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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. IceCube-260805A: Upper limits from a search for additional neutrino events in IceCube
  2. GRB 260809A: SVOM/VT optical counterpart
  3. EP260809a: J-band upper limit with WINTER
  4. GRB 260808B: J-band upper limit with WINTER
  5. GRB 260808B: SVOM/ECLAIRs refined analysis
  6. EP260809a:refined analysis of the EP-WXT and autonomous EP-FXT observation
  7. GRB 260809A: SVOM detection of a faint burst
  8. GRB 260808B: Liverpool Telescope optical observations
  9. GRB 260808B: NOT optical observations
  10. GRB 260808B: LCO optical observations
  11. GRB 260808A: NuSTAR detection of prompt emission
  12. EP260809a: COLIBRÍ optical observations
  13. EP260809a: LCO optical observation
  14. EP260809a: OHP/T193 optical observations
  15. GRB260808B: OHP/T193 optical observations
  16. GRB 260808B / EPF_J230056.0+082842: EP-FXT follow-up observation
  17. EP260809a: Einstein Probe detection of an X-ray transient
  18. GRB 260808B: SVOM/VT optical afterglow confirmation
  19. GRB 260808C: Fermi GBM Final Real-time Localization
  20. GRB 260808B: SVOM/VT optical candidate from VHF data ( localization correction for GCN 45317 )
  21. GRB 260808B: SVOM/VT optical candidate from VHF data
  22. GRB 260808B: SVOM detection of a faint burst
  23. GRB 260808A: BALROG localization (Fermi Trigger 807850307 / GRB 260808119)
  24. Fermi GRB 260808A: Global MASTER-Net observations report
  25. GRB 260808A: Fermi GBM Final Real-time Localization
  26. EP260806a: ZTF serendipitous detection of ZTF26abmjjnm / AT 2026yeh
  27. IceCube Alert 260807A: Global MASTER-Net observations report
  28. IceCube-260805A: One candidate from the Zwicky Transient Facility
  29. GRB 260807A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  30. GRB 260807A: SVOM possible detection of a faint burst
  31. IceCube-260807A - IceCube observation of a high-energy neutrino candidate track-like event
  32. EP260806a: COLIBRÍ optical observations
  33. EP260806a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  34. EP260806a: SVOM/VT optical observation
  35. EP260806a: Liverpool Telescope observations of the counterpart show a blue colour
  36. EP260806a: OSIRIS+/GTC redshift z=0.089
  37. EP260731a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  38. EP260806a: LCO likely optical counterpart
  39. EP260806a: Einstein Probe detection of an X-ray transient
  40. GRB 260715A: cubesat Avion detection
  41. GRB 260709A: cubesat Avion detection
  42. GRB 260708A: cubesat Avion detection
  43. SN 2026stf / GRB 260708A: ATLAS forced photometry
  44. IceCube-260805A - IceCube observation of a high-energy neutrino candidate track-like event
  45. GRB 260730B: Glowbug gamma-ray detection
  46. GRB 260805C: Glowbug gamma-ray detection
  47. GRB 260805B: Glowbug gamma-ray detection
  48. Fermi GRB 260805A: Global MASTER-Net observations report
  49. GRB 260805B: Fermi GBM Final Localization
  50. GRB 260804A: Glowbug gamma-ray detection
  51. GRB 260805B: BALROG localization (Fermi Trigger 807622617 / GRB 260805484)
  52. GRB 260805A: Fermi GBM Final Localization
  53. AT 2026wki: EP/FXT follow-up observations
  54. GRB 260730B: CALET Gamma-Ray Burst Monitor detection
  55. GRB 260708A / SN 2026stf: Spectroscopic host redshift z = 0.055 and confirmation of an associated type Ic-BL supernova
  56. IceCube-Cascade 260801A: Upper limits from a search for additional neutrino events in IceCube
  57. GRB 260804A: Fermi GBM Final Real-time Localization
  58. GRB 260708A: LCO further optical observations show supernova features
  59. GRB 260803A: Fermi GBM Final Real-time Localization
  60. Fermi GRB 260802B: Global MASTER-Net observations report
  61. GRB 260802A / EP J223759.5+521421: EP-FXT follow-up observation
  62. GRB 260802A / EP J223759.5+531421: SVOM/VT optical upper limit
  63. GRB 260802A: SVOM/VT optical upper limits from VHF data
  64. GRB 260802A: LCO optical upper limits
  65. GRB 260802B: Fermi GBM Final Localization
  66. GRB 260802A / EP J223759.5+531421: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  67. The EP-WXT trigger 01709277420 is likely a flaring star
  68. GRB 260802A/EP J223759.5+531421: SVOM detection of a possible magnetar burst
  69. GRB 260727A: EP-FXT further follow-up observations and candidate afterglow
  70. GRB 260618B: SVOM/VT continued optical observations indicated a steeper and redder decay
  71. GRB 260731A: AstroSat CZTI detection of a long burst
  72. Fermi-LAT Gamma-ray Observations of IceCube-260722A
  73. GRB 260730B: AstroSat CZTI detection
  74. EP260731a: COLIBRÍ optical upper limit
  75. EP260731a: NOT optical upper limit
  76. GRB 260730B: NuSTAR detection of prompt emission
  77. EP260731a: Einstein Probe detection of an X-ray transient
  78. GRB 260727A: SVOM/ECLAIRs refined analysis
  79. GRB 260726A: SVOM/ECLAIRs refined analysis
  80. GRB260730A: Fermi GBM Final Localization
  81. EP260728a: COLIBRÍ optical upper limit
  82. EP260727a: VLT/X-shooter spectroscopic redshift z = 2.817
  83. The EP-WXT trigger 01709277130 (EP260729a): refined EP-WXT analysis and association with a flaring star
  84. EP 260729a: Ondrejov D50 optical detection supports stellar flare origin
  85. EP260729a: Einstein Probe detection of an X-ray transient
  86. EP260727a: SAO RAS optical observations
  87. GRB 260727A: AbAO and SAO RAS optical observations
  88. EP260728a: EP-FXT follow-up observation
  89. GRB 260726A: EP-FXT follow-up observations
  90. EP260728a: Einstein Probe detection of a fast X-ray transient
  91. GRB 260727A: SVOM/GRM observation
  92. GRB 260726A: Fermi GBM Observation
  93. EP260727a: 1.5m OSN optical counterpart detection
  94. EP260727a:refined analysis of the EP-WXT and EP-FXT observation
  95. EP260727a: OHP/T193 optical observations
  96. Konus-Wind detection of GRB 260727A
  97. GRB 260726A: Liverpool Telescope optical observations
  98. GRB 260727A: Liverpool Telescope optical upper limits
  99. EP260727a: Liverpool Telescope confirmation of optical counterpart
  100. EP260727a: NUTTELA-TAO Early Optical Limits

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