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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: GOTO optical counterpart detection
  2. GRB 260516D: LCO optical observations
  3. GRB 260515A: further Liverpool Telescope observations
  4. GRB 260516D: SVOM/COLIBRÍ (FM-GFT) optical observations
  5. GRB 260516D: GTC/OSIRIS+ spectroscopic redshift z = 1.801
  6. GRB 260516D: GROWTH-India Telescope optical detection
  7. GRB 260516D: SVOM/VT optical bright candidate
  8. GRB 260516D: FRAM-ORM optical limit
  9. GRB 260515A: CrAO ZTSh BVRI optical observations
  10. Fermi GRB 260516C: Global MASTER-Net observations report
  11. SVOM GRB260516D: Global MASTER-Net observations report
  12. GRB 260516D: SVOM possible detection of a burst
  13. GRB 260516C: Fermi GBM Final Real-time Localization
  14. Konus-Wind detection of GRB 260515A
  15. GRB 260515A: Liverpool Telescope optical detection
  16. GRB 260515A: LCO optical counterpart detection
  17. Fermi Gamma-ray Burst Monitor trigger 800627191/260516518 is not a GRB
  18. GRB 260515A: SVOM/COLIBRÍ (FM-GFT) optical observations
  19. GRB 260515A: EP-FXT follow-up observation
  20. EP260514a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  21. EP260514a: NOT optical counterpart confirmation
  22. EP260514a: TRT optical counterpart candidate
  23. EP260514a: SVOM/VT optical candidate
  24. Fermi GRB 260516B: Global MASTER-Net observations report
  25. GRB 260516B: Fermi GBM Final Real-time Localization
  26. Fermi Gamma-ray Burst Monitor trigger 800592653/260516119 is not a GRB
  27. GRB 260515A: SVOM/VT optical observations
  28. GRB 260515A: OHP/T193 optical observations
  29. EP260514a: COLIBRÍ optical upper limits
  30. GRB 260516A: Fermi GBM Final Real-time Localization
  31. GRID detection of GRB 260507A
  32. GRB 260515A: GTC/OSIRIS+ spectroscopic redshift z = 0.764
  33. GRB 260515A: LCO optical observations
  34. SVOM GRB 260515A: Global MASTER-Net observations report
  35. GRB 260515A: NOT optical observations.
  36. SVOM GRB 260515A: MASTER OT J151044.43+243321.7 optical counterpart detection
  37. GRB 260515A: SVOM/VT optical candidate from VHF data
  38. GRB 260515A: JinShan optical counterpart candidate
  39. GRB 260515A: SVOM detection of a burst
  40. GRB 260510C: Glowbug gamma-ray detection
  41. IceCube-260504A: No Candidate Transients from the Zwicky Transient Facility
  42. EP260514a: GROWTH-India Telescope optical upper limit
  43. GRB 260511B: NOT optical observations
  44. Konus-Wind detection of GRB 260512A
  45. GRB 260510C: CALET Gamma-Ray Burst Monitor detection
  46. GRB 260511B: GMG Optical Upper Limit
  47. EP260514a: Global MASTER-Net observations report
  48. EP260514a: Einstein Probe detection of a fast X-ray transient
  49. EP260512a: LCO optical upper limits
  50. IPN triangulation of GRB 260512A
  51. GRB 260511B: Mephisto multi-band optical followup
  52. Fermi GRB 260514A: Global MASTER-Net observations report
  53. GRB 260512A: AstroSat CZTI detection
  54. The EP-WXT trigger 01709262077 is likely a flaring star
  55. EP260512a: EP-FXT follow-up observation
  56. EP260507a: Xinglong Schmidt optical counterpart detection
  57. GRB 260514A: Fermi GBM Final Real-time Localization
  58. EP260512a: Global MASTER-Net observations report
  59. Fermi GRB 260513A: Global MASTER-Net observations report
  60. Fermi GRB 260512A: Global MASTER-Net observations report
  61. GRB 260511B: further SAO RAS optical observations
  62. GRB 260513A: Fermi GBM Final Real-time Localization
  63. GRB 260509A: SVOM/VT optical observations
  64. Konus-Wind detection of GRB 260511B
  65. The EP-WXT trigger 01709262036 is likely a flaring star
  66. EP260512a: COLIBRÍ optical upper limits
  67. EP260512a: Einstein Probe detection of an X-ray transient
  68. GRB 260511B: further J-band observations by the SYSU 80 cm infrared telescope
  69. GRB 260511B: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  70. GRB 260512A: NuSTAR detection of prompt emission
  71. GRB 260509A: Infrared J and Hs observations with MDM/MIRAGE
  72. GRB 260510C: Infrared J and Hs detections with MDM/MIRAGE
  73. EP260507a: Infrared J and Hs upper limits with MDM/MIRAGE
  74. GRB 260512A: Fermi GBM Final Real-time Localization
  75. GRB 260511A: Glowbug gamma-ray detection
  76. Konus-Wind detection of GRB 260511A
  77. MASS-Cube (GRID 2.0) detection of GRB 260511A
  78. MASS-Cube (GRID 2.0) detection of GRB 260507A
  79. GRB 260511B: SAO RAS optical observations
  80. GRB 260510D: Glowbug gamma-ray detection of a likely short burst
  81. GRB 260511B: FRAM-ORM optical detection
  82. GRB 260511A: EP-FXT follow-up observation
  83. GRB 260511B: EP-FXT follow-up observation
  84. GRB 260511B: LCO optical counterpart detection
  85. GRB260511B: MAO/AZT-22 optical observations
  86. GRB 260511A: SVOM/VT optical observations
  87. GRB 260511B: LCO optical observations
  88. GRB 260511B: OHP/T193 spectroscopic observations
  89. GRB 260511B: GOTO optical counterpart detection
  90. GRB 260511B: Xinglong 2.16m/BEFOSC redshift confirmation
  91. GRB 260510C: SVOM/COLIBRÍ (FM-GFT) further optical observations
  92. GRB 260510A: AstroSat CZTI detection (Erroneous Submission)
  93. GRB 260511B: SVOM/VT optical observations
  94. GRB 260511B: SVOM/COLIBRÍ (FM-GFT) optical observations
  95. GRB 260510B: EP-FXT follow-up observation
  96. GRB 260511B: OSIRIS+/GTC redshift z=2.006
  97. GRB 260510C: Fermi GBM Observation
  98. GRB 260509A: SAO RAS optical observations
  99. GRB 260511A: REM near-infrared detection
  100. GRB 260511B: GROWTH-India Telescope optical observations

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