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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"

28126 results found.

  1. EP260602a: COLIBRÍ optical observations
  2. GRB260601B/EP260601a: NOT near-infrared observations
  3. SVOM GRB260603.23: Global MASTER-Net observations report
  4. GRB 260603A: SVOM detection of a burst
  5. EP260602b: Einstein Probe detection of a fast X-ray transient
  6. Fermi GRB 260602B: Global MASTER-Net observations report
  7. Fermi GRB 260602B: Global MASTER-Net observations report
  8. EP260530a: Xinglong optical spectroscopy of EP260530a / AT 2026nwl
  9. EP260602a: SVOM/VT optical candidate
  10. EP-WXT trigger 01709266414 (EP260602b): JinShan optical counterpart detection
  11. GRB 260601B/EP260601a: J-band upper limit with WINTER
  12. EP260530a/AT 2026nwl: COLIBRÍ optical follow up
  13. EP260530a/AT 2026nwl: KAIT optical observations
  14. GRB 260601B: CALET Gamma-Ray Burst Monitor detection
  15. EP260602a: Optical upper limits with Kinder observations
  16. GRB 260601B / EP260601a: NuSTAR detection of prompt emission
  17. EP260602a: Einstein Probe detection of a fast X-ray transient
  18. GRB 260601B/EP260601a: SVOM/VT optical observations
  19. GRB 260601B/EP260601a: GECAM-B analysis suggests a possible long duration Type I burst
  20. GRB 260601B: GECAM-B detection of a burst probably associated with EP260601a
  21. EP260601a: Einstein Probe detection of an X-ray transient
  22. EP-WXT trigger 01709266307 (EP260601a): COLIBRÍ optical observations
  23. EP-WXT trigger 01709266307 (EP260601a): JinShan optical counterpart detection
  24. GRB 260601A: Glowbug gamma-ray detection of a short burst
  25. GRB 260531B: Glowbug gamma-ray detection
  26. GRB 260601A: Fermi GBM Observation
  27. EP260530a/AT 2026nwl: COLIBRÍ optical observations
  28. GRB 260527A/EP260527a: Glowbug gamma-ray detection
  29. Fermi GRB 260601A: Global MASTER-Net observations report
  30. GRB 260601A: Fermi GBM Final Real-time Localization
  31. The EP-WXT trigger 01709266272 is likely a flaring star
  32. AT2026nik: EP-FXT X-ray counterpart
  33. Fermi trigger No 801900520: Global MASTER-Net observations report
  34. GRB 260531A: MAXI/GSC detection
  35. AT 2026nuz: COLIBRÍ optical observations
  36. EP260527a/GRB 260527A: optical upper limit with Kinder observations
  37. GRB 260429B / EP260429a: COLIBRÍ optical counterpart candidate
  38. GRB 260527A/EP260527a: VLT/X-shooter tentative redshift
  39. Fermi GRB 260529A: Global MASTER-Net observations report
  40. EP260526a: SVOM/VT optical upper limits
  41. EP260527a / GRB 260527A: VLT detection of the optical and nIR counterpart
  42. EP260527a/GRB 260527A: Infrared J upper limit with MDM/MIRAGE
  43. EP260527a/GRB 260527A: EP-FXT follow-up observation
  44. GRB 260527A: GECAM-B detection of a short burst probably associated with EP260527a
  45. EP260527a: SVOM/VT optical observation
  46. EP260527a: COLIBRÍ optical detection
  47. EP260527a: Einstein Probe detection of a fast X-ray transient
  48. Fermi trigger No 801580882: Global MASTER-Net observations report
  49. EP260526a: LCO optical upper limits
  50. EP260526a: Einstein Probe detection of a fast X-ray transient
  51. EP260526.405: COLIBRÍ optical upper limits
  52. The EP-WXT trigger 01709266106 is not a real source
  53. Fermi GRB 260526A: Global MASTER-Net observations report
  54. EP01709266106 (EP260526a?): Liverpool Telescope upper limits
  55. EP-WXT 01709266106: NOT optical upper limits
  56. Fermi GRB 260525A: Global MASTER-Net observations report
  57. GRB 260523B: AstroSat CZTI detection
  58. Fermi GRB 260523A: Global MASTER-Net observations report
  59. GRB 260522A: Fermi GBM Observation
  60. GRB 260522B: NuSTAR detection of prompt emission
  61. EP260518a (AT2026ndp): LCO observations and Gemini-South Redshift z = 2.28
  62. Fermi trigger No 801135305: Global MASTER-Net observations report
  63. Fermi GRB 260522A: Global MASTER-Net observations report
  64. EP260518a: Einstein Probe detection of an sub-threshold X-ray transient with counterpart AT 2026ndp
  65. GRB 260511A: iTelescope T-75 optical detection
  66. GRB 260520B: SVOM/GRM observation
  67. GRB 260411B: TERI Gamma-ray detection
  68. GRB 260407A: TERI Gamma-ray detection
  69. GRB 260307A: TERI Gamma-ray detection
  70. GRB 260225D: TERI Gamma-ray detection
  71. GRB 251118A: TERI Gamma-ray detection
  72. GRB 251113A: TERI Gamma-ray detection
  73. GRB 260428A: TERI Gamma-ray detection
  74. GRB 260519C: NuSTAR detection of prompt emission
  75. Konus-Wind detection of GRB 260518A
  76. GRB 260516D: SVOM/ECLAIRs refined analysis
  77. GRB 260421B: radio detection with the VLA
  78. GRB 260509A: CrAO ZTSh optical upper limit
  79. GRB 260516D: GOTO optical counterpart detection
  80. GRB 260516D: LCO optical observations
  81. GRB 260515A: further Liverpool Telescope observations
  82. GRB 260516D: SVOM/COLIBRÍ (FM-GFT) optical observations
  83. GRB 260516D: GROWTH-India Telescope optical detection
  84. GRB 260516D: SVOM/VT optical bright candidate
  85. GRB 260515A: CrAO ZTSh BVRI optical observations
  86. Fermi GRB 260516C: Global MASTER-Net observations report
  87. SVOM GRB260516D: Global MASTER-Net observations report
  88. GRB 260516D: SVOM possible detection of a burst
  89. GRB 260515A: LCO optical counterpart detection
  90. GRB 260515A: SVOM/COLIBRÍ (FM-GFT) optical observations
  91. EP260514a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  92. EP260514a: NOT optical counterpart confirmation
  93. EP260514a: TRT optical counterpart candidate
  94. EP260514a: SVOM/VT optical candidate
  95. Fermi GRB 260516B: Global MASTER-Net observations report
  96. GRB 260515A: OHP/T193 optical observations
  97. EP260514a: COLIBRÍ optical upper limits
  98. GRB 260515A: LCO optical observations
  99. SVOM GRB 260515A: Global MASTER-Net observations report
  100. SVOM GRB 260515A: MASTER OT J151044.43+243321.7 optical counterpart detection

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