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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"

32692 results found.

  1. GRB 260318A: SVOM/GRM observation
  2. GRB 260310A: classification as long GRB based on Eiso, Ep, and T_90
  3. GRB 260318A: GECAM-B observation
  4. GRB260310A/AT2026fgk: Further optical observation from 1.3m DFOT
  5. Fermi GRB 260318A: Global MASTER-Net observations report
  6. IceCube-260315A: No Candidate Transients from the Zwicky Transient Facility
  7. Fermi Gamma-ray Burst Monitor trigger 795096033/260312500 (GRB 260313A) is unlikely to be a GRB
  8. GRB 260316A / EP260316a: COLIBRÍ optical followup of counterpart candidate
  9. GRB 260310A / AT 2026fgk: radio detection with the VLA
  10. GRB 260310A / AT2026fgk: SVOM/VT optical observations
  11. GRB 260310A / AT2026fgk: LCO optical observations
  12. IceCube-260315A/AT2026fpm: EP-FXT follow-up observation
  13. GRB 260316B: GECAM-B observation
  14. GRB 260316B: SVOM/GRM observation
  15. EP260316a / GRB 260316A: SVOM/VT optical upper limits
  16. EP260316a: COLIBRÍ faint optical counterpart candidate
  17. Fermi-LAT Gamma-ray Observations of IceCube-260315A
  18. GRB 260316B: AstroSat CZTI detection
  19. EP260316a: refined analysis of the EP-WXT and EP-FXT observations
  20. IceCube-260315A: Upper limits from a search for additional neutrino events in IceCube
  21. EP260316a: Xinglong optical upper limit
  22. EP260316a: optical upper limit with Kinder observations
  23. EP260316a / GRB 260316A : Fermi-GBM Sub-Threshold Detection
  24. GRB 260314A: Glowbug gamma-ray detection
  25. IceCube-260315A: COLIBRÍ optical observations
  26. EP260314a: Xinglong optical upper limit
  27. EP260314a: optical upper limit with Kinder observations
  28. IceCube Alert-260315A/AT2026fpm Automatic MASTER optical blue counterpart candidate
  29. GRB 260310A / AT2026fgk: 1.3m DFOT optical observations
  30. GRB 260310A / AT2026fgk: ABObservatory and NOCTIS optical observations
  31. GRB 260310A / AT 2026fgk: iTelescope optical observations
  32. EP260314a: COLIBRÍ optical upper limit
  33. GRID detection of GRB 260312B
  34. IceCube-260315A - IceCube observation of a high-energy neutrino candidate track-like event
  35. EP260314a: refined analysis of the EP-WXT and EP-FXT observations
  36. EP260314a: Global MASTER-Net observations report
  37. EP260314a: SVOM/VT optical candidate
  38. GRB 260314A: GECAM-B observation of a burst
  39. GRB 260310A / AT2026fgk: SAO RAS optical observations
  40. GRB 260310A/AT2026fgk: radio detection at 15GHz
  41. GRB 260310A / AT2026fgk: TNG NIR detection
  42. GRB 260310A / AT2026fgk: OASDG optical observations
  43. GRB 260310A / AT2026fgk: Multiband optical follow-up with Kinder observations
  44. GRB 260310A / AT 2026fgk: COLIBRÍ continuing optical observations
  45. GRB 260310A / AT2026fgk: further CAHA 1.23m telescope optical observations suggest shallow decay
  46. Fermi GRB 260314A: Global MASTER-Net observations report
  47. Fermi GRB 260313A: Global MASTER-Net observations report
  48. GRB 260310A/AT 2026fgk: WINTER NIR Detections
  49. GRB 260313A: A Correction to the Fermi GBM Final Localization
  50. GRB 260310A: Einstein Probe Follow-up X-ray Telescope (FXT) Detection
  51. GRB 260310A/AT 2026fgk: J-band observations by the SYSU 80 cm infrared telescope
  52. GRB 260310B: Insight-HXMT/HE detection
  53. GRB 260310A/AT 2026fgk: DDOTI Optical Detection
  54. GRB 260310A: NOT optical polarimetry
  55. GRB 260312B: AstroSat CZTI detection
  56. GRB 260310A/AT 2026fgk: Bok spectroscopic observation
  57. GRB 260310A / AT2026fgk: OSIRIS+/GTC spectroscopy confirms redshift z = 0.153
  58. GRB 260308A: Insight-HXMT/HE detection
  59. GRB 260307A: CALET Gamma-Ray Burst Monitor detection
  60. GRB 260310A / AT 2026fgk: Location in the Epeak - Eiso diagram
  61. GRB 260310A / AT 2026fgk: COLIBRÍ optical observations
  62. GRB 260310A / AT2026fgk: CAHA 1.23m telescope optical observations
  63. GRB 260310A / AT2026fgk : MASTER OT rebrightening during 7h observations
  64. GRB260310A / AT2026fgk: P200 Spectroscopy
  65. GRB 260312B: Glowbug gamma-ray detection
  66. GRB 260310A: Fermi GBM Observation
  67. GRB 260310A: potential optical counterpart
  68. Fermi GRB 260312B: Global MASTER-Net observations report
  69. Fermi GRB 260311B: Global MASTER-Net observations report
  70. GRB 260310B: GECAM-B observation of a burst
  71. Retraction of GCN 43965: GRB is actually solar flare
  72. GRB 260131A/B: radio detection with the VLA
  73. EP260302a: MeerKAT radio counterpart
  74. GRB260307A: GECAM-B observation of a burst
  75. GRB 260308A: SVOM/GRM observation of a short GRB
  76. EP260306a: Mondy optical upper limit
  77. GRB 260310A: AstroSat CZTI detection of a long burst
  78. Fermi GRB 260310B: Global MASTER-Net observations report
  79. Fermi GRB 260310A: Global MASTER-Net observations report
  80. GRB 260307B: SVOM/ECLAIRs refined analysis
  81. GRB 260208A: radio detection with the VLA
  82. GRB 260307A: Glowbug gamma-ray detection
  83. Fermi GBM Sub-Threshold Detection of GRB 260307B
  84. GRB 260307B: Mephisto optical upper limits
  85. GRB 260307B: possible NOT optical counterpart
  86. GRB 260307B: SVOM/VT upper limit with X band data analysis
  87. Fermi GRB 260307A: Global MASTER-Net observations report
  88. GRB260307B: GROWTH-India Telescope optical upper limit
  89. GRB 260307B: SVOM/VT optical candidate
  90. GRB 260307B: SVOM/C-GFT upper limit
  91. GRB 260211A: late-time NOT i-band observations consistent with archival flux
  92. EP260306a: refined analysis of the EP-WXT and EP-FXT observations
  93. GRB 260207A: TESS Detection and Possible VLA Counterpart
  94. EP260302a: SVOM/VT optical observation
  95. EP260306a: Gemini-North redshift z = 4.773
  96. EP260306a: SVOM/VT optical observation
  97. EP260302a: Gemini-South redshift z = 1.535
  98. EP260306a: COLIBRÍ optical observations of the fading and red counterpart
  99. EP260306a: Einstein Probe detection of an X-ray transient
  100. EP260302a: Optical afterglow rebrightening

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