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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. 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"
  1. GRB 260522B: Fermi GBM Final Real-time Localization
  2. GRB 260522A: GOTO optical upper limit
  3. Fermi trigger No 801135305: Global MASTER-Net observations report
  4. Fermi GRB 260522A: Global MASTER-Net observations report
  5. EP260518a: Einstein Probe detection of an sub-threshold X-ray transient with counterpart AT 2026ndp
  6. GRB 260522A: Fermi-LAT detection
  7. GRB 260519C: SVOM/GRM observation
  8. GRB 260522A: Fermi GBM Final Real-time Localization
  9. GRB 260511A: iTelescope T-75 optical detection
  10. GRB 260520B: SVOM/GRM observation
  11. GRB 260411B: TERI Gamma-ray detection
  12. GRB 260407A: TERI Gamma-ray detection
  13. GRB 260307A: TERI Gamma-ray detection
  14. GRB 260225D: TERI Gamma-ray detection
  15. GRB 251118A: TERI Gamma-ray detection
  16. GRB 251113A: TERI Gamma-ray detection
  17. GRB 260428A: TERI Gamma-ray detection
  18. Konus-Wind detection of GRB 260519C
  19. GRB 260520B: Fermi GBM Final Localization
  20. GRB 260509A: SVOM/ECLAIRs refined analysis
  21. GRB 260520A: Fermi GBM Final Localization
  22. GRB 260519D: Fermi GBM Final Localization Correction
  23. GRB 260519C: NuSTAR detection of prompt emission
  24. Konus-Wind detection of GRB 260518A
  25. GRB 260519B: Fermi GBM Final Localization
  26. GRB 260519A: Fermi GBM Final Localization
  27. GRB 260518A: AstroSat CZTI detection of a long burst
  28. GRB 260516D: SVOM/ECLAIRs refined analysis
  29. GRB 260515A: SVOM/ECLAIRs refined analysis
  30. GRB 260421B: radio detection with the VLA
  31. GRID detection of GRB 260511A
  32. GRB 260509A: CrAO ZTSh optical upper limit (Duplicate Submission)
  33. GRB 260509A: CrAO ZTSh optical upper limit
  34. GRB 260516D: EP-FXT follow-up observation
  35. GRB 260516D: GOTO optical counterpart detection
  36. GRB 260516D: LCO optical observations
  37. GRB 260515A: further Liverpool Telescope observations
  38. GRB 260516D: SVOM/COLIBRÍ (FM-GFT) optical observations
  39. GRB 260516D: GTC/OSIRIS+ spectroscopic redshift z = 1.801
  40. GRB 260516D: GROWTH-India Telescope optical detection
  41. GRB 260516D: SVOM/VT optical bright candidate
  42. GRB 260516D: FRAM-ORM optical limit
  43. GRB 260515A: CrAO ZTSh BVRI optical observations
  44. Fermi GRB 260516C: Global MASTER-Net observations report
  45. SVOM GRB260516D: Global MASTER-Net observations report
  46. GRB 260516D: SVOM possible detection of a burst
  47. GRB 260516C: Fermi GBM Final Real-time Localization
  48. Konus-Wind detection of GRB 260515A
  49. GRB 260515A: Liverpool Telescope optical detection
  50. GRB 260515A: LCO optical counterpart detection
  51. Fermi Gamma-ray Burst Monitor trigger 800627191/260516518 is not a GRB
  52. GRB 260515A: SVOM/COLIBRÍ (FM-GFT) optical observations
  53. GRB 260515A: EP-FXT follow-up observation
  54. EP260514a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  55. EP260514a: NOT optical counterpart confirmation
  56. EP260514a: TRT optical counterpart candidate
  57. EP260514a: SVOM/VT optical candidate
  58. Fermi GRB 260516B: Global MASTER-Net observations report
  59. GRB 260516B: Fermi GBM Final Real-time Localization
  60. Fermi Gamma-ray Burst Monitor trigger 800592653/260516119 is not a GRB
  61. GRB 260515A: SVOM/VT optical observations
  62. GRB 260515A: OHP/T193 optical observations
  63. EP260514a: COLIBRÍ optical upper limits
  64. GRB 260516A: Fermi GBM Final Real-time Localization
  65. GRID detection of GRB 260507A
  66. GRB 260515A: GTC/OSIRIS+ spectroscopic redshift z = 0.764
  67. GRB 260515A: LCO optical observations
  68. SVOM GRB 260515A: Global MASTER-Net observations report
  69. GRB 260515A: NOT optical observations.
  70. SVOM GRB 260515A: MASTER OT J151044.43+243321.7 optical counterpart detection
  71. GRB 260515A: SVOM/VT optical candidate from VHF data
  72. GRB 260515A: JinShan optical counterpart candidate
  73. GRB 260515A: SVOM detection of a burst
  74. GRB 260510C: Glowbug gamma-ray detection
  75. IceCube-260504A: No Candidate Transients from the Zwicky Transient Facility
  76. EP260514a: GROWTH-India Telescope optical upper limit
  77. GRB 260511B: NOT optical observations
  78. Konus-Wind detection of GRB 260512A
  79. GRB 260510C: CALET Gamma-Ray Burst Monitor detection
  80. GRB 260511B: GMG Optical Upper Limit
  81. EP260514a: Global MASTER-Net observations report
  82. EP260514a: Einstein Probe detection of a fast X-ray transient
  83. EP260512a: LCO optical upper limits
  84. IPN triangulation of GRB 260512A
  85. GRB 260511B: Mephisto multi-band optical followup
  86. Fermi GRB 260514A: Global MASTER-Net observations report
  87. GRB 260512A: AstroSat CZTI detection
  88. The EP-WXT trigger 01709262077 is likely a flaring star
  89. EP260512a: EP-FXT follow-up observation
  90. EP260507a: Xinglong Schmidt optical counterpart detection
  91. GRB 260514A: Fermi GBM Final Real-time Localization
  92. EP260512a: Global MASTER-Net observations report
  93. Fermi GRB 260513A: Global MASTER-Net observations report
  94. Fermi GRB 260512A: Global MASTER-Net observations report
  95. GRB 260511B: further SAO RAS optical observations
  96. GRB 260513A: Fermi GBM Final Real-time Localization
  97. GRB 260509A: SVOM/VT optical observations
  98. Konus-Wind detection of GRB 260511B
  99. The EP-WXT trigger 01709262036 is likely a flaring star
  100. EP260512a: COLIBRÍ optical upper limits

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