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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"

43075 results found.

  1. GRB 250617B: Ondrejov D50 optical afterglow detection
  2. GRB 250617B: SAO RAS optical observations
  3. GRB 250617B: Swift detection of a burst with an optical counterpart
  4. GRB 250615A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  5. GRB 250617A: Fermi GBM Final Real-time Localization
  6. IPN triangulation of GRB 250612C (short/hard)
  7. EP#01709178975: Swift-XRT counterpart detection
  8. EP-WXT trigger 01709178975: GOTO optical upper limit
  9. The EP-WXT trigger 01709178975 is likely a flaring star
  10. Konus-Wind detection of GRB 250615A / EP250615a
  11. GRB 250615A / EP250615a: AstroSat CZTI detection
  12. SVOM sb25061207: AbAO AS-32 Optical Upper Limit
  13. GRB 250615A: COLIBRÍ optical upper limit
  14. GRB 250615A: DDOTI Optical Upper Limit
  15. GRB 250615A: Swift/UVOT Upper Limits
  16. Konus-Wind detection of GRB 250612C (short/hard with extended emission)
  17. GRB 250615A: Swift-XRT refined Analysis
  18. sb25061207/SVOM: T120 OHP optical upper limit
  19. EP250615a/GRB 250615A: EP-WXT detection of a fast X-ray transient
  20. Fermi trigger No 771752663: Global MASTER-Net observations report
  21. EP-WXT trigger 01709178875: confirmation of a stellar flare by BOOTES-6
  22. The EP-WXT trigger 01709178875 is likely a flaring star
  23. GRB 250615A: Enhanced Swift-XRT position
  24. GRB 250615A: Prompt enhanced Swift-XRT position
  25. GRB 250615A: Swift detection of a burst
  26. Swift GRB 250615A: Global MASTER-Net observations report
  27. Fermi trigger No 771718064: Global MASTER-Net observations report
  28. GRID detection of GRB 250612C
  29. sb25061207: Mephisto optical upper limits
  30. IceCube alert 141029_8144692 retraction
  31. GRB 250614A: Fermi GBM Final Real-time Localization
  32. EP250612a / GRB 250612B: NOT optical observations of the afterglow candidate
  33. sb25061218: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  34. sb25061207: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  35. Fermi trigger No 771494087: Global MASTER-Net observations report
  36. sb25061218: Swift-XRT observations
  37. EP250612a: refined analysis of the EP-WXT and EP-FXT observations
  38. GRB 250610B: J band upper limit by SYSU 80cm infrared telescope
  39. sb25061207: EP-FXT follow-up observation and afterglow candidate
  40. GRB 250612B: Fermi GBM Observation
  41. EP250612a / GRB 250612B: SVOM/VT optical candidate
  42. Fermi trigger No 771424081: Global MASTER-Net observations report
  43. EP250612a: Global MASTER-Net observations report
  44. GRB 250612C: Fermi GBM Observation
  45. sb25061218: SVOM detection of a X-ray transient
  46. sb25061207: Swift-XRT observations
  47. EP250612a/GRB 250612B: JinShan optical upper limit
  48. EP 250612a: AST3-3 Yaoan Optical Observation
  49. GRB 250612C: SVOM/GRM observation an intermedium duration burst
  50. sb25061207: SVOM/VT optical counterpart
  51. GRB 250612C: BALROG localization (Fermi Trigger 771432801 / GRB 250612620)
  52. GRB 250610B: Swift-XRT refined Analysis
  53. GRB 250612C: Fermi GBM Final Real-time Localization
  54. EP250610a: Upper limit from Fermi-GBM Observations
  55. GRB 250612B (250612519/771424081): Fermi GBM Final Localization
  56. GRB 250612B: BALROG localization (Fermi Trigger 771424081 / GRB 250612519)
  57. EP250612a: Einstein Probe detection of an X-ray transient
  58. GRB 250610B: Liverpool Telescope continued monitoring
  59. GRB 250610B: MISTRAL/T193 and T120 OHP further observations
  60. sb25061207: SVOM detection of a X-ray transient
  61. EP250610a: continuous follow-up observations with EP-FXT
  62. GRB 250610B - SVOM/ECLAIRs refined analysis
  63. GRB 250612A: Swift detection of a burst or new Galactic transient Swift J1643.6-3854
  64. Swift GRB250612.04: Global MASTER-Net observations report
  65. Fermi GBM Sub-Threshold Detection of GRB 250610B
  66. GRB 250610B: Swift/UVOT Detection
  67. GRB 250610B: SVOM/COLIBRÍ (FM-GFT) optical observations
  68. GRB 250610B: REM optical/NIR observations
  69. EP250610a: Liverpool Telescope optical upper limits
  70. GRB 250610B: SVOM/VT optical shallow decay
  71. GRB 250610B: additional Liverpool Telescope optical observations
  72. GRB 250610B: SVOM/GRM analysis
  73. GRB 250610B: Fermi/GBM sub-threshold detection of a possibly hard burst
  74. GRB 250610B: EP-FXT follow-up observation and afterglow counterpart
  75. GRB 250610B: Swift-XRT counterpart detection
  76. GRB 250610B: SVOM/VT optical counterpart
  77. GRB 250610B: LT detection of the optical counterpart
  78. GRB 250610B: OHP/T120 optical counterpart candidate
  79. GRB 250610C: Fermi GBM Final Real-time Localization
  80. GRB 250610B: GOTO optical upper limit
  81. EP250610a: Global MASTER-Net observations report
  82. GRB 250610B : SVOM/GWAC-F60A and F50 observations
  83. GRB 250610B: SVOM detection of a long burst
  84. EP250610a: refined analysis of the EP-WXT and EP-FXT observations
  85. GRB 250610A: Fermi GBM Final Real-time Localization
  86. GRB 250605A: Swift-BAT refined analysis
  87. EP250610a: SVOM/VT optical upper limit
  88. EP250610a: REM optical/NIR observations
  89. GRB 250609A: Fermi GBM Observation
  90. GRBAlpha reentry on June 9, 2025
  91. EP250610a: Swift-XRT counterpart detection
  92. EP250610a: COLIBRÍ optical upper limit
  93. EP250610a: Einstein Probe detection of an X-ray transient
  94. Fermi trigger No 771072240: Global MASTER-Net observations report
  95. GRB 250609A: Swift/BAT-GUANO localization skymap of a likely short burst
  96. GRB 250605A: Swift/UVOT Upper Limits
  97. The EP-WXT trigger 01709178283 is likely a flaring star
  98. GRB 250608A: SVOM/GRM detection of a possible magnetar X-ray burst
  99. GRB 250529A: GOTO optical counterpart candidate (GOTO25dea/AT 2025ndt)
  100. GRB 250527C: CrAO Optical Upper Limit

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