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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"

42538 results found.

  1. sb25061218: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  2. sb25061207: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  3. Fermi trigger No 771494087: Global MASTER-Net observations report
  4. sb25061218: Swift-XRT observations
  5. EP250612a: refined analysis of the EP-WXT and EP-FXT observations
  6. GRB 250610B: J band upper limit by SYSU 80cm infrared telescope
  7. sb25061207: EP-FXT follow-up observation and afterglow candidate
  8. GRB 250612B: Fermi GBM Observation
  9. EP250612a / GRB 250612B: SVOM/VT optical candidate
  10. Fermi trigger No 771424081: Global MASTER-Net observations report
  11. EP250612a: Global MASTER-Net observations report
  12. GRB 250612C: Fermi GBM Observation
  13. sb25061218: SVOM detection of a X-ray transient
  14. sb25061207: Swift-XRT observations
  15. EP250612a/GRB 250612B: JinShan optical upper limit
  16. EP 250612a: AST3-3 Yaoan Optical Observation
  17. GRB 250612C: SVOM/GRM observation an intermedium duration burst
  18. sb25061207: SVOM/VT optical counterpart
  19. GRB 250612C: BALROG localization (Fermi Trigger 771432801 / GRB 250612620)
  20. GRB 250610B: Swift-XRT refined Analysis
  21. GRB 250612C: Fermi GBM Final Real-time Localization
  22. EP250610a: Upper limit from Fermi-GBM Observations
  23. GRB 250612B (250612519/771424081): Fermi GBM Final Localization
  24. GRB 250612B: BALROG localization (Fermi Trigger 771424081 / GRB 250612519)
  25. EP250612a: Einstein Probe detection of an X-ray transient
  26. GRB 250610B: Liverpool Telescope continued monitoring
  27. GRB 250610B: MISTRAL/T193 and T120 OHP further observations
  28. sb25061207: SVOM detection of a X-ray transient
  29. EP250610a: continuous follow-up observations with EP-FXT
  30. GRB 250610B - SVOM/ECLAIRs refined analysis
  31. GRB 250612A: Swift detection of a burst or new Galactic transient Swift J1643.6-3854
  32. Swift GRB250612.04: Global MASTER-Net observations report
  33. Fermi GBM Sub-Threshold Detection of GRB 250610B
  34. GRB 250610B: Swift/UVOT Detection
  35. EP250610A: Swift/UVOT Upper limits
  36. GRB 250610B: SVOM/COLIBRÍ (FM-GFT) optical observations
  37. EP250610a: TNG NIR upper limit
  38. GRB 250610B: REM optical/NIR observations
  39. EP250610a: Liverpool Telescope optical upper limits
  40. GRB 250610B: SVOM/VT optical shallow decay
  41. GRB 250610B: additional Liverpool Telescope optical observations
  42. GRB 250610B: SVOM/GRM analysis
  43. GRB 250610B: Fermi/GBM sub-threshold detection of a possibly hard burst
  44. GRB 250610B: EP-FXT follow-up observation and afterglow counterpart
  45. GRB 250610B: Swift-XRT counterpart detection
  46. GRB 250610B: SVOM/VT optical counterpart
  47. GRB 250610B: LT detection of the optical counterpart
  48. GRB 250610B: OHP/T120 optical counterpart candidate
  49. GRB 250610C: Fermi GBM Final Real-time Localization
  50. GRB 250610B: GOTO optical upper limit
  51. EP250610a: Global MASTER-Net observations report
  52. GRB 250610B : SVOM/GWAC-F60A and F50 observations
  53. GRB 250610B: SVOM detection of a long burst
  54. EP250610a: refined analysis of the EP-WXT and EP-FXT observations
  55. GRB 250610A: Fermi GBM Final Real-time Localization
  56. GRB 250605A: Swift-BAT refined analysis
  57. EP250610a: SVOM/VT optical upper limit
  58. EP250610a: REM optical/NIR observations
  59. GRB 250609A: Fermi GBM Observation
  60. GRBAlpha reentry on June 9, 2025
  61. EP250610a: Swift-XRT counterpart detection
  62. EP250610a: COLIBRÍ optical upper limit
  63. EP250610a: Einstein Probe detection of an X-ray transient
  64. Fermi trigger No 771072240: Global MASTER-Net observations report
  65. GRB 250609A: Swift/BAT-GUANO localization skymap of a likely short burst
  66. GRB 250605A: Swift/UVOT Upper Limits
  67. The EP-WXT trigger 01709178283 is likely a flaring star
  68. GRB 250608A: SVOM/GRM detection of a possible magnetar X-ray burst
  69. GRB 250529A: GOTO optical counterpart candidate (GOTO25dea/AT 2025ndt)
  70. GRB 250527C: CrAO Optical Upper Limit
  71. GRB 250609A: Fermi GBM Final Real-time Localization
  72. GRB 250607A: SVOM/GRM observation of a long burst
  73. The EP-WXT trigger 01709178244 is likely a flaring star
  74. GRB 250607A: Fermi GBM Final Localization
  75. The EP-WXT trigger 01709178069 is likely a flaring star
  76. GRB 250605A: SVOM/VT optical upper limit
  77. GRB 250605A: Swift-XRT refined Analysis
  78. EP/WXT 01709177873: GOTO observations confirm stellar variability
  79. GRB 250605A: Enhanced Swift-XRT position
  80. Fermi GRB 250606A: Global MASTER-Net observations report
  81. GRB 250606A: Fermi GBM Final Real-time Localization
  82. GRB 250602A: GECAM detection
  83. Fermi trigger No 770867684: Global MASTER-Net observations report
  84. The EP-WXT trigger 01709177873 is likely a flaring star
  85. GRB 250605A: LT optical observations
  86. GRB 250605A: Swift detection of a burst
  87. Swift GRB250605.79: Global MASTER-Net observations report
  88. Konus-Wind detection of GRB 250601A
  89. IPN triangulation of GRB 250529A
  90. The EP-WXT trigger 01709177837 is likely a flaring star
  91. GRB 250601A: PRIME H band upper limit.
  92. GRB 250530A: SVOM/GRM analysis
  93. GRB 250601A: PRIME J band upper limit.
  94. GRB 250601A: VLT/FORS2 Optical Observation
  95. GRB 250601A: Fermi GBM Observation
  96. GRB 250602A: DDOTI Optical Follow-Up of the Fermi/LAT Localization
  97. GRB 250603A: Swift/UVOT Upper Limits
  98. GRB 250603A: Swift-XRT refined Analysis
  99. Fermi trigger No 770638414: Global MASTER-Net observations report
  100. GRB 250603A: Enhanced Swift-XRT position

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