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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"

45423 results found.

  1. The EP-WXT trigger 01709318601 is likely a flaring star
  2. EP Alert 260921.01: Global MASTER-Net observations report
  3. EP260920b: Global MASTER-Net observations report
  4. EP260920b: Einstein Probe detection of an X-ray transient
  5. IceCube-260919A: Upper limits from a search for additional neutrino events in IceCube
  6. EP Alert 260920.66: Global MASTER-Net observations report
  7. EP-WXT detected a brightening of HMXB LS V +44 17
  8. EP260920a: NOT early time optical upper limits
  9. EP260920a: NOT optical upper limits
  10. GRB 260920A: Fermi GBM Final Real-time Localization
  11. EP260920a: SVOM/VT optical upper limits
  12. EP260917a: Global MASTER-Net observations report
  13. EP260920a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  14. EP260920a: COLIBRÍ optical upper limits
  15. EP260920a: Update of the LCO optical counterpart candidate
  16. EP260917b: EP-FXT non-detection and upper limit
  17. IceCube Alert 260919A: Global MASTER-Net observations report
  18. EP260920a: LCO optical counterpart candidate
  19. EP260920a: Einstein Probe detection of an X-ray transient
  20. EP Alert 260919.40: Global MASTER-Net observations report
  21. GRB 260915A: VLT optical and near-infrared upper limits
  22. EP260917a: refined analysis of the EP-FXT observations
  23. IceCube-260919A - IceCube observation of a high-energy neutrino candidate track-like event
  24. The EP-WXT trigger 01709318491 is likely a flaring star
  25. EP260806a: Yamaguchi Interferometer radio detections
  26. EP260917a: SVOM/VT optical upper limits
  27. GRB 260918A: SVOM/C-GFT optical upper limits
  28. EP Alert 260918.62: Global MASTER-Net observations report
  29. Fermi GBM Sub-Threshold Detection of GRB 260918A
  30. EP Alert 260918.24: Global MASTER-Net observations report
  31. SVOM GRB260918.16: Global MASTER-Net observations report
  32. Konus-Wind detection of GRB 260916B (short/hard)
  33. The EP-WXT trigger 01709318279 is likely a flaring star
  34. GRB 260918A: SVOM/VT optical upper limits
  35. GRB 260916B: Glowbug gamma-ray detection of a short burst
  36. GRB 260918A: EP-FXT follow-up observation
  37. GRB 260917B: Mondy optical upper limit
  38. IPN triangulation of GRB 260916B (short)
  39. EP260917b: EP-WXT detection of an X-ray transient
  40. EP260917A: J-band upper limit with WINTER
  41. IPN triangulation of GRB 260810A
  42. EP Alert 260917.32: Global MASTER-Net observations report
  43. GRB 260917B: EP-FXT follow-up observation
  44. EP260917a: COLIBRÍ optical upper limits
  45. GRB 260915A: Swift-XRT afterglow detection
  46. GRB 260918A: LCO optical upper limits
  47. EP260917a: Einstein Probe detection of an X-ray transient
  48. GRB 260918A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  49. GRB 260918A: SVOM detection of a burst
  50. GRB 260917C: Fermi GBM Final Real-time Localization
  51. GRB 260917B: FRAM-Auger optical limits
  52. GRB 260916B: Fermi GBM Detection
  53. IceCube-260916A: Upper limits from a search for additional neutrino events in IceCube
  54. GRB 260916B: Fermi GBM Final Localization
  55. GRB 260917A: Glowbug gamma-ray detection
  56. GRB 260915A: SVOM/ECLAIRs refined analysis
  57. GRB 260917B: WINTER J-band observations
  58. GRB 260917B: SVOM/VT optical observations
  59. SVOM GRB260917.16: Global MASTER-Net observations report
  60. GRB 260917B: LCO optical observation
  61. GRB 260917B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  62. GRB 260917B: SVOM detection of a faint burst
  63. GRB 260914A: 2.2m CAHA optical afterglow detection and 10.4m GTC redshift confirmation
  64. GRB 260917A: BALROG localization (Fermi Trigger 811304653 / GRB 260917100)
  65. GRB 260917A: Fermi GBM Final Real-time Localization
  66. Fermi trigger No 811304653: Global MASTER-Net observations report
  67. The EP-WXT trigger 01709317235 is likely a flaring star
  68. GRB 260915A: J-band upper limit with WINTER
  69. Fermi trigger No 811264269: Global MASTER-Net observations report
  70. IceCube-260916A - IceCube observation of a high-energy neutrino candidate track-like event
  71. GRB 260909A: NOEMA detection
  72. GRB 260914A: SVOM/GRM observation
  73. GRB 260914A: Mondy and TShAO optical observations
  74. GRB 260914A: SVOM/ECLAIRs refined analysis
  75. GRB 260909A: Swift-XRT observations
  76. GRB 260916A: MAXI/GSC detection
  77. MAXI GRB260916.37: Global MASTER-Net observations report
  78. GRB 260915A: Swift ToO observations
  79. GRB 260915A: J-band upper limit by SYSU 80cm infrared telescope
  80. GRB 260915A: SVOM/C-GFT optical upper limits
  81. GRB 260915A: EP-FXT follow-up observation
  82. GRB 260915A: SVOM/VT refined early optical upper limits
  83. GRB 260915A: REM optical/NIR observations
  84. GRB 260914A: REM optical/NIR observations
  85. GRB 260914A: VLT/X-shooter observations and redshift confirmation
  86. GRB 260915A: SVOM/VT optical upper limits
  87. GRB 260915A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  88. GRB 260914A: VLT/X-shooter spectroscopic redshift z = 0.778
  89. GRB 260915A: 10.4m GTC deep optical limits
  90. GRB 260915A: NOT optical upper limit
  91. SVOM GRB260915.05: Global MASTER-Net observations report
  92. GRB 260915A: SVOM/VT optical upper limits from VHF data
  93. Fermi GBM Sub-Threshold Detection of GRB 260915A
  94. GRB 260915A: LCO optical upper limits
  95. EP Alert 260914.53: Global MASTER-Net observations report
  96. GRB 260914A: EP-FXT follow-up observation
  97. GRB 260915A: SVOM detection of a burst
  98. Fermi GBM Sub-Threshold Detection of GRB 260914A
  99. GRB 260914A: LCO optical observation
  100. GRB 260914A: SVOM/C-GFT optical observations

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