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

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