUANO localization skymap of a likely short burst
  100. GRB 250608A: SVOM/GRM detection of a possible magnetar X-ray burst

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