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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"

28262 results found.

  1. Fermi-LAT Gamma-ray Observations of IceCube-260315A
  2. EP260316a: refined analysis of the EP-WXT and EP-FXT observations
  3. IceCube-260315A: Upper limits from a search for additional neutrino events in IceCube
  4. EP260316a: Xinglong optical upper limit
  5. EP260316a: optical upper limit with Kinder observations
  6. EP260316a / GRB 260316A : Fermi-GBM Sub-Threshold Detection
  7. GRB 260314A: Glowbug gamma-ray detection
  8. The EP-WXT trigger 00199258890 (EP260316a): a correction to the trigger time and FXT automatic follow-up
  9. IceCube-260315A: COLIBRÍ optical observations
  10. EP260314a: Xinglong optical upper limit
  11. EP260314a: optical upper limit with Kinder observations
  12. IceCube Alert-260315A/AT2026fpm Automatic MASTER optical blue counterpart candidate
  13. GRB 260310A / AT2026fgk: 1.3m DFOT optical observations
  14. GRB 260310A / AT 2026fgk: iTelescope optical observations
  15. EP260314a: COLIBRÍ optical upper limit
  16. EP260314a: refined analysis of the EP-WXT and EP-FXT observations
  17. EP260314a: Global MASTER-Net observations report
  18. EP260314a: SVOM/VT optical candidate
  19. Fermi trigger No 795185313: Global MASTER-Net observations report
  20. IceCube Alert 260315A: Global MASTER-Net observations report
  21. EP260314a: Einstein Probe detection of an X-ray transient
  22. GRB 260310A / AT2026fgk: SAO RAS optical observations
  23. GRB 260310A / AT2026fgk: Multiband optical follow-up with Kinder observations
  24. GRB 260310A / AT 2026fgk: COLIBRÍ continuing optical observations
  25. Fermi GRB 260314A: Global MASTER-Net observations report
  26. Fermi GRB 260313A: Global MASTER-Net observations report
  27. GRB 260310A/AT 2026fgk: WINTER NIR Detections
  28. GRB 260310A/AT 2026fgk: J-band observations by the SYSU 80 cm infrared telescope
  29. GRB 260310A/AT 2026fgk: DDOTI Optical Detection
  30. GRB 260312B: AstroSat CZTI detection
  31. GRB 260310A / AT2026fgk: OSIRIS+/GTC spectroscopy confirms redshift z = 0.153
  32. GRB 260310A / AT 2026fgk: COLIBRÍ optical observations
  33. GRB 260310A / AT2026fgk : MASTER OT rebrightening during 7h observations
  34. GRB 260312B: Glowbug gamma-ray detection
  35. GRB 260310A: Fermi GBM Observation
  36. GRB 260310A: potential optical counterpart
  37. Fermi GRB 260312B: Global MASTER-Net observations report
  38. Fermi GRB 260311B: Global MASTER-Net observations report
  39. GRB 260312B: BALROG localization (Fermi Trigger 795001611 / GRB 260312407)
  40. GRB 260131A/B: radio detection with the VLA
  41. EP260302a: MeerKAT radio counterpart
  42. GRB 260308A: SVOM/GRM observation of a short GRB
  43. EP260306a: Mondy optical upper limit
  44. Fermi GRB 260310B: Global MASTER-Net observations report
  45. Fermi GRB 260310A: Global MASTER-Net observations report
  46. GRB 260208A: radio detection with the VLA
  47. GRB 260307A: Glowbug gamma-ray detection
  48. Fermi GBM Sub-Threshold Detection of GRB 260307B
  49. GRB 260307B: Mephisto optical upper limits
  50. GRB 260307B: possible NOT optical counterpart
  51. GRB 260307B: SVOM/VT upper limit with X band data analysis
  52. Fermi GRB 260307A: Global MASTER-Net observations report
  53. GRB260307B: GROWTH-India Telescope optical upper limit
  54. GRB 260307B: SVOM/VT optical candidate
  55. GRB 260307B: SVOM/C-GFT upper limit
  56. GRB 260307B: SVOM detection of a burst
  57. EP260306a: refined analysis of the EP-WXT and EP-FXT observations
  58. GRB 260207A: TESS Detection and Possible VLA Counterpart
  59. EP260302a: SVOM/VT optical observation
  60. EP260306a: Gemini-North redshift z = 4.773
  61. EP260306a: SVOM/VT optical observation
  62. EP260302a: Gemini-South redshift z = 1.535
  63. EP260306a: COLIBRÍ optical observations of the fading and red counterpart
  64. EP260306a: Einstein Probe detection of an X-ray transient
  65. EP260302a: Optical afterglow rebrightening
  66. GRB 260228A: further EP-FXT observations and X-ray afterglow confirmation
  67. GRB 260303A: 1.3m DFOT optical upper limit
  68. Fermi GRB 260305A: Global MASTER-Net observations report
  69. GRB 260303B: AstroSat CZTI detection
  70. GRB 260303A: SVOM/VT optical observations
  71. GRB 260303A: J-band observations with WINTER
  72. GRB 260303B: NuSTAR detection of prompt emission
  73. EP260302a: Global MASTER-Net observations report
  74. Fermi GRB 260303B: Global MASTER-Net observations report
  75. GRB 260303B: BALROG localization (Fermi Trigger 794237065 / GRB 260303559)
  76. EP260302a: analysis of the follow-up EP-FXT observation
  77. EP260302a: LCO observations
  78. EP260302a: BOOTES-7 optical counterpart detection at early times
  79. GRB 260303A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  80. GRB 260303A: SVOM detection of a burst
  81. GRB 260228A: EP-FXT follow-up observation
  82. EP260302a: Einstein Probe detection of an X-ray transient
  83. The EP-WXT trigger 01709258736: Las Cumbres discovery of the optical counterpart
  84. GRB 251130B: TERI Gamma-ray detection
  85. GRB 260208A: TERI Gamma-ray detection
  86. EP260227a: Mondy optical observations
  87. GRB 260228A: CAHA 2.2m telescope optical upper limit
  88. GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  89. EP260227a: Mephisto optical detection
  90. EP-WXT trigger 01709258652: 50cm Telescope multi-band observations
  91. EP260227a: SVOM/VT optical observation
  92. GRB 260228A: SVOM/VT optical upper limits
  93. GRB 260225D: SVOM/GRM observation
  94. EP260227A: 3.6m DOT optical afterglow detection
  95. GRB 260225B: SVOM/GRM observation
  96. EP260227a: Liverpool Telescope optical observations
  97. EP260227a: LCOGT Optical Observations
  98. GRB 260226A: Asiago r-band upper limit
  99. EP260227a: Liverpool Telescope observations
  100. EP260227a: COLIBRÍ optical observations

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