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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"

27211 results found.

  1. EP250427A: COLIBRÍ Optical Detection
  2. EP250427a: TRT optical counterpart detection
  3. EP250427a: Global MASTER-Net observations report
  4. EP250427a: Einstein Probe detection of a fast X-ray transient
  5. IceCube Alert 250426.74: Global MASTER-Net observations report
  6. GRB 250424A: Swift-BAT refined analysis
  7. GRB 250424A: SVOM/GRM observation of a long burst
  8. GRB 250424A: WINTER J-band detection
  9. GRB 250424A: EIRSAT-1 GMOD Detection
  10. GRB 250424A: SVOM/VT optical observation
  11. GRB 250419A: Mondy Optical Observations
  12. GRB 250424A: Swift/UVOT Detection
  13. GRB 250424A: Kilonova-Catcher optical afterglow detection
  14. GRB 250419a: Continued Liverpool Telescope observations
  15. GRB 250419A: Liverpool Telescope optical upper limit
  16. GRB 250330B: GRBAlpha detection
  17. GRB 250419A: SVOM/ECLAIRs refined analysis
  18. GRB 250424A: Swift-XRT refined Analysis
  19. GRB 250424A: AstroSat CZTI detection of a bright long burst
  20. GRB 250424A: COLIBRÍ Detection of a Bright Optical Counterpart
  21. GRB 250424A: BlackGEM optical afterglow detection
  22. GRB 250424A: VLT/X-shooter spectroscopic redshift z = 0.310
  23. GRB 250424A: DDOTI Afterglow Detection
  24. GRB 250424A: REM optical/NIR afterglow detection
  25. GRB 250424A: Swift detection of a burst with an optical counterpart
  26. Swift GRB 250424A: Global MASTER-Net observations report
  27. Swift GRB 250424A: Global MASTER-Net OT detection
  28. EP250421a: Nickel optical upper limit
  29. EP250421a: Upper limits from Fermi-GBM Observations
  30. SVOM/sb25042207: XRT observations
  31. SVOM/sb25042207: GOTO optical upper limits
  32. SVOM/sb25042207: SVOM detection of an X-ray transient
  33. IceCube-250421A: DDOTI Detection of the LAST Candidate
  34. GRB 250419A: Mephisto Multi-band Optical Detection
  35. EP250421a: NOT optical observations
  36. EP250421a: REM optical upper limit
  37. EP250421a: Swift/XRT counterpart detection
  38. EP250421A: COLIBRÍ Optical Upper Limit
  39. GRB 250419A: Mondy Continued Optical Observations
  40. Fermi GRB 250421A: Global MASTER-Net observations report
  41. EP250421a: Global MASTER-Net observations report
  42. EP250421a: Einstein Probe detection of an X-ray transient
  43. EP250421a: Mephisto optical counterpart confirmation
  44. IceCube Alert 250421.71: Global MASTER-Net observations report
  45. EP250421a: JinShan likely optical counterpart
  46. The EP-WXT trigger 01709135179: Kinder optical counterpart candidate
  47. GRB 250421A: Fermi GBM Final Real-time Localization
  48. GRB 250419A: Liverpool Telescope observations
  49. GRB 250419A: LCO optical observation
  50. GRB 250419A: JinShan optical observations
  51. GRB 250419A: SVOM/VT optical continuous observations
  52. GRB 250419A: SVOM/C-GFT optical observations
  53. GRB 250419A: Swift/UVOT Follow up
  54. GRB 250416C / EP250416a: SVOM/GRM observation of a burst
  55. GRB 250419A: LCO optical afterglow multi-band observations
  56. GRB 250419A: Mondy and AbAO Optical Observations
  57. GRB 250419A: AKO Optical Afterglow Detection
  58. GRB 250419A: MASTER optical afterglow observation
  59. GRB 250407A: GTC/OSIRIS+ spectroscopic redshift z = 1.36
  60. GRB 250419A: Swift-XRT refined Analysis
  61. GRB 250419A: GOTO optical counterpart detection
  62. GRB 250419A: KAIT optical afterglow observations
  63. GRB 250419A: SVOM/VT optical bright counterpart confirmation
  64. GRB 250419A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
  65. GRB 250419A: SVOM detection of a soft burst
  66. EP250416a: Swift/XRT counterpart fading
  67. EP250416a: refined EP-WXT and EP-FXT analysis
  68. EP20250416a: Swift/XRT counterpart detection
  69. IceCube-250416A: DDOTI Optical Observations
  70. EP250225a: SVOM/VT optical brightening
  71. SVOM/sb25041603 is not a GRB
  72. EP250416a: GSP optical upper limit
  73. EP250416a: Global MASTER-Net observations report
  74. Fermi Gamma-ray Burst Monitor trigger 766505186/250416588 (GRB 250416A) is not a GRB
  75. EP250416a: Einstein Probe detection of an X-ray transient
  76. IceCube-250416A: Global MASTER-Net observations report
  77. Fermi Gamma-ray Burst Monitor trigger 766511207/250416657 is not a GRB
  78. GRB 250416B: Fermi GBM Final Real-time Localization
  79. GRB 250416A: Fermi GBM Final Real-time Localization
  80. SVOM/sb25041603: SVOM/COLIBRÍ (FM-GFT) Upper Limit on the Optical Counterpart
  81. SVOM/sb25041603: SVOM detection of an X-ray transient
  82. Fermi Gamma-ray Burst Monitor trigger 766474855/250416237 is not a GRB
  83. IceCube 250414.324: DDOTI Optical Observations
  84. EP250304a: ATCA radio observations
  85. GRB 250412A: AstroSat CZTI detection
  86. EP250404a: Nanshan 0.43m Telescope optical observatios
  87. Fermi trigger No 766148493: Global MASTER-Net observations report
  88. Fermi trigger No 766173972: Global MASTER-Net observations report
  89. GRB 250411A: DDOTI Optical Observations
  90. Fermi GRB 250411A: Global MASTER-Net observations report
  91. GRB 250411A: Fermi GBM Final Real-time Localization
  92. GRB 250407A: Mondy and AbAO Optical Observations
  93. EP250227a: Further NOT optical observations
  94. IceCube-250406A: Swift-XRT observations
  95. IPN triangulation of GRB 250407A
  96. EP250407a: Global MASTER-Net observations report
  97. GRB 250407A: LCO detection of a fading optical counterpart
  98. GRB 250407A: SVOM/GRM observation of a bright long burst
  99. GRB 250407A: EP-WXT afterglow detection
  100. EP250407a: EP-WXT detection of a fast X-ray transient

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