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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"

42005 results found.

  1. EP260316a: Xinglong optical upper limit
  2. EP260316a: optical upper limit with Kinder observations
  3. EP260316a / GRB 260316A : Fermi-GBM Sub-Threshold Detection
  4. GRB 260314A: Glowbug gamma-ray detection
  5. The EP-WXT trigger 00199258890 (EP260316a): a correction to the trigger time and FXT automatic follow-up
  6. IceCube-260315A: COLIBRÍ optical observations
  7. EP260314a: Xinglong optical upper limit
  8. EP260314a: optical upper limit with Kinder observations
  9. IceCube Alert-260315A/AT2026fpm Automatic MASTER optical blue counterpart candidate
  10. GRB 260310A / AT2026fgk: 1.3m DFOT optical observations
  11. GRB 260310A / AT2026fgk: ABObservatory and NOCTIS optical observations
  12. GRB 260310A / AT 2026fgk: iTelescope optical observations
  13. EP260314a: COLIBRÍ optical upper limit
  14. GRID detection of GRB 260312B
  15. IceCube-260315A - IceCube observation of a high-energy neutrino candidate track-like event
  16. EP260314a: refined analysis of the EP-WXT and EP-FXT observations
  17. EP260314a: BOOTES-6/DPR optical upper limits at early times
  18. EP260314a: Global MASTER-Net observations report
  19. EP260314a: SVOM/VT optical candidate
  20. Fermi trigger No 795185313: Global MASTER-Net observations report
  21. IceCube Alert 260315A: Global MASTER-Net observations report
  22. EP260314a: Einstein Probe detection of an X-ray transient
  23. The EP-WXT trigger 01709258851: Las Cumbres upper limit
  24. GRB 260314A: GECAM-B observation of a burst
  25. Fermi Gamma-ray Burst Monitor trigger 795185313/260314534 is not a GRB
  26. GRB 260310A / AT2026fgk: SAO RAS optical observations
  27. GRB 260310A/AT2026fgk: radio detection at 15GHz
  28. GRB 260310A / AT2026fgk: TNG NIR detection
  29. GRB 260310A / AT2026fgk: OASDG optical observations
  30. GRB 260310A / AT2026fgk: Multiband optical follow-up with Kinder observations
  31. GRB 260310A / AT 2026fgk: COLIBRÍ continuing optical observations
  32. GRB 260310A / AT2026fgk: further CAHA 1.23m telescope optical observations suggest shallow decay
  33. Fermi GRB 260314A: Global MASTER-Net observations report
  34. Fermi GRB 260313A: Global MASTER-Net observations report
  35. GRB 260310A/AT 2026fgk: WINTER NIR Detections
  36. GRB 260313A: A Correction to the Fermi GBM Final Localization
  37. GRB 260310A: Einstein Probe Follow-up X-ray Telescope (FXT) Detection
  38. GRB 260310A/AT 2026fgk: J-band observations by the SYSU 80 cm infrared telescope
  39. GRB 260310B: Insight-HXMT/HE detection
  40. GRB 260310A/AT 2026fgk: DDOTI Optical Detection
  41. GRB 260310A: NOT optical polarimetry
  42. GRB 260312B: AstroSat CZTI detection
  43. GRB 260310A/AT 2026fgk: Bok spectroscopic observation
  44. GRB 260310A / AT2026fgk: OSIRIS+/GTC spectroscopy confirms redshift z = 0.153
  45. GRB 260308A: Insight-HXMT/HE detection
  46. GRB 260307A: CALET Gamma-Ray Burst Monitor detection
  47. GRB 260310A / AT 2026fgk: Location in the Epeak - Eiso diagram
  48. GRB 260310A / AT 2026fgk: COLIBRÍ optical observations
  49. GRB 260310A / AT2026fgk: CAHA 1.23m telescope optical observations
  50. GRB 260310A / AT2026fgk : MASTER OT rebrightening during 7h observations
  51. GRB260310A / AT2026fgk: P200 Spectroscopy
  52. GRB 260312B: Glowbug gamma-ray detection
  53. GRB 260310A: Fermi GBM Observation
  54. GRB 260310A: potential optical counterpart
  55. Fermi GRB 260312B: Global MASTER-Net observations report
  56. Fermi GRB 260311B: Global MASTER-Net observations report
  57. GRB 260310B: GECAM-B observation of a burst
  58. Retraction of GCN 43965: GRB is actually solar flare
  59. GRB 260312A: Swift detection of a burst
  60. GRB 260131A/B: radio detection with the VLA
  61. EP260302a: MeerKAT radio counterpart
  62. GRB260307A: GECAM-B observation of a burst
  63. GRB 260308A: SVOM/GRM observation of a short GRB
  64. EP260306a: Mondy optical upper limit
  65. GRB 260310A: AstroSat CZTI detection of a long burst
  66. Fermi GRB 260310B: Global MASTER-Net observations report
  67. Fermi GRB 260310A: Global MASTER-Net observations report
  68. GRB 260307B: SVOM/ECLAIRs refined analysis
  69. GRB 260208A: radio detection with the VLA
  70. GRB 260307A: Glowbug gamma-ray detection
  71. Fermi GBM Sub-Threshold Detection of GRB 260307B
  72. GRB 260307B: Mephisto optical upper limits
  73. GRB 260307B: possible NOT optical counterpart
  74. GRB 260307B: SVOM/VT upper limit with X band data analysis
  75. Fermi GRB 260307A: Global MASTER-Net observations report
  76. GRB260307B: GROWTH-India Telescope optical upper limit
  77. GRB 260307B: SVOM/VT optical candidate
  78. GRB 260307B: SVOM/C-GFT upper limit
  79. GRB 260307B: SVOM detection of a burst
  80. GRB 260211A: late-time NOT i-band observations consistent with archival flux
  81. EP260306a: refined analysis of the EP-WXT and EP-FXT observations
  82. GRB 260207A: TESS Detection and Possible VLA Counterpart
  83. EP260302a: SVOM/VT optical observation
  84. EP260306a: Gemini-North redshift z = 4.773
  85. EP260306a: SVOM/VT optical observation
  86. EP260302a: Gemini-South redshift z = 1.535
  87. EP260306a: COLIBRÍ optical observations of the fading and red counterpart
  88. EP260306a: Einstein Probe detection of an X-ray transient
  89. The EP-WXT trigger 01709258759: Las Cumbres discovery of the optical counterpart
  90. EP260302a: Optical afterglow rebrightening
  91. GRB 260228A: further EP-FXT observations and X-ray afterglow confirmation
  92. GRB 260303A: 1.3m DFOT optical upper limit (duplicate submission)
  93. GRB 260303A: 1.3m DFOT optical upper limit
  94. EP260214b: ATCA 6 GHz observations
  95. GRB 260211A: SVOM/VT optical rebrightening at 20 days after the burst, SN candidate
  96. GRB 260303A: SVOM/ECLAIRs refined analysis
  97. Fermi GRB 260305A: Global MASTER-Net observations report
  98. GRB 260303B: AstroSat CZTI detection
  99. GRB 260304A: AstroSat CZTI detection of a long burst
  100. SVOM/sb26030408: SVOM detection of an X-ray transient likely associated with Beta Persei

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