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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"

45901 results found.

  1. EP260405a: Global MASTER-Net observations report
  2. EP260405a: Einstein Probe detection of a fast X-ray transient
  3. The EP-WXT trigger 01709259621 is likely a flaring star
  4. EP260405a / EP-WXT 11900672904: COLIBRÍ optical upper limits
  5. The EP-WXT trigger 01709259615 is likely a flaring star
  6. Fermi trigger No 797039833: Global MASTER-Net observations report
  7. GRB 260403A: GECAM-B observation of a long burst
  8. EP260324A / AT 2026hir: COLIBRÍ further optical observations
  9. Fermi Gamma-ray Burst Monitor trigger 796972356/260404217 is not a GRB
  10. EP260403a: refined analysis of the EP-WXT and EP-FXT observations
  11. The EP-WXT trigger 01709259586 is likely a flaring star
  12. GRB 260330B: SVOM/VT further optical observation
  13. Fermi Gamma-ray Burst Monitor trigger 796931884/260403749 is not a GRB
  14. GRB 260330B: SVOM/ECLAIRs refined analysis
  15. EP260403a: LCO optical observations of the counterpart
  16. GRB 260310A/AT2026fgk: Kilonova-Catcher long term optical monitoring
  17. EP260403a: LCO optical counterpart detection
  18. EP260403a: COLIBRÍ optical counterpart candidate
  19. GRB 260330B: SVOM/VT optical candidate
  20. EP260403a: Einstein Probe detection of an X-ray transient
  21. GRB 260330B: EP-FXT follow-up and identification of candidate afterglow
  22. GRB 260403A: AstroSat CZTI detection
  23. EP260402a/GRB 260402A: refined analysis of the EP-WXT and EP-FXT observations
  24. GRB 260402B: GECAM-B observation
  25. EP260402a/GRB 260402A: Jinshan near-infrared upper limit
  26. GRB 260402C: NuSTAR detection of prompt emission
  27. GRB 260402C: AstroSat CZTI detection of a long burst
  28. EP260324A / AT 2026hir: COLIBRÍ optical observations
  29. GRB 260403A: Fermi GBM Final Real-time Localization
  30. EP260324A / AT 2026hir: Spectroscopic Observations with the Next Generation Palomar Spectrograph
  31. GRB 260402B: Fermi GBM Final Real-time Localization
  32. GRB 260402A: WINTER J-band upper limit
  33. GRB260402A: GROWTH-India Telescope optical upper limit
  34. GRB 260402A / EP260402a: SVOM/VT optical upper limits
  35. EP260402a/GRB 260402A: SVOM/C-GFT upper limit
  36. GRB 260401A: SVOM/GRM observation
  37. GRB 260401A: GECAM-B observation
  38. EP260402a/GRB 260402A: Einstein Probe detection of an X-ray transient
  39. GRB 260402A: Kilonova-Catcher optical upper limit
  40. GRB 260402A: MASTER optical observations
  41. GRB 260402A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  42. GRB 260402A: SVOM/MXT candidate X-ray afterglow
  43. GRB 260402A: SVOM detection of a burst
  44. Fermi GRB 260401A: Global MASTER-Net observations report
  45. GRB 260401A: Fermi GBM Observation
  46. GRB 260401A: NuSTAR detection of prompt emission
  47. GRB 260401A: CALET Gamma-Ray Burst Monitor detection
  48. GRB 260401A: MAXI/GSC detection
  49. GRB 260401A: BALROG localization (Fermi Trigger 796733611 / GRB 260401454)
  50. GRB 260401A: Fermi GBM Final Real-time Localization
  51. EP260329b: Mondy and Assy-Turgen optical upper limits
  52. GRB 260310A / AT2026fgk: Luminance-band optical follow-up with a 28cm telescope in Daocheng
  53. EP260321a :Xinglong optical observations
  54. EP260327a: Xinglong optical upper limit
  55. EP260329b: GOTO detection of optical counterpart
  56. GRB 260330B: SVOM/VT optical upper limits
  57. Konus-Wind detection of GRB 260320A
  58. Konus-Wind detection of GRB 260316B (duplicate submission)
  59. Konus-Wind detection of GRB 260316B
  60. GRB 260321A: SVOM/ECLAIRs refined analysis
  61. EP260329b: J-band upper limits with WINTER
  62. EP260329a: J-band upper limit with WINTER
  63. GRB 260330A: Glowbug gamma-ray detection
  64. GRB 260310A: VLA Multi-frequency Radio Observations
  65. Fermi GBM Sub-Threshold Detection of GRB 260330B
  66. GRB 260330B: LCO optical upper limits
  67. GRB 260330B: SVOM detection of a burst
  68. EP260324a / AT2026hir: g- and r-band optical follow-up with the PKU 60cm Telescope
  69. EP260329b: refined analysis of the EP-WXT and EP-FXT observations
  70. EP260329a: COLIBRÍ optical upper limit
  71. EP260329a: EP-FXT follow up observation
  72. EP260329a: NOT optical counterpart candidate
  73. GRB 260330A: Fermi GBM Final Real-time Localization
  74. EP260329b: Global MASTER-Net observations report
  75. Fermi trigger No 796485221: Global MASTER-Net observations report
  76. GRB 260327A: Insight-HXMT/HE detection
  77. EP260329b: Optical follow-up with Kinder observations
  78. EP 260329b: COLIBRÍ optical observations
  79. EP260329a: Optical upper limit with Kinder observations
  80. EP260329b: LCO optical observations of the counterpart
  81. GRB 260326A: Insight-HXMT/HE detection
  82. EP260329b: Einstein Probe detection of an X-ray transient
  83. EP260329a: Einstein Probe detection of an X-ray transient
  84. EP-WXT trigger 01709259209: TRT optical counterpart detection
  85. The EP-WXT trigger 01709259209 (EP260329b?): Las Cumbres discovery of the optical counterpart
  86. GRID detection of GRB 260326A
  87. GRB 260310A: Gemini-North Spectral Confirmation of Supernova Features
  88. EP260327a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  89. EP260327a: SVOM/VT optical upper limits
  90. SMA Detection of GRB 260310A / AT 2026fgk
  91. GRB 260307B: ATCA Radio Upper Limits
  92. EP260327a: WINTER J-band upper limit
  93. EP260327a: COLIBRÍ optical upper limits
  94. GRB 260327A: AstroSat CZTI detection of a long burst
  95. EP260327a: Gemini-North optical upper limits
  96. EP260324a: GROWTH-India Telescope optical observation
  97. EP260327a: Global MASTER-Net observations report
  98. EP260327a: Einstein Probe detection of an X-ray transient
  99. GRB 260310A / AT 2026fgk: COLIBRÍ photometric evidence of the emerging supernova
  100. GRB 260310A: OSIRIS+/GTC spectroscopic detection of the associated BL-Ic, SN 2026fgk

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