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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"

27617 results found.

  1. GRB 260318A: SVOM/GRM observation
  2. The EP-WXT trigger 01709258989 is likely a flaring star
  3. GRB 260310A: classification as long GRB based on Eiso, Ep, and T_90
  4. GRB260310A/AT2026fgk: Further optical observation from 1.3m DFOT
  5. Fermi GRB 260318A: Global MASTER-Net observations report
  6. GRB 260318A: Fermi GBM Final Real-time Localization
  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 / AT2026fgk: LCO optical observations
  10. GRB 260317A: Fermi GBM Final Localization
  11. EP260316a / GRB 260316A: SVOM/VT optical upper limits
  12. EP260316a: COLIBRÍ faint optical counterpart candidate
  13. GRB 260316B: AstroSat CZTI detection
  14. EP260316a: Xinglong optical upper limit
  15. GRB 260316B: Fermi GBM Final Real-time Localization
  16. EP260316a / GRB 260316A : Fermi-GBM Sub-Threshold Detection
  17. The EP-WXT trigger 00199258890 (EP260316a): a correction to the trigger time and FXT automatic follow-up
  18. IceCube-260315A: COLIBRÍ optical observations
  19. EP260314a: Xinglong optical upper limit
  20. IceCube Alert-260315A/AT2026fpm Automatic MASTER optical blue counterpart candidate
  21. GRB 260310A / AT2026fgk: 1.3m DFOT optical observations
  22. GRB 260310A / AT2026fgk: ABObservatory and NOCTIS optical observations
  23. GRB 260310A / AT 2026fgk: iTelescope optical observations
  24. EP260314a: COLIBRÍ optical upper limit
  25. EP260314a: BOOTES-6/DPR optical upper limits at early times
  26. EP260314a: Global MASTER-Net observations report
  27. EP260314a: SVOM/VT optical candidate
  28. Fermi trigger No 795185313: Global MASTER-Net observations report
  29. IceCube Alert 260315A: Global MASTER-Net observations report
  30. The EP-WXT trigger 01709258851: Las Cumbres upper limit
  31. Fermi Gamma-ray Burst Monitor trigger 795185313/260314534 is not a GRB
  32. GRB 260310A / AT2026fgk: SAO RAS optical observations
  33. GRB 260310A / AT2026fgk: TNG NIR detection
  34. GRB 260310A / AT2026fgk: OASDG optical observations
  35. GRB 260310A / AT 2026fgk: COLIBRÍ continuing optical observations
  36. GRB 260310A / AT2026fgk: further CAHA 1.23m telescope optical observations suggest shallow decay
  37. Fermi GRB 260314A: Global MASTER-Net observations report
  38. Fermi GRB 260313A: Global MASTER-Net observations report
  39. GRB 260314A: Fermi GBM Final Real-time Localization
  40. GRB 260310A/AT 2026fgk: WINTER NIR Detections
  41. GRB 260313A: A Correction to the Fermi GBM Final Localization
  42. GRB 260310A/AT 2026fgk: J-band observations by the SYSU 80 cm infrared telescope
  43. GRB 260310A/AT 2026fgk: DDOTI Optical Detection
  44. GRB 260310A: NOT optical polarimetry
  45. Swift BAT trigger 1500295: A solar flare
  46. GRB 260313A: Fermi GBM Final Real-time Localization
  47. Swift BAT trigger 1500287: A solar flare
  48. GRB 260310A / AT2026fgk: OSIRIS+/GTC spectroscopy confirms redshift z = 0.153
  49. GRB 260310A / AT 2026fgk: COLIBRÍ optical observations
  50. GRB 260310A / AT2026fgk: CAHA 1.23m telescope optical observations
  51. GRB260310A / AT2026fgk: P200 Spectroscopy
  52. GRB 260310A: Fermi GBM Observation
  53. Fermi GRB 260312B: Global MASTER-Net observations report
  54. Fermi GRB 260311B: Global MASTER-Net observations report
  55. Swift BAT trigger 1500148: A solar flare
  56. GRB 260312B: BALROG localization (Fermi Trigger 795001611 / GRB 260312407)
  57. GRB 260312B: Fermi GBM Final Real-time Localization
  58. The EP-WXT trigger 01709258843 is not a real source
  59. GRB 260312A: Swift detection of a burst
  60. GRB 260311B: Fermi GBM Final Real-time Localization
  61. GRB 260308A: SVOM/GRM observation of a short GRB
  62. GRB 260311A: Fermi GBM Final Real-time Localization
  63. Fermi GRB 260310B: Global MASTER-Net observations report
  64. GRB 260310B: Fermi GBM Final Real-time Localization
  65. Fermi GRB 260310A: Global MASTER-Net observations report
  66. GRB 260307B: SVOM/ECLAIRs refined analysis
  67. GRB 260310A: Fermi GBM Final Real-time Localization
  68. GRB 260307A: Glowbug gamma-ray detection
  69. GRB 260308A: Fermi GBM Final Real-time Localization
  70. Fermi GBM Sub-Threshold Detection of GRB 260307B
  71. GRB 260307B: Mephisto optical upper limits
  72. GRB 260307B: possible NOT optical counterpart
  73. Fermi GRB 260307A: Global MASTER-Net observations report
  74. GRB260307B: GROWTH-India Telescope optical upper limit
  75. GRB 260307B: SVOM/VT optical candidate
  76. GRB 260307B: SVOM/C-GFT upper limit
  77. GRB 260307B: SVOM detection of a burst
  78. GRB 260307A: Fermi GBM Final Localization
  79. GRB 260211A: late-time NOT i-band observations consistent with archival flux
  80. EP260302a: SVOM/VT optical observation
  81. EP260306a: Gemini-North redshift z = 4.773
  82. EP260306a: SVOM/VT optical observation
  83. EP260302a: Gemini-South redshift z = 1.535
  84. EP260306a: COLIBRÍ optical observations of the fading and red counterpart
  85. The EP-WXT trigger 01709258759: Las Cumbres discovery of the optical counterpart
  86. EP260302a: Optical afterglow rebrightening
  87. GRB 260228A: further EP-FXT observations and X-ray afterglow confirmation
  88. GRB 260303A: 1.3m DFOT optical upper limit
  89. EP260214b: ATCA 6 GHz observations
  90. GRB 260211A: SVOM/VT optical rebrightening at 20 days after the burst, SN candidate
  91. GRB 260303A: SVOM/ECLAIRs refined analysis
  92. Fermi GRB 260305A: Global MASTER-Net observations report
  93. GRB 260305A: Fermi GBM Final Real-time Localization
  94. SVOM/sb26030408: SVOM detection of an X-ray transient likely associated with Beta Persei
  95. GRB 260303A: SVOM/VT optical observations
  96. GRB 260303A: J-band observations with WINTER
  97. EP260302a: Global MASTER-Net observations report
  98. Fermi GRB 260303B: Global MASTER-Net observations report
  99. GRB 260225A: SVOM/ECLAIRs refined analysis
  100. GRB 260303B: BALROG localization (Fermi Trigger 794237065 / GRB 260303559)

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