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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"

19602 results found.

  1. GRB 250610B: Swift/UVOT Detection
  2. EP250610A: Swift/UVOT Upper limits
  3. GRB 250610B: SVOM/COLIBRÍ (FM-GFT) optical observations
  4. EP250610a: TNG NIR upper limit
  5. GRB 250610B: REM optical/NIR observations
  6. EP250610a: Liverpool Telescope optical upper limits
  7. GRB 250610B: additional Liverpool Telescope optical observations
  8. GRB 250610B: SVOM/VT optical counterpart
  9. GRB 250610B: OHP/T120 optical counterpart candidate
  10. GRB 250610B : SVOM/GWAC-F60A and F50 observations
  11. GRB 250610B: SVOM detection of a long burst
  12. EP250610a: refined analysis of the EP-WXT and EP-FXT observations
  13. EP250610a: SVOM/VT optical upper limit
  14. EP250610a: REM optical/NIR observations
  15. EP250610a: COLIBRÍ optical upper limit
  16. EP250610a: Einstein Probe detection of an X-ray transient
  17. GRB 250609A: Swift/BAT-GUANO localization skymap of a likely short burst
  18. GRB 250605A: Swift/UVOT Upper Limits
  19. GRB 250527C: CrAO Optical Upper Limit
  20. GRB 250607A: SVOM/GRM observation of a long burst
  21. EP-WXT trigger 01709178244: confirmation of a stellar flare by BOOTES-5 & BOOTES-7
  22. EP-WXT trigger 01709178069: confirmation of a stellar flare by BOOTES-6 & BOOTES-7
  23. The EP-WXT trigger 01709178069 is likely a flaring star
  24. GRB 250605A: Enhanced Swift-XRT position
  25. Fermi trigger No 770867684: Global MASTER-Net observations report
  26. GRB 250605A: Swift detection of a burst
  27. IPN triangulation of GRB 250404B
  28. IPN triangulation of GRB 250529A
  29. GRB 250601A: PRIME H band upper limit.
  30. GRB 250601A: PRIME J band upper limit.
  31. GRB 250601A: VLT/FORS2 Optical Observation
  32. GRB 250602A: DDOTI Optical Follow-Up of the Fermi/LAT Localization
  33. GRB 250603A: Swift/UVOT Upper Limits
  34. GRB 250603A: Enhanced Swift-XRT position
  35. GRB 250603A: Swift-XRT position and confirmation of GRB nature
  36. GRB 250603A: Swift detection of a burst or new Galactic transient Swift J0839.7-3916
  37. GRB 250602A: DDOTI Optical Upper Limit
  38. GRB 250601A: Swift ToO observations
  39. EP#01709177494: SVOM/VT optical observations
  40. GRB 250521C/ZTF25aarhkyn/AT2025mgj: COLIBRÍ optical observations
  41. GRB 250530A: TNG detection of a NIR source inside the Swift/XRT error circle
  42. GRB 250530C: Enhanced Swift-XRT position
  43. GRB 250530C: Swift detection of a burst
  44. GRB 250521C/AT2025mgj: NOT optical observations of the afterglow candidate
  45. GRB 250530A: SVOM/VT optical upper limit
  46. GRB 250530A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate retraction and detection limit
  47. GRB 250530A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  48. GRB 250530A: SVOM detection of a burst
  49. GRB 250527C: Swift/UVOT Upper Limits
  50. GRB 250527D: Swift/BAT-GUANO localization skymap of a burst
  51. GRB 250527B: Swift-XRT observations
  52. GRB 250527C: Swift ToO observations
  53. GRB 250527B: Tiled Swift observations
  54. EP250526a: refined analysis of the EP-WXT and EP-FXT observations
  55. EP250526a: COLIBRÍ optical upper limits
  56. EP250526a: Einstein Probe detection of a fast X-ray transient
  57. EP J1350.0-8622: Einstein Probe detection of an X-ray transient candidate
  58. EP-WXT trigger 01709176712: SVOM/C-GFT observations of blue-to-red color variation
  59. The EP-WXT trigger 01709176612: SVOM/VT optical observations
  60. GRB 250521D: DDOTI Optical Upper Limit
  61. GRB 250521B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  62. GRB 250521D: LAST tentative optical counterpart candidate
  63. GRB 250521B: Swift ToO observations
  64. GRB 250521A: DDOTI Optical Upper Limit
  65. GRB 250521B: SVOM detection of a burst through offline search
  66. GRB 250520A: VLT/FORS2 Optical Observation
  67. GRB 250502A: Tautenburg observations
  68. GRB 250520A: Swift/UVOT Upper Limits
  69. IPN triangulation of GRB 250516B
  70. GRB 250520A: J-band observations with WINTER
  71. GRB 250520A: Gemini-South optical observations
  72. GRB 250520A: REM optical/NIR early observations
  73. GRB 250520A：SVOM/VT optical candidate
  74. GRB 250520A: COLIBRÍ optical upper limit
  75. GRB 250520A: DDOTI Optical Upper Limit
  76. GRB 250520A: Enhanced Swift-XRT position
  77. GRB 250520A: Swift detection of a burst
  78. GRB 250516A: COLIBRÍ optical upper limit
  79. EP-WXT trigger (ID: 01709176312): a new X-ray outburst of HMXB RX J0111.2-7317
  80. GRB 250515A: Swift-XRT observations
  81. GRB 250515A:COLIBRÍ optical observations of the GOTO candidate
  82. GRB 250515A: 1.6m Mephisto optical detection
  83. GRB 250516A: AstroSat CZTI detection
  84. GRB 250516A: Swift/UVOT Detection
  85. GRB 250515A: Swift ToO observations
  86. GRB 250516A: Enhanced Swift-XRT position
  87. GRB 250516A: Swift detection of a burst
  88. GRB 250424A: COLIBRÍ detection of the associated supernova
  89. Konus-Wind detection of GRB 250512B / EP250512a
  90. LIGO/Virgo/KAGRA S250328ae: DECam DESGW Candidates (Final Epochs)
  91. EP250512a/GRB 250512B: REM optical/NIR observations
  92. EP250511a: Koshka Zeiss-1000 Optical Upper Limit
  93. GRB 250507B: AstroSat CZTI detection
  94. EP250511a: Gemini optical counterpart observation
  95. EP250512a/GRB 250512B refined analysis of the EP-WXT and EP-FXT observations
  96. EP250511a: Mephisto optical upper limits
  97. GRB 250512B: SVOM detection of a burst
  98. EP250512a: Einstein Probe detection of an X-ray transient
  99. EP250511a: REM optical/NIR observations
  100. EP250511a: Einstein Probe follow-up obsevation and refined analysis

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