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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"

26719 results found.

  1. The EP-WXT trigger 01709178283 is likely a flaring star
  2. GRB 250608A: SVOM/GRM detection of a possible magnetar X-ray burst
  3. GRB 250527C: CrAO Optical Upper Limit
  4. GRB 250607A: SVOM/GRM observation of a long burst
  5. The EP-WXT trigger 01709178244 is likely a flaring star
  6. EP-WXT trigger 01709178069: confirmation of a stellar flare by BOOTES-6 & BOOTES-7
  7. The EP-WXT trigger 01709178069 is likely a flaring star
  8. GRB 250605A: Swift-XRT refined Analysis
  9. GRB 250605A: Enhanced Swift-XRT position
  10. The EP-WXT trigger 01709177873 is likely a flaring star
  11. GRB 250605A: LT optical observations
  12. GRB 250605A: Swift detection of a burst
  13. Konus-Wind detection of GRB 250601A
  14. IPN triangulation of GRB 250404B
  15. IPN triangulation of GRB 250529A
  16. The EP-WXT trigger 01709177837 is likely a flaring star
  17. GRB 250601A: PRIME H band upper limit.
  18. GRB 250530A: SVOM/GRM analysis
  19. GRB 250601A: PRIME J band upper limit.
  20. GRB 250601A: VLT/FORS2 Optical Observation
  21. GRB 250601A: Fermi GBM Observation
  22. GRB 250602A: DDOTI Optical Follow-Up of the Fermi/LAT Localization
  23. GRB 250603A: Swift/UVOT Upper Limits
  24. GRB 250603A: Swift-XRT refined Analysis
  25. GRB 250603A: Enhanced Swift-XRT position
  26. GRB 250603A: Swift-XRT position and confirmation of GRB nature
  27. Swift GRB250603.05: Global MASTER-Net observations report
  28. GRB 250603A: Swift detection of a burst or new Galactic transient Swift J0839.7-3916
  29. GRB 250602A: Fermi GBM Observation
  30. GRB 250602A: DDOTI Optical Upper Limit
  31. GRB 250601A: EP-FXT follow-up observation and afterglow candidates
  32. GRB 250601A: Swift/XRT candidate afterglow
  33. GRB 250601A: Swift-XRT observations
  34. GRB 250602A: Fermi GBM Final Real-time Localization
  35. EP#01709177494: SVOM/VT optical observations
  36. EP#01709177494: Swift-XRT counterpart detection of known source
  37. GRB 250521C/ZTF25aarhkyn/AT2025mgj: COLIBRÍ optical observations
  38. GRB 250530C: Swift-XRT refined Analysis
  39. GRB 250530A: TNG detection of a NIR source inside the Swift/XRT error circle
  40. GRB 250530C: Enhanced Swift-XRT position
  41. GRB 250530C: Swift detection of a burst
  42. GRB 250530A: EP-FXT counterpart detection
  43. GRB 250530A: SVOM/VT optical upper limit
  44. GRB 250530A: Swift-XRT counterpart detection
  45. GRB 250530A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate retraction and detection limit
  46. GRB 250530A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  47. GRB 250530A: SVOM detection of a burst
  48. GRB 250527C: Swift/UVOT Upper Limits
  49. GRB 250527D: Swift/BAT-GUANO localization skymap of a burst
  50. EP J1350.0-8622: EP-FXT follow-up observation
  51. GRB 250527B: Swift-XRT observations
  52. EP-WXT trigger 01709177124: confirmation of a stellar flare by BOOTES-6
  53. The EP-WXT trigger 01709177124 is likely a flaring star
  54. GRB 250521D: SVOM/GRM analysis suggests a possible “long” duration type I burst
  55. GRB 250527A: Fermi GBM Final Localization
  56. EP250526a: refined analysis of the EP-WXT and EP-FXT observations
  57. GRB 250314A: CIDER NB1008 upper limit
  58. EP250526a: COLIBRÍ optical upper limits
  59. EP250526a: Einstein Probe detection of a fast X-ray transient
  60. EP J1350.0-8622: Einstein Probe detection of an X-ray transient candidate
  61. EP-WXT trigger 01709176712: SVOM/C-GFT observations of blue-to-red color variation
  62. GRB 250520A: 3 GHz MeerKAT Detection
  63. The EP-WXT trigger 01709176712 is likely a flaring star
  64. The EP-WXT trigger 01709176612: SVOM/VT optical observations
  65. GRB 250521B: EP-FXT follow-up observation and afterglow candidates
  66. EP#01709176612: Swift-XRT counterpart detection of flaring star
  67. GRB 250521D: DDOTI Optical Upper Limit
  68. The EP-WXT trigger 01709176612 is likely a flaring star
  69. GRB 250521B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  70. GRB 250521D: LAST tentative optical counterpart candidate
  71. GRB 250520A: 10 GHz VLA radio source
  72. GRB 250521A: DDOTI Optical Upper Limit
  73. Konus-Wind detection of GRB 250520A (short/hard)
  74. GRB 250520A: VLT/FORS2 Optical Observation
  75. GRB 250502A: Tautenburg observations
  76. GRB 250520A: Swift/UVOT Upper Limits
  77. IPN triangulation of GRB 250516B
  78. GRB 250520A: J-band observations with WINTER
  79. GRB 250520A: Gemini-South optical observations
  80. GRB 250520A: Swift-XRT refined Analysis
  81. GRB 250520A: REM optical/NIR early observations
  82. GRB 250520A：SVOM/VT optical candidate
  83. GRB 250520A: COLIBRÍ optical upper limit
  84. GRB 250520A: DDOTI Optical Upper Limit
  85. GRB 250520A: SVOM/GRM observation
  86. GRB 250520A: Enhanced Swift-XRT position
  87. GRB 250520A: Swift detection of a burst
  88. GRB 250516A: COLIBRÍ optical upper limit
  89. Konus-Wind detection of GRB 250516A
  90. EP-WXT trigger (ID: 01709176312): a new X-ray outburst of HMXB RX J0111.2-7317
  91. GRB 250515A: Swift-XRT observations
  92. GRB 250515A:COLIBRÍ optical observations of the GOTO candidate
  93. GRB 250515A: 1.6m Mephisto optical detection
  94. GRB 250516A: Fermi GBM Observation
  95. GRB 250516A: Swift-XRT refined Analysis
  96. GRB 250516A: Swift/UVOT Detection
  97. GRB 250516B: GECAM-B detection of a bright long burst
  98. GRB 250516A: Enhanced Swift-XRT position
  99. GRB 250516A: Swift detection of a burst
  100. GRB 250512B / EP250512a: SVOM/GRM analysis

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