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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"

19219 results found.

  1. GRB260808B: MAO/AZT-22 optical observations
  2. GRB 260809A: J-band upper limit with WINTER
  3. EP260809a: VLT/X-shooter spectroscopic redshift z = 3.07
  4. GRB 260806A: Glowbug gamma-ray detection
  5. GRB 260808A: CALET Gamma-Ray Burst Monitor detection
  6. GRB 260805C: CALET Gamma-Ray Burst Monitor detection
  7. GRB 260804A: CALET Gamma-Ray Burst Monitor detection
  8. GRB260809A/EPF_J234751.2+210212: EP-FXT follow-up observation
  9. The EP-WXT trigger 01709278015 is likely a flaring star
  10. GRB 260809A: SVOM/COLIBRÍ (FM-GFT) optical observation
  11. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) optical observation
  12. GRB 260809A: NOT optical observations
  13. GRB260809A: MAO/AZT-22 optical observations
  14. IceCube-260805A: Upper limits from a search for additional neutrino events in IceCube
  15. GRB 260809A: SVOM/VT optical counterpart
  16. EP260809a: J-band upper limit with WINTER
  17. GRB 260808B: J-band upper limit with WINTER
  18. GRB 260808B: SVOM/ECLAIRs refined analysis
  19. EP260809a:refined analysis of the EP-WXT and autonomous EP-FXT observation
  20. GRB 260809A: SVOM detection of a faint burst
  21. GRB 260808B: Liverpool Telescope optical observations
  22. GRB 260808B: NOT optical observations
  23. GRB 260808B: LCO optical observations
  24. GRB 260808A: NuSTAR detection of prompt emission
  25. EP260809a: COLIBRÍ optical observations
  26. EP260809a: LCO optical observation
  27. GRB 260808B / EPF_J230056.0+082842: EP-FXT follow-up observation
  28. EP260809a: Einstein Probe detection of an X-ray transient
  29. GRB 260808B: SVOM/VT optical afterglow confirmation
  30. GRB 260808C: Fermi GBM Final Real-time Localization
  31. GRB 260808B: SVOM/VT optical candidate from VHF data ( localization correction for GCN 45317 )
  32. GRB 260808B: SVOM/VT optical candidate from VHF data
  33. GRB 260808B: SVOM detection of a faint burst
  34. GRB 260808A: BALROG localization (Fermi Trigger 807850307 / GRB 260808119)
  35. Fermi GRB 260808A: Global MASTER-Net observations report
  36. GRB 260808A: Fermi GBM Final Real-time Localization
  37. IceCube Alert 260807A: Global MASTER-Net observations report
  38. IceCube-260805A: One candidate from the Zwicky Transient Facility
  39. GRB 260807A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  40. GRB 260807A: SVOM possible detection of a faint burst
  41. IceCube-260807A - IceCube observation of a high-energy neutrino candidate track-like event
  42. EP260806a: COLIBRÍ optical observations
  43. EP260806a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  44. EP260806a: SVOM/VT optical observation
  45. EP260806a: Liverpool Telescope observations of the counterpart show a blue colour
  46. EP260806a: OSIRIS+/GTC redshift z=0.089
  47. EP260731a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  48. EP260806a: LCO likely optical counterpart
  49. EP260806a: Einstein Probe detection of an X-ray transient
  50. GRB 260715A: cubesat Avion detection
  51. GRB 260709A: cubesat Avion detection
  52. GRB 260708A: cubesat Avion detection
  53. SN 2026stf / GRB 260708A: ATLAS forced photometry
  54. GRB 260730B: Glowbug gamma-ray detection
  55. GRB 260805C: Glowbug gamma-ray detection
  56. GRB 260805B: Glowbug gamma-ray detection
  57. Fermi GRB 260805A: Global MASTER-Net observations report
  58. GRB 260805B: Fermi GBM Final Localization
  59. GRB 260804A: Glowbug gamma-ray detection
  60. GRB 260805B: BALROG localization (Fermi Trigger 807622617 / GRB 260805484)
  61. GRB 260805A: Fermi GBM Final Localization
  62. AT 2026wki: EP/FXT follow-up observations
  63. GRB 260730B: CALET Gamma-Ray Burst Monitor detection
  64. GRB 260708A / SN 2026stf: Spectroscopic host redshift z = 0.055 and confirmation of an associated type Ic-BL supernova
  65. IceCube-Cascade 260801A: Upper limits from a search for additional neutrino events in IceCube
  66. GRB 260804A: Fermi GBM Final Real-time Localization
  67. GRB 260708A: LCO further optical observations show supernova features
  68. GRB 260803A: Fermi GBM Final Real-time Localization
  69. Fermi GRB 260802B: Global MASTER-Net observations report
  70. GRB 260802A / EP J223759.5+521421: EP-FXT follow-up observation
  71. GRB 260802A / EP J223759.5+531421: SVOM/VT optical upper limit
  72. GRB 260802A: SVOM/VT optical upper limits from VHF data
  73. GRB 260802A: LCO optical upper limits
  74. GRB 260802B: Fermi GBM Final Localization
  75. GRB 260802A / EP J223759.5+531421: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  76. The EP-WXT trigger 01709277420 is likely a flaring star
  77. GRB 260802A/EP J223759.5+531421: SVOM detection of a possible magnetar burst
  78. GRB 260727A: EP-FXT further follow-up observations and candidate afterglow
  79. GRB 260618B: SVOM/VT continued optical observations indicated a steeper and redder decay
  80. GRB 260731A: AstroSat CZTI detection of a long burst
  81. Fermi-LAT Gamma-ray Observations of IceCube-260722A
  82. GRB 260730B: AstroSat CZTI detection
  83. EP260731a: COLIBRÍ optical upper limit
  84. EP260731a: NOT optical upper limit
  85. GRB 260730B: NuSTAR detection of prompt emission
  86. EP260731a: Einstein Probe detection of an X-ray transient
  87. GRB 260727A: SVOM/ECLAIRs refined analysis
  88. GRB 260726A: SVOM/ECLAIRs refined analysis
  89. GRB260730A: Fermi GBM Final Localization
  90. EP260728a: COLIBRÍ optical upper limit
  91. EP260727a: VLT/X-shooter spectroscopic redshift z = 2.817
  92. The EP-WXT trigger 01709277130 (EP260729a): refined EP-WXT analysis and association with a flaring star
  93. EP 260729a: Ondrejov D50 optical detection supports stellar flare origin
  94. EP260729a: Einstein Probe detection of an X-ray transient
  95. EP260727a: SAO RAS optical observations
  96. GRB 260727A: AbAO and SAO RAS optical observations
  97. EP260728a: EP-FXT follow-up observation
  98. GRB 260726A: EP-FXT follow-up observations
  99. EP260728a: Einstein Probe detection of a fast X-ray transient
  100. GRB 260727A: SVOM/GRM observation

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