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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. EP260920a: NOT early time optical upper limits
  2. EP260920a: NOT optical upper limits
  3. GRB 260920A: Fermi GBM Final Real-time Localization
  4. EP260920a: SVOM/VT optical upper limits
  5. EP260917a: Global MASTER-Net observations report
  6. EP260920a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  7. EP260920a: COLIBRÍ optical upper limits
  8. EP260920a: Update of the LCO optical counterpart candidate
  9. EP260917b: EP-FXT non-detection and upper limit
  10. IceCube Alert 260919A: Global MASTER-Net observations report
  11. EP260920a: LCO optical counterpart candidate
  12. EP260920a: Einstein Probe detection of an X-ray transient
  13. EP Alert 260919.40: Global MASTER-Net observations report
  14. GRB 260915A: VLT optical and near-infrared upper limits
  15. EP260917a: refined analysis of the EP-FXT observations
  16. IceCube-260919A - IceCube observation of a high-energy neutrino candidate track-like event
  17. The EP-WXT trigger 01709318491 is likely a flaring star
  18. EP260806a: Yamaguchi Interferometer radio detections
  19. EP260917a: SVOM/VT optical upper limits
  20. GRB 260918A: SVOM/C-GFT optical upper limits
  21. EP Alert 260918.62: Global MASTER-Net observations report
  22. Fermi GBM Sub-Threshold Detection of GRB 260918A
  23. EP Alert 260918.24: Global MASTER-Net observations report
  24. SVOM GRB260918.16: Global MASTER-Net observations report
  25. Konus-Wind detection of GRB 260916B (short/hard)
  26. The EP-WXT trigger 01709318279 is likely a flaring star
  27. GRB 260918A: SVOM/VT optical upper limits
  28. GRB 260916B: Glowbug gamma-ray detection of a short burst
  29. GRB 260918A: EP-FXT follow-up observation
  30. GRB 260917B: Mondy optical upper limit
  31. IPN triangulation of GRB 260916B (short)
  32. EP260917b: EP-WXT detection of an X-ray transient
  33. EP260917A: J-band upper limit with WINTER
  34. IPN triangulation of GRB 260810A
  35. EP Alert 260917.32: Global MASTER-Net observations report
  36. GRB 260917B: EP-FXT follow-up observation
  37. EP260917a: COLIBRÍ optical upper limits
  38. GRB 260915A: Swift-XRT afterglow detection
  39. GRB 260918A: LCO optical upper limits
  40. EP260917a: Einstein Probe detection of an X-ray transient
  41. GRB 260918A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  42. GRB 260918A: SVOM detection of a burst
  43. GRB 260917C: Fermi GBM Final Real-time Localization
  44. GRB 260917B: FRAM-Auger optical limits
  45. GRB 260916B: Fermi GBM Detection
  46. IceCube-260916A: Upper limits from a search for additional neutrino events in IceCube
  47. GRB 260916B: Fermi GBM Final Localization
  48. GRB 260917A: Glowbug gamma-ray detection
  49. GRB 260915A: SVOM/ECLAIRs refined analysis
  50. GRB 260917B: WINTER J-band observations
  51. GRB 260917B: SVOM/VT optical observations
  52. SVOM GRB260917.16: Global MASTER-Net observations report
  53. GRB 260917B: LCO optical observation
  54. GRB 260917B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  55. GRB 260917B: SVOM detection of a faint burst
  56. GRB 260914A: 2.2m CAHA optical afterglow detection and 10.4m GTC redshift confirmation
  57. GRB 260917A: BALROG localization (Fermi Trigger 811304653 / GRB 260917100)
  58. GRB 260917A: Fermi GBM Final Real-time Localization
  59. Fermi trigger No 811304653: Global MASTER-Net observations report
  60. The EP-WXT trigger 01709317235 is likely a flaring star
  61. GRB 260915A: J-band upper limit with WINTER
  62. Fermi trigger No 811264269: Global MASTER-Net observations report
  63. IceCube-260916A - IceCube observation of a high-energy neutrino candidate track-like event
  64. GRB 260909A: NOEMA detection
  65. GRB 260914A: SVOM/GRM observation
  66. GRB 260914A: Mondy and TShAO optical observations
  67. GRB 260914A: SVOM/ECLAIRs refined analysis
  68. GRB 260909A: Swift-XRT observations
  69. GRB 260916A: MAXI/GSC detection
  70. MAXI GRB260916.37: Global MASTER-Net observations report
  71. GRB 260915A: Swift ToO observations
  72. GRB 260915A: J-band upper limit by SYSU 80cm infrared telescope
  73. GRB 260915A: SVOM/C-GFT optical upper limits
  74. GRB 260915A: EP-FXT follow-up observation
  75. GRB 260915A: SVOM/VT refined early optical upper limits
  76. GRB 260915A: EP-FXT follow-up observation
  77. GRB 260915A: REM optical/NIR observations
  78. GRB 260914A: REM optical/NIR observations
  79. GRB 260914A: VLT/X-shooter observations and redshift confirmation
  80. GRB 260915A: SVOM/VT optical upper limits
  81. GRB 260915A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  82. GRB 260914A: VLT/X-shooter spectroscopic redshift z = 0.778
  83. GRB 260915A: 10.4m GTC deep optical limits
  84. GRB 260915A: NOT optical upper limit
  85. SVOM GRB260915.05: Global MASTER-Net observations report
  86. GRB 260915A: SVOM/VT optical upper limits from VHF data
  87. Fermi GBM Sub-Threshold Detection of GRB 260915A
  88. GRB 260915A: LCO optical upper limits
  89. EP Alert 260914.53: Global MASTER-Net observations report
  90. GRB 260914A: EP-FXT follow-up observation
  91. GRB 260915A: SVOM detection of a burst
  92. Fermi GBM Sub-Threshold Detection of GRB 260914A
  93. GRB 260914A: LCO optical observation
  94. GRB 260914A: SVOM/C-GFT optical observations
  95. GRB 260914A: SVOM/VT optical counterpart confirmation
  96. GRB 260914A: SVOM/VT optical observation from VHF data
  97. GRB 260914A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  98. SVOM GRB260914.47: Global MASTER-Net observations report
  99. GRB 260914A: SVOM detection of a burst
  100. GRB 260913A: SVOM trigger sb26091302 is not an astrophysical event

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