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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"

32711 results found.

  1. EP260321a: refined analysis of the EP-WXT and EP-FXT observations, implying a possible supernova shock breakout candidate
  2. EP260321a: SVOM/VT optical upper limit
  3. GRB 260310A: continued optical observation at Mondy
  4. Fermi GBM Sub-Threshold Detection of GRB 260321A
  5. EP260321a: Kinder observations detect a blue variable star and set limits on a source from the z =0.034 galaxy within the error circle
  6. EP260321a: Global MASTER-Net observations report
  7. GRB 260310A / AT2026fgk: ABObservatory and NOCTIS new optical observations
  8. GRB 260318A: Glowbug gamma-ray detection
  9. GRB 260310A / AT 2026fgk: KAIT optical observations
  10. GRB 260320A: NuSTAR detection of prompt emission
  11. GRB 260310A / AT2026fgk: NuSTAR follow-up detection
  12. EP-WXT trigger 01709258989: KAIT confirmation of a stellar flare
  13. GRB 260310A / AT 2026fgk: FTW optical and NIR observations show no rebrightening
  14. GRB 260310A: no evidence of re-brightening up to 9.6 days in optical observation at Mondy
  15. GRB 260310A / AT 2026fgk: COLIBRÍ evidence of a late rebrightening
  16. GRB 260310A/AT2026fgk: LBT near-infrared observations
  17. NOEMA Detection of GRB 260310A / AT 2026fgk
  18. EP-WXT trigger 01709258989: confirmation of a stellar flare by BOOTES-7
  19. GRB 260318A: SVOM/GRM observation
  20. GRB 260310A: classification as long GRB based on Eiso, Ep, and T_90
  21. GRB 260318A: GECAM-B observation
  22. GRB260310A/AT2026fgk: Further optical observation from 1.3m DFOT
  23. Fermi GRB 260318A: Global MASTER-Net observations report
  24. IceCube-260315A: No Candidate Transients from the Zwicky Transient Facility
  25. Fermi Gamma-ray Burst Monitor trigger 795096033/260312500 (GRB 260313A) is unlikely to be a GRB
  26. GRB 260316A / EP260316a: COLIBRÍ optical followup of counterpart candidate
  27. GRB 260310A / AT 2026fgk: radio detection with the VLA
  28. GRB 260310A / AT2026fgk: SVOM/VT optical observations
  29. GRB 260310A / AT2026fgk: LCO optical observations
  30. IceCube-260315A/AT2026fpm: EP-FXT follow-up observation
  31. GRB 260316B: GECAM-B observation
  32. GRB 260316B: SVOM/GRM observation
  33. EP260316a / GRB 260316A: SVOM/VT optical upper limits
  34. EP260316a: COLIBRÍ faint optical counterpart candidate
  35. Fermi-LAT Gamma-ray Observations of IceCube-260315A
  36. GRB 260316B: AstroSat CZTI detection
  37. EP260316a: refined analysis of the EP-WXT and EP-FXT observations
  38. IceCube-260315A: Upper limits from a search for additional neutrino events in IceCube
  39. EP260316a: Xinglong optical upper limit
  40. EP260316a: optical upper limit with Kinder observations
  41. EP260316a / GRB 260316A : Fermi-GBM Sub-Threshold Detection
  42. GRB 260314A: Glowbug gamma-ray detection
  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: Global MASTER-Net observations report
  55. EP260314a: SVOM/VT optical candidate
  56. GRB 260314A: GECAM-B observation of a burst
  57. GRB 260310A / AT2026fgk: SAO RAS optical observations
  58. GRB 260310A/AT2026fgk: radio detection at 15GHz
  59. GRB 260310A / AT2026fgk: TNG NIR detection
  60. GRB 260310A / AT2026fgk: OASDG optical observations
  61. GRB 260310A / AT2026fgk: Multiband optical follow-up with Kinder observations
  62. GRB 260310A / AT 2026fgk: COLIBRÍ continuing optical observations
  63. GRB 260310A / AT2026fgk: further CAHA 1.23m telescope optical observations suggest shallow decay
  64. Fermi GRB 260314A: Global MASTER-Net observations report
  65. Fermi GRB 260313A: Global MASTER-Net observations report
  66. GRB 260310A/AT 2026fgk: WINTER NIR Detections
  67. GRB 260313A: A Correction to the Fermi GBM Final Localization
  68. GRB 260310A: Einstein Probe Follow-up X-ray Telescope (FXT) Detection
  69. GRB 260310A/AT 2026fgk: J-band observations by the SYSU 80 cm infrared telescope
  70. GRB 260310B: Insight-HXMT/HE detection
  71. GRB 260310A/AT 2026fgk: DDOTI Optical Detection
  72. GRB 260310A: NOT optical polarimetry
  73. GRB 260312B: AstroSat CZTI detection
  74. GRB 260310A/AT 2026fgk: Bok spectroscopic observation
  75. GRB 260310A / AT2026fgk: OSIRIS+/GTC spectroscopy confirms redshift z = 0.153
  76. GRB 260308A: Insight-HXMT/HE detection
  77. GRB 260307A: CALET Gamma-Ray Burst Monitor detection
  78. GRB 260310A / AT 2026fgk: Location in the Epeak - Eiso diagram
  79. GRB 260310A / AT 2026fgk: COLIBRÍ optical observations
  80. GRB 260310A / AT2026fgk: CAHA 1.23m telescope optical observations
  81. GRB 260310A / AT2026fgk : MASTER OT rebrightening during 7h observations
  82. GRB260310A / AT2026fgk: P200 Spectroscopy
  83. GRB 260312B: Glowbug gamma-ray detection
  84. GRB 260310A: Fermi GBM Observation
  85. GRB 260310A: potential optical counterpart
  86. Fermi GRB 260312B: Global MASTER-Net observations report
  87. Fermi GRB 260311B: Global MASTER-Net observations report
  88. GRB 260310B: GECAM-B observation of a burst
  89. Retraction of GCN 43965: GRB is actually solar flare
  90. GRB 260131A/B: radio detection with the VLA
  91. EP260302a: MeerKAT radio counterpart
  92. GRB260307A: GECAM-B observation of a burst
  93. GRB 260308A: SVOM/GRM observation of a short GRB
  94. EP260306a: Mondy optical upper limit
  95. GRB 260310A: AstroSat CZTI detection of a long burst
  96. Fermi GRB 260310B: Global MASTER-Net observations report
  97. Fermi GRB 260310A: Global MASTER-Net observations report
  98. GRB 260307B: SVOM/ECLAIRs refined analysis
  99. GRB 260208A: radio detection with the VLA
  100. GRB 260307A: Glowbug gamma-ray detection

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