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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. 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"

32501 results found.

  1. GRB 251222A: radio detection with the VLA
  2. GRB 260114A: VLT/HAWK-I near-infrared upper limits
  3. Konus-Wind detection of GRB 260114A
  4. GRB 260114A: 6 GHz VLA observations
  5. GRB 260114A: VLT/X-shooter redshift of the putative host galaxy
  6. GRB 260114A : MITSuME Akeno optical upper limits
  7. GRB 260114A: COLIBRÍ optical upper limits
  8. GRB 260114A: TNG NIR upper limit
  9. GRB 260114A: NOT optical observations
  10. Konus-Wind detection of GRB 251230A / EP251230a
  11. GRB 260114A: SVOM/GRM observation of a short burst
  12. Swift GRB 260114A: Global MASTER-Net observations report
  13. GRB 260114A: GECAM-B observation of a short burst
  14. GRB 260114A: Mondy optical observations
  15. GRB 260114A: Fermi GBM observation
  16. GRB 260112B: GECAM-B observation
  17. GRB 260114A: GMG Optical Observation
  18. Fermi-LAT Gamma-ray Observations of IceCube-260111A
  19. EP-WXT trigger 01709251266: SVOM/C-GFT confirmation of a stellar flare
  20. IceCube-260111A: Upper limits from a search for additional neutrino events in IceCube
  21. EP260110a: NOT and GTC Optical and Near-Infrared Observations
  22. EP260110a: TRT optical upper limits
  23. Konus-Wind detection of GRB 260101A
  24. GRB 260111A: Swift-XRT observations
  25. GRB 260111A: COLIBRÍ optical afterglow candidate
  26. GRB 260111A: GECAM-B observation of a burst
  27. GRB 260111A: Fermi GBM Observation
  28. Swift Trigger 1434591 is not a GRB
  29. GRB 260111A: GOTO optical upper limits
  30. GRB 260111A: Swift ToO observations
  31. GRB 251230A: Mondy Optical Observations
  32. GRB 260111A: Swift/BAT-GUANO arcminute localization of a burst
  33. EP260110a: SVOM/VT optical upper limits
  34. EP260110a: Global MASTER-Net observations report
  35. Fermi GRB 260111A: Global MASTER-Net observations report
  36. EP260110a: KAIT optical upper limit
  37. EP260110a: refined analysis of the EP-WXT and EP-FXT observations
  38. EP 260110a: COLIBRÍ optical observations
  39. EP260110a: SVOM/C-GFT upper limit
  40. EP260110a: BOOTES-5/JGU optical upper limit
  41. GRB 260109C: LCO optical upper limits
  42. GRB 260109C: Kilonova-Catcher optical upper limit
  43. EP260105b / GRB 260105C : Fermi-GBM Sub-Threshold Detection
  44. GRB 260104A: Swift-BAT refined analysis
  45. GRB 260101A: Swift-BAT refined analysis
  46. Swift GRB 251230A: Global MASTER-Net OT detection
  47. Fermi GRB 260107A: Global MASTER-Net observations report
  48. GRB 260102A: AbAO optical observations
  49. EP260105b/EP-WXT trigger 01709251028: Einstein Probe detection of an X-ray transient
  50. Fermi GRB 260105A: Global MASTER-Net observations report
  51. EP260105a: FTW optical observations
  52. EP260104a: FTW optical observations
  53. GRB 260105A: SVOM/GRM observation
  54. GRB 260105B: SVOM/GRM observation
  55. FRB 20251229A: COLIBRÍ optical upper limits
  56. Fermi GRB 260105B: Global MASTER-Net observations report
  57. EP260105a: SVOM/VT optical upperlimit
  58. EP260105a: refined analysis of the EP-WXT and EP-FXT observations
  59. EP260105a: LCO Optical Upper limit
  60. EP260104a: Global MASTER-Net observations report
  61. GRB 260101A: COLIBRÍ optical upper limits
  62. EP260105a: Global MASTER-Net observations report
  63. GRB 260103A: Insight-HXMT/HE detection
  64. GRB 260104A: COLIBRÍ optical upper limits
  65. Fermi GRB 260104B: Global MASTER-Net observations report
  66. Swift GRB 260104A: Global MASTER-Net observations report
  67. GRB 251230A/EP-WXT trigger 01709250693: Mephisto optical upper limits
  68. GRB 260101A: Swift/UVOT Detection
  69. GRB 260103A: GECAM-B observation of a burst
  70. Fermi-LAT Gamma-ray Observations of IceCube-251225A
  71. GRB 260101A: COLIBRÍ optical observations
  72. Fermi GBM Sub-Threshold Detection of GRB 260102A
  73. GRB 260102A: EP-FXT follow-up observation
  74. EP260101a: Global MASTER-Net observations report
  75. GRB 260102A: LCO optical upper limits
  76. GRB 260102A: Swift-XRT observations
  77. GRB 260102A: SVOM/COLIBRÍ (FM-GFT) optical observations
  78. GRB 251230A / EP251230a: GECAM-B detection
  79. GRB 260102A: SVOM/VT optical counterpart
  80. GRB 251230A / EP251230a: Insight-HXMT/HE detection
  81. GRB 260102A: Swift ToO observations
  82. GRB 260101A: Fermi GBM Observation
  83. EP260101a: refined analysis of the EP-WXT and EP-FXT observations
  84. GRB 260101A: GECAM-B detection
  85. GRB 260101A: NOT spectroscopic observations
  86. GRB 260101A: SVOM/GRM observation
  87. Swift GRB 260101A: Global MASTER-Net observations report
  88. GRB 260101A: OSIRIS+ redshift z = 2.623 for the new year burst
  89. GRB 260101A: LCO detection of the optical counterpart
  90. GRB 251230A / EP251230a: SVOM/VT optical continued observations and upper limit
  91. GRB 251230A: GRANDMA/TAROT Early Detection
  92. GRB 251230A / EP251230a: further NOT optical observations revealing shallower decay or possible rebrightening
  93. GRB 251230A/EP251230a: Optical upper limit with Kinder observations
  94. EP251229a: Optical upper limit with Kinder observations
  95. GRB 251230A: 1.3m DFOT optical upper limit
  96. GRB 251222A: Mondy Optical Observations
  97. EP251230a / GRB 251230A: refined analysis of the EP-WXT and EP-FXT observations
  98. GRB 251230A: Swift/UVOT detection
  99. GRB251230A: 7DT optical upper limits
  100. GRB 251230A / EP251230a: NOT observations and spectroscopic redshift upper limit z < 2.2

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