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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"

27930 results found.

  1. GRB 250625A: Fermi-LAT detection
  2. GRB 250625A: Swift-XRT refined Analysis
  3. GRB 250625A: JinShan optical observations
  4. GRB250625A: Fermi GBM Observation
  5. Swift GRB 250625A: Global MASTER-Net observations report
  6. GRB 250625A: SVOM/VT optical confirmation
  7. GRB 250620B: Fermi GBM Observation
  8. GRB 250625A: Enhanced Swift-XRT position
  9. GRB 250625A: Swift detection of a burst
  10. GRB 250625A: Fermi GBM Final Real-time Localization
  11. GRB 250620A: AstroSat CZTI detection
  12. GRB 241018A: Maidanak optical observations
  13. GRB 250620C: AstroSat CZTI detection
  14. GRB 250624A: Fermi GBM Final Real-time Localization
  15. sb25061207/GRB 250612D - SVOM/ECLAIRs refined analysis
  16. GRB 250623A: Fermi GBM Final Real-time Localization
  17. GRB 250521A: VZLUSAT-2 detection
  18. GRB 250617B: Swift-BAT refined analysis
  19. Konus-Wind detection of GRB 250620C
  20. IPN triangulation of GRB 250620C (long/bright)
  21. GRB 250621B: SVOM/GRM detection of a possible magnetar X-ray burst
  22. GRB 250620A: SVOM/GRM observation of a short burst
  23. GRB250620A: Fermi GBM Observation
  24. GRB 250617B: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  25. GRB 250619B: Fermi GBM Observation
  26. GRB 250621A: Fermi GBM Final Real-time Localization
  27. GRB 250620B: Swift/BAT-GUANO localization skymap of a burst
  28. GRB 250620A: Swift/BAT-GUANO subthreshold detection of a possibly short burst
  29. GRB 250619B: Swift/BAT-GUANO localization skymap of a burst
  30. GRB 250620C: Fermi GBM Final Real-time Localization
  31. GRB 250620B: Fermi GBM Final Real-time Localization
  32. GRB 250620A: Fermi GBM Final Real-time Localization
  33. EP-WXT trigger 01709179036: a new outburst of GRS 1739-278
  34. GRB 250619B: Fermi GBM Final Real-time Localization
  35. GRB 250615A: Kilonova-Catcher optical upper limits
  36. GRB 250619A: Fermi GBM Final Real-time Localization
  37. GRB 250617B: Assy AZT-20 Optical Observations
  38. GRB 250612A / Swift J1643.6−3854: Swift-BAT refined analysis
  39. GRB 250615A/EP250615a: FTW optical and NIR observations
  40. sb25061218/SVOM: OHP/T120 and OHP/T193 optical imaging and spectroscopic observations
  41. GRB 250617B: Swift/UVOT Detection
  42. GRB 250617B: Kilonova-Catcher optical afterglow detection
  43. GRB 250617B: VLT/X-shooter spectroscopic redshift z = 1.396
  44. GRB 250617B: NOT NIR observations of the afterglow
  45. GRB 250617B: Swift-XRT refined Analysis
  46. GRB 250617B: SVOM/VT optical observation
  47. GRB 250617B: NUTTelA-TAO early time optical observations
  48. Swift GRB 250617B: Global MASTER-Net observations report
  49. GRB 250617B: GOTO optical upper limit
  50. GRB 250617B: Enhanced Swift-XRT position
  51. GRB 250617B: Fermi GBM Observation
  52. GRB 250615A: Swift-BAT refined analysis
  53. GRB 250617B: Fermi GBM Final Localization
  54. GRB 250617B: Ondrejov D50 optical afterglow detection
  55. GRB 250617B: Swift detection of a burst with an optical counterpart
  56. GRB 250615A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  57. GRB 250617A: Fermi GBM Final Real-time Localization
  58. IPN triangulation of GRB 250612C (short/hard)
  59. EP#01709178975: Swift-XRT counterpart detection
  60. Konus-Wind detection of GRB 250615A / EP250615a
  61. GRB 250615A / EP250615a: AstroSat CZTI detection
  62. GRB 250615A: COLIBRÍ optical upper limit
  63. GRB 250615A: DDOTI Optical Upper Limit
  64. GRB 250615A: Swift/UVOT Upper Limits
  65. Konus-Wind detection of GRB 250612C (short/hard with extended emission)
  66. GRB 250615A: Swift-XRT refined Analysis
  67. EP250615a/GRB 250615A: EP-WXT detection of a fast X-ray transient
  68. EP-WXT trigger 01709178875: confirmation of a stellar flare by BOOTES-6
  69. GRB 250615A: Enhanced Swift-XRT position
  70. GRB 250615A: Prompt enhanced Swift-XRT position
  71. GRB 250615A: Swift detection of a burst
  72. Swift GRB 250615A: Global MASTER-Net observations report
  73. GRID detection of GRB 250612C
  74. sb25061207: Mephisto optical upper limits
  75. IceCube alert 141029_8144692 retraction
  76. GRB 250614A: Fermi GBM Final Real-time Localization
  77. sb25061218: Swift-XRT observations
  78. sb25061207: EP-FXT follow-up observation and afterglow candidate
  79. sb25061218: SVOM detection of a X-ray transient
  80. sb25061207: Swift-XRT observations
  81. EP 250612a: AST3-3 Yaoan Optical Observation
  82. GRB 250610B: Swift-XRT refined Analysis
  83. GRB 250612C: Fermi GBM Final Real-time Localization
  84. GRB 250612B (250612519/771424081): Fermi GBM Final Localization
  85. GRB 250612B: BALROG localization (Fermi Trigger 771424081 / GRB 250612519)
  86. EP250612a: Einstein Probe detection of an X-ray transient
  87. sb25061207: SVOM detection of a X-ray transient
  88. EP250610a: continuous follow-up observations with EP-FXT
  89. GRB 250612A: Swift detection of a burst or new Galactic transient Swift J1643.6-3854
  90. Swift GRB250612.04: Global MASTER-Net observations report
  91. Fermi GBM Sub-Threshold Detection of GRB 250610B
  92. GRB 250610B: Swift/UVOT Detection
  93. EP250610A: Swift/UVOT Upper limits
  94. EP250610a: Liverpool Telescope optical upper limits
  95. GRB 250610B: Fermi/GBM sub-threshold detection of a possibly hard burst
  96. GRB 250610B: EP-FXT follow-up observation and afterglow counterpart
  97. GRB 250610B: Swift-XRT counterpart detection
  98. GRB 250610B: SVOM/VT optical counterpart
  99. GRB 250610B: LT detection of the optical counterpart
  100. GRB 250610C: Fermi GBM Final Real-time Localization

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