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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"

28255 results found.

  1. The EP-WXT trigger 00199258890 (EP260316a): a correction to the trigger time and FXT automatic follow-up
  2. IceCube-260315A: COLIBRÍ optical observations
  3. EP260314a: Xinglong optical upper limit
  4. EP260314a: optical upper limit with Kinder observations
  5. IceCube Alert-260315A/AT2026fpm Automatic MASTER optical blue counterpart candidate
  6. GRB 260310A / AT2026fgk: 1.3m DFOT optical observations
  7. GRB 260310A / AT 2026fgk: iTelescope optical observations
  8. EP260314a: COLIBRÍ optical upper limit
  9. EP260314a: refined analysis of the EP-WXT and EP-FXT observations
  10. EP260314a: Global MASTER-Net observations report
  11. EP260314a: SVOM/VT optical candidate
  12. Fermi trigger No 795185313: Global MASTER-Net observations report
  13. IceCube Alert 260315A: Global MASTER-Net observations report
  14. EP260314a: Einstein Probe detection of an X-ray transient
  15. GRB 260310A / AT2026fgk: SAO RAS optical observations
  16. GRB 260310A / AT2026fgk: Multiband optical follow-up with Kinder observations
  17. GRB 260310A / AT 2026fgk: COLIBRÍ continuing optical observations
  18. Fermi GRB 260314A: Global MASTER-Net observations report
  19. Fermi GRB 260313A: Global MASTER-Net observations report
  20. GRB 260310A/AT 2026fgk: WINTER NIR Detections
  21. GRB 260310A/AT 2026fgk: J-band observations by the SYSU 80 cm infrared telescope
  22. GRB 260310A/AT 2026fgk: DDOTI Optical Detection
  23. GRB 260312B: AstroSat CZTI detection
  24. GRB 260310A / AT2026fgk: OSIRIS+/GTC spectroscopy confirms redshift z = 0.153
  25. GRB 260310A / AT 2026fgk: COLIBRÍ optical observations
  26. GRB 260310A / AT2026fgk : MASTER OT rebrightening during 7h observations
  27. GRB 260312B: Glowbug gamma-ray detection
  28. GRB 260310A: Fermi GBM Observation
  29. GRB 260310A: potential optical counterpart
  30. Fermi GRB 260312B: Global MASTER-Net observations report
  31. Fermi GRB 260311B: Global MASTER-Net observations report
  32. GRB 260312B: BALROG localization (Fermi Trigger 795001611 / GRB 260312407)
  33. GRB 260131A/B: radio detection with the VLA
  34. EP260302a: MeerKAT radio counterpart
  35. GRB 260308A: SVOM/GRM observation of a short GRB
  36. EP260306a: Mondy optical upper limit
  37. Fermi GRB 260310B: Global MASTER-Net observations report
  38. Fermi GRB 260310A: Global MASTER-Net observations report
  39. GRB 260208A: radio detection with the VLA
  40. GRB 260307A: Glowbug gamma-ray detection
  41. Fermi GBM Sub-Threshold Detection of GRB 260307B
  42. GRB 260307B: Mephisto optical upper limits
  43. GRB 260307B: possible NOT optical counterpart
  44. GRB 260307B: SVOM/VT upper limit with X band data analysis
  45. Fermi GRB 260307A: Global MASTER-Net observations report
  46. GRB260307B: GROWTH-India Telescope optical upper limit
  47. GRB 260307B: SVOM/VT optical candidate
  48. GRB 260307B: SVOM/C-GFT upper limit
  49. GRB 260307B: SVOM detection of a burst
  50. EP260306a: refined analysis of the EP-WXT and EP-FXT observations
  51. GRB 260207A: TESS Detection and Possible VLA Counterpart
  52. EP260302a: SVOM/VT optical observation
  53. EP260306a: Gemini-North redshift z = 4.773
  54. EP260306a: SVOM/VT optical observation
  55. EP260302a: Gemini-South redshift z = 1.535
  56. EP260306a: COLIBRÍ optical observations of the fading and red counterpart
  57. EP260306a: Einstein Probe detection of an X-ray transient
  58. EP260302a: Optical afterglow rebrightening
  59. GRB 260228A: further EP-FXT observations and X-ray afterglow confirmation
  60. GRB 260303A: 1.3m DFOT optical upper limit
  61. Fermi GRB 260305A: Global MASTER-Net observations report
  62. GRB 260303B: AstroSat CZTI detection
  63. GRB 260303A: SVOM/VT optical observations
  64. GRB 260303A: J-band observations with WINTER
  65. GRB 260303B: NuSTAR detection of prompt emission
  66. EP260302a: Global MASTER-Net observations report
  67. Fermi GRB 260303B: Global MASTER-Net observations report
  68. GRB 260303B: BALROG localization (Fermi Trigger 794237065 / GRB 260303559)
  69. EP260302a: analysis of the follow-up EP-FXT observation
  70. EP260302a: LCO observations
  71. EP260302a: BOOTES-7 optical counterpart detection at early times
  72. GRB 260303A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  73. GRB 260303A: SVOM detection of a burst
  74. GRB 260228A: EP-FXT follow-up observation
  75. EP260302a: Einstein Probe detection of an X-ray transient
  76. The EP-WXT trigger 01709258736: Las Cumbres discovery of the optical counterpart
  77. GRB 251130B: TERI Gamma-ray detection
  78. GRB 260208A: TERI Gamma-ray detection
  79. EP260227a: Mondy optical observations
  80. GRB 260228A: CAHA 2.2m telescope optical upper limit
  81. GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  82. EP260227a: Mephisto optical detection
  83. EP-WXT trigger 01709258652: 50cm Telescope multi-band observations
  84. EP260227a: SVOM/VT optical observation
  85. GRB 260228A: SVOM/VT optical upper limits
  86. GRB 260225D: SVOM/GRM observation
  87. EP260227A: 3.6m DOT optical afterglow detection
  88. GRB 260225B: SVOM/GRM observation
  89. EP260227a: Liverpool Telescope optical observations
  90. EP260227a: LCOGT Optical Observations
  91. GRB 260226A: Asiago r-band upper limit
  92. EP260227a: Liverpool Telescope observations
  93. EP260227a: COLIBRÍ optical observations
  94. EP260227a: NOT optical observations
  95. EP260227a: Global MASTER-Net observations report
  96. EP260227a: Einstein Probe detection of an X-ray transient and refined analysis
  97. The EP-WXT trigger 01709258681 (EP260227a?): Las Cumbres follow-up observation of the optical counterpart
  98. EP/WXT trigger 01709258681 (EP260227a?): LCO candidate afterglow
  99. GRB 260223A: 7DT detection and Medium-band SED of Afterglow
  100. EP260214a: VLT/FORS2 optical observations

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