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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"

28097 results found.

  1. GRB 260610B / AT 2026owq: COLIBRÍ optical observations
  2. GRB 260610B / AT2026owq: Early ATLAS observations
  3. GRB 260610B: TRT optical observation
  4. EP260610a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  5. EP260610b: COLIBRÍ optical observations
  6. GRB 260610B: DDOTI optical observations
  7. EP260610b: MAO/AZT-22 optical observations
  8. EP260610b: NOT optical observation
  9. EP260610b: SVOM/VT optical confirmation with blue color
  10. GRB 260515A: SOAR optical observations
  11. EP260610a: SVOM/VT optical upper limits
  12. EP260610b: Einstein Probe detection of an X-ray transient
  13. EP260610a: COLIBRÍ optical upper limits
  14. EP260610a: Einstein Probe detection of a fast X-ray transient
  15. GRB 260608A: Fermi GRB Observation
  16. GRB 260604C: further SAO RAS optical observations
  17. GRB 260607A / GOTO26fqf / AT2026ong: COLIBRÍ optical observations
  18. GRB 260604C: SVOM/COLIBRÍ (FM-GFT) colour evolution and confirmation of the late rebrightening
  19. GRB 260604C: SVOM/C-GFT upper limit
  20. EP260605a: EP-FXT follow-up observation
  21. GRB 260607A: TRT optical observations
  22. GRB 260604A: SVOM/GRM detection
  23. GRB 260604C: Mondy optical observations: evidence of a possible brightening
  24. GRB 260607B: Fermi GBM Observation
  25. GRB 260604C: Simeiz Zeiss-1000 optical observations of the afterglow
  26. GRB 260604C: OPD1.6m - GRANDMA observations - detection
  27. GRB 260604C: 6 GHz VLA observations
  28. GRB 260604C: SAO RAS optical observations
  29. GRB 260604B: SVOM/GRM detection
  30. EP260605a: Einstein Probe detection of a fast X-ray transient
  31. EP260603a: COLIBRÍ optical upper limit
  32. GRB 260604A: Glowbug gamma-ray detection
  33. GRB 260604C: LCO optical upper limit
  34. EP260602d: EP-FXT follow-up observation
  35. EP260602c: EP-FXT follow-up observation
  36. GRB 260601B / EP260601a: AstroSat CZTI detection
  37. GRB 260527A/EP260527a: 6 GHz VLA observations
  38. GRB 260604C: Kilonova-Catcher optical afterglow detection
  39. GRB 260604C: SVOM/COLIBRÍ (FM-GFT) optical observations
  40. GRB 260604C: Jinshan optical observations
  41. GRB 260604C: Fermi GBM Observation
  42. EP260602d: J-band upper limit with WINTER
  43. EP260602b: J-band upper limit with WINTER
  44. GRB 260604C: LAST detection of optical counterpart candidate
  45. Fermi GRB 260604C: Global MASTER-Net observations report
  46. Fermi GRB 260604C: Global MASTER-Net observations report
  47. SVOM GRB260604.85: Global MASTER-Net observations report
  48. GRB 260603A: Simeiz Zeiss-1000 optical upper limit
  49. GRB 260601A: CALET Gamma-Ray Burst Monitor detection
  50. EP260602a: EP-FXT follow-up observation
  51. EP260603a: Global MASTER-Net observations report
  52. EP260603a: Einstein Probe detection of a fast X-ray transient
  53. EP260602d: Optical Upper limits with kinder observations
  54. EP260602b: Liverpool Telescope observations
  55. EP260602a: Liverpool Telescope optical upper limits
  56. EP260602b: Liverpool Telescope and LCO observations
  57. EP260602a: GTC and Liverpool Telescope optical observations
  58. EP260601a/GRB 260601B: EP-FXT follow-up observation
  59. GRB 260601B / EP260601a: Mondy optical upper limit
  60. EP260602b: EP-FXT follow-up observation
  61. GRB 260601B/EP260601a: Glowbug gamma-ray detection
  62. GRB 260603A: Kilonova-Catcher optical upper limit
  63. GRB 260603A: SVOM/VT optical observations
  64. EP260602a: NOT NIR J-band observations
  65. GRB 260603A: SVOM/COLIBRÍ (FM-GFT) photometric redshift z = 3.57
  66. EP260602d: Einstein Probe detection of a fast X-ray transient
  67. Fermi trigger No 802141998: Global MASTER-Net observations report
  68. GRB 260601A: SVOM/GRM observation of a short burst
  69. EP260602c: Einstein Probe detection of a fast X-ray transient
  70. GRB 260603A: SVOM/COLIBRÍ (GFT-FM) optical counterpart candidate
  71. EP260602a: COLIBRÍ optical observations
  72. GRB260601B/EP260601a: NOT near-infrared observations
  73. SVOM GRB260603.23: Global MASTER-Net observations report
  74. GRB 260603A: SVOM detection of a burst
  75. EP260602b: Einstein Probe detection of a fast X-ray transient
  76. Fermi GRB 260602B: Global MASTER-Net observations report
  77. Fermi GRB 260602B: Global MASTER-Net observations report
  78. EP260530a: Xinglong optical spectroscopy of EP260530a / AT 2026nwl
  79. EP260602a: SVOM/VT optical candidate
  80. EP-WXT trigger 01709266414 (EP260602b): JinShan optical counterpart detection
  81. GRB 260601B/EP260601a: J-band upper limit with WINTER
  82. EP260530a/AT 2026nwl: COLIBRÍ optical follow up
  83. EP260530a/AT 2026nwl: KAIT optical observations
  84. GRB 260601B: CALET Gamma-Ray Burst Monitor detection
  85. EP260602a: Optical upper limits with Kinder observations
  86. GRB 260601B / EP260601a: NuSTAR detection of prompt emission
  87. EP260602a: Einstein Probe detection of a fast X-ray transient
  88. GRB 260601B/EP260601a: SVOM/VT optical observations
  89. GRB 260601B/EP260601a: GECAM-B analysis suggests a possible long duration Type I burst
  90. GRB 260601B: GECAM-B detection of a burst probably associated with EP260601a
  91. EP260601a: Einstein Probe detection of an X-ray transient
  92. EP-WXT trigger 01709266307 (EP260601a): COLIBRÍ optical observations
  93. EP-WXT trigger 01709266307 (EP260601a): JinShan optical counterpart detection
  94. GRB 260601A: Glowbug gamma-ray detection of a short burst
  95. GRB 260531B: Glowbug gamma-ray detection
  96. GRB 260601A: Fermi GBM Observation
  97. EP260530a/AT 2026nwl: COLIBRÍ optical observations
  98. GRB 260527A/EP260527a: Glowbug gamma-ray detection
  99. Fermi GRB 260601A: Global MASTER-Net observations report
  100. GRB 260601A: Fermi GBM Final Real-time Localization

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