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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"

45898 results found.

  1. EP260126a: Einstein Probe detection of a fast X-ray transient
  2. Fermi-LAT Gamma-ray Observations of IceCube-260125A
  3. GRB 260125A: NOT optical observations on GOTO26acv / AT 2026bjf
  4. Konus-Wind detection of GRB 260120B
  5. GRB 251222A: SVOM/ECLAIRs refined analysis
  6. GRB 260125A: Swift ToO observations
  7. GRB 260125A: GOTO candidate optical counterpart
  8. Fermi GRB 260125B: Global MASTER-Net observations report
  9. IceCube-260125A - IceCube observation of a high-energy neutrino candidate track-like event
  10. GRB 260125B: Fermi GBM Final Real-time Localization
  11. GRB 260125A: Fermi GBM Final Real-time Localization
  12. GRB 260114A: SVOM/VT optical upper limits
  13. GRB 260120A: AstroSat CZTI detection
  14. GRB 260122B: Swift-BAT refined analysis
  15. GRB 260120B: SVOM/GRM observation
  16. GRB 260120A: GECAM-B observation
  17. GRB 260120B: AstroSat CZTI detection
  18. GRB 260114A: Insight-HXMT/HE detection
  19. GRB 260122B: Swift detection of a burst
  20. Swift GRB260122.97: Global MASTER-Net observations report
  21. EP260119a: Assy AZT-20 optical observations
  22. EP260119a: Mondy and SAO RAS optical upper limits
  23. GRB 260122A: Fermi GBM Final Real-time Localization
  24. IceCube-260115A: No Candidate Transients from the Zwicky Transient Facility
  25. EP260119a: Xinglong optical upper limit
  26. The EP-WXT trigger 01709251871 is likely a flaring star
  27. Fermi GRB 260120C: Global MASTER-Net observations report
  28. GRB 260120B: Swift-BAT refined analysis
  29. GRB 260120B: Swift-XRT refined Analysis
  30. EP260116a: COLIBRÍ further observations
  31. GRB 251122A / EP251122a: VLT/X-shooter host redshift z = 1.765
  32. GRB 260120B: Fermi GBM Observation
  33. EP260105a: GTC/HiPERCAM optical observations
  34. GRB 260120B: Swift/UVOT Detection
  35. GRB 260120B: COLIBRÍ optical upper limits
  36. SVOM GRB260121.06: Global MASTER-Net observations report
  37. GRB 260120B: Enhanced Swift-XRT position
  38. GRB 260120B: SVOM/C-GFT optical counterpart detection
  39. GRB 260120C: Fermi GBM Final Real-time Localization
  40. GRB 260101A: 239Alferov CubeSat detection
  41. EP260116a: COLIBRÍ observations of a tentative optical rebrightening
  42. GRB 260120B: Swift detection of a burst
  43. Swift GRB260120B: Global MASTER-Net observations report
  44. GRB 260120B: Fermi GBM Final Real-time Localization
  45. EP260119A: Mondy I-Band Observations
  46. Fermi trigger No 790601190: Global MASTER-Net observations report
  47. Fermi trigger No 790570272: Global MASTER-Net observations report
  48. GRB 260114A: Swift/UVOT Upper Limits
  49. EP260119a: Liverpool Telescope optical follow-up observations
  50. GRB 251202A: further radio observations with the VLA
  51. Trigger 1442421: Swift detection of HMXB 1A 1118-61
  52. EP260119A: GTC/OSIRIS+ spectroscopic redshift z = 5.47
  53. EP260119a: KAIT optical observations
  54. GRB 260120A: Fermi GBM Final Real-time Localization
  55. EP260119a: SVOM/VT optical observation
  56. EP260119a: update of EP-FXT follow-up observation
  57. EP260119a: NOT optical observations
  58. EP260119a: SAO RAS optical observations
  59. SVOM GRB260119.92: Global MASTER-Net observations report
  60. SVOM GRB260119.92: Global MASTER-Net observations report
  61. SVOM GRB260119.90: Global MASTER-Net observations report
  62. EP260116a: COLIBRÍ detection of a fading optical source
  63. GRB 251208D: SVOM/ECLAIRs refined analysis
  64. GRB 251208D: SVOM/ECLAIRs refined analysis
  65. GRB 260117A: Swift-XRT afterglow detection
  66. EP260119a: COLIBRÍ photometric redshift z ≈ 5.6
  67. EP260119a: Global MASTER-Net observations report
  68. GRB 260115A: AstroSat CZTI detection
  69. EP260119a: LCO optical observations
  70. GRB 260117A: ZTSh optical upper limit
  71. EP260119a: COLIBRÍ optical counterpart candidate
  72. EP260119a: preliminary result from the EP-FXT observation
  73. GRB 260110A: SVOM detection of a burst through offline search
  74. EP260119a: EP-WXT detection of a fast X-ray transient
  75. Swift GRB260118.48: Global MASTER-Net observations report
  76. GRB 260117A: SVOM/COLIBRÍ (FM-GFT) optical observations
  77. SVOM GRB260117.82: Global MASTER-Net observations report
  78. Fermi-LAT Gamma-ray Observations of IceCube-260115A
  79. Swift trigger on the HMXB 1A 1118-61
  80. GRB 260117A: SVOM/VT optical candidate
  81. GRB 260117A: SVOM/C-GFT upper limit
  82. GRB 260117A: Swift-XRT observations
  83. GRB 260117A: Swift ToO observations
  84. GRB 260117A: SVOM detection of a long faint burst
  85. EP 260116a: COLIBRÍ optical upper limit
  86. Swift triggered on the HMXB 1A 1118-61
  87. GRB 260115A: GECAM-B observation
  88. FRB 20251229A: COLIBRÍ further inspection of the updated localization
  89. EP260116a: Liverpool Telescope upper limits
  90. FRB 20251229A: Updated CHIME/FRB Baseband Localization of FRB 20251229A
  91. EP260116A: 1.3m DFOT optical upper limit
  92. GRB 260114A: VLT/MUSE spectroscopic observations
  93. IceCube-260115A: Upper limits from a search for additional neutrino events in IceCube
  94. EP260116a: Global MASTER-Net observations report
  95. GRB 260111A: COLIBRÍ fading of the optical counterpart candidate
  96. EP260116a: Xinglong optical upper limit
  97. EP260116a: Einstein Probe detection of an X-ray transient
  98. GRB 260114A: VLT/HAWK-I further near-infrared upper limits
  99. IceCube Alert 260115.73: Global MASTER-Net observations report
  100. IceCube-260115A - IceCube observation of a high-energy neutrino candidate track-like event

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