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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 260509A: SVOM/ECLAIRs refined analysis
  2. GRB 260520A: Fermi GBM Final Localization
  3. GRB 260519D: Fermi GBM Final Localization Correction
  4. GRB 260519C: NuSTAR detection of prompt emission
  5. Konus-Wind detection of GRB 260518A
  6. GRB 260519B: Fermi GBM Final Localization
  7. GRB 260519A: Fermi GBM Final Localization
  8. GRB 260518A: AstroSat CZTI detection of a long burst
  9. GRB 260516D: SVOM/ECLAIRs refined analysis
  10. GRB 260515A: SVOM/ECLAIRs refined analysis
  11. GRB 260421B: radio detection with the VLA
  12. GRID detection of GRB 260511A
  13. GRB 260509A: CrAO ZTSh optical upper limit (Duplicate Submission)
  14. GRB 260509A: CrAO ZTSh optical upper limit
  15. GRB 260516D: EP-FXT follow-up observation
  16. GRB 260516D: GOTO optical counterpart detection
  17. GRB 260516D: LCO optical observations
  18. GRB 260515A: further Liverpool Telescope observations
  19. GRB 260516D: SVOM/COLIBRÍ (FM-GFT) optical observations
  20. GRB 260516D: GTC/OSIRIS+ spectroscopic redshift z = 1.801
  21. GRB 260516D: GROWTH-India Telescope optical detection
  22. GRB 260516D: SVOM/VT optical bright candidate
  23. GRB 260516D: FRAM-ORM optical limit
  24. GRB 260515A: CrAO ZTSh BVRI optical observations
  25. Fermi GRB 260516C: Global MASTER-Net observations report
  26. SVOM GRB260516D: Global MASTER-Net observations report
  27. GRB 260516D: SVOM possible detection of a burst
  28. GRB 260516C: Fermi GBM Final Real-time Localization
  29. Konus-Wind detection of GRB 260515A
  30. GRB 260515A: Liverpool Telescope optical detection
  31. GRB 260515A: LCO optical counterpart detection
  32. Fermi Gamma-ray Burst Monitor trigger 800627191/260516518 is not a GRB
  33. GRB 260515A: SVOM/COLIBRÍ (FM-GFT) optical observations
  34. GRB 260515A: EP-FXT follow-up observation
  35. EP260514a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  36. EP260514a: NOT optical counterpart confirmation
  37. EP260514a: TRT optical counterpart candidate
  38. EP260514a: SVOM/VT optical candidate
  39. Fermi GRB 260516B: Global MASTER-Net observations report
  40. GRB 260516B: Fermi GBM Final Real-time Localization
  41. Fermi Gamma-ray Burst Monitor trigger 800592653/260516119 is not a GRB
  42. GRB 260515A: SVOM/VT optical observations
  43. GRB 260515A: OHP/T193 optical observations
  44. EP260514a: COLIBRÍ optical upper limits
  45. GRB 260516A: Fermi GBM Final Real-time Localization
  46. GRID detection of GRB 260507A
  47. GRB 260515A: GTC/OSIRIS+ spectroscopic redshift z = 0.764
  48. GRB 260515A: LCO optical observations
  49. SVOM GRB 260515A: Global MASTER-Net observations report
  50. GRB 260515A: NOT optical observations.
  51. SVOM GRB 260515A: MASTER OT J151044.43+243321.7 optical counterpart detection
  52. GRB 260515A: SVOM/VT optical candidate from VHF data
  53. GRB 260515A: JinShan optical counterpart candidate
  54. GRB 260515A: SVOM detection of a burst
  55. GRB 260510C: Glowbug gamma-ray detection
  56. IceCube-260504A: No Candidate Transients from the Zwicky Transient Facility
  57. EP260514a: GROWTH-India Telescope optical upper limit
  58. GRB 260511B: NOT optical observations
  59. Konus-Wind detection of GRB 260512A
  60. GRB 260510C: CALET Gamma-Ray Burst Monitor detection
  61. GRB 260511B: GMG Optical Upper Limit
  62. EP260514a: Global MASTER-Net observations report
  63. EP260514a: Einstein Probe detection of a fast X-ray transient
  64. EP260512a: LCO optical upper limits
  65. IPN triangulation of GRB 260512A
  66. GRB 260511B: Mephisto multi-band optical followup
  67. Fermi GRB 260514A: Global MASTER-Net observations report
  68. GRB 260512A: AstroSat CZTI detection
  69. The EP-WXT trigger 01709262077 is likely a flaring star
  70. EP260512a: EP-FXT follow-up observation
  71. EP260507a: Xinglong Schmidt optical counterpart detection
  72. GRB 260514A: Fermi GBM Final Real-time Localization
  73. EP260512a: Global MASTER-Net observations report
  74. Fermi GRB 260513A: Global MASTER-Net observations report
  75. Fermi GRB 260512A: Global MASTER-Net observations report
  76. GRB 260511B: further SAO RAS optical observations
  77. GRB 260513A: Fermi GBM Final Real-time Localization
  78. GRB 260509A: SVOM/VT optical observations
  79. Konus-Wind detection of GRB 260511B
  80. The EP-WXT trigger 01709262036 is likely a flaring star
  81. EP260512a: COLIBRÍ optical upper limits
  82. EP260512a: Einstein Probe detection of an X-ray transient
  83. GRB 260511B: further J-band observations by the SYSU 80 cm infrared telescope
  84. GRB 260511B: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  85. GRB 260512A: NuSTAR detection of prompt emission
  86. GRB 260509A: Infrared J and Hs observations with MDM/MIRAGE
  87. GRB 260510C: Infrared J and Hs detections with MDM/MIRAGE
  88. EP260507a: Infrared J and Hs upper limits with MDM/MIRAGE
  89. GRB 260512A: Fermi GBM Final Real-time Localization
  90. GRB 260511A: Glowbug gamma-ray detection
  91. Konus-Wind detection of GRB 260511A
  92. MASS-Cube (GRID 2.0) detection of GRB 260511A
  93. MASS-Cube (GRID 2.0) detection of GRB 260507A
  94. GRB 260511B: SAO RAS optical observations
  95. GRB 260510D: Glowbug gamma-ray detection of a likely short burst
  96. GRB 260511B: FRAM-ORM optical detection
  97. GRB 260511A: EP-FXT follow-up observation
  98. GRB 260511B: EP-FXT follow-up observation
  99. GRB 260511B: LCO optical counterpart detection
  100. GRB260511B: MAO/AZT-22 optical observations

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