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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"

26053 results found.

  1. GRB 251230A: GOTO optical upper limit
  2. GRB 251230A / EP251230a: SVOM/VT optical observation
  3. GRB 251230A: Enhanced Swift-XRT position
  4. GRB 251230A: Early optical counterpart detection by LCO.
  5. EP251230a / GRB 251230A: Einstein Probe detection of an X-ray transient
  6. GRB 251230A/EP#01709250693 (likely EP251230a): FTW optical and NIR observations
  7. Swift GRB 251230A: Global MASTER-Net observations report
  8. GRB 251230A: Swift detection of a burst with a bright optical counterpart
  9. GRB 251129A: redshift correction and SN detection at z = 0.505 with GTC
  10. GRB 251222A/EP251222b: Optical detection with Kinder observations
  11. GRB 251221A: Swift-BAT refined analysis
  12. GRB 251205A: Kilonova-Catcher optical afterglow detection
  13. GRB 251222A / EP251222b: Kilonova-Catcher optical afterglow detection
  14. GRB 251129A / EP251129a: VLA detection of a radio counterpart
  15. GRB 251222A: SVOM/COLIBRÍ (FM-GFT) optical observations
  16. GRB 251222A: Continued 1.3m DFOT optical observation
  17. EP251220a: 3.6m DOT optical afterglow detection
  18. GRB 251222A: Fermi GBM Observation
  19. GRB 251222A: Swift-XRT afterglow detection
  20. GRB 251222A / EP251222b: LCO detection of the optical counterpart
  21. GRB 251222A / EP251222b: GOTO optical counterpart detection
  22. GRB 251222A: 1.3m DFOT optical detection
  23. GRB251221A: 7DT optical upper limits
  24. GRB 251222A: NOT optical observations
  25. IPN triangulation of GRB 251220B (short)
  26. GRB 251222A: Swift ToO observations
  27. GRB 251221A: PRIME near-infrared observation
  28. GRB 251221A: UAFO and Mondy optical upper limit
  29. GRB 251221A: Swift-XRT refined Analysis
  30. GRB 251221A: Swift/UVOT Upper Limits
  31. GRB 251221A: Enhanced Swift-XRT position
  32. GRB 251221A: Fermi GBM Observation
  33. EP251220a: COLIBRÍ confirmation of fading and photometric redshift upper limit of z < 3.4
  34. GRB 251221A: COLIBRÍ detection of the optical counterpart
  35. GRB 251221A: Swift detection of a burst
  36. Swift GRB251221A: Global MASTER-Net observations report
  37. GRB 251215A: Swift-XRT afterglow detection
  38. GRB 251214B: VIRT Optical Upper Limit
  39. GRB 251215A: Swift/UVOT Upper LImits
  40. GRB 251215A: Fermi GBM Observation
  41. GRB 251214B: Mondy optical upper limit
  42. GRB 251215A: COLIBRÍ optical upper limit
  43. GRB 251215A: Swift-XRT observations
  44. GRB 251214B: 1.6m Mephisto observations with newly installed mosaic cameras
  45. GRB 251215A: Glowbug gamma-ray detection
  46. GRB 251214B: UAFO optical upper limit
  47. GRB 251214B: VLT/X-shooter observations
  48. GRB 251214B: Swift-BAT refined analysis
  49. GRB 251202A: radio detection with the VLA
  50. GRB 251214B: AbAO optical observations
  51. GRB 251214B: LCO detection of the optical counterpart
  52. GRB 251214B: Fermi GBM Observation
  53. GRB 251215A: Swift ToO observations
  54. EP251214b (EP trigger 01709250023): LCO optical limits
  55. GRB 251215A: Swift/BAT-GUANO arcminute localization of a burst
  56. GRB 251214B: Swift-XRT refined Analysis
  57. GRB 251214B: Swift/UVOT Detection
  58. GRB 251214B: COLIBRÍ observations of the afterglow
  59. GRB 251214B: 1.3m DFOT optical detection
  60. GRB 251214B: Enhanced Swift-XRT position
  61. GRB 251214B: Xinglong-2.16m optical observation
  62. GRB 251214B : MASTER optical afterglow detection
  63. GRB 251214B: SVOM/C-GFT optical observations
  64. Swift GRB 251214B: Global MASTER-Net observations report
  65. GRB 251214B: Swift detection of a burst with an optical counterpart
  66. EP251214a: EP-WXT detection of an X-ray transient possibly associated with GRB 251214A
  67. GRB 251205A: 1.3m DFOT optical upper limit
  68. GRB 251129A/EP251129a: AbAO and Mondy optical observations
  69. EP251130a: Mondy and AbAO optical observations
  70. Fermi GBM Sub-Threshold Detection of GRB 251205A
  71. GRB 251208B: COLIBRÍ optical upper limits
  72. EP251118a / GRB 251118C: VLT/MUSE redshift confirmation
  73. GRB 251208B: Swift-XRT afterglow detection
  74. GRB 251208D: LCO analysis of the XRT sources
  75. GRB 251208B: Fermi GBM Observation
  76. GRB 251208B: GROWTH-India Telescope optical upper limits
  77. GRB 251208D: Swift-XRT observations
  78. GRB 251208B: Swift ToO observations
  79. GRB 251208B: Fermi-LAT detection
  80. GRB 251208B: Swift/BAT-GUANO arcminute localization of a burst
  81. GRB 251205A : MITSuME Akeno optical afterglow candidate detection
  82. GRB 251205A: ZTF and ATLAS optical afterglow detections
  83. GRB 251205A: GROWTH-India Telescope optical observations
  84. GRB 251205A: Swift-BAT refined analysis
  85. GRB 251205A: Swift-XRT refined Analysis
  86. GRB 251205A: Swift/UVOT Detection
  87. GRB 251203C: Swift/UVOT Upper Limit
  88. GRB 251205A: Zeiss-1000 Koshka observatory optical observations
  89. GRB 251205A: COLIBRÍ optical observations
  90. GRB 251205A: GOTO optical afterglow detection
  91. GRB 251205A: NOT optical observations
  92. GRB 251205A: GTC/OSIRIS+ redshift z = 1.100
  93. GRB 251205A: Enhanced Swift-XRT position
  94. Swift GRB 251205A : MASTER OT detection with host galaxy
  95. GRB 251205A: Swift detection of a burst with an optical afterglow
  96. Swift GRB251205A: Global MASTER-Net observations report
  97. GRB 251202A / EP251202a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm and 1-m telescopes at McDonald Observatory
  98. GRB 251202A: SVOM/GRM observation
  99. GRB 251201B: SALT spectroscopic redshift z = 1.599
  100. GRB 251129B: Glowbug gamma-ray detection of a short burst

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