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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"

23608 results found.

  1. The EP-WXT trigger 01709259209 (EP260329b?): Las Cumbres discovery of the optical counterpart
  2. GRB 260310A: Gemini-North Spectral Confirmation of Supernova Features
  3. EP260327a: WINTER J-band upper limit
  4. EP260327a: COLIBRÍ optical upper limits
  5. GRB 260327A: AstroSat CZTI detection of a long burst
  6. GRB 260310A / AT 2026fgk: COLIBRÍ photometric evidence of the emerging supernova
  7. GRB 260310A: OSIRIS+/GTC spectroscopic detection of the associated BL-Ic, SN 2026fgk
  8. GRB 260310A / AT2026fgk: Late-time infrared detection with MIRAGE on the MDM 1.3m telescope
  9. EP260321a: Upper limits from a neutrino search with IceCube
  10. GRB 260310A/AT2026fgk: Kilonova-Catcher late optical afterglow detection at about 15 days post trigger time
  11. IPN triangulation of GRB 260316B
  12. EP260321a: VLT/FORS2 spectroscopy confirmation of an associated type Ic-BL supernova SN 2026gzf
  13. GRB 260321A: SVOM/COLIBRÍ (FM-GFT) optical upper limits at the FXT positions
  14. EP-WXT trigger 01709259112: confirmation of a stellar flare by BOOTES-5 & BOOTES-7
  15. GRB 260316B: CALET Gamma-Ray Burst Monitor detection
  16. GRB 260310A/AT2026fgk: Detection of temporal steepening in Einstein Probe X-ray data
  17. GRB 260320A: Glowbug gamma-ray detection
  18. EP260321a: COLIBRÍ further optical observations and brightening
  19. EP260321a: Continued brightening from Kinder follow-up of the emerging supernova candidate
  20. EP260214b: ATCA 6 GHz detection
  21. EP260321a: Early TRT rising followed by JinShan decaying and then re-rising
  22. EP260321a: GOTO detection of blue variable source
  23. EP260321a: further Kinder optical observations
  24. GRB 260321A: SVOM/VT optical upper limits
  25. GRB 260321A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  26. EP260321a: COLIBRÍ optical upper limit on any supernova shock breakout emission
  27. GRB 260321A: SVOM detection of a burst
  28. EP260321a: Kinder observations detect a blue variable star and set limits on a source from the z =0.034 galaxy within the error circle
  29. GRB 260310A / AT2026fgk: ABObservatory and NOCTIS new optical observations
  30. GRB 260318A: Glowbug gamma-ray detection
  31. GRB 260310A / AT 2026fgk: KAIT optical observations
  32. EP-WXT trigger 01709258989: KAIT confirmation of a stellar flare
  33. GRB 260310A / AT 2026fgk: COLIBRÍ evidence of a late rebrightening
  34. EP-WXT trigger 01709258989: confirmation of a stellar flare by BOOTES-7
  35. GRB 260316A / EP260316a: COLIBRÍ optical followup of counterpart candidate
  36. GRB 260310A / AT 2026fgk: radio detection with the VLA
  37. GRB 260310A / AT2026fgk: LCO optical observations
  38. EP260316a: COLIBRÍ faint optical counterpart candidate
  39. GRB 260316B: AstroSat CZTI detection
  40. EP260316a: Xinglong optical upper limit
  41. EP260316a: optical upper limit with Kinder observations
  42. EP260316a / GRB 260316A : Fermi-GBM Sub-Threshold Detection
  43. GRB 260314A: Glowbug gamma-ray detection
  44. IceCube-260315A: COLIBRÍ optical observations
  45. EP260314a: Xinglong optical upper limit
  46. EP260314a: optical upper limit with Kinder observations
  47. GRB 260310A / AT2026fgk: ABObservatory and NOCTIS optical observations
  48. GRB 260310A / AT 2026fgk: iTelescope optical observations
  49. EP260314a: COLIBRÍ optical upper limit
  50. EP260314a: BOOTES-6/DPR optical upper limits at early times
  51. GRB 260310A / AT2026fgk: SAO RAS optical observations
  52. GRB 260310A / AT2026fgk: TNG NIR detection
  53. GRB 260310A / AT2026fgk: OASDG optical observations
  54. GRB 260310A / AT2026fgk: Multiband optical follow-up with Kinder observations
  55. GRB 260310A / AT 2026fgk: COLIBRÍ continuing optical observations
  56. GRB 260310A / AT2026fgk: further CAHA 1.23m telescope optical observations suggest shallow decay
  57. GRB 260310A/AT 2026fgk: WINTER NIR Detections
  58. GRB 260310A: Einstein Probe Follow-up X-ray Telescope (FXT) Detection
  59. GRB 260310A/AT 2026fgk: DDOTI Optical Detection
  60. GRB 260310A: NOT optical polarimetry
  61. GRB 260312B: AstroSat CZTI detection
  62. GRB 260310A/AT 2026fgk: Bok spectroscopic observation
  63. GRB 260310A / AT2026fgk: OSIRIS+/GTC spectroscopy confirms redshift z = 0.153
  64. GRB 260307A: CALET Gamma-Ray Burst Monitor detection
  65. GRB 260310A / AT 2026fgk: Location in the Epeak - Eiso diagram
  66. GRB 260310A / AT 2026fgk: COLIBRÍ optical observations
  67. GRB 260310A / AT2026fgk: CAHA 1.23m telescope optical observations
  68. GRB260310A / AT2026fgk: P200 Spectroscopy
  69. GRB 260312B: Glowbug gamma-ray detection
  70. GRB 260310A: potential optical counterpart
  71. The EP-WXT trigger 01709258843 is not a real source
  72. GRB 260310B: GECAM-B observation of a burst
  73. Retraction of GCN 43965: GRB is actually solar flare
  74. GRB 260312A: Swift detection of a burst
  75. GRB 260131A/B: radio detection with the VLA
  76. GRB 260310A: AstroSat CZTI detection of a long burst
  77. GRB 260307B: SVOM/ECLAIRs refined analysis
  78. GRB 260208A: radio detection with the VLA
  79. GRB 260307A: Glowbug gamma-ray detection
  80. GRB 260307B: Mephisto optical upper limits
  81. GRB 260307B: SVOM/VT optical candidate
  82. GRB 260307B: SVOM detection of a burst
  83. GRB 260207A: TESS Detection and Possible VLA Counterpart
  84. EP260306a: COLIBRÍ optical observations of the fading and red counterpart
  85. EP260214b: ATCA 6 GHz observations
  86. GRB 260303A: SVOM/ECLAIRs refined analysis
  87. GRB 260303B: AstroSat CZTI detection
  88. GRB 260304A: AstroSat CZTI detection of a long burst
  89. SVOM/sb26030408: SVOM detection of an X-ray transient likely associated with Beta Persei
  90. GRB 260303A: J-band observations with WINTER
  91. GRB 260228A: SVOM/ECLAIRs refined analysis
  92. GRB 260225A: SVOM/ECLAIRs refined analysis
  93. EP260302a: LCO observations
  94. EP260302a: BOOTES-7 optical counterpart detection at early times
  95. GRB 260303A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  96. GRB 251130B: TERI Gamma-ray detection
  97. GRB 260208A: TERI Gamma-ray detection
  98. GRB 260228A: CAHA 2.2m telescope optical upper limit
  99. GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  100. EP260227a: Mephisto optical detection

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