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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"

27019 results found.

  1. GRB 261104A: LCO optical upper limits
  2. EP261015a/SN 2026ahoa: MMT optical counterpart detection
  3. EP241208a: SVOM/ECLAIRs refined analysis
  4. GRB 261104A: SVOM detection of burst
  5. GRB 260924A: CrAO ZTSh optical observations
  6. EP261103a: NTT optical observation
  7. GRB 261029A : MITSuME Akeno optical afterglow detection
  8. GRB 261030C: AstroSat CZTI detection
  9. EP261103a: SVOM/VT optical observation
  10. EP261103a: BOOTES-6/DPRT early optical upper limits
  11. EP261103a: NOT optical counterpart candidate
  12. EP261103a: Einstein Probe detection of an X-ray transient
  13. GRB 261029A: VST/OmegaCAM detection of the optical afterglow at 3 days
  14. GRB 261029A: Calapai Observatory, Massa S. Giorgio (Messina), optical observation
  15. GRB 261103A: LCO optical upper limits
  16. GRB 261103A: SVOM/ECLAIRs detection of a burst through on-ground search
  17. EP-WXT trigger 01709322206: confirmation of a stellar flare by BOOTES-5
  18. GRB 261029A: SAO RAS optical observations
  19. The EP-WXT trigger 01709322206 is likely a flaring star
  20. EP261015a/SN 2026ahoa: VLT/FORS2 discovery of a pre-peak type Ic-BL supernova at a tentative spectroscopic redshift z=0.31
  21. GRB 261102A: Fermi GBM Detection
  22. GRB 261029C: AstroSat CZTI detection of a short burst
  23. GRB 261102A: Fermi GBM Final Real-time Localization
  24. GRB 261101B: BALROG localization (Fermi Trigger 815240277 / GRB 261101651)
  25. GRB 261101B: Fermi GBM Final Real-time Localization
  26. EP261030a: EP-FXT follow-up observation
  27. GRB 261101A: Fermi GBM Final Real-time Localization
  28. EP261030a: Einstein Probe detection of a fast X-ray transient
  29. GRB 261030A: Fermi GBM Detection
  30. GRB 261030B: Fermi GBM Final Real-time Localization
  31. GRB 261029A: SVOM/ECLAIRs refined analysis
  32. The EP-WXT trigger 01709321980: KAIT confirmation of a stellar flare
  33. GRB 261030A: BALROG localization (Fermi Trigger 815070447 / GRB 261030686)
  34. GRB 261030A: Fermi GBM Final Real-time Localization
  35. GRB 261029A / AT 2026ahaw: Optical upper limits from the PKU 60cm Telescope
  36. GRB 261029A: Glowbug gamma-ray detection
  37. GRB 261024D: SVOM/GRM observation
  38. GRB 261026A: Mondy, SAO RAS and Terskol optical observations
  39. GRB 261029A : SVOM/GWAC-F60 observations
  40. GRB 261029A: GECAM-B detection of a bright burst
  41. EP-WXT trigger 01709321980: confirmation of a stellar flare by BOOTES-5
  42. The EP-WXT trigger 01709321980 is likely a flaring star
  43. GRB 261029A: ULL-ASTRO-MASTER observations with LCO 1-m telescope at Siding Spring Observatory
  44. GRB 261029A: Liverpool Telescope observations
  45. GRB 261029A: NuSTAR detection of bright prompt emission
  46. GRB 261029A: Optical detection with 60cm Panzhihua Telescope
  47. GRB 261029A: Fermi GBM Observation
  48. GRB 261029A: SVOM/GRM observation of a bright burst
  49. GRB 261029A: CALET Gamma-Ray Burst Monitor detection
  50. IPN triangulation of GRB 261024D
  51. GRB261029A: Infrared fading detected with MDM/MIRAGE
  52. GRB 261029A: SVOM/VT optical observation
  53. GRB 261029B : AstroSat CZTI detection
  54. GRB 261029A : AstroSat CZTI detection
  55. GRB 261029A: SVOM/C-GFT optical observations
  56. EP261010a: Xinglong optical follow-up
  57. GRB 261029A: EP-FXT follow-up observation
  58. GRB 261029A: Fermi-LAT detection
  59. GRB 261029A: LCO optical observations (correction to GCN 46082)
  60. GRB 261029A: SVOM/COLIBRÍ (FM-GFT) optical observations
  61. GRB 261029A: LCO optical observations
  62. GRB 261029A: NOT imaging and spectroscopic redshift z = 3.27
  63. GRB261029A: Early infrared detection with MDM/MIRAGE
  64. GRB 261029A: KAIT optical observations
  65. GRB 261029A: TRT optical observations
  66. EP261006a / AT 2026aetp: Xinglong 2.16-m optical follow-up
  67. EP261025a: EP-FXT follow-up observations
  68. GRB 261029B: Fermi GBM Final Real-time Localization
  69. GRB 261028B / MAXI J1609-487: MAXI GSC detection
  70. GRB 261029A: GOTO optical counterpart candidate
  71. GRB 261029A: SVOM detection of a burst
  72. GRB 261029A: Fermi GBM Final Real-time Localization
  73. GRB 261021A: Glowbug gamma-ray detection
  74. GRB 261028A: Fermi GBM Final Localization
  75. GRB 261026A: SVOM/ECLAIRs refined analysis
  76. GRB 261024C: GECAM-B observation
  77. GRB 261026B: AstroSat CZTI detection
  78. GRB 261024D: Insight-HXMT/HE detection
  79. GRB261026A: Infrared detection with MDM/MIRAGE
  80. GRB 261026A: SVOM/VT optical blue bump
  81. GRB 261026A: SAO RAS optical observations
  82. GRB 261024D: GECAM-B observation
  83. The EP-WXT trigger 01709321750 is likely a flaring star
  84. GRB 261026A: EP-FXT follow-up observation
  85. GRB 261024A: SVOM/GRM observation
  86. GRB 261026A: Upper Limit with 60cm Panzhihua Telescope
  87. GRB 261026A: OHP/T120 optical imaging
  88. GRB 261024D: Glowbug gamma-ray detection
  89. GRB 261026B: NuSTAR detection of prompt emission
  90. GRB 261024D: NuSTAR detection of prompt emission
  91. GRB 261024C: NuSTAR detection of prompt emission
  92. GRB 261026A: Ondrejov D50 optical limit
  93. GRB 261026A: ULL-ASTRO-MASTER optical detection with LCO 40-cm telescope at Haleakalā Observatory
  94. GRB 261026A: J-band observations by the SYSU 80cm infrared telescope
  95. GRB 261026A: SVOM/VT optical observations
  96. IPN triangulation of GRB 260730B
  97. GRB 261026C: Fermi GBM Final Real-time Localization
  98. GRB 261020A: Insight-HXMT/HE detection
  99. GRB 261026A: WINTER J-band observations
  100. GRB 261024D: AstroSat CZTI detection of a long burst

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