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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"

45534 results found.

  1. Konus-Wind detection of GRB 260316B (duplicate submission)
  2. Konus-Wind detection of GRB 260316B
  3. GRB 260321A: SVOM/ECLAIRs refined analysis
  4. EP260329b: J-band upper limits with WINTER
  5. EP260329a: J-band upper limit with WINTER
  6. GRB 260330A: Glowbug gamma-ray detection
  7. GRB 260310A: VLA Multi-frequency Radio Observations
  8. Fermi GBM Sub-Threshold Detection of GRB 260330B
  9. GRB 260330B: LCO optical upper limits
  10. GRB 260330B: SVOM detection of a burst
  11. EP260324a / AT2026hir: g- and r-band optical follow-up with the PKU 60cm Telescope
  12. EP260329b: refined analysis of the EP-WXT and EP-FXT observations
  13. EP260329a: COLIBRÍ optical upper limit
  14. EP260329a: EP-FXT follow up observation
  15. EP260329a: NOT optical counterpart candidate
  16. GRB 260330A: Fermi GBM Final Real-time Localization
  17. EP260329b: Global MASTER-Net observations report
  18. Fermi trigger No 796485221: Global MASTER-Net observations report
  19. GRB 260327A: Insight-HXMT/HE detection
  20. EP260329b: Optical follow-up with Kinder observations
  21. EP 260329b: COLIBRÍ optical observations
  22. EP260329a: Optical upper limit with Kinder observations
  23. EP260329b: LCO optical observations of the counterpart
  24. GRB 260326A: Insight-HXMT/HE detection
  25. EP260329b: Einstein Probe detection of an X-ray transient
  26. EP260329a: Einstein Probe detection of an X-ray transient
  27. EP-WXT trigger 01709259209: TRT optical counterpart detection
  28. The EP-WXT trigger 01709259209 (EP260329b?): Las Cumbres discovery of the optical counterpart
  29. GRID detection of GRB 260326A
  30. GRB 260310A: Gemini-North Spectral Confirmation of Supernova Features
  31. EP260327a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  32. EP260327a: SVOM/VT optical upper limits
  33. SMA Detection of GRB 260310A / AT 2026fgk
  34. GRB 260307B: ATCA Radio Upper Limits
  35. EP260327a: WINTER J-band upper limit
  36. EP260327a: COLIBRÍ optical upper limits
  37. GRB 260327A: AstroSat CZTI detection of a long burst
  38. EP260327a: Gemini-North optical upper limits
  39. EP260324a: GROWTH-India Telescope optical observation
  40. EP260327a: Global MASTER-Net observations report
  41. EP260327a: Einstein Probe detection of an X-ray transient
  42. GRB 260310A / AT 2026fgk: COLIBRÍ photometric evidence of the emerging supernova
  43. GRB 260310A: OSIRIS+/GTC spectroscopic detection of the associated BL-Ic, SN 2026fgk
  44. The EP-WXT trigger 01709259173 is likely a flaring star
  45. GRB 260310A / AT2026fgk: Late-time infrared detection with MIRAGE on the MDM 1.3m telescope
  46. IPN triangulation of GRB 260320A
  47. EP260324a: ZTF discovery of the optical counterpart ZTF26aapviim/AT2026hir
  48. GRB 260310A / AT2026fgk: R- and I-band observations with the PKU 60 cm optical telescope
  49. GRB 260326A: Fermi GBM Detection
  50. EP260321a: JinShan near-infrared observations
  51. GRB 260325A: Fermi GBM Final Localization
  52. GRB 260326A: Fermi GBM Final Real-time Localization
  53. EP260321a: Upper limits from a neutrino search with IceCube
  54. Fermi Gamma-ray Burst Monitor trigger 796145512/260325647 is not a GRB
  55. GRB 260310A/AT2026fgk: Kilonova-Catcher late optical afterglow detection at about 15 days post trigger time
  56. IPN triangulation of GRB 260316B
  57. EP260321a: J-band observations by the SYSU 80 cm infrared telescope
  58. GRID detection of GRB 260320A
  59. EP260321a: Gemini-South confirmation of a supernova (duplicate submission)
  60. EP260321a: Gemini-South confirmation of a supernova
  61. Fermi Gamma-ray Burst Monitor trigger 796060650/260324665 is not a GRB
  62. EP260321a: VLT/FORS2 spectroscopy confirmation of an associated type Ic-BL supernova SN 2026gzf
  63. GRB 260310A: LBT optical observations
  64. EP260321A: Mondy optical observations
  65. GRB 260321A: SVOM/COLIBRÍ (FM-GFT) optical upper limits at the FXT positions
  66. EP-WXT trigger 01709259112: confirmation of a stellar flare by BOOTES-5 & BOOTES-7
  67. GRB 260316B: CALET Gamma-Ray Burst Monitor detection
  68. The EP-WXT trigger 01709259112 is likely a flaring star
  69. Fermi GRB 260323A: Global MASTER-Net observations report
  70. GRB 260323A: Fermi GBM Final Real-time Localization
  71. GRB260310A: Palomar 60-inch photometry of an extremely bright late-time afterglow with a temporal break at 8 days
  72. GRB 260310A/AT2026fgk: Detection of temporal steepening in Einstein Probe X-ray data
  73. GRB 260322A: Fermi GBM Final Localization
  74. GRB 260320A: Glowbug gamma-ray detection
  75. EP260321a / AT2026gzf: VLT/X-shooter detection of supernova-like spectral features at z = 0.0344
  76. EP260321a: COLIBRÍ further optical observations and brightening
  77. Fermi Gamma-ray Burst Monitor trigger 795918973/260323025 is not a GRB
  78. EP260321a: Continued brightening from Kinder follow-up of the emerging supernova candidate
  79. EP260214b: ATCA 6 GHz detection
  80. EP260321a: Early TRT rising followed by JinShan decaying and then re-rising
  81. GRB 260321A: EP-FXT follow-up observation
  82. The EP-WXT trigger 01709259045 is likely a flaring star
  83. EP260321a: ZTF and Rubin detections of the candidate optical counterpart to EP260321a
  84. EP260321a: GOTO detection of blue variable source
  85. EP260321a: VLT imaging and spectroscopy show the variable source to be at z = 0.0343
  86. EP260321a: further Kinder optical observations
  87. GRB 260321A: SVOM/VT optical upper limits
  88. EP260321a: Las Cumbres upper limit
  89. GRB 260321A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  90. GRB 260320A: Insight-HXMT/HE detection
  91. EP260321a: COLIBRÍ optical upper limit on any supernova shock breakout emission
  92. EP260321a: refined analysis of the EP-WXT and EP-FXT observations, implying a possible supernova shock breakout candidate
  93. EP260321a: SVOM/VT optical upper limit
  94. GRB 260310A: continued optical observation at Mondy
  95. Fermi GBM Sub-Threshold Detection of GRB 260321A
  96. GRB 260321A: SVOM detection of a burst
  97. EP260321a: Kinder observations detect a blue variable star and set limits on a source from the z =0.034 galaxy within the error circle
  98. EP260321a: Global MASTER-Net observations report
  99. EP260321a: Einstein Probe detection of an X-ray transient
  100. GRB 260310A / AT2026fgk: ABObservatory and NOCTIS new optical observations

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