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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"

42879 results found.

  1. Fermi trigger No 796485221: Global MASTER-Net observations report
  2. GRB 260327A: Insight-HXMT/HE detection
  3. EP260329b: Optical follow-up with Kinder observations
  4. EP 260329b: COLIBRÍ optical observations
  5. EP260329a: Optical upper limit with Kinder observations
  6. EP260329b: LCO optical observations of the counterpart
  7. GRB 260326A: Insight-HXMT/HE detection
  8. EP260329b: Einstein Probe detection of an X-ray transient
  9. EP260329a: Einstein Probe detection of an X-ray transient
  10. EP-WXT trigger 01709259209: TRT optical counterpart detection
  11. The EP-WXT trigger 01709259209 (EP260329b?): Las Cumbres discovery of the optical counterpart
  12. GRID detection of GRB 260326A
  13. GRB 260310A: Gemini-North Spectral Confirmation of Supernova Features
  14. EP260327a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  15. EP260327a: SVOM/VT optical upper limits
  16. SMA Detection of GRB 260310A / AT 2026fgk
  17. GRB 260307B: ATCA Radio Upper Limits
  18. EP260327a: WINTER J-band upper limit
  19. EP260327a: COLIBRÍ optical upper limits
  20. GRB 260327A: AstroSat CZTI detection of a long burst
  21. EP260327a: Gemini-North optical upper limits
  22. EP260324a: GROWTH-India Telescope optical observation
  23. EP260327a: Global MASTER-Net observations report
  24. EP260327a: Einstein Probe detection of an X-ray transient
  25. GRB 260310A / AT 2026fgk: COLIBRÍ photometric evidence of the emerging supernova
  26. GRB 260310A: OSIRIS+/GTC spectroscopic detection of the associated BL-Ic, SN 2026fgk
  27. The EP-WXT trigger 01709259173 is likely a flaring star
  28. GRB 260310A / AT2026fgk: Late-time infrared detection with MIRAGE on the MDM 1.3m telescope
  29. IPN triangulation of GRB 260320A
  30. EP260324a: ZTF discovery of the optical counterpart ZTF26aapviim/AT2026hir
  31. GRB 260310A / AT2026fgk: R- and I-band observations with the PKU 60 cm optical telescope
  32. GRB 260326A: Fermi GBM Detection
  33. EP260321a: JinShan near-infrared observations
  34. GRB 260325A: Fermi GBM Final Localization
  35. GRB 260326A: Fermi GBM Final Real-time Localization
  36. EP260321a: Upper limits from a neutrino search with IceCube
  37. Fermi Gamma-ray Burst Monitor trigger 796145512/260325647 is not a GRB
  38. GRB 260310A/AT2026fgk: Kilonova-Catcher late optical afterglow detection at about 15 days post trigger time
  39. IPN triangulation of GRB 260316B
  40. EP260321a: J-band observations by the SYSU 80 cm infrared telescope
  41. GRID detection of GRB 260320A
  42. EP260321a: Gemini-South confirmation of a supernova
  43. EP260321a: VLT/FORS2 spectroscopy confirmation of an associated type Ic-BL supernova SN 2026gzf
  44. GRB 260310A: LBT optical observations
  45. EP260321A: Mondy optical observations
  46. GRB 260321A: SVOM/COLIBRÍ (FM-GFT) optical upper limits at the FXT positions
  47. EP-WXT trigger 01709259112: confirmation of a stellar flare by BOOTES-5 & BOOTES-7
  48. GRB 260316B: CALET Gamma-Ray Burst Monitor detection
  49. The EP-WXT trigger 01709259112 is likely a flaring star
  50. Fermi GRB 260323A: Global MASTER-Net observations report
  51. GRB 260323A: Fermi GBM Final Real-time Localization
  52. GRB260310A: Palomar 60-inch photometry of an extremely bright late-time afterglow with a temporal break at 8 days
  53. GRB 260310A/AT2026fgk: Detection of temporal steepening in Einstein Probe X-ray data
  54. GRB 260322A: Fermi GBM Final Localization
  55. GRB 260320A: Glowbug gamma-ray detection
  56. EP260321a / AT2026gzf: VLT/X-shooter detection of supernova-like spectral features at z = 0.0344
  57. EP260321a: COLIBRÍ further optical observations and brightening
  58. EP260321a: Continued brightening from Kinder follow-up of the emerging supernova candidate
  59. EP260214b: ATCA 6 GHz detection
  60. EP260321a: Early TRT rising followed by JinShan decaying and then re-rising
  61. GRB 260321A: EP-FXT follow-up observation
  62. The EP-WXT trigger 01709259045 is likely a flaring star
  63. EP260321a: ZTF and Rubin detections of the candidate optical counterpart to EP260321a
  64. EP260321a: GOTO detection of blue variable source
  65. EP260321a: VLT imaging and spectroscopy show the variable source to be at z = 0.0343
  66. EP260321a: further Kinder optical observations
  67. GRB 260321A: SVOM/VT optical upper limits
  68. EP260321a: Las Cumbres upper limit
  69. GRB 260321A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  70. GRB 260320A: Insight-HXMT/HE detection
  71. EP260321a: COLIBRÍ optical upper limit on any supernova shock breakout emission
  72. EP260321a: refined analysis of the EP-WXT and EP-FXT observations, implying a possible supernova shock breakout candidate
  73. EP260321a: SVOM/VT optical upper limit
  74. GRB 260310A: continued optical observation at Mondy
  75. Fermi GBM Sub-Threshold Detection of GRB 260321A
  76. GRB 260321A: SVOM detection of a burst
  77. EP260321a: Kinder observations detect a blue variable star and set limits on a source from the z =0.034 galaxy within the error circle
  78. EP260321a: Global MASTER-Net observations report
  79. EP260321a: Einstein Probe detection of an X-ray transient
  80. GRB 260310A / AT2026fgk: ABObservatory and NOCTIS new optical observations
  81. GRB 260318A: Glowbug gamma-ray detection
  82. GRB 260310A / AT 2026fgk: KAIT optical observations
  83. GRB 260320A: NuSTAR detection of prompt emission
  84. GRB 260310A / AT2026fgk: NuSTAR follow-up detection
  85. EP-WXT trigger 01709258989: KAIT confirmation of a stellar flare
  86. GRB 260310A / AT 2026fgk: FTW optical and NIR observations show no rebrightening
  87. GRB 260310A: no evidence of re-brightening up to 9.6 days in optical observation at Mondy
  88. GRB 260310A / AT 2026fgk: COLIBRÍ evidence of a late rebrightening
  89. GRB 260310A/AT2026fgk: LBT near-infrared observations
  90. NOEMA Detection of GRB 260310A / AT 2026fgk
  91. EP-WXT trigger 01709258989: confirmation of a stellar flare by BOOTES-7
  92. GRB 260318A: SVOM/GRM observation
  93. The EP-WXT trigger 01709258989 is likely a flaring star
  94. GRB 260310A: classification as long GRB based on Eiso, Ep, and T_90
  95. GRB 260318A: GECAM-B observation
  96. GRB260310A/AT2026fgk: Further optical observation from 1.3m DFOT
  97. Fermi GRB 260318A: Global MASTER-Net observations report
  98. GRB 260318A: Fermi GBM Final Real-time Localization
  99. IceCube-260315A: No Candidate Transients from the Zwicky Transient Facility
  100. GRB 260316A / EP260316a: COLIBRÍ optical followup of counterpart candidate

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