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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"

45721 results found.

  1. EP250615a/GRB 250615A: EP-WXT detection of a fast X-ray transient
  2. Fermi trigger No 771752663: Global MASTER-Net observations report
  3. EP-WXT trigger 01709178875: confirmation of a stellar flare by BOOTES-6
  4. The EP-WXT trigger 01709178875 is likely a flaring star
  5. GRB 250615A: Enhanced Swift-XRT position
  6. Fermi Gamma-ray Burst Monitor trigger 771718064/250615922 is not a GRB
  7. GRB 250615A: Prompt enhanced Swift-XRT position
  8. GRB 250615A: Swift detection of a burst
  9. Swift GRB 250615A: Global MASTER-Net observations report
  10. Fermi trigger No 771718064: Global MASTER-Net observations report
  11. Fermi Gamma-ray Burst Monitor trigger 771704505/250615765 is not a GRB
  12. GRID detection of GRB 250612C
  13. sb25061207: Mephisto optical upper limits
  14. IceCube alert 141029_8144692 retraction
  15. Fermi Gamma-ray Burst Monitor trigger 771596290/250614513 is not a GRB
  16. GRB 250614A: Fermi GBM Final Real-time Localization
  17. EP250612a / GRB 250612B: NOT optical observations of the afterglow candidate
  18. Fermi Gamma-ray Burst Monitor trigger 771547945/250613953 is not a GRB
  19. Fermi Gamma-ray Burst Monitor trigger 771541927/250613883 is not a GRB
  20. sb25061218: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  21. sb25061207: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  22. Fermi trigger No 771494087: Global MASTER-Net observations report
  23. sb25061218: Swift-XRT observations
  24. EP250612a: refined analysis of the EP-WXT and EP-FXT observations
  25. GRB 250610B: J band upper limit by SYSU 80cm infrared telescope
  26. sb25061207: EP-FXT follow-up observation and afterglow candidate
  27. GRB 250612B: Fermi GBM Observation
  28. EP250612a / GRB 250612B: SVOM/VT optical candidate
  29. Fermi trigger No 771424081: Global MASTER-Net observations report
  30. EP250612a: Global MASTER-Net observations report
  31. GRB 250612C: Fermi GBM Observation
  32. sb25061218: SVOM detection of a X-ray transient
  33. sb25061207: Swift-XRT observations
  34. EP250612a/GRB 250612B: JinShan optical upper limit
  35. EP 250612a: AST3-3 Yaoan Optical Observation
  36. GRB 250612C: SVOM/GRM observation an intermedium duration burst
  37. sb25061207: SVOM/VT optical counterpart
  38. GRB 250612C: BALROG localization (Fermi Trigger 771432801 / GRB 250612620)
  39. GRB 250610B: Swift-XRT refined Analysis
  40. GRB 250612C: Fermi GBM Final Real-time Localization
  41. EP250610a: Upper limit from Fermi-GBM Observations
  42. GRB 250612B (250612519/771424081): Fermi GBM Final Localization
  43. GRB 250612B: BALROG localization (Fermi Trigger 771424081 / GRB 250612519)
  44. EP250612a: Einstein Probe detection of an X-ray transient
  45. GRB 250610B: Liverpool Telescope continued monitoring
  46. GRB 250610B: MISTRAL/T193 and T120 OHP further observations
  47. sb25061207: SVOM detection of a X-ray transient
  48. EP250610a: continuous follow-up observations with EP-FXT
  49. GRB 250610B - SVOM/ECLAIRs refined analysis
  50. GRB 250612A: Swift detection of a burst or new Galactic transient Swift J1643.6-3854
  51. Swift GRB250612.04: Global MASTER-Net observations report
  52. Fermi GBM Sub-Threshold Detection of GRB 250610B
  53. GRB 250610B: Swift/UVOT Detection
  54. EP250610A: Swift/UVOT Upper limits
  55. GRB 250610B: SVOM/COLIBRÍ (FM-GFT) optical observations
  56. EP250610a: TNG NIR upper limit
  57. GRB 250610B: REM optical/NIR observations
  58. EP250610a: Liverpool Telescope optical upper limits
  59. GRB 250610B: SVOM/VT optical shallow decay
  60. GRB 250610B: additional Liverpool Telescope optical observations
  61. GRB 250610B: SVOM/GRM analysis
  62. GRB 250610B: Fermi/GBM sub-threshold detection of a possibly hard burst
  63. GRB 250610B: EP-FXT follow-up observation and afterglow counterpart
  64. Fermi Gamma-ray Burst Monitor trigger 771286888/250610932 is not a GRB
  65. GRB 250610B: Swift-XRT counterpart detection
  66. GRB 250610B: SVOM/VT optical counterpart
  67. GRB 250610B: LT detection of the optical counterpart
  68. GRB 250610B: OHP/T120 optical counterpart candidate
  69. GRB 250610C: Fermi GBM Final Real-time Localization
  70. GRB 250610B: GOTO optical upper limit
  71. EP250610a: Global MASTER-Net observations report
  72. GRB 250610B : SVOM/GWAC-F60A and F50 observations
  73. GRB 250610B: SVOM detection of a long burst
  74. Fermi Gamma-ray Burst Monitor trigger 771256110/250610575 is not a GRB
  75. EP250610a: refined analysis of the EP-WXT and EP-FXT observations
  76. GRB 250610A: Fermi GBM Final Real-time Localization
  77. GRB 250605A: Swift-BAT refined analysis
  78. EP250610a: SVOM/VT optical upper limit
  79. EP250610a: REM optical/NIR observations
  80. GRB 250609A: Fermi GBM Observation
  81. GRBAlpha reentry on June 9, 2025
  82. EP250610a: Swift-XRT counterpart detection
  83. EP250610a: COLIBRÍ optical upper limit
  84. EP250610a: Einstein Probe detection of an X-ray transient
  85. Fermi trigger No 771072240: Global MASTER-Net observations report
  86. GRB 250609A: Swift/BAT-GUANO localization skymap of a likely short burst
  87. GRB 250605A: Swift/UVOT Upper Limits
  88. The EP-WXT trigger 01709178283 is likely a flaring star
  89. GRB 250608A: SVOM/GRM detection of a possible magnetar X-ray burst
  90. GRB 250529A: GOTO optical counterpart candidate (GOTO25dea/AT 2025ndt)
  91. GRB 250527C: CrAO Optical Upper Limit
  92. GRB 250609A: Fermi GBM Final Real-time Localization
  93. GRB 250607A: SVOM/GRM observation of a long burst
  94. EP-WXT trigger 01709178244: confirmation of a stellar flare by BOOTES-5 & BOOTES-7
  95. The EP-WXT trigger 01709178244 is likely a flaring star
  96. GRB 250607A: Fermi GBM Final Localization
  97. EP-WXT trigger 01709178069: confirmation of a stellar flare by BOOTES-6 & BOOTES-7
  98. The EP-WXT trigger 01709178069 is likely a flaring star
  99. GRB 250605A: SVOM/VT optical upper limit
  100. GRB 250605A: Swift-XRT refined Analysis

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