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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 260428A: TERI Gamma-ray detection
  2. Konus-Wind detection of GRB 260519C
  3. GRB 260520B: Fermi GBM Final Localization
  4. GRB 260509A: SVOM/ECLAIRs refined analysis
  5. GRB 260520A: Fermi GBM Final Localization
  6. GRB 260519D: Fermi GBM Final Localization Correction
  7. GRB 260519C: NuSTAR detection of prompt emission
  8. Konus-Wind detection of GRB 260518A
  9. GRB 260519B: Fermi GBM Final Localization
  10. GRB 260519A: Fermi GBM Final Localization
  11. GRB 260518A: AstroSat CZTI detection of a long burst
  12. GRB 260516D: SVOM/ECLAIRs refined analysis
  13. GRB 260515A: SVOM/ECLAIRs refined analysis
  14. GRB 260421B: radio detection with the VLA
  15. GRID detection of GRB 260511A
  16. GRB 260509A: CrAO ZTSh optical upper limit (Duplicate Submission)
  17. GRB 260509A: CrAO ZTSh optical upper limit
  18. GRB 260516D: EP-FXT follow-up observation
  19. GRB 260516D: GOTO optical counterpart detection
  20. GRB 260516D: LCO optical observations
  21. GRB 260515A: further Liverpool Telescope observations
  22. GRB 260516D: SVOM/COLIBRÍ (FM-GFT) optical observations
  23. GRB 260516D: GTC/OSIRIS+ spectroscopic redshift z = 1.801
  24. GRB 260516D: GROWTH-India Telescope optical detection
  25. GRB 260516D: SVOM/VT optical bright candidate
  26. GRB 260516D: FRAM-ORM optical limit
  27. GRB 260515A: CrAO ZTSh BVRI optical observations
  28. Fermi GRB 260516C: Global MASTER-Net observations report
  29. SVOM GRB260516D: Global MASTER-Net observations report
  30. GRB 260516D: SVOM possible detection of a burst
  31. GRB 260516C: Fermi GBM Final Real-time Localization
  32. Konus-Wind detection of GRB 260515A
  33. GRB 260515A: Liverpool Telescope optical detection
  34. GRB 260515A: LCO optical counterpart detection
  35. Fermi Gamma-ray Burst Monitor trigger 800627191/260516518 is not a GRB
  36. GRB 260515A: SVOM/COLIBRÍ (FM-GFT) optical observations
  37. GRB 260515A: EP-FXT follow-up observation
  38. EP260514a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  39. EP260514a: NOT optical counterpart confirmation
  40. EP260514a: TRT optical counterpart candidate
  41. EP260514a: SVOM/VT optical candidate
  42. Fermi GRB 260516B: Global MASTER-Net observations report
  43. GRB 260516B: Fermi GBM Final Real-time Localization
  44. Fermi Gamma-ray Burst Monitor trigger 800592653/260516119 is not a GRB
  45. GRB 260515A: SVOM/VT optical observations
  46. GRB 260515A: OHP/T193 optical observations
  47. EP260514a: COLIBRÍ optical upper limits
  48. GRB 260516A: Fermi GBM Final Real-time Localization
  49. GRID detection of GRB 260507A
  50. GRB 260515A: GTC/OSIRIS+ spectroscopic redshift z = 0.764
  51. GRB 260515A: LCO optical observations
  52. SVOM GRB 260515A: Global MASTER-Net observations report
  53. GRB 260515A: NOT optical observations.
  54. SVOM GRB 260515A: MASTER OT J151044.43+243321.7 optical counterpart detection
  55. GRB 260515A: SVOM/VT optical candidate from VHF data
  56. GRB 260515A: JinShan optical counterpart candidate
  57. GRB 260515A: SVOM detection of a burst
  58. GRB 260510C: Glowbug gamma-ray detection
  59. IceCube-260504A: No Candidate Transients from the Zwicky Transient Facility
  60. EP260514a: GROWTH-India Telescope optical upper limit
  61. GRB 260511B: NOT optical observations
  62. Konus-Wind detection of GRB 260512A
  63. GRB 260510C: CALET Gamma-Ray Burst Monitor detection
  64. GRB 260511B: GMG Optical Upper Limit
  65. EP260514a: Global MASTER-Net observations report
  66. EP260514a: Einstein Probe detection of a fast X-ray transient
  67. EP260512a: LCO optical upper limits
  68. IPN triangulation of GRB 260512A
  69. GRB 260511B: Mephisto multi-band optical followup
  70. Fermi GRB 260514A: Global MASTER-Net observations report
  71. GRB 260512A: AstroSat CZTI detection
  72. The EP-WXT trigger 01709262077 is likely a flaring star
  73. EP260512a: EP-FXT follow-up observation
  74. EP260507a: Xinglong Schmidt optical counterpart detection
  75. GRB 260514A: Fermi GBM Final Real-time Localization
  76. EP260512a: Global MASTER-Net observations report
  77. Fermi GRB 260513A: Global MASTER-Net observations report
  78. Fermi GRB 260512A: Global MASTER-Net observations report
  79. GRB 260511B: further SAO RAS optical observations
  80. GRB 260513A: Fermi GBM Final Real-time Localization
  81. GRB 260509A: SVOM/VT optical observations
  82. Konus-Wind detection of GRB 260511B
  83. The EP-WXT trigger 01709262036 is likely a flaring star
  84. EP260512a: COLIBRÍ optical upper limits
  85. EP260512a: Einstein Probe detection of an X-ray transient
  86. GRB 260511B: further J-band observations by the SYSU 80 cm infrared telescope
  87. GRB 260511B: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  88. GRB 260512A: NuSTAR detection of prompt emission
  89. GRB 260509A: Infrared J and Hs observations with MDM/MIRAGE
  90. GRB 260510C: Infrared J and Hs detections with MDM/MIRAGE
  91. EP260507a: Infrared J and Hs upper limits with MDM/MIRAGE
  92. GRB 260512A: Fermi GBM Final Real-time Localization
  93. GRB 260511A: Glowbug gamma-ray detection
  94. Konus-Wind detection of GRB 260511A
  95. MASS-Cube (GRID 2.0) detection of GRB 260511A
  96. MASS-Cube (GRID 2.0) detection of GRB 260507A
  97. GRB 260511B: SAO RAS optical observations
  98. GRB 260510D: Glowbug gamma-ray detection of a likely short burst
  99. GRB 260511B: FRAM-ORM optical detection
  100. GRB 260511A: EP-FXT follow-up observation

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