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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"

2417 results found.

  1. GRB 260131A: FTW optical and NIR observations
  2. GRID detection of GRB 260131A/B
  3. GRB 260130A: Insight-HXMT/HE detection
  4. GRB 260130A: GECAM-B observation of a short burst
  5. GRB 260131A/B (AT2026bwg): J-band observations by SYSU 80cm infrared telescope
  6. GRB 260131A/B: EP/FXT X-ray afterglow detection
  7. GRB 260131A/B (AT2026bwg): COLIBRÍ further optical observations
  8. GRB 260127B: Insight-HXMT/HE detection
  9. GRB 260127B: GECAM-B observation of a short burst
  10. GRB 260127A: GECAM-B observation
  11. GRB 260131A: NOT spectroscopic redshift z = 1.434
  12. EP260131a: Liverpool Telescope optical upper limits
  13. EP260131a: COLIBRÍ further observations
  14. GRB 260131A: Insight-HXMT/HE detection
  15. EP260131a: SVOM/VT optical observation
  16. EP260131a: Xinglong optical upper limit
  17. GRB 260131A/B (AT2026bwg): COLIBRÍ optical observations and confirmation of fading
  18. GRB 260131A/B: GOTO candidate optical counterpart consistent with the MAXI localisation
  19. GRB 260131A/B: Fermi GBM Observation
  20. EP260131a: COLIBRÍ observations of slow optical fading
  21. EP260131a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  22. EP260131a: VLT/X-shooter spectroscopic redshift z = 0.937
  23. EP260131a: NOT early detection of the counterpart in "rapid response mode"
  24. GRB 260131B: MAXI/GSC detection
  25. GRB 260131A: Fermi GBM Final Real-time Localization
  26. EP260131a: COLIBRÍ optical observations of the counterpart
  27. GRB 260127B: AstroSat CZTI detection
  28. GRB 260130A: Fermi GBM Detection
  29. EP260131a: Einstein Probe detection of an X-ray transient
  30. GRB 260127B: Fermi GBM Detection
  31. EP260128a / GRB 260128A: COLIBRÍ optical upper limit
  32. Fermi GRB 260130A: Global MASTER-Net observations report
  33. EP260128a / GRB 260128A: NOT and TNG optical and NIR upper limits
  34. GRB 260130A: Fermi GBM Final Real-time Localization
  35. Fermi GRB 260129A: Global MASTER-Net observations report
  36. GRB 260128B: LCO optical upper limits
  37. GRB 260128B: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  38. EP260128a: J band upper limit by SYSU 80cm infrared telescope
  39. GRB 260129B: Fermi GBM Final Localization
  40. GRB 260128B: SVOM detection of a burst through offline search
  41. GRB 260129A: Fermi GBM Final Localization
  42. GRB 260127A: INASAN-Kislovodsk, SAO RAS, and Terskol K-800 optical observations
  43. GRB 260128A / EP260128a: Fermi-GBM Sub-Threshold Detection
  44. EP260128a: NOT optical counterpart candidate
  45. EP260128a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  46. EP260128a: Liverpool Telescope optical observations and possible counterpart
  47. EP260128a: LCO optical upper limits
  48. EP260126a: SVOM/VT optical upperlimit
  49. EP260128a: Global MASTER-Net observations report
  50. EP260128a: Einstein Probe detection of an X-ray transient
  51. Fermi GRB 260127A: Global MASTER-Net observations report
  52. IceCube-260125A: No Candidate Transients from the Zwicky Transient Facility
  53. GRB 260127A: Fermi GBM Observation
  54. IceCube-260125A: Upper limits from a search for additional neutrino events in IceCube
  55. GRB 260127A: COLIBRÍ optical observations
  56. EP260126a: Seimei/TriCCS optical upper limit
  57. GRB 260127A : MITSuME Akeno optical afterglow candidate detection
  58. GRB 260127B: GOTO candidate optical counterpart
  59. GRB 260127A: SVOM/C-GFT optical observations
  60. The EP-WXT trigger 01709253145 is likely a flaring star
  61. Fermi GRB 260127B: Global MASTER-Net observations report
  62. GRB 260127B: Fermi GBM Final Real-time Localization
  63. Swift GRB 260127A: Global MASTER-Net observations report
  64. GRB 260127A: LCO optical afterglow discovery
  65. GRB 260127A: Fermi GBM Final Real-time Localization
  66. EP260126a: Optical upper limit with Kinder observations
  67. EP260126a: Liverpool Telescope optical upper limits
  68. EP260126a: Further NOT optical upper limits
  69. EP260126a: COLIBRÍ optical upper limits
  70. EP260126a: NOT optical observations
  71. EP260126a: Einstein Probe detection of a fast X-ray transient
  72. Fermi-LAT Gamma-ray Observations of IceCube-260125A
  73. GRB 260125A: NOT optical observations on GOTO26acv / AT 2026bjf
  74. GRB 260125A: GOTO candidate optical counterpart
  75. Fermi GRB 260125B: Global MASTER-Net observations report
  76. GRB 260125B: Fermi GBM Final Real-time Localization
  77. GRB 260125A: Fermi GBM Final Real-time Localization
  78. GRB 260114A: SVOM/VT optical upper limits
  79. GRB 260120A: AstroSat CZTI detection
  80. GRB 260120B: SVOM/GRM observation
  81. GRB 260120A: GECAM-B observation
  82. GRB 260120B: AstroSat CZTI detection
  83. GRB 260114A: Insight-HXMT/HE detection
  84. GRB 260122B: Swift detection of a burst
  85. Swift GRB260122.97: Global MASTER-Net observations report
  86. EP260119a: Assy AZT-20 optical observations
  87. EP260119a: Mondy and SAO RAS optical upper limits
  88. GRB 260122A: Fermi GBM Final Real-time Localization
  89. IceCube-260115A: No Candidate Transients from the Zwicky Transient Facility
  90. EP260119a: Xinglong optical upper limit
  91. The EP-WXT trigger 01709251871 is likely a flaring star
  92. Fermi GRB 260120C: Global MASTER-Net observations report
  93. EP260116a: COLIBRÍ further observations
  94. GRB 260120B: Fermi GBM Observation
  95. EP260105a: GTC/HiPERCAM optical observations
  96. GRB 260120B: COLIBRÍ optical upper limits
  97. SVOM GRB260121.06: Global MASTER-Net observations report
  98. GRB 260120B: SVOM/C-GFT optical counterpart detection
  99. GRB 260120C: Fermi GBM Final Real-time Localization
  100. EP260116a: COLIBRÍ observations of a tentative optical rebrightening

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