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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"

26670 results found.

  1. EP260131a: NOT early detection of the counterpart in "rapid response mode"
  2. GRB 260131B: MAXI/GSC detection
  3. EP260131a: COLIBRÍ optical observations of the counterpart
  4. EP260131a: Las Cumbres detection of an optical counterpart
  5. GRB 260127B: AstroSat CZTI detection
  6. GRB 260130A: Fermi GBM Detection
  7. EP260131a: Einstein Probe detection of an X-ray transient
  8. GRB 260127B: Fermi GBM Detection
  9. EP260128a / GRB 260128A: COLIBRÍ optical upper limit
  10. Fermi GRB 260130A: Global MASTER-Net observations report
  11. Fermi GRB 260129A: Global MASTER-Net observations report
  12. GRB 260128B: LCO optical upper limits
  13. GRB 260128B: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  14. EP260128a: J band upper limit by SYSU 80cm infrared telescope
  15. GRB 260127A: Swift-BAT refined analysis
  16. GRB 260127B: Swift-XRT observations
  17. GRB 260127A: INASAN-Kislovodsk, SAO RAS, and Terskol K-800 optical observations
  18. GRB 260128A / EP260128a: Fermi-GBM Sub-Threshold Detection
  19. EP260128a: NOT optical counterpart candidate
  20. EP260128a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  21. EP260128a: Liverpool Telescope optical observations and possible counterpart
  22. EP260128a: LCO optical upper limits
  23. EP260128a: Global MASTER-Net observations report
  24. EP260128a: Einstein Probe detection of an X-ray transient
  25. Fermi GRB 260127A: Global MASTER-Net observations report
  26. GRB 260127A: Fermi GBM Observation
  27. IceCube-260125A: Upper limits from a search for additional neutrino events in IceCube
  28. GRB 260127A: COLIBRÍ optical observations
  29. EP260126a: Seimei/TriCCS optical upper limit
  30. GRB 260127A : MITSuME Akeno optical afterglow candidate detection
  31. GRB 260127A: Swift-XRT refined Analysis
  32. GRB 260127A: SVOM/C-GFT optical observations
  33. GRB 260127A: Enhanced Swift-XRT position
  34. Fermi GRB 260127B: Global MASTER-Net observations report
  35. Swift GRB 260127A: Global MASTER-Net observations report
  36. GRB 260127A: LCO optical afterglow discovery
  37. GRB 260127A: Swift detection of a burst
  38. GRB 260125A: Swift-XRT observations
  39. EP260126a: Optical upper limit with Kinder observations
  40. EP260126a: Liverpool Telescope optical upper limits
  41. EP260126a: Further NOT optical upper limits
  42. EP260126a: COLIBRÍ optical upper limits
  43. EP260126a: NOT optical observations
  44. EP260126a: Einstein Probe detection of a fast X-ray transient
  45. Fermi-LAT Gamma-ray Observations of IceCube-260125A
  46. GRB 251222A: SVOM/ECLAIRs refined analysis
  47. GRB 260125A: GOTO candidate optical counterpart
  48. Fermi GRB 260125B: Global MASTER-Net observations report
  49. GRB 260114A: SVOM/VT optical upper limits
  50. GRB 260122B: Swift-BAT refined analysis
  51. GRB 260120B: SVOM/GRM observation
  52. Swift GRB260122.97: Global MASTER-Net observations report
  53. EP260119a: Assy AZT-20 optical observations
  54. EP260119a: Mondy and SAO RAS optical upper limits
  55. EP260119a: Xinglong optical upper limit
  56. Fermi GRB 260120C: Global MASTER-Net observations report
  57. GRB 260120B: Swift-BAT refined analysis
  58. GRB 260120B: Swift-XRT refined Analysis
  59. EP260116a: COLIBRÍ further observations
  60. GRB 251122A / EP251122a: VLT/X-shooter host redshift z = 1.765
  61. GRB 260120B: Fermi GBM Observation
  62. EP260105a: GTC/HiPERCAM optical observations
  63. GRB 260120B: Swift/UVOT Detection
  64. GRB 260120B: COLIBRÍ optical upper limits
  65. SVOM GRB260121.06: Global MASTER-Net observations report
  66. GRB 260120B: Enhanced Swift-XRT position
  67. GRB 260120B: SVOM/C-GFT optical counterpart detection
  68. GRB 260101A: 239Alferov CubeSat detection
  69. EP260116a: COLIBRÍ observations of a tentative optical rebrightening
  70. GRB 260120B: Swift detection of a burst
  71. Swift GRB260120B: Global MASTER-Net observations report
  72. EP260119A: Mondy I-Band Observations
  73. Fermi trigger No 790601190: Global MASTER-Net observations report
  74. Fermi trigger No 790570272: Global MASTER-Net observations report
  75. GRB 260114A: Swift/UVOT Upper Limits
  76. EP260119a: Liverpool Telescope optical follow-up observations
  77. GRB 251202A: further radio observations with the VLA
  78. EP260119a: KAIT optical observations
  79. EP260119a: SVOM/VT optical observation
  80. EP260119a: NOT optical observations
  81. EP260119a: SAO RAS optical observations
  82. SVOM GRB260119.92: Global MASTER-Net observations report
  83. SVOM GRB260119.92: Global MASTER-Net observations report
  84. SVOM GRB260119.90: Global MASTER-Net observations report
  85. EP260116a: COLIBRÍ detection of a fading optical source
  86. GRB 260117A: Swift-XRT afterglow detection
  87. EP260119a: COLIBRÍ photometric redshift z ≈ 5.6
  88. EP260119a: Global MASTER-Net observations report
  89. EP260119a: LCO optical observations
  90. GRB 260117A: ZTSh optical upper limit
  91. EP260119a: COLIBRÍ optical counterpart candidate
  92. EP260119a: EP-WXT detection of a fast X-ray transient
  93. Swift GRB260118.48: Global MASTER-Net observations report
  94. GRB 260117A: SVOM/COLIBRÍ (FM-GFT) optical observations
  95. SVOM GRB260117.82: Global MASTER-Net observations report
  96. Fermi-LAT Gamma-ray Observations of IceCube-260115A
  97. Swift trigger on the HMXB 1A 1118-61
  98. GRB 260117A: SVOM/VT optical candidate
  99. GRB 260117A: SVOM/C-GFT upper limit
  100. GRB 260117A: Swift-XRT observations

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