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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"

27174 results found.

  1. sb25061218: Swift-XRT observations
  2. EP250612a: refined analysis of the EP-WXT and EP-FXT observations
  3. GRB 250610B: J band upper limit by SYSU 80cm infrared telescope
  4. sb25061207: EP-FXT follow-up observation and afterglow candidate
  5. GRB 250612B: Fermi GBM Observation
  6. EP250612a: SVOM/VT optical candidate
  7. Fermi trigger No 771424081: Global MASTER-Net observations report
  8. EP250612a: Global MASTER-Net observations report
  9. GRB 250612C: Fermi GBM Observation
  10. sb25061218: SVOM detection of a X-ray transient
  11. sb25061207: Swift-XRT observations
  12. EP250612a/GRB 250612B: JinShan optical upper limit
  13. GRB 250612C: SVOM/GRM observation an intermedium duration burst
  14. sb25061207: SVOM/VT optical counterpart
  15. GRB 250612C: BALROG localization (Fermi Trigger 771432801 / GRB 250612620)
  16. GRB 250610B: Swift-XRT refined Analysis
  17. GRB 250612C: Fermi GBM Final Real-time Localization
  18. EP250610a: Upper limit from Fermi-GBM Observations
  19. GRB 250612B (250612519/771424081): Fermi GBM Final Localization
  20. GRB 250612B: BALROG localization (Fermi Trigger 771424081 / GRB 250612519)
  21. EP250612a: Einstein Probe detection of an X-ray transient
  22. GRB 250610B: Liverpool Telescope continued monitoring
  23. GRB 250610B: MISTRAL/T193 and T120 OHP further observations
  24. sb25061207: SVOM detection of a X-ray transient
  25. EP250610a: continuous follow-up observations with EP-FXT
  26. GRB 250610B - SVOM/ECLAIRs refined analysis
  27. GRB 250612A: Swift detection of a burst or new Galactic transient Swift J1643.6-3854
  28. Swift GRB250612.04: Global MASTER-Net observations report
  29. Fermi GBM Sub-Threshold Detection of GRB 250610B
  30. GRB 250610B: Swift/UVOT Detection
  31. EP250610A: Swift/UVOT Upper limits
  32. GRB 250610B: SVOM/COLIBRÍ (FM-GFT) optical observations
  33. GRB 250610B: REM optical/NIR observations
  34. GRB 250610B: SVOM/VT optical shallow decay
  35. GRB 250610B: additional Liverpool Telescope optical observations
  36. GRB 250610B: SVOM/GRM analysis
  37. GRB 250610B: Fermi/GBM sub-threshold detection of a possibly hard burst
  38. GRB 250610B: EP-FXT follow-up observation and afterglow counterpart
  39. Fermi Gamma-ray Burst Monitor trigger 771286888/250610932 is not a GRB
  40. GRB 250610B: Swift-XRT counterpart detection
  41. GRB 250610B: SVOM/VT optical counterpart
  42. GRB 250610B: LT detection of the optical counterpart
  43. GRB 250610B: OHP/T120 optical counterpart candidate
  44. GRB 250610C: Fermi GBM Final Real-time Localization
  45. GRB 250610B: GOTO optical upper limit
  46. EP250610a: Global MASTER-Net observations report
  47. GRB 250610B: SVOM detection of a long burst
  48. Fermi Gamma-ray Burst Monitor trigger 771256110/250610575 is not a GRB
  49. EP250610a: refined analysis of the EP-WXT and EP-FXT observations
  50. GRB 250610A: Fermi GBM Final Real-time Localization
  51. GRB 250605A: Swift-BAT refined analysis
  52. EP250610a: SVOM/VT optical upper limit
  53. EP250610a: REM optical/NIR observations
  54. GRB 250609A: Fermi GBM Observation
  55. EP250610a: Swift-XRT counterpart detection
  56. EP250610a: COLIBRÍ optical upper limit
  57. EP250610a: Einstein Probe detection of an X-ray transient
  58. Fermi trigger No 771072240: Global MASTER-Net observations report
  59. GRB 250609A: Swift/BAT-GUANO localization skymap of a likely short burst
  60. GRB 250605A: Swift/UVOT Upper Limits
  61. The EP-WXT trigger 01709178283 is likely a flaring star
  62. GRB 250608A: SVOM/GRM detection of a possible magnetar X-ray burst
  63. GRB 250529A: GOTO optical counterpart candidate (GOTO25dea/AT 2025ndt)
  64. GRB 250527C: CrAO Optical Upper Limit
  65. GRB 250609A: Fermi GBM Final Real-time Localization
  66. GRB 250607A: SVOM/GRM observation of a long burst
  67. EP-WXT trigger 01709178244: confirmation of a stellar flare by BOOTES-5 & BOOTES-7
  68. The EP-WXT trigger 01709178244 is likely a flaring star
  69. GRB 250607A: Fermi GBM Final Localization
  70. EP-WXT trigger 01709178069: confirmation of a stellar flare by BOOTES-6 & BOOTES-7
  71. The EP-WXT trigger 01709178069 is likely a flaring star
  72. GRB 250605A: SVOM/VT optical upper limit
  73. GRB 250605A: Swift-XRT refined Analysis
  74. EP/WXT 01709177873: GOTO observations confirm stellar variability
  75. Fermi GRB 250606A: Global MASTER-Net observations report
  76. GRB 250606A: Fermi GBM Final Real-time Localization
  77. Fermi Gamma-ray Burst Monitor trigger 770867684/250606080 is not a GRB
  78. Fermi Gamma-ray Burst Monitor trigger 770867684/250606080 is not a GRB
  79. GRB 250602A: GECAM detection
  80. Fermi trigger No 770867684: Global MASTER-Net observations report
  81. The EP-WXT trigger 01709177873 is likely a flaring star
  82. GRB 250605A: LT optical observations
  83. GRB 250605A: Swift detection of a burst
  84. Swift GRB250605.79: Global MASTER-Net observations report
  85. Konus-Wind detection of GRB 250601A
  86. The EP-WXT trigger 01709177837 is likely a flaring star
  87. Fermi Gamma-ray Burst Monitor trigger 770470765/250601486 is not a GRB
  88. GRB 250601A: PRIME H band upper limit.
  89. GRB 250530A: SVOM/GRM analysis
  90. GRB 250601A: PRIME J band upper limit.
  91. Fermi Gamma-ray Burst Monitor trigger 770675211/250603852 is not a GRB
  92. GRB 250601A: VLT/FORS2 Optical Observation
  93. GRB 250601A: Fermi GBM Observation
  94. GRB 250602A: DDOTI Optical Follow-Up of the Fermi/LAT Localization
  95. GRB 250603A: Swift/UVOT Upper Limits
  96. GRB 250603A: Swift-XRT refined Analysis
  97. Fermi trigger No 770638414: Global MASTER-Net observations report
  98. GRB 250603A: Swift-XRT position and confirmation of GRB nature
  99. Swift GRB250603.05: Global MASTER-Net observations report
  100. GRB 250603A: Swift detection of a burst or new Galactic transient Swift J0839.7-3916

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