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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"

42542 results found.

  1. sb25061207: Mephisto optical upper limits
  2. IceCube alert 141029_8144692 retraction
  3. GRB 250614A: Fermi GBM Final Real-time Localization
  4. EP250612a / GRB 250612B: NOT optical observations of the afterglow candidate
  5. sb25061218: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  6. sb25061207: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  7. Fermi trigger No 771494087: Global MASTER-Net observations report
  8. sb25061218: Swift-XRT observations
  9. EP250612a: refined analysis of the EP-WXT and EP-FXT observations
  10. GRB 250610B: J band upper limit by SYSU 80cm infrared telescope
  11. sb25061207: EP-FXT follow-up observation and afterglow candidate
  12. GRB 250612B: Fermi GBM Observation
  13. EP250612a / GRB 250612B: SVOM/VT optical candidate
  14. Fermi trigger No 771424081: Global MASTER-Net observations report
  15. EP250612a: Global MASTER-Net observations report
  16. GRB 250612C: Fermi GBM Observation
  17. sb25061218: SVOM detection of a X-ray transient
  18. sb25061207: Swift-XRT observations
  19. EP250612a/GRB 250612B: JinShan optical upper limit
  20. EP 250612a: AST3-3 Yaoan Optical Observation
  21. GRB 250612C: SVOM/GRM observation an intermedium duration burst
  22. sb25061207: SVOM/VT optical counterpart
  23. GRB 250612C: BALROG localization (Fermi Trigger 771432801 / GRB 250612620)
  24. GRB 250610B: Swift-XRT refined Analysis
  25. GRB 250612C: Fermi GBM Final Real-time Localization
  26. EP250610a: Upper limit from Fermi-GBM Observations
  27. GRB 250612B (250612519/771424081): Fermi GBM Final Localization
  28. GRB 250612B: BALROG localization (Fermi Trigger 771424081 / GRB 250612519)
  29. EP250612a: Einstein Probe detection of an X-ray transient
  30. GRB 250610B: Liverpool Telescope continued monitoring
  31. GRB 250610B: MISTRAL/T193 and T120 OHP further observations
  32. sb25061207: SVOM detection of a X-ray transient
  33. EP250610a: continuous follow-up observations with EP-FXT
  34. GRB 250610B - SVOM/ECLAIRs refined analysis
  35. GRB 250612A: Swift detection of a burst or new Galactic transient Swift J1643.6-3854
  36. Swift GRB250612.04: Global MASTER-Net observations report
  37. Fermi GBM Sub-Threshold Detection of GRB 250610B
  38. GRB 250610B: Swift/UVOT Detection
  39. EP250610A: Swift/UVOT Upper limits
  40. GRB 250610B: SVOM/COLIBRÍ (FM-GFT) optical observations
  41. EP250610a: TNG NIR upper limit
  42. GRB 250610B: REM optical/NIR observations
  43. EP250610a: Liverpool Telescope optical upper limits
  44. GRB 250610B: SVOM/VT optical shallow decay
  45. GRB 250610B: additional Liverpool Telescope optical observations
  46. GRB 250610B: SVOM/GRM analysis
  47. GRB 250610B: Fermi/GBM sub-threshold detection of a possibly hard burst
  48. GRB 250610B: EP-FXT follow-up observation and afterglow counterpart
  49. GRB 250610B: Swift-XRT counterpart detection
  50. GRB 250610B: SVOM/VT optical counterpart
  51. GRB 250610B: LT detection of the optical counterpart
  52. GRB 250610B: OHP/T120 optical counterpart candidate
  53. GRB 250610C: Fermi GBM Final Real-time Localization
  54. GRB 250610B: GOTO optical upper limit
  55. EP250610a: Global MASTER-Net observations report
  56. GRB 250610B : SVOM/GWAC-F60A and F50 observations
  57. GRB 250610B: SVOM detection of a long burst
  58. EP250610a: refined analysis of the EP-WXT and EP-FXT observations
  59. GRB 250610A: Fermi GBM Final Real-time Localization
  60. GRB 250605A: Swift-BAT refined analysis
  61. EP250610a: SVOM/VT optical upper limit
  62. EP250610a: REM optical/NIR observations
  63. GRB 250609A: Fermi GBM Observation
  64. GRBAlpha reentry on June 9, 2025
  65. EP250610a: Swift-XRT counterpart detection
  66. EP250610a: COLIBRÍ optical upper limit
  67. EP250610a: Einstein Probe detection of an X-ray transient
  68. Fermi trigger No 771072240: Global MASTER-Net observations report
  69. GRB 250609A: Swift/BAT-GUANO localization skymap of a likely short burst
  70. GRB 250605A: Swift/UVOT Upper Limits
  71. The EP-WXT trigger 01709178283 is likely a flaring star
  72. GRB 250608A: SVOM/GRM detection of a possible magnetar X-ray burst
  73. GRB 250529A: GOTO optical counterpart candidate (GOTO25dea/AT 2025ndt)
  74. GRB 250527C: CrAO Optical Upper Limit
  75. GRB 250609A: Fermi GBM Final Real-time Localization
  76. GRB 250607A: SVOM/GRM observation of a long burst
  77. The EP-WXT trigger 01709178244 is likely a flaring star
  78. GRB 250607A: Fermi GBM Final Localization
  79. The EP-WXT trigger 01709178069 is likely a flaring star
  80. GRB 250605A: SVOM/VT optical upper limit
  81. GRB 250605A: Swift-XRT refined Analysis
  82. EP/WXT 01709177873: GOTO observations confirm stellar variability
  83. GRB 250605A: Enhanced Swift-XRT position
  84. Fermi GRB 250606A: Global MASTER-Net observations report
  85. GRB 250606A: Fermi GBM Final Real-time Localization
  86. GRB 250602A: GECAM detection
  87. Fermi trigger No 770867684: Global MASTER-Net observations report
  88. The EP-WXT trigger 01709177873 is likely a flaring star
  89. GRB 250605A: LT optical observations
  90. GRB 250605A: Swift detection of a burst
  91. Swift GRB250605.79: Global MASTER-Net observations report
  92. Konus-Wind detection of GRB 250601A
  93. IPN triangulation of GRB 250529A
  94. The EP-WXT trigger 01709177837 is likely a flaring star
  95. GRB 250601A: PRIME H band upper limit.
  96. GRB 250530A: SVOM/GRM analysis
  97. GRB 250601A: PRIME J band upper limit.
  98. GRB 250601A: VLT/FORS2 Optical Observation
  99. GRB 250601A: Fermi GBM Observation
  100. GRB 250602A: DDOTI Optical Follow-Up of the Fermi/LAT Localization

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