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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"

32571 results found.

  1. EP260316a: optical upper limit with Kinder observations
  2. EP260316a / GRB 260316A : Fermi-GBM Sub-Threshold Detection
  3. GRB 260314A: Glowbug gamma-ray detection
  4. IceCube-260315A: COLIBRÍ optical observations
  5. EP260314a: Xinglong optical upper limit
  6. EP260314a: optical upper limit with Kinder observations
  7. IceCube Alert-260315A/AT2026fpm Automatic MASTER optical blue counterpart candidate
  8. GRB 260310A / AT2026fgk: 1.3m DFOT optical observations
  9. GRB 260310A / AT2026fgk: ABObservatory and NOCTIS optical observations
  10. GRB 260310A / AT 2026fgk: iTelescope optical observations
  11. EP260314a: COLIBRÍ optical upper limit
  12. GRID detection of GRB 260312B
  13. IceCube-260315A - IceCube observation of a high-energy neutrino candidate track-like event
  14. EP260314a: refined analysis of the EP-WXT and EP-FXT observations
  15. EP260314a: Global MASTER-Net observations report
  16. EP260314a: SVOM/VT optical candidate
  17. GRB 260314A: GECAM-B observation of a burst
  18. GRB 260310A / AT2026fgk: SAO RAS optical observations
  19. GRB 260310A/AT2026fgk: radio detection at 15GHz
  20. GRB 260310A / AT2026fgk: TNG NIR detection
  21. GRB 260310A / AT2026fgk: OASDG optical observations
  22. GRB 260310A / AT2026fgk: Multiband optical follow-up with Kinder observations
  23. GRB 260310A / AT 2026fgk: COLIBRÍ continuing optical observations
  24. GRB 260310A / AT2026fgk: further CAHA 1.23m telescope optical observations suggest shallow decay
  25. Fermi GRB 260314A: Global MASTER-Net observations report
  26. Fermi GRB 260313A: Global MASTER-Net observations report
  27. GRB 260310A/AT 2026fgk: WINTER NIR Detections
  28. GRB 260313A: A Correction to the Fermi GBM Final Localization
  29. GRB 260310A: Einstein Probe Follow-up X-ray Telescope (FXT) Detection
  30. GRB 260310A/AT 2026fgk: J-band observations by the SYSU 80 cm infrared telescope
  31. GRB 260310B: Insight-HXMT/HE detection
  32. GRB 260310A/AT 2026fgk: DDOTI Optical Detection
  33. GRB 260310A: NOT optical polarimetry
  34. GRB 260312B: AstroSat CZTI detection
  35. GRB 260310A/AT 2026fgk: Bok spectroscopic observation
  36. GRB 260310A / AT2026fgk: OSIRIS+/GTC spectroscopy confirms redshift z = 0.153
  37. GRB 260308A: Insight-HXMT/HE detection
  38. GRB 260307A: CALET Gamma-Ray Burst Monitor detection
  39. GRB 260310A / AT 2026fgk: Location in the Epeak - Eiso diagram
  40. GRB 260310A / AT 2026fgk: COLIBRÍ optical observations
  41. GRB 260310A / AT2026fgk: CAHA 1.23m telescope optical observations
  42. GRB 260310A / AT2026fgk : MASTER OT rebrightening during 7h observations
  43. GRB260310A / AT2026fgk: P200 Spectroscopy
  44. GRB 260312B: Glowbug gamma-ray detection
  45. GRB 260310A: Fermi GBM Observation
  46. GRB 260310A: potential optical counterpart
  47. Fermi GRB 260312B: Global MASTER-Net observations report
  48. Fermi GRB 260311B: Global MASTER-Net observations report
  49. GRB 260310B: GECAM-B observation of a burst
  50. Retraction of GCN 43965: GRB is actually solar flare
  51. GRB 260131A/B: radio detection with the VLA
  52. EP260302a: MeerKAT radio counterpart
  53. GRB260307A: GECAM-B observation of a burst
  54. GRB 260308A: SVOM/GRM observation of a short GRB
  55. EP260306a: Mondy optical upper limit
  56. GRB 260310A: AstroSat CZTI detection of a long burst
  57. Fermi GRB 260310B: Global MASTER-Net observations report
  58. Fermi GRB 260310A: Global MASTER-Net observations report
  59. GRB 260307B: SVOM/ECLAIRs refined analysis
  60. GRB 260208A: radio detection with the VLA
  61. GRB 260307A: Glowbug gamma-ray detection
  62. Fermi GBM Sub-Threshold Detection of GRB 260307B
  63. GRB 260307B: Mephisto optical upper limits
  64. GRB 260307B: possible NOT optical counterpart
  65. GRB 260307B: SVOM/VT upper limit with X band data analysis
  66. Fermi GRB 260307A: Global MASTER-Net observations report
  67. GRB260307B: GROWTH-India Telescope optical upper limit
  68. GRB 260307B: SVOM/VT optical candidate
  69. GRB 260307B: SVOM/C-GFT upper limit
  70. GRB 260211A: late-time NOT i-band observations consistent with archival flux
  71. EP260306a: refined analysis of the EP-WXT and EP-FXT observations
  72. GRB 260207A: TESS Detection and Possible VLA Counterpart
  73. EP260302a: SVOM/VT optical observation
  74. EP260306a: Gemini-North redshift z = 4.773
  75. EP260306a: SVOM/VT optical observation
  76. EP260302a: Gemini-South redshift z = 1.535
  77. EP260306a: COLIBRÍ optical observations of the fading and red counterpart
  78. EP260306a: Einstein Probe detection of an X-ray transient
  79. EP260302a: Optical afterglow rebrightening
  80. GRB 260228A: further EP-FXT observations and X-ray afterglow confirmation
  81. GRB 260303A: 1.3m DFOT optical upper limit (duplicate submission)
  82. GRB 260303A: 1.3m DFOT optical upper limit
  83. EP260214b: ATCA 6 GHz observations
  84. GRB 260211A: SVOM/VT optical rebrightening at 20 days after the burst, SN candidate
  85. GRB 260303A: SVOM/ECLAIRs refined analysis
  86. Fermi GRB 260305A: Global MASTER-Net observations report
  87. GRB 260303B: AstroSat CZTI detection
  88. GRB 260303A: SVOM/VT optical observations
  89. GRB 260303A: J-band observations with WINTER
  90. GRB 260303B: NuSTAR detection of prompt emission
  91. EP260302a: Global MASTER-Net observations report
  92. Fermi GRB 260303B: Global MASTER-Net observations report
  93. IceCube-260217A: No Candidate Transients from the Zwicky Transient Facility
  94. GRB 260228A: SVOM/ECLAIRs refined analysis
  95. GRB 260225A: SVOM/ECLAIRs refined analysis
  96. EP260302a: analysis of the follow-up EP-FXT observation
  97. EP260227a: Gemini-South optical observations
  98. EP260302a: LCO observations
  99. EP260302a: BOOTES-7 optical counterpart detection at early times
  100. GRB 260303A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate

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