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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"

27604 results found.

  1. EP260316a: Xinglong optical upper limit
  2. GRB 260316B: Fermi GBM Final Real-time Localization
  3. EP260316a / GRB 260316A : Fermi-GBM Sub-Threshold Detection
  4. The EP-WXT trigger 00199258890 (EP260316a): a correction to the trigger time and FXT automatic follow-up
  5. IceCube-260315A: COLIBRÍ optical observations
  6. EP260314a: Xinglong optical upper limit
  7. IceCube Alert-260315A/AT2026fpm Automatic MASTER optical blue counterpart candidate
  8. GRB 260310A / AT2026fgk: 1.3m DFOT optical observations
  9. GRB 260310A / AT2026fgk: ABObservatory and NOCTIS optical observations
  10. GRB 260310A / AT 2026fgk: iTelescope optical observations
  11. EP260314a: COLIBRÍ optical upper limit
  12. EP260314a: BOOTES-6/DPR optical upper limits at early times
  13. EP260314a: Global MASTER-Net observations report
  14. EP260314a: SVOM/VT optical candidate
  15. Fermi trigger No 795185313: Global MASTER-Net observations report
  16. IceCube Alert 260315A: Global MASTER-Net observations report
  17. The EP-WXT trigger 01709258851: Las Cumbres upper limit
  18. Fermi Gamma-ray Burst Monitor trigger 795185313/260314534 is not a GRB
  19. GRB 260310A / AT2026fgk: SAO RAS optical observations
  20. GRB 260310A / AT2026fgk: TNG NIR detection
  21. GRB 260310A / AT2026fgk: OASDG optical observations
  22. GRB 260310A / AT 2026fgk: COLIBRÍ continuing optical observations
  23. GRB 260310A / AT2026fgk: further CAHA 1.23m telescope optical observations suggest shallow decay
  24. Fermi GRB 260314A: Global MASTER-Net observations report
  25. Fermi GRB 260313A: Global MASTER-Net observations report
  26. GRB 260314A: Fermi GBM Final Real-time Localization
  27. GRB 260310A/AT 2026fgk: WINTER NIR Detections
  28. GRB 260313A: A Correction to the Fermi GBM Final Localization
  29. GRB 260310A/AT 2026fgk: J-band observations by the SYSU 80 cm infrared telescope
  30. GRB 260310A/AT 2026fgk: DDOTI Optical Detection
  31. GRB 260310A: NOT optical polarimetry
  32. Swift BAT trigger 1500295: A solar flare
  33. GRB 260313A: Fermi GBM Final Real-time Localization
  34. Swift BAT trigger 1500287: A solar flare
  35. GRB 260310A / AT2026fgk: OSIRIS+/GTC spectroscopy confirms redshift z = 0.153
  36. GRB 260310A / AT 2026fgk: COLIBRÍ optical observations
  37. GRB 260310A / AT2026fgk: CAHA 1.23m telescope optical observations
  38. GRB260310A / AT2026fgk: P200 Spectroscopy
  39. GRB 260310A: Fermi GBM Observation
  40. Fermi GRB 260312B: Global MASTER-Net observations report
  41. Fermi GRB 260311B: Global MASTER-Net observations report
  42. Swift BAT trigger 1500148: A solar flare
  43. GRB 260312B: BALROG localization (Fermi Trigger 795001611 / GRB 260312407)
  44. GRB 260312B: Fermi GBM Final Real-time Localization
  45. The EP-WXT trigger 01709258843 is not a real source
  46. GRB 260312A: Swift detection of a burst
  47. GRB 260311B: Fermi GBM Final Real-time Localization
  48. GRB 260308A: SVOM/GRM observation of a short GRB
  49. GRB 260311A: Fermi GBM Final Real-time Localization
  50. Fermi GRB 260310B: Global MASTER-Net observations report
  51. GRB 260310B: Fermi GBM Final Real-time Localization
  52. Fermi GRB 260310A: Global MASTER-Net observations report
  53. GRB 260307B: SVOM/ECLAIRs refined analysis
  54. GRB 260310A: Fermi GBM Final Real-time Localization
  55. GRB 260307A: Glowbug gamma-ray detection
  56. GRB 260308A: Fermi GBM Final Real-time Localization
  57. Fermi GBM Sub-Threshold Detection of GRB 260307B
  58. GRB 260307B: Mephisto optical upper limits
  59. GRB 260307B: possible NOT optical counterpart
  60. Fermi GRB 260307A: Global MASTER-Net observations report
  61. GRB260307B: GROWTH-India Telescope optical upper limit
  62. GRB 260307B: SVOM/VT optical candidate
  63. GRB 260307B: SVOM/C-GFT upper limit
  64. GRB 260307B: SVOM detection of a burst
  65. GRB 260307A: Fermi GBM Final Localization
  66. GRB 260211A: late-time NOT i-band observations consistent with archival flux
  67. EP260302a: SVOM/VT optical observation
  68. EP260306a: Gemini-North redshift z = 4.773
  69. EP260306a: SVOM/VT optical observation
  70. EP260302a: Gemini-South redshift z = 1.535
  71. EP260306a: COLIBRÍ optical observations of the fading and red counterpart
  72. The EP-WXT trigger 01709258759: Las Cumbres discovery of the optical counterpart
  73. EP260302a: Optical afterglow rebrightening
  74. GRB 260228A: further EP-FXT observations and X-ray afterglow confirmation
  75. GRB 260303A: 1.3m DFOT optical upper limit
  76. EP260214b: ATCA 6 GHz observations
  77. GRB 260211A: SVOM/VT optical rebrightening at 20 days after the burst, SN candidate
  78. GRB 260303A: SVOM/ECLAIRs refined analysis
  79. Fermi GRB 260305A: Global MASTER-Net observations report
  80. GRB 260305A: Fermi GBM Final Real-time Localization
  81. SVOM/sb26030408: SVOM detection of an X-ray transient likely associated with Beta Persei
  82. GRB 260303A: SVOM/VT optical observations
  83. GRB 260303A: J-band observations with WINTER
  84. EP260302a: Global MASTER-Net observations report
  85. Fermi GRB 260303B: Global MASTER-Net observations report
  86. GRB 260225A: SVOM/ECLAIRs refined analysis
  87. GRB 260303B: BALROG localization (Fermi Trigger 794237065 / GRB 260303559)
  88. GRB 260303B: Fermi GBM Final Real-time Localization
  89. EP260302a: analysis of the follow-up EP-FXT observation
  90. EP260302a: LCO observations
  91. EP260302a: BOOTES-7 optical counterpart detection at early times
  92. GRB 260303A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  93. GRB 260303A: SVOM detection of a burst
  94. GRB 260228A: EP-FXT follow-up observation
  95. The EP-WXT trigger 01709258736: Las Cumbres discovery of the optical counterpart
  96. GRB 260302A: Fermi GBM Final Real-time Localization
  97. GRB 260228A: CAHA 2.2m telescope optical upper limit
  98. GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  99. EP260227a: Mephisto optical detection
  100. EP-WXT trigger 01709258652: 50cm Telescope multi-band observations

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