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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"

43058 results found.

  1. sb25061207/SVOM: T120 OHP optical upper limit
  2. EP250615a/GRB 250615A: EP-WXT detection of a fast X-ray transient
  3. Fermi trigger No 771752663: Global MASTER-Net observations report
  4. EP-WXT trigger 01709178875: confirmation of a stellar flare by BOOTES-6
  5. The EP-WXT trigger 01709178875 is likely a flaring star
  6. GRB 250615A: Enhanced Swift-XRT position
  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. GRID detection of GRB 250612C
  12. sb25061207: Mephisto optical upper limits
  13. IceCube alert 141029_8144692 retraction
  14. GRB 250614A: Fermi GBM Final Real-time Localization
  15. EP250612a / GRB 250612B: NOT optical observations of the afterglow candidate
  16. sb25061218: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  17. sb25061207: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  18. Fermi trigger No 771494087: Global MASTER-Net observations report
  19. sb25061218: Swift-XRT observations
  20. EP250612a: refined analysis of the EP-WXT and EP-FXT observations
  21. GRB 250610B: J band upper limit by SYSU 80cm infrared telescope
  22. sb25061207: EP-FXT follow-up observation and afterglow candidate
  23. GRB 250612B: Fermi GBM Observation
  24. EP250612a / GRB 250612B: SVOM/VT optical candidate
  25. Fermi trigger No 771424081: Global MASTER-Net observations report
  26. EP250612a: Global MASTER-Net observations report
  27. GRB 250612C: Fermi GBM Observation
  28. sb25061218: SVOM detection of a X-ray transient
  29. sb25061207: Swift-XRT observations
  30. EP250612a/GRB 250612B: JinShan optical upper limit
  31. EP 250612a: AST3-3 Yaoan Optical Observation
  32. GRB 250612C: SVOM/GRM observation an intermedium duration burst
  33. sb25061207: SVOM/VT optical counterpart
  34. GRB 250612C: BALROG localization (Fermi Trigger 771432801 / GRB 250612620)
  35. GRB 250610B: Swift-XRT refined Analysis
  36. GRB 250612C: Fermi GBM Final Real-time Localization
  37. EP250610a: Upper limit from Fermi-GBM Observations
  38. GRB 250612B (250612519/771424081): Fermi GBM Final Localization
  39. GRB 250612B: BALROG localization (Fermi Trigger 771424081 / GRB 250612519)
  40. EP250612a: Einstein Probe detection of an X-ray transient
  41. GRB 250610B: Liverpool Telescope continued monitoring
  42. GRB 250610B: MISTRAL/T193 and T120 OHP further observations
  43. sb25061207: SVOM detection of a X-ray transient
  44. EP250610a: continuous follow-up observations with EP-FXT
  45. GRB 250610B - SVOM/ECLAIRs refined analysis
  46. GRB 250612A: Swift detection of a burst or new Galactic transient Swift J1643.6-3854
  47. Swift GRB250612.04: Global MASTER-Net observations report
  48. Fermi GBM Sub-Threshold Detection of GRB 250610B
  49. GRB 250610B: Swift/UVOT Detection
  50. GRB 250610B: SVOM/COLIBRÍ (FM-GFT) optical observations
  51. GRB 250610B: REM optical/NIR observations
  52. EP250610a: Liverpool Telescope optical upper limits
  53. GRB 250610B: SVOM/VT optical shallow decay
  54. GRB 250610B: additional Liverpool Telescope optical observations
  55. GRB 250610B: SVOM/GRM analysis
  56. GRB 250610B: Fermi/GBM sub-threshold detection of a possibly hard burst
  57. GRB 250610B: EP-FXT follow-up observation and afterglow counterpart
  58. GRB 250610B: Swift-XRT counterpart detection
  59. GRB 250610B: SVOM/VT optical counterpart
  60. GRB 250610B: LT detection of the optical counterpart
  61. GRB 250610B: OHP/T120 optical counterpart candidate
  62. GRB 250610C: Fermi GBM Final Real-time Localization
  63. GRB 250610B: GOTO optical upper limit
  64. EP250610a: Global MASTER-Net observations report
  65. GRB 250610B : SVOM/GWAC-F60A and F50 observations
  66. GRB 250610B: SVOM detection of a long burst
  67. EP250610a: refined analysis of the EP-WXT and EP-FXT observations
  68. GRB 250610A: Fermi GBM Final Real-time Localization
  69. GRB 250605A: Swift-BAT refined analysis
  70. EP250610a: SVOM/VT optical upper limit
  71. EP250610a: REM optical/NIR observations
  72. GRB 250609A: Fermi GBM Observation
  73. GRBAlpha reentry on June 9, 2025
  74. EP250610a: Swift-XRT counterpart detection
  75. EP250610a: COLIBRÍ optical upper limit
  76. EP250610a: Einstein Probe detection of an X-ray transient
  77. Fermi trigger No 771072240: Global MASTER-Net observations report
  78. GRB 250609A: Swift/BAT-GUANO localization skymap of a likely short burst
  79. GRB 250605A: Swift/UVOT Upper Limits
  80. The EP-WXT trigger 01709178283 is likely a flaring star
  81. GRB 250608A: SVOM/GRM detection of a possible magnetar X-ray burst
  82. GRB 250529A: GOTO optical counterpart candidate (GOTO25dea/AT 2025ndt)
  83. GRB 250527C: CrAO Optical Upper Limit
  84. GRB 250609A: Fermi GBM Final Real-time Localization
  85. GRB 250607A: SVOM/GRM observation of a long burst
  86. EP-WXT trigger 01709178244: confirmation of a stellar flare by BOOTES-5 & BOOTES-7
  87. The EP-WXT trigger 01709178244 is likely a flaring star
  88. GRB 250607A: Fermi GBM Final Localization
  89. EP-WXT trigger 01709178069: confirmation of a stellar flare by BOOTES-6 & BOOTES-7
  90. The EP-WXT trigger 01709178069 is likely a flaring star
  91. GRB 250605A: SVOM/VT optical upper limit
  92. GRB 250605A: Swift-XRT refined Analysis
  93. EP/WXT 01709177873: GOTO observations confirm stellar variability
  94. GRB 250605A: Enhanced Swift-XRT position
  95. Fermi GRB 250606A: Global MASTER-Net observations report
  96. GRB 250606A: Fermi GBM Final Real-time Localization
  97. GRB 250602A: GECAM detection
  98. Fermi trigger No 770867684: Global MASTER-Net observations report
  99. The EP-WXT trigger 01709177873 is likely a flaring star
  100. GRB 250605A: LT optical observations

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