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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"

41979 results found.

  1. EP250610a: TNG NIR upper limit
  2. GRB 250610B: REM optical/NIR observations
  3. EP250610a: Liverpool Telescope optical upper limits
  4. GRB 250610B: SVOM/VT optical shallow decay
  5. GRB 250610B: additional Liverpool Telescope optical observations
  6. GRB 250610B: SVOM/GRM analysis
  7. GRB 250610B: Fermi/GBM sub-threshold detection of a possibly hard burst
  8. GRB 250610B: EP-FXT follow-up observation and afterglow counterpart
  9. GRB 250610B: Swift-XRT counterpart detection
  10. GRB 250610B: SVOM/VT optical counterpart
  11. GRB 250610B: LT detection of the optical counterpart
  12. GRB 250610B: OHP/T120 optical counterpart candidate
  13. GRB 250610C: Fermi GBM Final Real-time Localization
  14. GRB 250610B: GOTO optical upper limit
  15. EP250610a: Global MASTER-Net observations report
  16. GRB 250610B : SVOM/GWAC-F60A and F50 observations
  17. GRB 250610B: SVOM detection of a long burst
  18. EP250610a: refined analysis of the EP-WXT and EP-FXT observations
  19. GRB 250610A: Fermi GBM Final Real-time Localization
  20. GRB 250605A: Swift-BAT refined analysis
  21. EP250610a: SVOM/VT optical upper limit
  22. EP250610a: REM optical/NIR observations
  23. GRB 250609A: Fermi GBM Observation
  24. GRBAlpha reentry on June 9, 2025
  25. EP250610a: Swift-XRT counterpart detection
  26. EP250610a: COLIBRÍ optical upper limit
  27. EP250610a: Einstein Probe detection of an X-ray transient
  28. Fermi trigger No 771072240: Global MASTER-Net observations report
  29. GRB 250609A: Swift/BAT-GUANO localization skymap of a likely short burst
  30. GRB 250605A: Swift/UVOT Upper Limits
  31. The EP-WXT trigger 01709178283 is likely a flaring star
  32. GRB 250608A: SVOM/GRM detection of a possible magnetar X-ray burst
  33. GRB 250529A: GOTO optical counterpart candidate (GOTO25dea/AT 2025ndt)
  34. GRB 250527C: CrAO Optical Upper Limit
  35. GRB 250609A: Fermi GBM Final Real-time Localization
  36. GRB 250607A: SVOM/GRM observation of a long burst
  37. EP-WXT trigger 01709178244: confirmation of a stellar flare by BOOTES-5 & BOOTES-7
  38. The EP-WXT trigger 01709178244 is likely a flaring star
  39. GRB 250607A: Fermi GBM Final Localization
  40. EP-WXT trigger 01709178069: confirmation of a stellar flare by BOOTES-6 & BOOTES-7
  41. The EP-WXT trigger 01709178069 is likely a flaring star
  42. GRB 250605A: SVOM/VT optical upper limit
  43. GRB 250605A: Swift-XRT refined Analysis
  44. EP/WXT 01709177873: GOTO observations confirm stellar variability
  45. GRB 250605A: Enhanced Swift-XRT position
  46. Fermi GRB 250606A: Global MASTER-Net observations report
  47. GRB 250606A: Fermi GBM Final Real-time Localization
  48. GRB 250602A: GECAM detection
  49. Fermi trigger No 770867684: Global MASTER-Net observations report
  50. The EP-WXT trigger 01709177873 is likely a flaring star
  51. GRB 250605A: LT optical observations
  52. GRB 250605A: Swift detection of a burst
  53. Swift GRB250605.79: Global MASTER-Net observations report
  54. Konus-Wind detection of GRB 250601A
  55. IPN triangulation of GRB 250529A
  56. The EP-WXT trigger 01709177837 is likely a flaring star
  57. GRB 250601A: PRIME H band upper limit.
  58. GRB 250530A: SVOM/GRM analysis
  59. GRB 250601A: PRIME J band upper limit.
  60. GRB 250601A: VLT/FORS2 Optical Observation
  61. GRB 250601A: Fermi GBM Observation
  62. GRB 250602A: DDOTI Optical Follow-Up of the Fermi/LAT Localization
  63. GRB 250603A: Swift/UVOT Upper Limits
  64. GRB 250603A: Swift-XRT refined Analysis
  65. Fermi trigger No 770638414: Global MASTER-Net observations report
  66. GRB 250603A: Enhanced Swift-XRT position
  67. GRB 250603A: Swift-XRT position and confirmation of GRB nature
  68. Swift GRB250603.05: Global MASTER-Net observations report
  69. GRB 250603A: Swift detection of a burst or new Galactic transient Swift J0839.7-3916
  70. GRB 250602A: Fermi GBM Observation
  71. GRB 250602A: Fermi-LAT detection
  72. GRB 250602A: DDOTI Optical Upper Limit
  73. GRB 250530C: Swift-BAT refined analysis
  74. GRB 250521C: NOT spectroscopic observations exclude the afterglow candidate AT2025mgj
  75. GRB 250601A: EP-FXT follow-up observation and afterglow candidates
  76. GRB 250601A: Swift/XRT candidate afterglow
  77. GRB 250521C / AT2025mgj: Pan-STARRS multi-band and multi-epoch imaging and photometry
  78. GRB 250601A: Swift-XRT observations
  79. Fermi GRB 250601A: Global MASTER-Net observations report
  80. GRB 250602A: Fermi GBM Final Real-time Localization
  81. Fermi trigger No 770470765: Global MASTER-Net observations report
  82. GRB 250601A: Swift/BAT-GUANO arcminute localization of a likely short burst
  83. GRB 250601A: Swift ToO observations
  84. GRB 250530A: VLT/HAWK-I NIR counterpart fading
  85. GRB 250521C/AT2025mgj: FTW optical and NIR observations
  86. GRB 250601A: Fermi GBM Final Real-time Localization
  87. EP#01709177494: SVOM/VT optical observations
  88. Fermi GRB 250531A: Global MASTER-Net observations report
  89. GRB 250531A: Fermi GBM Final Real-time Localization
  90. EP#01709177494: Swift-XRT counterpart detection of known source
  91. GRB 250521C/ZTF25aarhkyn/AT2025mgj: COLIBRÍ optical observations
  92. GRB 250530C: Swift-XRT refined Analysis
  93. GRB 250530A: TNG detection of a NIR source inside the Swift/XRT error circle
  94. Swift GRB 250530C: Global MASTER-Net observations report
  95. GRB 250530C: Enhanced Swift-XRT position
  96. GRB 250530C: Swift detection of a burst
  97. GRB 250521C/AT2025mgj: NOT optical observations of the afterglow candidate
  98. GRB 250530A: EP-FXT counterpart detection
  99. GRB 250530A: SVOM/VT optical upper limit
  100. GRB 250530B: Fermi GBM Final Real-time Localization

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