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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"

36314 results found.

  1. GRB 250624A: Fermi GBM Final Real-time Localization
  2. sb25061207/GRB 250612D - SVOM/ECLAIRs refined analysis
  3. Fermi GRB 250623A: Global MASTER-Net observations report
  4. GRB 250623A: Fermi GBM Final Real-time Localization
  5. GRB 250521A: VZLUSAT-2 detection
  6. GRB 250617B: Swift-BAT refined analysis
  7. Konus-Wind detection of GRB 250620C
  8. IPN triangulation of GRB 250620C (long/bright)
  9. GRB 250621B: SVOM/GRM detection of a possible magnetar X-ray burst
  10. GRB 250620C: SVOM/GRM observation
  11. GRB 250620A: SVOM/GRM observation of a short burst
  12. GRB250620A: Fermi GBM Observation
  13. GRB 250617B: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  14. Fermi GRB 250621A: Global MASTER-Net observations report
  15. GRB 250619B: Fermi GBM Observation
  16. GRB 250621A: Fermi GBM Final Real-time Localization
  17. GRB 250620B: Swift/BAT-GUANO localization skymap of a burst
  18. GRB250620C: Fermi GBM Observation
  19. GRB 250506A - SVOM/ECLAIRs Refined analysis
  20. GRB 250620A: Swift/BAT-GUANO subthreshold detection of a possibly short burst
  21. GRB 250619B: Swift/BAT-GUANO localization skymap of a burst
  22. GRB 250620C: Fermi GBM Final Real-time Localization
  23. GRB 250620B: Fermi GBM Final Real-time Localization
  24. GRB 250620A: Fermi GBM Final Real-time Localization
  25. GRB 250617B: Nickel telescope optical observations
  26. GRB 250619B: Fermi GBM Final Real-time Localization
  27. Fermi Gamma-ray Burst Monitor trigger 772058337/250619860 is not a GRB
  28. GRB 250615A: Kilonova-Catcher optical upper limits
  29. GRB 250619A: Fermi GBM Final Real-time Localization
  30. GRB 250617B: Assy AZT-20 Optical Observations
  31. GRB 250612A / Swift J1643.6−3854: Swift-BAT refined analysis
  32. Fermi GRB 250617A: Global MASTER-Net observations report
  33. GRB 250615A/EP250615a: FTW optical and NIR observations
  34. sb25061218/SVOM: OHP/T120 and OHP/T193 optical imaging and spectroscopic observations
  35. GRB 250617B: Swift/UVOT Detection
  36. GRB 250617B: Kilonova-Catcher optical afterglow detection
  37. GRB 250617B: VLT/X-shooter spectroscopic redshift z = 1.396
  38. GRB 250617B: COLIBRÍ optical observations
  39. GRB 250617B: NOT NIR observations of the afterglow
  40. GRB 250617B: Swift-XRT refined Analysis
  41. GRB 250617B: SVOM/VT optical observation
  42. GRB 250617B: NUTTelA-TAO early time optical observations
  43. Swift GRB 250617B: Global MASTER-Net observations report
  44. GRB 250617B: GOTO optical upper limit
  45. GRB 250617B: Enhanced Swift-XRT position
  46. GRB 250617B: Fermi GBM Observation
  47. GRB 250615A: Swift-BAT refined analysis
  48. GRB 250617B: Fermi GBM Final Localization
  49. GRB 250617B: Ondrejov D50 optical afterglow detection
  50. GRB 250617B: SAO RAS optical observations
  51. GRB 250617B: Swift detection of a burst with an optical counterpart
  52. GRB 250615A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  53. GRB 250617A: Fermi GBM Final Real-time Localization
  54. IPN triangulation of GRB 250612C (short/hard)
  55. Konus-Wind detection of GRB 250615A / EP250615a
  56. GRB 250615A / EP250615a: AstroSat CZTI detection
  57. Fermi Gamma-ray Burst Monitor trigger 771803204/250616907 is not a GRB
  58. SVOM sb25061207: AbAO AS-32 Optical Upper Limit
  59. GRB 250615A: COLIBRÍ optical upper limit
  60. GRB 250615A: DDOTI Optical Upper Limit
  61. GRB 250615A: Swift/UVOT Upper Limits
  62. Konus-Wind detection of GRB 250612C (short/hard with extended emission)
  63. GRB 250615A: Swift-XRT refined Analysis
  64. EP250615a/GRB 250615A: EP-WXT detection of a fast X-ray transient
  65. GRB 250615A: Enhanced Swift-XRT position
  66. Fermi Gamma-ray Burst Monitor trigger 771718064/250615922 is not a GRB
  67. GRB 250615A: Prompt enhanced Swift-XRT position
  68. GRB 250615A: Swift detection of a burst
  69. Swift GRB 250615A: Global MASTER-Net observations report
  70. Fermi Gamma-ray Burst Monitor trigger 771704505/250615765 is not a GRB
  71. GRID detection of GRB 250612C
  72. Fermi Gamma-ray Burst Monitor trigger 771596290/250614513 is not a GRB
  73. GRB 250614A: Fermi GBM Final Real-time Localization
  74. EP250612a / GRB 250612B: NOT optical observations of the afterglow candidate
  75. Fermi Gamma-ray Burst Monitor trigger 771547945/250613953 is not a GRB
  76. Fermi Gamma-ray Burst Monitor trigger 771541927/250613883 is not a GRB
  77. GRB 250610B: J band upper limit by SYSU 80cm infrared telescope
  78. GRB 250612B: Fermi GBM Observation
  79. EP250612a / GRB 250612B: SVOM/VT optical candidate
  80. GRB 250612C: Fermi GBM Observation
  81. EP250612a/GRB 250612B: JinShan optical upper limit
  82. GRB 250612C: SVOM/GRM observation an intermedium duration burst
  83. GRB 250612C: BALROG localization (Fermi Trigger 771432801 / GRB 250612620)
  84. GRB 250610B: Swift-XRT refined Analysis
  85. GRB 250612C: Fermi GBM Final Real-time Localization
  86. EP250610a: Upper limit from Fermi-GBM Observations
  87. GRB 250612B (250612519/771424081): Fermi GBM Final Localization
  88. GRB 250612B: BALROG localization (Fermi Trigger 771424081 / GRB 250612519)
  89. GRB 250610B: Liverpool Telescope continued monitoring
  90. GRB 250610B: MISTRAL/T193 and T120 OHP further observations
  91. GRB 250610B - SVOM/ECLAIRs refined analysis
  92. GRB 250612A: Swift detection of a burst or new Galactic transient Swift J1643.6-3854
  93. Fermi GBM Sub-Threshold Detection of GRB 250610B
  94. GRB 250610B: Swift/UVOT Detection
  95. GRB 250610B: SVOM/COLIBRÍ (FM-GFT) optical observations
  96. GRB 250610B: REM optical/NIR observations
  97. GRB 250610B: SVOM/VT optical shallow decay
  98. GRB 250610B: additional Liverpool Telescope optical observations
  99. GRB 250610B: SVOM/GRM analysis
  100. GRB 250610B: Fermi/GBM sub-threshold detection of a possibly hard burst

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