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

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