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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"

41644 results found.

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

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