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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"

27932 results found.

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

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