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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"

28057 results found.

  1. EP260128a: J band upper limit by SYSU 80cm infrared telescope
  2. GRB 260127A: Swift-BAT refined analysis
  3. GRB 260127B: Swift-XRT observations
  4. GRB 260127A: INASAN-Kislovodsk, SAO RAS, and Terskol K-800 optical observations
  5. GRB 260128A / EP260128a: Fermi-GBM Sub-Threshold Detection
  6. EP260128a: NOT optical counterpart candidate
  7. EP260128a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  8. EP260128a: Liverpool Telescope optical observations and possible counterpart
  9. EP260128a: LCO optical upper limits
  10. EP260128a: Global MASTER-Net observations report
  11. EP260128a: Einstein Probe detection of an X-ray transient
  12. Fermi GRB 260127A: Global MASTER-Net observations report
  13. GRB 260127A: Fermi GBM Observation
  14. IceCube-260125A: Upper limits from a search for additional neutrino events in IceCube
  15. GRB 260127A: COLIBRÍ optical observations
  16. EP260126a: Seimei/TriCCS optical upper limit
  17. GRB 260127A : MITSuME Akeno optical afterglow candidate detection
  18. GRB 260127A: Swift-XRT refined Analysis
  19. GRB 260127A: SVOM/C-GFT optical observations
  20. GRB 260127A: Enhanced Swift-XRT position
  21. Fermi GRB 260127B: Global MASTER-Net observations report
  22. Swift GRB 260127A: Global MASTER-Net observations report
  23. GRB 260127A: LCO optical afterglow discovery
  24. GRB 260127A: Swift detection of a burst
  25. GRB 260125A: Swift-XRT observations
  26. EP260126a: Optical upper limit with Kinder observations
  27. EP260126a: Liverpool Telescope optical upper limits
  28. EP260126a: Further NOT optical upper limits
  29. EP260126a: COLIBRÍ optical upper limits
  30. EP260126a: NOT optical observations
  31. EP260126a: Einstein Probe detection of a fast X-ray transient
  32. Fermi-LAT Gamma-ray Observations of IceCube-260125A
  33. GRB 251222A: SVOM/ECLAIRs refined analysis
  34. GRB 260125A: GOTO candidate optical counterpart
  35. Fermi GRB 260125B: Global MASTER-Net observations report
  36. GRB 260114A: SVOM/VT optical upper limits
  37. GRB 260122B: Swift-BAT refined analysis
  38. GRB 260120B: SVOM/GRM observation
  39. Swift GRB260122.97: Global MASTER-Net observations report
  40. EP260119a: Assy AZT-20 optical observations
  41. EP260119a: Mondy and SAO RAS optical upper limits
  42. EP260119a: Xinglong optical upper limit
  43. Fermi GRB 260120C: Global MASTER-Net observations report
  44. GRB 260120B: Swift-BAT refined analysis
  45. GRB 260120B: Swift-XRT refined Analysis
  46. EP260116a: COLIBRÍ further observations
  47. GRB 251122A / EP251122a: VLT/X-shooter host redshift z = 1.765
  48. GRB 260120B: Fermi GBM Observation
  49. EP260105a: GTC/HiPERCAM optical observations
  50. GRB 260120B: Swift/UVOT Detection
  51. GRB 260120B: COLIBRÍ optical upper limits
  52. SVOM GRB260121.06: Global MASTER-Net observations report
  53. GRB 260120B: Enhanced Swift-XRT position
  54. GRB 260120B: SVOM/C-GFT optical counterpart detection
  55. GRB 260101A: 239Alferov CubeSat detection
  56. EP260116a: COLIBRÍ observations of a tentative optical rebrightening
  57. GRB 260120B: Swift detection of a burst
  58. Swift GRB260120B: Global MASTER-Net observations report
  59. EP260119A: Mondy I-Band Observations
  60. Fermi trigger No 790601190: Global MASTER-Net observations report
  61. Fermi trigger No 790570272: Global MASTER-Net observations report
  62. GRB 260114A: Swift/UVOT Upper Limits
  63. EP260119a: Liverpool Telescope optical follow-up observations
  64. GRB 251202A: further radio observations with the VLA
  65. EP260119a: KAIT optical observations
  66. EP260119a: SVOM/VT optical observation
  67. EP260119a: NOT optical observations
  68. EP260119a: SAO RAS optical observations
  69. SVOM GRB260119.92: Global MASTER-Net observations report
  70. SVOM GRB260119.92: Global MASTER-Net observations report
  71. SVOM GRB260119.90: Global MASTER-Net observations report
  72. EP260116a: COLIBRÍ detection of a fading optical source
  73. GRB 260117A: Swift-XRT afterglow detection
  74. EP260119a: COLIBRÍ photometric redshift z ≈ 5.6
  75. EP260119a: Global MASTER-Net observations report
  76. EP260119a: LCO optical observations
  77. GRB 260117A: ZTSh optical upper limit
  78. EP260119a: COLIBRÍ optical counterpart candidate
  79. EP260119a: EP-WXT detection of a fast X-ray transient
  80. Swift GRB260118.48: Global MASTER-Net observations report
  81. GRB 260117A: SVOM/COLIBRÍ (FM-GFT) optical observations
  82. SVOM GRB260117.82: Global MASTER-Net observations report
  83. Fermi-LAT Gamma-ray Observations of IceCube-260115A
  84. Swift trigger on the HMXB 1A 1118-61
  85. GRB 260117A: SVOM/VT optical candidate
  86. GRB 260117A: SVOM/C-GFT upper limit
  87. GRB 260117A: Swift-XRT observations
  88. GRB 260117A: SVOM detection of a long faint burst
  89. EP 260116a: COLIBRÍ optical upper limit
  90. Swift triggered on the HMXB 1A 1118-61
  91. FRB 20251229A: COLIBRÍ further inspection of the updated localization
  92. EP260116a: Liverpool Telescope upper limits
  93. FRB 20251229A: Updated CHIME/FRB Baseband Localization of FRB 20251229A
  94. EP260116A: 1.3m DFOT optical upper limit
  95. GRB 260114A: VLT/MUSE spectroscopic observations
  96. IceCube-260115A: Upper limits from a search for additional neutrino events in IceCube
  97. EP260116a: Global MASTER-Net observations report
  98. GRB 260111A: COLIBRÍ fading of the optical counterpart candidate
  99. EP260116a: Xinglong optical upper limit
  100. EP260116a: Einstein Probe detection of an X-ray transient

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