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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"

19613 results found.

  1. GRB 251230A / EP251230a: GECAM-B detection
  2. GRB 260102A: SVOM/VT optical counterpart
  3. GRB 251230A / EP251230a: Insight-HXMT/HE detection
  4. GRB 260102A: Swift ToO observations
  5. GRB 260101A: Fermi GBM Observation
  6. GRB 260101A: GECAM-B detection
  7. GRB 260101A: NOT spectroscopic observations
  8. GRB 260101A: SVOM/GRM observation
  9. GRB 260101A: Swift-XRT refined Analysis
  10. Swift GRB 260101A: Global MASTER-Net observations report
  11. GRB 260101A: Enhanced Swift-XRT position
  12. GRB 260101A: LCO detection of the optical counterpart
  13. GRB 260101A: Swift detection of a burst with an optical counterpart
  14. GRB 251230A / EP251230a: SVOM/VT optical continued observations and upper limit
  15. GRB 251230A: GRANDMA/TAROT Early Detection
  16. GRB 251230A / EP251230a: further NOT optical observations revealing shallower decay or possible rebrightening
  17. GRB 251230A/EP251230a: Optical upper limit with Kinder observations
  18. GRB 251230A: 1.3m DFOT optical upper limit
  19. GRB 251230A: Swift-XRT refined Analysis
  20. EP251230a / GRB 251230A: refined analysis of the EP-WXT and EP-FXT observations
  21. GRB 251230A: Swift/UVOT detection
  22. GRB251230A: 7DT optical upper limits
  23. GRB 251230A / EP251230a: NOT observations and spectroscopic redshift upper limit z < 2.2
  24. GRB 251230A: GOTO optical upper limit
  25. GRB 251230A / EP251230a: SVOM/VT optical observation
  26. GRB 251230A: Enhanced Swift-XRT position
  27. GRB 251230A: Early optical counterpart detection by LCO.
  28. EP251230a / GRB 251230A: Einstein Probe detection of an X-ray transient
  29. GRB 251230A/EP#01709250693 (likely EP251230a): FTW optical and NIR observations
  30. Swift GRB 251230A: Global MASTER-Net observations report
  31. GRB 251230A: Swift detection of a burst with a bright optical counterpart
  32. GRB 251222A/EP251222b: Optical detection with Kinder observations
  33. GRB 251221A: Swift-BAT refined analysis
  34. GRB 251205A: Kilonova-Catcher optical afterglow detection
  35. GRB 251129A / EP251129a: VLA detection of a radio counterpart
  36. GRB 251222A: Fermi GBM Observation
  37. GRB 251222A: Swift-XRT afterglow detection
  38. GRB 251222A / EP251222b: LCO detection of the optical counterpart
  39. GRB251221A: 7DT optical upper limits
  40. IPN triangulation of GRB 251220B (short)
  41. GRB 251222A: Swift ToO observations
  42. GRB 251221A: PRIME near-infrared observation
  43. GRB 251221A: UAFO and Mondy optical upper limit
  44. GRB 251221A: Swift-XRT refined Analysis
  45. GRB 251221A: Swift/UVOT Upper Limits
  46. GRB 251221A: Enhanced Swift-XRT position
  47. GRB 251221A: Fermi GBM Observation
  48. GRB 251221A: COLIBRÍ detection of the optical counterpart
  49. GRB 251221A: Swift detection of a burst
  50. Swift GRB251221A: Global MASTER-Net observations report
  51. GRB 251215A: Swift-XRT afterglow detection
  52. GRB 251214B: VIRT Optical Upper Limit
  53. GRB 251215A: Swift/UVOT Upper LImits
  54. GRB 251215A: Fermi GBM Observation
  55. GRB 251214B: Mondy optical upper limit
  56. GRB 251215A: COLIBRÍ optical upper limit
  57. GRB 251215A: Swift-XRT observations
  58. GRB 251214B: 1.6m Mephisto observations with newly installed mosaic cameras
  59. GRB 251215A: Glowbug gamma-ray detection
  60. GRB 251214B: UAFO optical upper limit
  61. GRB 251214B: VLT/X-shooter observations
  62. GRB 251214B: Swift-BAT refined analysis
  63. GRB 251202A: radio detection with the VLA
  64. GRB 251214B: AbAO optical observations
  65. GRB 251214B: LCO detection of the optical counterpart
  66. GRB 251214B: Fermi GBM Observation
  67. GRB 251215A: Swift ToO observations
  68. EP251214b (EP trigger 01709250023): LCO optical limits
  69. GRB 251215A: Swift/BAT-GUANO arcminute localization of a burst
  70. GRB 251214B: Swift-XRT refined Analysis
  71. GRB 251214B: Swift/UVOT Detection
  72. GRB 251214B: COLIBRÍ observations of the afterglow
  73. GRB 251214B: 1.3m DFOT optical detection
  74. GRB 251214B: Enhanced Swift-XRT position
  75. GRB 251214B: Xinglong-2.16m optical observation
  76. GRB 251214B : MASTER optical afterglow detection
  77. GRB 251214B: SVOM/C-GFT optical observations
  78. Swift GRB 251214B: Global MASTER-Net observations report
  79. GRB 251214B: Swift detection of a burst with an optical counterpart
  80. GRB 251205A: 1.3m DFOT optical upper limit
  81. GRB 251129A/EP251129a: AbAO and Mondy optical observations
  82. EP251130a: Mondy and AbAO optical observations
  83. Fermi GBM Sub-Threshold Detection of GRB 251205A
  84. GRB 251208B: COLIBRÍ optical upper limits
  85. EP251118a / GRB 251118C: VLT/MUSE redshift confirmation
  86. GRB 251208B: Swift-XRT afterglow detection
  87. GRB 251208D: LCO analysis of the XRT sources
  88. GRB 251208B: Fermi GBM Observation
  89. GRB 251208B: GROWTH-India Telescope optical upper limits
  90. GRB 251208D: Swift-XRT observations
  91. GRB 251208B: Swift ToO observations
  92. GRB 251208B: Fermi-LAT detection
  93. GRB 251208B: Swift/BAT-GUANO arcminute localization of a burst
  94. GRB 251205A : MITSuME Akeno optical afterglow candidate detection
  95. GRB 251205A: ZTF and ATLAS optical afterglow detections
  96. GRB 251205A: GROWTH-India Telescope optical observations
  97. GRB 251205A: Swift-BAT refined analysis
  98. GRB 251205A: Swift-XRT refined Analysis
  99. GRB 251205A: Swift/UVOT Detection
  100. GRB 251203C: Swift/UVOT Upper Limit

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