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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"

2437 results found.

  1. GRB 260208A: Fermi GBM Final Real-time Localization
  2. GRB 260207B: Fermi GBM Detection of a Short Burst with Extended Emission
  3. GRB 260207A : MASTER optical counterpart discovery
  4. GRB 260131A/B: Mondy and Terskol optical observations
  5. Fermi GRB 260207B: Global MASTER-Net observations report
  6. GRB 260207B: Fermi GBM Final Real-time Localization
  7. GRB 260207A: Fermi GBM Final Localization
  8. Fermi trigger No 792135758: Global MASTER-Net observations report
  9. EP260131a: VLA detection
  10. GRB 260206A (or XRB from 4U 0513-40): MAXI/GSC detection
  11. GRB 260204A: SVOM/VT confirms fading of the optical afterglow
  12. GRB 260204A: SVOM/VT optical candidate
  13. GRB 260204A : MASTER Global robotic net optical observations
  14. Fermi GBM Sub-Threshold Detection of GRB 260204A
  15. GRB 260204A: GOTO optical upper limit
  16. GRB 260204A: LCO optical upper limits
  17. EP260110a: Late GTC/EMIR near-infrared observations
  18. GRB 260204B: Fermi GBM Final Real-time Localization
  19. GRB 260204A: SVOM detection of a burst
  20. GRB 260131A/B: OHP/T193 optical observations
  21. GRB 260131A: FTW optical and NIR observations
  22. GRID detection of GRB 260131A/B
  23. GRB 260130A: Insight-HXMT/HE detection
  24. GRB 260130A: GECAM-B observation of a short burst
  25. GRB 260131A/B (AT2026bwg): J-band observations by SYSU 80cm infrared telescope
  26. GRB 260131A/B: EP/FXT X-ray afterglow detection
  27. GRB 260131A/B (AT2026bwg): COLIBRÍ further optical observations
  28. GRB 260127B: Insight-HXMT/HE detection
  29. GRB 260127B: GECAM-B observation of a short burst
  30. GRB 260127A: GECAM-B observation
  31. GRB 260131A: NOT spectroscopic redshift z = 1.434
  32. EP260131a: Liverpool Telescope optical upper limits
  33. EP260131a: COLIBRÍ further observations
  34. GRB 260131A: Insight-HXMT/HE detection
  35. EP260131a: SVOM/VT optical observation
  36. EP260131a: Xinglong optical upper limit
  37. GRB 260131A/B (AT2026bwg): COLIBRÍ optical observations and confirmation of fading
  38. GRB 260131A/B: GOTO candidate optical counterpart consistent with the MAXI localisation
  39. GRB 260131A/B: Fermi GBM Observation
  40. EP260131a: COLIBRÍ observations of slow optical fading
  41. EP260131a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  42. EP260131a: VLT/X-shooter spectroscopic redshift z = 0.937
  43. EP260131a: NOT early detection of the counterpart in "rapid response mode"
  44. GRB 260131B: MAXI/GSC detection
  45. GRB 260131A: Fermi GBM Final Real-time Localization
  46. EP260131a: COLIBRÍ optical observations of the counterpart
  47. GRB 260127B: AstroSat CZTI detection
  48. GRB 260130A: Fermi GBM Detection
  49. EP260131a: Einstein Probe detection of an X-ray transient
  50. GRB 260127B: Fermi GBM Detection
  51. EP260128a / GRB 260128A: COLIBRÍ optical upper limit
  52. Fermi GRB 260130A: Global MASTER-Net observations report
  53. EP260128a / GRB 260128A: NOT and TNG optical and NIR upper limits
  54. GRB 260130A: Fermi GBM Final Real-time Localization
  55. Fermi GRB 260129A: Global MASTER-Net observations report
  56. GRB 260128B: LCO optical upper limits
  57. GRB 260128B: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  58. EP260128a: J band upper limit by SYSU 80cm infrared telescope
  59. GRB 260129B: Fermi GBM Final Localization
  60. GRB 260128B: SVOM detection of a burst through offline search
  61. GRB 260129A: Fermi GBM Final Localization
  62. GRB 260127A: INASAN-Kislovodsk, SAO RAS, and Terskol K-800 optical observations
  63. GRB 260128A / EP260128a: Fermi-GBM Sub-Threshold Detection
  64. EP260128a: NOT optical counterpart candidate
  65. EP260128a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  66. EP260128a: Liverpool Telescope optical observations and possible counterpart
  67. EP260128a: LCO optical upper limits
  68. EP260126a: SVOM/VT optical upperlimit
  69. EP260128a: Global MASTER-Net observations report
  70. EP260128a: Einstein Probe detection of an X-ray transient
  71. Fermi GRB 260127A: Global MASTER-Net observations report
  72. IceCube-260125A: No Candidate Transients from the Zwicky Transient Facility
  73. GRB 260127A: Fermi GBM Observation
  74. IceCube-260125A: Upper limits from a search for additional neutrino events in IceCube
  75. GRB 260127A: COLIBRÍ optical observations
  76. EP260126a: Seimei/TriCCS optical upper limit
  77. GRB 260127A : MITSuME Akeno optical afterglow candidate detection
  78. GRB 260127B: GOTO candidate optical counterpart
  79. GRB 260127A: SVOM/C-GFT optical observations
  80. The EP-WXT trigger 01709253145 is likely a flaring star
  81. Fermi GRB 260127B: Global MASTER-Net observations report
  82. GRB 260127B: Fermi GBM Final Real-time Localization
  83. Swift GRB 260127A: Global MASTER-Net observations report
  84. GRB 260127A: LCO optical afterglow discovery
  85. GRB 260127A: Fermi GBM Final Real-time Localization
  86. EP260126a: Optical upper limit with Kinder observations
  87. EP260126a: Liverpool Telescope optical upper limits
  88. EP260126a: Further NOT optical upper limits
  89. EP260126a: COLIBRÍ optical upper limits
  90. EP260126a: NOT optical observations
  91. EP260126a: Einstein Probe detection of a fast X-ray transient
  92. Fermi-LAT Gamma-ray Observations of IceCube-260125A
  93. GRB 260125A: NOT optical observations on GOTO26acv / AT 2026bjf
  94. GRB 260125A: GOTO candidate optical counterpart
  95. Fermi GRB 260125B: Global MASTER-Net observations report
  96. GRB 260125B: Fermi GBM Final Real-time Localization
  97. GRB 260125A: Fermi GBM Final Real-time Localization
  98. GRB 260114A: SVOM/VT optical upper limits
  99. GRB 260120A: AstroSat CZTI detection
  100. GRB 260120B: SVOM/GRM observation

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