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

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