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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 260516D: SVOM/ECLAIRs refined analysis
  2. GRB 260515A: SVOM/ECLAIRs refined analysis
  3. GRB 260421B: radio detection with the VLA
  4. GRID detection of GRB 260511A
  5. GRB 260509A: CrAO ZTSh optical upper limit (Duplicate Submission)
  6. GRB 260509A: CrAO ZTSh optical upper limit
  7. GRB 260516D: EP-FXT follow-up observation
  8. GRB 260516D: GOTO optical counterpart detection
  9. GRB 260516D: LCO optical observations
  10. GRB 260515A: further Liverpool Telescope observations
  11. GRB 260516D: SVOM/COLIBRÍ (FM-GFT) optical observations
  12. GRB 260516D: GTC/OSIRIS+ spectroscopic redshift z = 1.801
  13. GRB 260516D: GROWTH-India Telescope optical detection
  14. GRB 260516D: SVOM/VT optical bright candidate
  15. GRB 260516D: FRAM-ORM optical limit
  16. GRB 260515A: CrAO ZTSh BVRI optical observations
  17. Fermi GRB 260516C: Global MASTER-Net observations report
  18. SVOM GRB260516D: Global MASTER-Net observations report
  19. GRB 260516D: SVOM possible detection of a burst
  20. GRB 260516C: Fermi GBM Final Real-time Localization
  21. Konus-Wind detection of GRB 260515A
  22. GRB 260515A: Liverpool Telescope optical detection
  23. GRB 260515A: LCO optical counterpart detection
  24. Fermi Gamma-ray Burst Monitor trigger 800627191/260516518 is not a GRB
  25. GRB 260515A: SVOM/COLIBRÍ (FM-GFT) optical observations
  26. GRB 260515A: EP-FXT follow-up observation
  27. EP260514a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  28. EP260514a: NOT optical counterpart confirmation
  29. EP260514a: TRT optical counterpart candidate
  30. EP260514a: SVOM/VT optical candidate
  31. Fermi GRB 260516B: Global MASTER-Net observations report
  32. GRB 260516B: Fermi GBM Final Real-time Localization
  33. Fermi Gamma-ray Burst Monitor trigger 800592653/260516119 is not a GRB
  34. GRB 260515A: SVOM/VT optical observations
  35. GRB 260515A: OHP/T193 optical observations
  36. EP260514a: COLIBRÍ optical upper limits
  37. GRB 260516A: Fermi GBM Final Real-time Localization
  38. GRID detection of GRB 260507A
  39. GRB 260515A: GTC/OSIRIS+ spectroscopic redshift z = 0.764
  40. GRB 260515A: LCO optical observations
  41. SVOM GRB 260515A: Global MASTER-Net observations report
  42. GRB 260515A: NOT optical observations.
  43. SVOM GRB 260515A: MASTER OT J151044.43+243321.7 optical counterpart detection
  44. GRB 260515A: SVOM/VT optical candidate from VHF data
  45. GRB 260515A: JinShan optical counterpart candidate
  46. GRB 260515A: SVOM detection of a burst
  47. GRB 260510C: Glowbug gamma-ray detection
  48. IceCube-260504A: No Candidate Transients from the Zwicky Transient Facility
  49. EP260514a: GROWTH-India Telescope optical upper limit
  50. GRB 260511B: NOT optical observations
  51. Konus-Wind detection of GRB 260512A
  52. GRB 260510C: CALET Gamma-Ray Burst Monitor detection
  53. GRB 260511B: GMG Optical Upper Limit
  54. EP260514a: Global MASTER-Net observations report
  55. EP260514a: Einstein Probe detection of a fast X-ray transient
  56. EP260512a: LCO optical upper limits
  57. IPN triangulation of GRB 260512A
  58. GRB 260511B: Mephisto multi-band optical followup
  59. Fermi GRB 260514A: Global MASTER-Net observations report
  60. GRB 260512A: AstroSat CZTI detection
  61. The EP-WXT trigger 01709262077 is likely a flaring star
  62. EP260512a: EP-FXT follow-up observation
  63. EP260507a: Xinglong Schmidt optical counterpart detection
  64. GRB 260514A: Fermi GBM Final Real-time Localization
  65. EP260512a: Global MASTER-Net observations report
  66. Fermi GRB 260513A: Global MASTER-Net observations report
  67. Fermi GRB 260512A: Global MASTER-Net observations report
  68. GRB 260511B: further SAO RAS optical observations
  69. GRB 260513A: Fermi GBM Final Real-time Localization
  70. GRB 260509A: SVOM/VT optical observations
  71. Konus-Wind detection of GRB 260511B
  72. The EP-WXT trigger 01709262036 is likely a flaring star
  73. EP260512a: COLIBRÍ optical upper limits
  74. EP260512a: Einstein Probe detection of an X-ray transient
  75. GRB 260511B: further J-band observations by the SYSU 80 cm infrared telescope
  76. GRB 260511B: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  77. GRB 260512A: NuSTAR detection of prompt emission
  78. GRB 260509A: Infrared J and Hs observations with MDM/MIRAGE
  79. GRB 260510C: Infrared J and Hs detections with MDM/MIRAGE
  80. EP260507a: Infrared J and Hs upper limits with MDM/MIRAGE
  81. GRB 260512A: Fermi GBM Final Real-time Localization
  82. GRB 260511A: Glowbug gamma-ray detection
  83. Konus-Wind detection of GRB 260511A
  84. MASS-Cube (GRID 2.0) detection of GRB 260511A
  85. MASS-Cube (GRID 2.0) detection of GRB 260507A
  86. GRB 260511B: SAO RAS optical observations
  87. GRB 260510D: Glowbug gamma-ray detection of a likely short burst
  88. GRB 260511B: FRAM-ORM optical detection
  89. GRB 260511A: EP-FXT follow-up observation
  90. GRB 260511B: EP-FXT follow-up observation
  91. GRB 260511B: LCO optical counterpart detection
  92. GRB260511B: MAO/AZT-22 optical observations
  93. GRB 260511A: SVOM/VT optical observations
  94. GRB 260511B: LCO optical observations
  95. GRB 260511B: OHP/T193 spectroscopic observations
  96. GRB 260511B: GOTO optical counterpart detection
  97. GRB 260511B: Xinglong 2.16m/BEFOSC redshift confirmation
  98. GRB 260510C: SVOM/COLIBRÍ (FM-GFT) further optical observations
  99. GRB 260510A: AstroSat CZTI detection (Erroneous Submission)
  100. GRB 260511B: SVOM/VT optical observations

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