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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"

24366 results found.

  1. Swift GRB260122.97: Global MASTER-Net observations report
  2. GRB 260122A: Fermi GBM Final Real-time Localization
  3. IceCube-260115A: No Candidate Transients from the Zwicky Transient Facility
  4. EP260119a: Xinglong optical upper limit
  5. The EP-WXT trigger 01709251871 is likely a flaring star
  6. Fermi GRB 260120C: Global MASTER-Net observations report
  7. GRB 260120B: Swift-BAT refined analysis
  8. GRB 251122A / EP251122a: VLT/X-shooter host redshift z = 1.765
  9. GRB 260120B: Fermi GBM Observation
  10. EP260105a: GTC/HiPERCAM optical observations
  11. GRB 260120B: COLIBRÍ optical upper limits
  12. SVOM GRB260121.06: Global MASTER-Net observations report
  13. GRB 260120B: SVOM/C-GFT optical counterpart detection
  14. GRB 260120C: Fermi GBM Final Real-time Localization
  15. GRB 260120B: Swift detection of a burst
  16. Swift GRB260120B: Global MASTER-Net observations report
  17. GRB 260120B: Fermi GBM Final Real-time Localization
  18. Fermi trigger No 790601190: Global MASTER-Net observations report
  19. Fermi trigger No 790570272: Global MASTER-Net observations report
  20. EP260119a: Liverpool Telescope optical follow-up observations
  21. EP260119A: GTC/OSIRIS+ spectroscopic redshift z = 5.47
  22. EP260119a: KAIT optical observations
  23. GRB 260120A: Fermi GBM Final Real-time Localization
  24. EP260119a: SVOM/VT optical observation
  25. EP260119a: update of EP-FXT follow-up observation
  26. SVOM GRB260119.92: Global MASTER-Net observations report
  27. SVOM GRB260119.92: Global MASTER-Net observations report
  28. SVOM GRB260119.90: Global MASTER-Net observations report
  29. GRB 251208D: SVOM/ECLAIRs refined analysis
  30. GRB 251208D: SVOM/ECLAIRs refined analysis
  31. GRB 260117A: Swift-XRT afterglow detection
  32. EP260119a: COLIBRÍ photometric redshift z ≈ 5.6
  33. EP260119a: Global MASTER-Net observations report
  34. GRB 260110A: SVOM detection of a burst through offline search
  35. Swift GRB260118.48: Global MASTER-Net observations report
  36. SVOM GRB260117.82: Global MASTER-Net observations report
  37. Fermi-LAT Gamma-ray Observations of IceCube-260115A
  38. GRB 260117A: SVOM/VT optical candidate
  39. GRB 260117A: SVOM/C-GFT upper limit
  40. GRB 260117A: Swift-XRT observations
  41. GRB 260117A: SVOM detection of a long faint burst
  42. Swift triggered on the HMXB 1A 1118-61
  43. GRB 260115A: GECAM-B observation
  44. FRB 20251229A: COLIBRÍ further inspection of the updated localization
  45. FRB 20251229A: Updated CHIME/FRB Baseband Localization of FRB 20251229A
  46. EP260116A: 1.3m DFOT optical upper limit
  47. GRB 260114A: VLT/MUSE spectroscopic observations
  48. IceCube-260115A: Upper limits from a search for additional neutrino events in IceCube
  49. EP260116a: Global MASTER-Net observations report
  50. EP260116a: Xinglong optical upper limit
  51. EP260116a: Einstein Probe detection of an X-ray transient
  52. GRB 260114A: VLT/HAWK-I further near-infrared upper limits
  53. IceCube Alert 260115.73: Global MASTER-Net observations report
  54. IceCube-260115A - IceCube observation of a high-energy neutrino candidate track-like event
  55. GRB 260115A: BALROG localization (Fermi Trigger 790192010 / GRB 260115741)
  56. IceCube: GCN Notices for high-energy track alerts now streamed via Kafka
  57. Fermi GRB 260115A: Global MASTER-Net observations report
  58. GRB 260115A: Fermi GBM Final Real-time Localization
  59. Konus-Wind detection of GRB 260114A
  60. GRB 260114A: VLT/X-shooter redshift of the putative host galaxy
  61. GRB 260114A : MITSuME Akeno optical upper limits
  62. GRB 260114A: TNG NIR upper limit
  63. GRB 260114A: NOT optical observations
  64. Konus-Wind detection of GRB 251230A / EP251230a
  65. GRB 260114A: SVOM/GRM observation of a short burst
  66. Swift GRB 260114A: Global MASTER-Net observations report
  67. GRB 260114A: GECAM-B observation of a short burst
  68. GRB 260114A: Fermi GBM observation
  69. Fermi-LAT Gamma-ray Observations of IceCube-260111A
  70. GRB 260114A: Swift detection of a short burst
  71. GRB 260114A: Fermi GBM Final Real-time Localization
  72. IceCube-260111A: Upper limits from a search for additional neutrino events in IceCube
  73. Swift GRB260113.43: Global MASTER-Net observations report
  74. EP260110a: NOT and GTC Optical and Near-Infrared Observations
  75. EP260110a: TRT optical upper limits
  76. Konus-Wind detection of GRB 260101A
  77. GRB 260111A: Fermi GBM Observation
  78. The EP-WXT trigger 01709251266 is likely a flaring star
  79. Swift Trigger 1434591 is not a GRB
  80. GRB 260111A: GOTO optical upper limits
  81. GRB 260112B: Fermi GBM Final Real-time Localization
  82. GRB 260111A: Swift/BAT-GUANO arcminute localization of a burst
  83. GRB 260112A: Fermi GBM Final Real-time Localization
  84. EP260110a: SVOM/VT optical upper limits
  85. IceCube-260111A - IceCube observation of a high-energy neutrino candidate track-like event
  86. IceCube Alert 260111A: Global MASTER-Net observations report
  87. EP260110a: Global MASTER-Net observations report
  88. Fermi GRB 260111A: Global MASTER-Net observations report
  89. GRB 260111A: Fermi GBM Final Real-time Localization
  90. Swift trigger 1436759 is not an astrophysical event
  91. EP260110a: KAIT optical upper limit
  92. EP260110a: refined analysis of the EP-WXT and EP-FXT observations
  93. EP 260110a: COLIBRÍ optical observations
  94. EP260110a: SVOM/C-GFT upper limit
  95. EP260110a: BOOTES-5/JGU optical upper limit
  96. GRB 260109C: LCO optical upper limits
  97. EP260105b / GRB 260105C : Fermi-GBM Sub-Threshold Detection
  98. GRB 260109B: Fermi GBM Final Real-time Localization
  99. GRB 260102A: Swift-XRT afterglow detection
  100. GRB 260109A: Fermi GBM Final Real-time Localization

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