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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"

18512 results found.

  1. GRB 250607A: SVOM/GRM observation of a long burst
  2. The EP-WXT trigger 01709178244 is likely a flaring star
  3. The EP-WXT trigger 01709178069 is likely a flaring star
  4. GRB 250605A: Enhanced Swift-XRT position
  5. The EP-WXT trigger 01709177873 is likely a flaring star
  6. GRB 250605A: Swift detection of a burst
  7. IPN triangulation of GRB 250404B
  8. IPN triangulation of GRB 250529A
  9. The EP-WXT trigger 01709177837 is likely a flaring star
  10. GRB 250601A: PRIME H band upper limit.
  11. GRB 250601A: PRIME J band upper limit.
  12. GRB 250601A: VLT/FORS2 Optical Observation
  13. GRB 250602A: DDOTI Optical Follow-Up of the Fermi/LAT Localization
  14. GRB 250603A: Swift/UVOT Upper Limits
  15. GRB 250603A: Enhanced Swift-XRT position
  16. GRB 250603A: Swift-XRT position and confirmation of GRB nature
  17. GRB 250603A: Swift detection of a burst or new Galactic transient Swift J0839.7-3916
  18. GRB 250602A: DDOTI Optical Upper Limit
  19. GRB 250601A: EP-FXT follow-up observation and afterglow candidates
  20. EP#01709177494: SVOM/VT optical observations
  21. GRB 250521C/ZTF25aarhkyn/AT2025mgj: COLIBRÍ optical observations
  22. GRB 250530C: Swift-XRT refined Analysis
  23. GRB 250530A: TNG detection of a NIR source inside the Swift/XRT error circle
  24. GRB 250530C: Enhanced Swift-XRT position
  25. GRB 250530C: Swift detection of a burst
  26. GRB 250530A: EP-FXT counterpart detection
  27. GRB 250530A: SVOM/VT optical upper limit
  28. GRB 250530A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate retraction and detection limit
  29. GRB 250530A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  30. GRB 250530A: SVOM detection of a burst
  31. GRB 250527C: Swift/UVOT Upper Limits
  32. GRB 250527D: Swift/BAT-GUANO localization skymap of a burst
  33. EP J1350.0-8622: EP-FXT follow-up observation
  34. GRB 250527B: Swift-XRT observations
  35. The EP-WXT trigger 01709177124 is likely a flaring star
  36. EP250526a: refined analysis of the EP-WXT and EP-FXT observations
  37. EP250526a: COLIBRÍ optical upper limits
  38. EP250526a: Einstein Probe detection of a fast X-ray transient
  39. EP J1350.0-8622: Einstein Probe detection of an X-ray transient candidate
  40. EP-WXT trigger 01709176712: SVOM/C-GFT observations of blue-to-red color variation
  41. The EP-WXT trigger 01709176712 is likely a flaring star
  42. The EP-WXT trigger 01709176612: SVOM/VT optical observations
  43. GRB 250521B: EP-FXT follow-up observation and afterglow candidates
  44. GRB 250521D: DDOTI Optical Upper Limit
  45. The EP-WXT trigger 01709176612 is likely a flaring star
  46. GRB 250521B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  47. GRB 250521D: LAST tentative optical counterpart candidate
  48. GRB 250521A: DDOTI Optical Upper Limit
  49. GRB 250520A: VLT/FORS2 Optical Observation
  50. GRB 250502A: Tautenburg observations
  51. GRB 250520A: Swift/UVOT Upper Limits
  52. IPN triangulation of GRB 250516B
  53. GRB 250520A: J-band observations with WINTER
  54. GRB 250520A: Gemini-South optical observations
  55. GRB 250520A: Swift-XRT refined Analysis
  56. GRB 250520A: REM optical/NIR early observations
  57. GRB 250520A：SVOM/VT optical candidate
  58. GRB 250520A: COLIBRÍ optical upper limit
  59. GRB 250520A: DDOTI Optical Upper Limit
  60. GRB 250520A: AstroSat CZTI detection of a short burst
  61. GRB 250520A: Enhanced Swift-XRT position
  62. GRB 250520A: Swift detection of a burst
  63. GRB 250516A: COLIBRÍ optical upper limit
  64. Konus-Wind detection of GRB 250516A
  65. EP-WXT trigger (ID: 01709176312): a new X-ray outburst of HMXB RX J0111.2-7317
  66. GRB 250515A: Swift-XRT observations
  67. GRB 250515A:COLIBRÍ optical observations of the GOTO candidate
  68. GRB 250515A: 1.6m Mephisto optical detection
  69. GRB 250516A: AstroSat CZTI detection
  70. GRB 250516A: Swift/UVOT Detection
  71. GRB 250516A: Enhanced Swift-XRT position
  72. GRB 250516A: Swift detection of a burst
  73. GRB 250512B / EP250512a: SVOM/GRM analysis
  74. GRB 250424A: COLIBRÍ detection of the associated supernova
  75. EP250512a/GRB 250512B: REM optical/NIR observations
  76. EP250511a: Koshka Zeiss-1000 Optical Upper Limit
  77. EP250511a: Gemini optical counterpart observation
  78. EP250512a/GRB 250512B refined analysis of the EP-WXT and EP-FXT observations
  79. EP250511a: Mephisto optical upper limits
  80. GRB 250512B: SVOM detection of a burst
  81. EP250512a: Einstein Probe detection of an X-ray transient
  82. EP250511a: REM optical/NIR observations
  83. EP250511a: Einstein Probe follow-up obsevation and refined analysis
  84. EP250511a: COLIBRÍ optical counterpart candidate
  85. EP250511a: Einstein Probe detection of an X-ray transient
  86. EP250508a: Gemini NIR upper limits
  87. Fermi GRB 250510B: Global MASTER-Net observations report
  88. GRB 250510A: Swift-XRT observations
  89. IceCube-250506A: No Transient Candidates from the Zwicky Transient Facility
  90. GRB 250510A: follow-up observation with EP-FXT
  91. GRB 250510B: Swift/BAT-GUANO localization skymap of a burst
  92. GRB 250510A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  93. GRB 250507A: J-band observations with WINTER
  94. GRB 250509A: Enhanced Swift-XRT position
  95. GRB 250509A: Swift detection of a burst
  96. GRB 250509A: Fermi GBM Final Real-time Localization
  97. GRB 250506A: NOT optical upper limits
  98. EP250508a: Liverpool Telescope optical upper limits
  99. EP250508a: follow-up observation with EP-FXT
  100. EP250508a: KAIT optical upper limit

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