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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"

38621 results found.

  1. GRB 260310A: continued optical observation at Mondy
  2. Fermi GBM Sub-Threshold Detection of GRB 260321A
  3. GRB 260321A: SVOM detection of a burst
  4. EP260321a: Kinder observations detect a blue variable star and set limits on a source from the z =0.034 galaxy within the error circle
  5. EP260321a: Einstein Probe detection of an X-ray transient
  6. GRB 260318A: Glowbug gamma-ray detection
  7. GRB 260310A / AT 2026fgk: KAIT optical observations
  8. GRB 260320A: NuSTAR detection of prompt emission
  9. EP-WXT trigger 01709258989: KAIT confirmation of a stellar flare
  10. GRB 260310A: no evidence of re-brightening up to 9.6 days in optical observation at Mondy
  11. GRB 260310A / AT 2026fgk: COLIBRÍ evidence of a late rebrightening
  12. GRB 260310A/AT2026fgk: LBT near-infrared observations
  13. NOEMA Detection of GRB 260310A / AT 2026fgk
  14. EP-WXT trigger 01709258989: confirmation of a stellar flare by BOOTES-7
  15. GRB 260318A: SVOM/GRM observation
  16. The EP-WXT trigger 01709258989 is likely a flaring star
  17. GRB 260310A: classification as long GRB based on Eiso, Ep, and T_90
  18. GRB 260318A: GECAM-B observation
  19. GRB260310A/AT2026fgk: Further optical observation from 1.3m DFOT
  20. GRB 260318A: Fermi GBM Final Real-time Localization
  21. IceCube-260315A: No Candidate Transients from the Zwicky Transient Facility
  22. Fermi Gamma-ray Burst Monitor trigger 795096033/260312500 (GRB 260313A) is unlikely to be a GRB
  23. GRB 260316A / EP260316a: COLIBRÍ optical followup of counterpart candidate
  24. GRB 260310A / AT 2026fgk: radio detection with the VLA
  25. GRB 260310A / AT2026fgk: SVOM/VT optical observations
  26. GRB 260310A / AT2026fgk: LCO optical observations
  27. IceCube-260315A/AT2026fpm: EP-FXT follow-up observation
  28. GRB 260317A: Fermi GBM Final Localization
  29. GRB 260316B: GECAM-B observation
  30. GRB 260316B: SVOM/GRM observation
  31. EP260316a / GRB 260316A: SVOM/VT optical upper limits
  32. EP260316a: COLIBRÍ faint optical counterpart candidate
  33. Fermi-LAT Gamma-ray Observations of IceCube-260315A
  34. GRB 260316B: AstroSat CZTI detection
  35. EP260316a: refined analysis of the EP-WXT and EP-FXT observations
  36. IceCube-260315A: Upper limits from a search for additional neutrino events in IceCube
  37. EP260316a: Xinglong optical upper limit
  38. GRB 260316B: Fermi GBM Final Real-time Localization
  39. EP260316a: optical upper limit with Kinder observations
  40. EP260316a / GRB 260316A : Fermi-GBM Sub-Threshold Detection
  41. GRB 260314A: Glowbug gamma-ray detection
  42. The EP-WXT trigger 00199258890 (EP260316a): a correction to the trigger time and FXT automatic follow-up
  43. IceCube-260315A: COLIBRÍ optical observations
  44. EP260314a: Xinglong optical upper limit
  45. EP260314a: optical upper limit with Kinder observations
  46. IceCube Alert-260315A/AT2026fpm Automatic MASTER optical blue counterpart candidate
  47. GRB 260310A / AT2026fgk: 1.3m DFOT optical observations
  48. GRB 260310A / AT2026fgk: ABObservatory and NOCTIS optical observations
  49. GRB 260310A / AT 2026fgk: iTelescope optical observations
  50. EP260314a: COLIBRÍ optical upper limit
  51. GRID detection of GRB 260312B
  52. IceCube-260315A - IceCube observation of a high-energy neutrino candidate track-like event
  53. EP260314a: refined analysis of the EP-WXT and EP-FXT observations
  54. EP260314a: BOOTES-6/DPR optical upper limits at early times
  55. EP260314a: SVOM/VT optical candidate
  56. EP260314a: Einstein Probe detection of an X-ray transient
  57. GRB 260314A: GECAM-B observation of a burst
  58. Fermi Gamma-ray Burst Monitor trigger 795185313/260314534 is not a GRB
  59. GRB 260310A / AT2026fgk: SAO RAS optical observations
  60. GRB 260310A / AT2026fgk: TNG NIR detection
  61. GRB 260310A / AT2026fgk: OASDG optical observations
  62. GRB 260310A / AT2026fgk: Multiband optical follow-up with Kinder observations
  63. GRB 260310A / AT 2026fgk: COLIBRÍ continuing optical observations
  64. GRB 260310A / AT2026fgk: further CAHA 1.23m telescope optical observations suggest shallow decay
  65. GRB 260314A: Fermi GBM Final Real-time Localization
  66. GRB 260313A: A Correction to the Fermi GBM Final Localization
  67. GRB 260310A: Einstein Probe Follow-up X-ray Telescope (FXT) Detection
  68. GRB 260310A/AT 2026fgk: J-band observations by the SYSU 80 cm infrared telescope
  69. GRB 260310B: Insight-HXMT/HE detection
  70. GRB 260310A/AT 2026fgk: DDOTI Optical Detection
  71. GRB 260310A: NOT optical polarimetry
  72. GRB 260312B: AstroSat CZTI detection
  73. Swift BAT trigger 1500295: A solar flare
  74. GRB 260313A: Fermi GBM Final Real-time Localization
  75. GRB 260310A/AT 2026fgk: Bok spectroscopic observation
  76. Swift BAT trigger 1500287: A solar flare
  77. GRB 260310A / AT2026fgk: OSIRIS+/GTC spectroscopy confirms redshift z = 0.153
  78. GRB 260308A: Insight-HXMT/HE detection
  79. GRB 260307A: CALET Gamma-Ray Burst Monitor detection
  80. GRB 260310A / AT 2026fgk: Location in the Epeak - Eiso diagram
  81. GRB 260310A / AT 2026fgk: COLIBRÍ optical observations
  82. GRB 260310A / AT2026fgk: CAHA 1.23m telescope optical observations
  83. GRB260310A / AT2026fgk: P200 Spectroscopy
  84. GRB 260312B: Glowbug gamma-ray detection
  85. GRB 260310A: Fermi GBM Observation
  86. GRB 260310A: potential optical counterpart
  87. Swift BAT trigger 1500148: A solar flare
  88. GRB 260312B: BALROG localization (Fermi Trigger 795001611 / GRB 260312407)
  89. GRB 260312B: Fermi GBM Final Real-time Localization
  90. The EP-WXT trigger 01709258843 is not a real source
  91. GRB 260310B: GECAM-B observation of a burst
  92. Retraction of GCN 43965: GRB is actually solar flare
  93. GRB 260312A: Swift detection of a burst
  94. GRB 260311B: Fermi GBM Final Real-time Localization
  95. GRB 260131A/B: radio detection with the VLA
  96. EP260302a: MeerKAT radio counterpart
  97. GRB260307A: GECAM-B observation of a burst
  98. GRB 260308A: SVOM/GRM observation of a short GRB
  99. EP260306a: Mondy optical upper limit
  100. GRB 260310A: AstroSat CZTI detection of a long burst

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