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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"
  1. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical rebrightening
  2. GRB 260810A: AstroSat CZTI detection of a long burst
  3. EP260812a: Einstein Probe detection of an X-ray transient
  4. GRB 260809A: SAO RAS optical observations
  5. GRB 260808B: SAO RAS optical observations
  6. GRB 260808B: SVOM/VT optical re-brightening at day 3
  7. GRB 260317A: SVOM/ECLAIRs detection through offline targeted search and its possible association to magnetar 1E 1841-04.5
  8. GRB 260806A: CALET Gamma-Ray Burst Monitor detection
  9. GRB 260808A: GECAM-B observation
  10. GRB 260807A: SVOM/ECLAIRs refined analysis
  11. EP260806a: MAO/AZT-22 optical observations
  12. IceCube-260807A: Upper limits from a search for additional neutrino events in IceCube
  13. GRB260808B: MAO/AZT-22 optical observations
  14. GRB 250607A: SVOM/ECLAIRs detection through offline targeted search
  15. GRB 260809A: J-band upper limit with WINTER
  16. EP260809a: VLT/X-shooter spectroscopic redshift z = 3.07
  17. GRB 260806A: Glowbug gamma-ray detection
  18. GRB 260808A: CALET Gamma-Ray Burst Monitor detection
  19. GRB 260805C: CALET Gamma-Ray Burst Monitor detection
  20. GRB 260804A: CALET Gamma-Ray Burst Monitor detection
  21. GRB260809A/EPF_J234751.2+210212: EP-FXT follow-up observation
  22. The EP-WXT trigger 01709278015 is likely a flaring star
  23. GRB 260809A: SVOM/COLIBRÍ (FM-GFT) optical observation
  24. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) optical observation
  25. GRB 260809A: NOT optical observations
  26. GRB260809A: MAO/AZT-22 optical observations
  27. GRB260809A: OHP/T193 optical observations
  28. IceCube-260805A: Upper limits from a search for additional neutrino events in IceCube
  29. GRB 260809A: SVOM/VT optical counterpart
  30. EP260809a: J-band upper limit with WINTER
  31. GRB 260808B: J-band upper limit with WINTER
  32. GRB 260808B: SVOM/ECLAIRs refined analysis
  33. EP260809a:refined analysis of the EP-WXT and autonomous EP-FXT observation
  34. GRB 260809A: SVOM detection of a faint burst
  35. GRB 260808B: Liverpool Telescope optical observations
  36. GRB 260808B: NOT optical observations
  37. GRB 260808B: LCO optical observations
  38. GRB 260808A: NuSTAR detection of prompt emission
  39. EP260809a: COLIBRÍ optical observations
  40. EP260809a: LCO optical observation
  41. EP260809a: OHP/T193 optical observations
  42. GRB260808B: OHP/T193 optical observations
  43. GRB 260808B / EPF_J230056.0+082842: EP-FXT follow-up observation
  44. EP260809a: Einstein Probe detection of an X-ray transient
  45. GRB 260808B: SVOM/VT optical afterglow confirmation
  46. GRB 260808C: Fermi GBM Final Real-time Localization
  47. GRB 260808B: SVOM/VT optical candidate from VHF data ( localization correction for GCN 45317 )
  48. GRB 260808B: SVOM/VT optical candidate from VHF data
  49. GRB 260808B: SVOM detection of a faint burst
  50. GRB 260808A: BALROG localization (Fermi Trigger 807850307 / GRB 260808119)
  51. Fermi GRB 260808A: Global MASTER-Net observations report
  52. GRB 260808A: Fermi GBM Final Real-time Localization
  53. EP260806a: ZTF serendipitous detection of ZTF26abmjjnm / AT 2026yeh
  54. IceCube Alert 260807A: Global MASTER-Net observations report
  55. IceCube-260805A: One candidate from the Zwicky Transient Facility
  56. GRB 260807A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  57. GRB 260807A: SVOM possible detection of a faint burst
  58. IceCube-260807A - IceCube observation of a high-energy neutrino candidate track-like event
  59. EP260806a: COLIBRÍ optical observations
  60. EP260806a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  61. EP260806a: SVOM/VT optical observation
  62. EP260806a: Liverpool Telescope observations of the counterpart show a blue colour
  63. EP260806a: OSIRIS+/GTC redshift z=0.089
  64. EP260731a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  65. EP260806a: LCO likely optical counterpart
  66. EP260806a: Einstein Probe detection of an X-ray transient
  67. GRB 260715A: cubesat Avion detection
  68. GRB 260709A: cubesat Avion detection
  69. GRB 260708A: cubesat Avion detection
  70. SN 2026stf / GRB 260708A: ATLAS forced photometry
  71. IceCube-260805A - IceCube observation of a high-energy neutrino candidate track-like event
  72. GRB 260730B: Glowbug gamma-ray detection
  73. GRB 260805C: Glowbug gamma-ray detection
  74. GRB 260805B: Glowbug gamma-ray detection
  75. Fermi GRB 260805A: Global MASTER-Net observations report
  76. GRB 260805B: Fermi GBM Final Localization
  77. GRB 260804A: Glowbug gamma-ray detection
  78. GRB 260805B: BALROG localization (Fermi Trigger 807622617 / GRB 260805484)
  79. GRB 260805A: Fermi GBM Final Localization
  80. AT 2026wki: EP/FXT follow-up observations
  81. GRB 260730B: CALET Gamma-Ray Burst Monitor detection
  82. GRB 260708A / SN 2026stf: Spectroscopic host redshift z = 0.055 and confirmation of an associated type Ic-BL supernova
  83. IceCube-Cascade 260801A: Upper limits from a search for additional neutrino events in IceCube
  84. GRB 260804A: Fermi GBM Final Real-time Localization
  85. GRB 260708A: LCO further optical observations show supernova features
  86. GRB 260803A: Fermi GBM Final Real-time Localization
  87. Fermi GRB 260802B: Global MASTER-Net observations report
  88. GRB 260802A / EP J223759.5+521421: EP-FXT follow-up observation
  89. GRB 260802A / EP J223759.5+531421: SVOM/VT optical upper limit
  90. GRB 260802A: SVOM/VT optical upper limits from VHF data
  91. GRB 260802A: LCO optical upper limits
  92. GRB 260802B: Fermi GBM Final Localization
  93. GRB 260802A / EP J223759.5+531421: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  94. The EP-WXT trigger 01709277420 is likely a flaring star
  95. GRB 260802A/EP J223759.5+531421: SVOM detection of a possible magnetar burst
  96. GRB 260727A: EP-FXT further follow-up observations and candidate afterglow
  97. GRB 260618B: SVOM/VT continued optical observations indicated a steeper and redder decay
  98. GRB 260731A: AstroSat CZTI detection of a long burst
  99. Fermi-LAT Gamma-ray Observations of IceCube-260722A
  100. GRB 260730B: AstroSat CZTI detection

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