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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"

45450 results found.

  1. GRB 260921A: Swift-BAT refined analysis
  2. GRB 260921B: Fermi GBM Final Localization
  3. GRB 260921A: Fermi GBM Observation
  4. EP260920b: 2.2m CAHA optical afterglow detection and 10.4m GTC redshift confirmation
  5. EP Alert 260921.58: Global MASTER-Net observations report
  6. GRB 260917B:: SVOM/ECLAIRs refined analysis
  7. The EP-WXT trigger 01709319528 is likely a flaring star
  8. EP260920a: VLT/HAWK-I near-infrared candidate
  9. Swift GRB 260921A: MASTER OT J094129.58+025052.5 possible optical counterpart detection with host galaxy (z=1.3)
  10. Swift GRB 260921A: Global MASTER-Net observations report
  11. GRB 260921A: Swift detection of a burst
  12. EP260920b: VLT/X-shooter spectroscopic redshift z = 3.582
  13. GRB 260921A: Fermi GBM Final Real-time Localization
  14. EP260920b: LCO observations
  15. GRB 260920A: AstroSat CZTI detection
  16. EP260920b: SVOM/VT optical observation
  17. EP260920b: refined analysis of the EP-WXT and EP-FXT observations
  18. EP260920b: COLIBRÍ optical observations
  19. EP260920b: LCO optical counterpart detection
  20. The EP-WXT trigger 01709318601 is likely a flaring star
  21. EP Alert 260921.01: Global MASTER-Net observations report
  22. EP260920b: Global MASTER-Net observations report
  23. EP260920b: Einstein Probe detection of an X-ray transient
  24. IceCube-260919A: Upper limits from a search for additional neutrino events in IceCube
  25. EP Alert 260920.66: Global MASTER-Net observations report
  26. EP-WXT detected a brightening of HMXB LS V +44 17
  27. EP260920a: NOT early time optical upper limits
  28. EP260920a: NOT optical upper limits
  29. GRB 260920A: Fermi GBM Final Real-time Localization
  30. EP260920a: SVOM/VT optical upper limits
  31. EP260917a: Global MASTER-Net observations report
  32. EP260920a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  33. EP260920a: COLIBRÍ optical upper limits
  34. EP260920a: Update of the LCO optical counterpart candidate
  35. EP260917b: EP-FXT non-detection and upper limit
  36. IceCube Alert 260919A: Global MASTER-Net observations report
  37. EP260920a: LCO optical counterpart candidate
  38. EP260920a: Einstein Probe detection of an X-ray transient
  39. EP Alert 260919.40: Global MASTER-Net observations report
  40. GRB 260915A: VLT optical and near-infrared upper limits
  41. EP260917a: refined analysis of the EP-FXT observations
  42. IceCube-260919A - IceCube observation of a high-energy neutrino candidate track-like event
  43. The EP-WXT trigger 01709318491 is likely a flaring star
  44. EP260806a: Yamaguchi Interferometer radio detections
  45. EP260917a: SVOM/VT optical upper limits
  46. GRB 260918A: SVOM/C-GFT optical upper limits
  47. EP Alert 260918.62: Global MASTER-Net observations report
  48. Fermi GBM Sub-Threshold Detection of GRB 260918A
  49. EP Alert 260918.24: Global MASTER-Net observations report
  50. SVOM GRB260918.16: Global MASTER-Net observations report
  51. Konus-Wind detection of GRB 260916B (short/hard)
  52. The EP-WXT trigger 01709318279 is likely a flaring star
  53. GRB 260918A: SVOM/VT optical upper limits
  54. GRB 260916B: Glowbug gamma-ray detection of a short burst
  55. GRB 260918A: EP-FXT follow-up observation
  56. GRB 260917B: Mondy optical upper limit
  57. IPN triangulation of GRB 260916B (short)
  58. EP260917b: EP-WXT detection of an X-ray transient
  59. EP260917A: J-band upper limit with WINTER
  60. IPN triangulation of GRB 260810A
  61. EP Alert 260917.32: Global MASTER-Net observations report
  62. GRB 260917B: EP-FXT follow-up observation
  63. EP260917a: COLIBRÍ optical upper limits
  64. GRB 260915A: Swift-XRT afterglow detection
  65. GRB 260918A: LCO optical upper limits
  66. EP260917a: Einstein Probe detection of an X-ray transient
  67. GRB 260918A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  68. GRB 260918A: SVOM detection of a burst
  69. GRB 260917C: Fermi GBM Final Real-time Localization
  70. GRB 260917B: FRAM-Auger optical limits
  71. GRB 260916B: Fermi GBM Detection
  72. IceCube-260916A: Upper limits from a search for additional neutrino events in IceCube
  73. GRB 260916B: Fermi GBM Final Localization
  74. GRB 260917A: Glowbug gamma-ray detection
  75. GRB 260915A: SVOM/ECLAIRs refined analysis
  76. GRB 260917B: WINTER J-band observations
  77. GRB 260917B: SVOM/VT optical observations
  78. SVOM GRB260917.16: Global MASTER-Net observations report
  79. GRB 260917B: LCO optical observation
  80. GRB 260917B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  81. GRB 260917B: SVOM detection of a faint burst
  82. GRB 260914A: 2.2m CAHA optical afterglow detection and 10.4m GTC redshift confirmation
  83. GRB 260917A: BALROG localization (Fermi Trigger 811304653 / GRB 260917100)
  84. GRB 260917A: Fermi GBM Final Real-time Localization
  85. Fermi trigger No 811304653: Global MASTER-Net observations report
  86. The EP-WXT trigger 01709317235 is likely a flaring star
  87. GRB 260915A: J-band upper limit with WINTER
  88. Fermi trigger No 811264269: Global MASTER-Net observations report
  89. IceCube-260916A - IceCube observation of a high-energy neutrino candidate track-like event
  90. GRB 260909A: NOEMA detection
  91. GRB 260914A: SVOM/GRM observation
  92. GRB 260914A: Mondy and TShAO optical observations
  93. GRB 260914A: SVOM/ECLAIRs refined analysis
  94. GRB 260909A: Swift-XRT observations
  95. GRB 260916A: MAXI/GSC detection
  96. MAXI GRB260916.37: Global MASTER-Net observations report
  97. GRB 260915A: Swift ToO observations
  98. GRB 260915A: J-band upper limit by SYSU 80cm infrared telescope
  99. GRB 260915A: SVOM/C-GFT optical upper limits
  100. GRB 260915A: EP-FXT follow-up observation

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