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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"

43909 results found.

  1. GRB 250612C: SVOM/GRM observation an intermedium duration burst
  2. sb25061207: SVOM/VT optical counterpart
  3. GRB 250612C: BALROG localization (Fermi Trigger 771432801 / GRB 250612620)
  4. GRB 250610B: Swift-XRT refined Analysis
  5. GRB 250612C: Fermi GBM Final Real-time Localization
  6. EP250610a: Upper limit from Fermi-GBM Observations
  7. GRB 250612B (250612519/771424081): Fermi GBM Final Localization
  8. GRB 250612B: BALROG localization (Fermi Trigger 771424081 / GRB 250612519)
  9. EP250612a: Einstein Probe detection of an X-ray transient
  10. GRB 250610B: Liverpool Telescope continued monitoring
  11. GRB 250610B: MISTRAL/T193 and T120 OHP further observations
  12. sb25061207: SVOM detection of a X-ray transient
  13. EP250610a: continuous follow-up observations with EP-FXT
  14. GRB 250610B - SVOM/ECLAIRs refined analysis
  15. GRB 250612A: Swift detection of a burst or new Galactic transient Swift J1643.6-3854
  16. Swift GRB250612.04: Global MASTER-Net observations report
  17. Fermi GBM Sub-Threshold Detection of GRB 250610B
  18. GRB 250610B: SVOM/COLIBRÍ (FM-GFT) optical observations
  19. EP250610a: TNG NIR upper limit
  20. GRB 250610B: REM optical/NIR observations
  21. EP250610a: Liverpool Telescope optical upper limits
  22. GRB 250610B: SVOM/VT optical shallow decay
  23. GRB 250610B: additional Liverpool Telescope optical observations
  24. GRB 250610B: SVOM/GRM analysis
  25. GRB 250610B: Fermi/GBM sub-threshold detection of a possibly hard burst
  26. GRB 250610B: EP-FXT follow-up observation and afterglow counterpart
  27. Fermi Gamma-ray Burst Monitor trigger 771286888/250610932 is not a GRB
  28. GRB 250610B: Swift-XRT counterpart detection
  29. GRB 250610B: SVOM/VT optical counterpart
  30. GRB 250610B: LT detection of the optical counterpart
  31. GRB 250610B: OHP/T120 optical counterpart candidate
  32. GRB 250610C: Fermi GBM Final Real-time Localization
  33. GRB 250610B: GOTO optical upper limit
  34. EP250610a: Global MASTER-Net observations report
  35. GRB 250610B : SVOM/GWAC-F60A and F50 observations
  36. GRB 250610B: SVOM detection of a long burst
  37. Fermi Gamma-ray Burst Monitor trigger 771256110/250610575 is not a GRB
  38. EP250610a: refined analysis of the EP-WXT and EP-FXT observations
  39. GRB 250610A: Fermi GBM Final Real-time Localization
  40. GRB 250605A: Swift-BAT refined analysis
  41. EP250610a: SVOM/VT optical upper limit
  42. EP250610a: REM optical/NIR observations
  43. GRB 250609A: Fermi GBM Observation
  44. GRBAlpha reentry on June 9, 2025
  45. EP250610a: Swift-XRT counterpart detection
  46. EP250610a: COLIBRÍ optical upper limit
  47. EP250610a: Einstein Probe detection of an X-ray transient
  48. Fermi trigger No 771072240: Global MASTER-Net observations report
  49. GRB 250609A: Swift/BAT-GUANO localization skymap of a likely short burst
  50. The EP-WXT trigger 01709178283 is likely a flaring star
  51. GRB 250608A: SVOM/GRM detection of a possible magnetar X-ray burst
  52. GRB 250529A: GOTO optical counterpart candidate (GOTO25dea/AT 2025ndt)
  53. GRB 250527C: CrAO Optical Upper Limit
  54. GRB 250609A: Fermi GBM Final Real-time Localization
  55. GRB 250607A: SVOM/GRM observation of a long burst
  56. EP-WXT trigger 01709178244: confirmation of a stellar flare by BOOTES-5 & BOOTES-7
  57. The EP-WXT trigger 01709178244 is likely a flaring star
  58. GRB 250607A: Fermi GBM Final Localization
  59. EP-WXT trigger 01709178069: confirmation of a stellar flare by BOOTES-6 & BOOTES-7
  60. The EP-WXT trigger 01709178069 is likely a flaring star
  61. GRB 250605A: SVOM/VT optical upper limit
  62. GRB 250605A: Swift-XRT refined Analysis
  63. EP/WXT 01709177873: GOTO observations confirm stellar variability
  64. GRB 250605A: Enhanced Swift-XRT position
  65. Fermi GRB 250606A: Global MASTER-Net observations report
  66. GRB 250606A: Fermi GBM Final Real-time Localization
  67. Fermi Gamma-ray Burst Monitor trigger 770867684/250606080 is not a GRB
  68. Fermi Gamma-ray Burst Monitor trigger 770867684/250606080 is not a GRB
  69. GRB 250602A: GECAM detection
  70. Fermi trigger No 770867684: Global MASTER-Net observations report
  71. The EP-WXT trigger 01709177873 is likely a flaring star
  72. GRB 250605A: LT optical observations
  73. GRB 250605A: Swift detection of a burst
  74. Swift GRB250605.79: Global MASTER-Net observations report
  75. Konus-Wind detection of GRB 250601A
  76. IPN triangulation of GRB 250404B
  77. IPN triangulation of GRB 250529A
  78. The EP-WXT trigger 01709177837 is likely a flaring star
  79. Fermi Gamma-ray Burst Monitor trigger 770470765/250601486 is not a GRB
  80. GRB 250601A: PRIME H band upper limit.
  81. GRB 250530A: SVOM/GRM analysis
  82. GRB 250601A: PRIME J band upper limit.
  83. Fermi Gamma-ray Burst Monitor trigger 770675211/250603852 is not a GRB
  84. GRB 250601A: Fermi GBM Observation
  85. GRB 250602A: DDOTI Optical Follow-Up of the Fermi/LAT Localization
  86. GRB 250603A: Swift-XRT refined Analysis
  87. Fermi trigger No 770638414: Global MASTER-Net observations report
  88. GRB 250603A: Enhanced Swift-XRT position
  89. GRB 250603A: Swift-XRT position and confirmation of GRB nature
  90. Swift GRB250603.05: Global MASTER-Net observations report
  91. GRB 250603A: Swift detection of a burst or new Galactic transient Swift J0839.7-3916
  92. GRB 250602A: Fermi GBM Observation
  93. GRB 250602A: Fermi-LAT detection
  94. GRB 250602A: DDOTI Optical Upper Limit
  95. GRB 250530C: Swift-BAT refined analysis
  96. GRB 250521C: NOT spectroscopic observations exclude the afterglow candidate AT2025mgj
  97. GRB 250601A: EP-FXT follow-up observation and afterglow candidates
  98. GRB 250601A: Swift/XRT candidate afterglow
  99. GRB 250521C / AT2025mgj: Pan-STARRS multi-band and multi-epoch imaging and photometry
  100. GRB 250601A: Swift-XRT observations

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