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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"

21471 results found.

  1. GRB 250527C: Swift/BAT-GUANO arcminute localization of a burst
  2. GRB 250527B: Tiled Swift observations
  3. GRB 250520A: Gemini-South optical afterglow detection
  4. GRB 250520A: 10 GHz VLA Afterglow Confirmation
  5. GRB 250520A: GRBAlpha detection
  6. GRB 250521B: SVOM/VT optical upper limit
  7. The EP-WXT trigger 01709176612: refined analysis of the EP-FXT observation
  8. GRB 250521B: EP-FXT follow-up observation and afterglow candidates
  9. EP#01709176612: Swift-XRT counterpart detection of flaring star
  10. GRB 250520A: CALET Gamma-Ray Burst Monitor detection
  11. GRB 250521B: Swift ToO observations
  12. Konus-Wind detection of GRB 250520A (short/hard)
  13. GRB 250520A: VLT/FORS2 Optical Observation
  14. GRB 250520A: Swift/UVOT Upper Limits
  15. IPN triangulation of GRB 250516B
  16. GRB 250520A: J-band observations with WINTER
  17. GRB 250520A: Gemini-South optical observations
  18. GRB 250520A: Swift-XRT refined Analysis
  19. GRB 250520A: REM optical/NIR early observations
  20. GRB 250520A:SVOM/VT optical candidate
  21. GRB 250520A: COLIBRÍ optical upper limit
  22. GRB 250520A: DDOTI Optical Upper Limit
  23. GRB 250520A: AstroSat CZTI detection of a short burst
  24. GRB 250520A: SVOM/GRM observation
  25. GRB 250520A: Enhanced Swift-XRT position
  26. GRB 250520A: GOTO optical upper limit
  27. GRB 250520A: Prompt enhanced Swift-XRT position
  28. GRB 250520A: Swift detection of a burst
  29. Swift GRB 250520A: Global MASTER-Net observations report
  30. EP250427a/GRB250427A: VLA Detection of Radio Counterpart
  31. GRB 250516A: Swift-BAT refined analysis
  32. GRB 250516A: COLIBRÍ optical upper limit
  33. Konus-Wind detection of GRB 250516A
  34. GRB 250515A: Swift-XRT observations
  35. Swift GRB 250516A: Global MASTER-Net observations report
  36. GRB 250516A: AstroSat CZTI detection
  37. GRB 250516A: Fermi GBM Observation
  38. GRB 250516A: Swift-XRT refined Analysis
  39. GRB 250516A: Swift/UVOT Detection
  40. GRB 250515A: Swift ToO observations
  41. GRB 250516A: Enhanced Swift-XRT position
  42. GRB 250516A: Swift detection of a burst
  43. GRB 250509A: Swift-BAT refined analysis
  44. LIGO/Virgo/KAGRA S250328ae: DECam DESGW Candidates (Final Epochs)
  45. GRB 250510B: Fermi GBM Observation
  46. GRB 250510A: Swift-XRT observations
  47. GRB 250509A: Fermi GBM Observation
  48. GRB 250510B: Swift/BAT-GUANO localization skymap of a burst
  49. GRB 250509A: Swift-XRT refined Analysis
  50. GRB 250507A: J-band observations with WINTER
  51. GRB 250509A: Enhanced Swift-XRT position
  52. GRB 250509A: Prompt enhanced Swift-XRT position
  53. Swift GRB 250509A: Global MASTER-Net observations report
  54. GRB 250509A: Swift detection of a burst
  55. GRB 250506A: NOT optical upper limits
  56. GRB 250506A: GECAM detection
  57. GRB 250506A: Swift-XRT afterglow detection
  58. GRB 250506A: SVOM/VT optical upper limit
  59. GRB 250507A: Swift-XRT refined Analysis
  60. GRB 250506A: Swift/UVOT Upper Limits
  61. GRB 250430A / EP250430a: AstroSat CZTI detection
  62. EP#01709175213/IGR J19566+0326: Swift-XRT detection
  63. GRB 250506A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  64. GRB 250506A: Swift-XRT observations
  65. EP-WXT trigger 01709175213: a new X-ray outburst of LMXB MAXI J1957+032
  66. GRB 250504A: EIRSAT-1 GMOD Detection
  67. GRB 250506A: Swift ToO observations
  68. GRB 250430A: Konus-Wind detection and joint Konus-Wind+Swift-BAT spectral analysis
  69. GRB 250506A: SVOM improved position and MXT detection of a fading X-ray afterglow
  70. GRB 250506A: Swift XRT observations and possible counterpart detection
  71. GRB 250506A: TRT optical observations
  72. GRB 250504A: Swift-BAT refined analysis
  73. GRB 250430A: Swift-BAT refined analysis
  74. GRB 250504A: Swift-XRT refined Analysis
  75. GRB 250504A: VLT/X-shooter upper limits
  76. GRB 250504A: SVOM/VT upper limit
  77. GRB 250504A: REM optical/NIR observations
  78. GRB 250504A: MeerLICHT optical afterglow detection
  79. GRB 250504A: Fermi GBM Observation
  80. GRB 250504A: Enhanced Swift-XRT position
  81. GRB 250504A: Swift detection of a burst
  82. Swift GRB250504.98: Global MASTER-Net observations report
  83. GRB 250502A: Swift/UVOT Follow up
  84. GRB 250502A: Mondy and Tien-Shan Optical Observations
  85. GRB 250502A: Swift-XRT afterglow detection
  86. GRB 250502A: Swift ToO observations
  87. GRB 250430A: Swift-XRT refined Analysis
  88. GRB 250430A: Swift/UVOT Detection
  89. GRB 250430A: Enhanced Swift-XRT position
  90. GRB 250430A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  91. GRB 250430A: NUTTelA-TAO Early Measurements
  92. GRB 250430A: DDOTI Optical Observations
  93. GRB 250430A: Leavitt Observatory optical upper limit
  94. GRB 250430A: Bassano Bresciano Observatory upper limit
  95. GRB 250430A : MITSuME Akeno optical upper limits
  96. GRB 250430A / EP250430a: VLT/X-shooter spectroscopic redshift z = 0.767
  97. EP250430a/GRB 250430A: Einstein Probe WXT detection of the X-ray prompt emission
  98. GRB 250424A: CALET Gamma-Ray Burst Monitor detection
  99. GRB 250430A: AKO Optical Afterglow Detection
  100. GRB 250430A: Swift detection of a burst with optical counterpart

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