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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"

24361 results found.

  1. Fermi GRB 260120C: Global MASTER-Net observations report
  2. GRB 260120B: Swift-BAT refined analysis
  3. GRB 251122A / EP251122a: VLT/X-shooter host redshift z = 1.765
  4. GRB 260120B: Fermi GBM Observation
  5. EP260105a: GTC/HiPERCAM optical observations
  6. GRB 260120B: COLIBRÍ optical upper limits
  7. SVOM GRB260121.06: Global MASTER-Net observations report
  8. GRB 260120B: SVOM/C-GFT optical counterpart detection
  9. GRB 260120C: Fermi GBM Final Real-time Localization
  10. GRB 260120B: Swift detection of a burst
  11. Swift GRB260120B: Global MASTER-Net observations report
  12. GRB 260120B: Fermi GBM Final Real-time Localization
  13. Fermi trigger No 790601190: Global MASTER-Net observations report
  14. Fermi trigger No 790570272: Global MASTER-Net observations report
  15. EP260119a: Liverpool Telescope optical follow-up observations
  16. EP260119A: GTC/OSIRIS+ spectroscopic redshift z = 5.47
  17. EP260119a: KAIT optical observations
  18. GRB 260120A: Fermi GBM Final Real-time Localization
  19. EP260119a: SVOM/VT optical observation
  20. EP260119a: update of EP-FXT follow-up observation
  21. SVOM GRB260119.92: Global MASTER-Net observations report
  22. SVOM GRB260119.92: Global MASTER-Net observations report
  23. SVOM GRB260119.90: Global MASTER-Net observations report
  24. GRB 251208D: SVOM/ECLAIRs refined analysis
  25. GRB 251208D: SVOM/ECLAIRs refined analysis
  26. GRB 260117A: Swift-XRT afterglow detection
  27. EP260119a: COLIBRÍ photometric redshift z ≈ 5.6
  28. EP260119a: Global MASTER-Net observations report
  29. GRB 260110A: SVOM detection of a burst through offline search
  30. Swift GRB260118.48: Global MASTER-Net observations report
  31. SVOM GRB260117.82: Global MASTER-Net observations report
  32. Fermi-LAT Gamma-ray Observations of IceCube-260115A
  33. GRB 260117A: SVOM/VT optical candidate
  34. GRB 260117A: SVOM/C-GFT upper limit
  35. GRB 260117A: Swift-XRT observations
  36. GRB 260117A: SVOM detection of a long faint burst
  37. Swift triggered on the HMXB 1A 1118-61
  38. GRB 260115A: GECAM-B observation
  39. FRB 20251229A: COLIBRÍ further inspection of the updated localization
  40. FRB 20251229A: Updated CHIME/FRB Baseband Localization of FRB 20251229A
  41. EP260116A: 1.3m DFOT optical upper limit
  42. GRB 260114A: VLT/MUSE spectroscopic observations
  43. IceCube-260115A: Upper limits from a search for additional neutrino events in IceCube
  44. EP260116a: Global MASTER-Net observations report
  45. EP260116a: Xinglong optical upper limit
  46. EP260116a: Einstein Probe detection of an X-ray transient
  47. GRB 260114A: VLT/HAWK-I further near-infrared upper limits
  48. IceCube Alert 260115.73: Global MASTER-Net observations report
  49. IceCube-260115A - IceCube observation of a high-energy neutrino candidate track-like event
  50. GRB 260115A: BALROG localization (Fermi Trigger 790192010 / GRB 260115741)
  51. IceCube: GCN Notices for high-energy track alerts now streamed via Kafka
  52. Fermi GRB 260115A: Global MASTER-Net observations report
  53. GRB 260115A: Fermi GBM Final Real-time Localization
  54. Konus-Wind detection of GRB 260114A
  55. GRB 260114A: VLT/X-shooter redshift of the putative host galaxy
  56. GRB 260114A : MITSuME Akeno optical upper limits
  57. GRB 260114A: TNG NIR upper limit
  58. GRB 260114A: NOT optical observations
  59. Konus-Wind detection of GRB 251230A / EP251230a
  60. GRB 260114A: SVOM/GRM observation of a short burst
  61. Swift GRB 260114A: Global MASTER-Net observations report
  62. GRB 260114A: GECAM-B observation of a short burst
  63. GRB 260114A: Fermi GBM observation
  64. Fermi-LAT Gamma-ray Observations of IceCube-260111A
  65. GRB 260114A: Swift detection of a short burst
  66. GRB 260114A: Fermi GBM Final Real-time Localization
  67. IceCube-260111A: Upper limits from a search for additional neutrino events in IceCube
  68. Swift GRB260113.43: Global MASTER-Net observations report
  69. EP260110a: NOT and GTC Optical and Near-Infrared Observations
  70. EP260110a: TRT optical upper limits
  71. Konus-Wind detection of GRB 260101A
  72. GRB 260111A: Fermi GBM Observation
  73. The EP-WXT trigger 01709251266 is likely a flaring star
  74. Swift Trigger 1434591 is not a GRB
  75. GRB 260111A: GOTO optical upper limits
  76. GRB 260112B: Fermi GBM Final Real-time Localization
  77. GRB 260111A: Swift/BAT-GUANO arcminute localization of a burst
  78. GRB 260112A: Fermi GBM Final Real-time Localization
  79. EP260110a: SVOM/VT optical upper limits
  80. IceCube-260111A - IceCube observation of a high-energy neutrino candidate track-like event
  81. IceCube Alert 260111A: Global MASTER-Net observations report
  82. EP260110a: Global MASTER-Net observations report
  83. Fermi GRB 260111A: Global MASTER-Net observations report
  84. GRB 260111A: Fermi GBM Final Real-time Localization
  85. Swift trigger 1436759 is not an astrophysical event
  86. EP260110a: KAIT optical upper limit
  87. EP260110a: refined analysis of the EP-WXT and EP-FXT observations
  88. EP 260110a: COLIBRÍ optical observations
  89. EP260110a: SVOM/C-GFT upper limit
  90. EP260110a: BOOTES-5/JGU optical upper limit
  91. GRB 260109C: LCO optical upper limits
  92. EP260105b / GRB 260105C : Fermi-GBM Sub-Threshold Detection
  93. GRB 260109B: Fermi GBM Final Real-time Localization
  94. GRB 260102A: Swift-XRT afterglow detection
  95. GRB 260109A: Fermi GBM Final Real-time Localization
  96. GRB 260104A: Swift-BAT refined analysis
  97. GRB 260101A: Swift-BAT refined analysis
  98. Swift GRB 251230A: Global MASTER-Net OT detection
  99. Fermi GRB 260107A: Global MASTER-Net observations report
  100. GRB 260107A: Fermi GBM Final Real-time Localization

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