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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. Konus-Wind detection of GRB 260518A
  2. GRB 260519B: Fermi GBM Final Localization
  3. GRB 260519A: Fermi GBM Final Localization
  4. GRB 260518A: AstroSat CZTI detection of a long burst
  5. GRB 260516D: SVOM/ECLAIRs refined analysis
  6. GRB 260515A: SVOM/ECLAIRs refined analysis
  7. GRB 260421B: radio detection with the VLA
  8. GRID detection of GRB 260511A
  9. GRB 260509A: CrAO ZTSh optical upper limit (Duplicate Submission)
  10. GRB 260509A: CrAO ZTSh optical upper limit
  11. GRB 260516D: EP-FXT follow-up observation
  12. GRB 260516D: GOTO optical counterpart detection
  13. GRB 260516D: LCO optical observations
  14. GRB 260515A: further Liverpool Telescope observations
  15. GRB 260516D: SVOM/COLIBRÍ (FM-GFT) optical observations
  16. GRB 260516D: GTC/OSIRIS+ spectroscopic redshift z = 1.801
  17. GRB 260516D: GROWTH-India Telescope optical detection
  18. GRB 260516D: SVOM/VT optical bright candidate
  19. GRB 260516D: FRAM-ORM optical limit
  20. GRB 260515A: CrAO ZTSh BVRI optical observations
  21. Fermi GRB 260516C: Global MASTER-Net observations report
  22. SVOM GRB260516D: Global MASTER-Net observations report
  23. GRB 260516D: SVOM possible detection of a burst
  24. GRB 260516C: Fermi GBM Final Real-time Localization
  25. Konus-Wind detection of GRB 260515A
  26. GRB 260515A: Liverpool Telescope optical detection
  27. GRB 260515A: LCO optical counterpart detection
  28. Fermi Gamma-ray Burst Monitor trigger 800627191/260516518 is not a GRB
  29. GRB 260515A: SVOM/COLIBRÍ (FM-GFT) optical observations
  30. GRB 260515A: EP-FXT follow-up observation
  31. EP260514a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  32. EP260514a: NOT optical counterpart confirmation
  33. EP260514a: TRT optical counterpart candidate
  34. EP260514a: SVOM/VT optical candidate
  35. Fermi GRB 260516B: Global MASTER-Net observations report
  36. GRB 260516B: Fermi GBM Final Real-time Localization
  37. Fermi Gamma-ray Burst Monitor trigger 800592653/260516119 is not a GRB
  38. GRB 260515A: SVOM/VT optical observations
  39. GRB 260515A: OHP/T193 optical observations
  40. EP260514a: COLIBRÍ optical upper limits
  41. GRB 260516A: Fermi GBM Final Real-time Localization
  42. GRID detection of GRB 260507A
  43. GRB 260515A: GTC/OSIRIS+ spectroscopic redshift z = 0.764
  44. GRB 260515A: LCO optical observations
  45. SVOM GRB 260515A: Global MASTER-Net observations report
  46. GRB 260515A: NOT optical observations.
  47. SVOM GRB 260515A: MASTER OT J151044.43+243321.7 optical counterpart detection
  48. GRB 260515A: SVOM/VT optical candidate from VHF data
  49. GRB 260515A: JinShan optical counterpart candidate
  50. GRB 260515A: SVOM detection of a burst
  51. GRB 260510C: Glowbug gamma-ray detection
  52. IceCube-260504A: No Candidate Transients from the Zwicky Transient Facility
  53. EP260514a: GROWTH-India Telescope optical upper limit
  54. GRB 260511B: NOT optical observations
  55. Konus-Wind detection of GRB 260512A
  56. GRB 260510C: CALET Gamma-Ray Burst Monitor detection
  57. GRB 260511B: GMG Optical Upper Limit
  58. EP260514a: Global MASTER-Net observations report
  59. EP260514a: Einstein Probe detection of a fast X-ray transient
  60. EP260512a: LCO optical upper limits
  61. IPN triangulation of GRB 260512A
  62. GRB 260511B: Mephisto multi-band optical followup
  63. Fermi GRB 260514A: Global MASTER-Net observations report
  64. GRB 260512A: AstroSat CZTI detection
  65. The EP-WXT trigger 01709262077 is likely a flaring star
  66. EP260512a: EP-FXT follow-up observation
  67. EP260507a: Xinglong Schmidt optical counterpart detection
  68. GRB 260514A: Fermi GBM Final Real-time Localization
  69. EP260512a: Global MASTER-Net observations report
  70. Fermi GRB 260513A: Global MASTER-Net observations report
  71. Fermi GRB 260512A: Global MASTER-Net observations report
  72. GRB 260511B: further SAO RAS optical observations
  73. GRB 260513A: Fermi GBM Final Real-time Localization
  74. GRB 260509A: SVOM/VT optical observations
  75. Konus-Wind detection of GRB 260511B
  76. The EP-WXT trigger 01709262036 is likely a flaring star
  77. EP260512a: COLIBRÍ optical upper limits
  78. EP260512a: Einstein Probe detection of an X-ray transient
  79. GRB 260511B: further J-band observations by the SYSU 80 cm infrared telescope
  80. GRB 260511B: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  81. GRB 260512A: NuSTAR detection of prompt emission
  82. GRB 260509A: Infrared J and Hs observations with MDM/MIRAGE
  83. GRB 260510C: Infrared J and Hs detections with MDM/MIRAGE
  84. EP260507a: Infrared J and Hs upper limits with MDM/MIRAGE
  85. GRB 260512A: Fermi GBM Final Real-time Localization
  86. GRB 260511A: Glowbug gamma-ray detection
  87. Konus-Wind detection of GRB 260511A
  88. MASS-Cube (GRID 2.0) detection of GRB 260511A
  89. MASS-Cube (GRID 2.0) detection of GRB 260507A
  90. GRB 260511B: SAO RAS optical observations
  91. GRB 260510D: Glowbug gamma-ray detection of a likely short burst
  92. GRB 260511B: FRAM-ORM optical detection
  93. GRB 260511A: EP-FXT follow-up observation
  94. GRB 260511B: EP-FXT follow-up observation
  95. GRB 260511B: LCO optical counterpart detection
  96. GRB260511B: MAO/AZT-22 optical observations
  97. GRB 260511A: SVOM/VT optical observations
  98. GRB 260511B: LCO optical observations
  99. GRB 260511B: OHP/T193 spectroscopic observations
  100. GRB 260511B: GOTO optical counterpart detection

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