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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"

26921 results found.

  1. GRB 251230A: GOTO optical upper limit
  2. EP251229a: NOT optical upper limits
  3. GRB 251230A / EP251230a: SVOM/VT optical observation
  4. EP251229a: refined analysis of the EP-WXT and EP-FXT observations
  5. GRB 251230A: Early optical counterpart detection by LCO.
  6. EP-WXT trigger 01709250662 Mephisto and 50cm telescope follow-up
  7. EP251230a / GRB 251230A: Einstein Probe detection of an X-ray transient
  8. GRB 251230A/EP#01709250693 (likely EP251230a): FTW optical and NIR observations
  9. Swift GRB 251230A: Global MASTER-Net observations report
  10. The EP-WXT trigger 01709250693/GRB 251230A: Las Cumbres detection of the optical counterpart
  11. EP251229a: Global MASTER-Net observations report
  12. EP251229a: Einstein Probe detection of an X-ray transient
  13. GRB 251230A: Swift detection of a burst with a bright optical counterpart
  14. GRB 251222A/EP251222b: 1.6m Mephisto optical followup
  15. Fermi GRB 251228A: Global MASTER-Net observations report
  16. The EP-WXT trigger 01709250662 is likely a flaring star
  17. GRB 251228A: Fermi GBM Final Real-time Localization
  18. GRB 251226A: SVOM/GRM observation
  19. GRB 251226A: GECAM-B detection
  20. SVOM GRB251227.07: Global MASTER-Net observations report
  21. The EP-WXT trigger 01709250617 is likely a flaring star
  22. IceCube Alert 251225.84: Global MASTER-Net observations report
  23. Fermi Gamma-ray Burst Monitor trigger 788368008/251225630 is not a GRB
  24. GRB 251222A: NUTTelA-TAO Early Measurements
  25. EP251222a: Optical upper limit with Kinder observations
  26. GRB 251221A: Swift-BAT refined analysis
  27. GRB 251222A/EP251222b: FTW optical and NIR observations
  28. EP251222a: FTW optical and NIR observations
  29. GRB 251205A: Kilonova-Catcher optical afterglow detection
  30. GRB 251222A: AbAO optical observations
  31. GRB 251222A / EP251222b: Kilonova-Catcher optical afterglow detection
  32. GRB 251129A / EP251129a: VLA detection of a radio counterpart
  33. EP251222a: VLT/FORS2 spectroscopic redshift z = 0.505
  34. GRB 251222A: ZTSH BVRI optical observations
  35. GRB 251222A: SVOM/COLIBRÍ (FM-GFT) optical observations
  36. GRB 251222A: Continued 1.3m DFOT optical observation
  37. EP251220a: 3.6m DOT optical afterglow detection
  38. GRB 251222A: Fermi GBM Observation
  39. EP251220a: CrAO ZTSh optical observations
  40. EP251221a: PRIME upper limit
  41. EP251222a: Global MASTER-Net observations report
  42. GRB 251222A / EP251222b: GECAM-B observation
  43. EP251221a: Liverpool Telescope upper limits
  44. EP251222a: refined analysis of the EP-WXT and EP-FXT observations
  45. EP251222b/GRB 251222A: refined analysis of the EP-WXT and EP-FXT observations
  46. EP251222a: NTT/ULTRACAM optical observations
  47. EP251222a: GOTO optical upper limit
  48. GRB 251222A / EP251222b: GOTO optical counterpart detection
  49. GRB 251222A / EP251222b: LCO optical observations
  50. GRB 251222A: 1.3m DFOT optical detection
  51. GRB251221A: 7DT optical upper limits
  52. EP251222a: GSP Optical Counterpart Detection
  53. GRB 251222A / EP251222b: VLT/X-shooter spectroscopic redshift z = 3.171
  54. GRB 251222A / EP251222b: SVOM/VT optical rebrightening
  55. EP251222b/GRB 251222A: SVOM/GRM observation
  56. EP251222b/GRB 251222A: Einstein Probe detection of an X-ray transient
  57. EP251222a: Einstein Probe detection of an X-ray transient
  58. The EP-WXT trigger 01709250397 is likely a flaring star
  59. EP251221a: Global MASTER-Net observations report
  60. EP251221a: NOT optical upper limit
  61. GRB 251222A: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  62. GRB 251222A: NOT optical observations
  63. IPN triangulation of GRB 251220B (short)
  64. GRB 251222A: BALROG localization (Fermi Trigger / GRB 251222712)
  65. GRB 251222A: SVOM/VT optical candidate
  66. GRB 251222A: SVOM detection of a long burst
  67. SVOM GRB251222A: Global MASTER-Net observations report
  68. GRB 251222A: Fermi GBM Final Real-time Localization
  69. EP251220a: PRIME upper limit
  70. EP251220a: VLT/FORS2 spectroscopic redshift z = 2.375
  71. GRB 251221A: PRIME near-infrared observation
  72. EP251220a: NOT optical observations
  73. EP251220a: FTW optical and NIR observations
  74. GRB 251221A: UAFO and Mondy optical upper limit
  75. GRB 251221A: Swift-XRT refined Analysis
  76. EP251221a: Einstein Probe detection of a fast X-ray transient
  77. GRB 251221A: Swift/UVOT Upper Limits
  78. Fermi Gamma-ray Burst Monitor trigger 788028118/251221696 is not a GRB
  79. GRB 251221A: Fermi GBM Observation
  80. GRB 251221B: Fermi GBM Final Real-time Localization
  81. EP251220a: EP-FXT follow-up observation
  82. GRB 251220B: SVOM/GRM observation of a short burst
  83. EP251220a: COLIBRÍ confirmation of fading and photometric redshift upper limit of z < 3.4
  84. EP 251220a: GOTO optical counterpart detection
  85. GRB 251221A: COLIBRÍ detection of the optical counterpart
  86. EP 251220a: COLIBRÍ detection of the optical counterpart
  87. GRB 251221A: Swift detection of a burst
  88. Swift GRB251221A: Global MASTER-Net observations report
  89. GRB 251221A: Fermi GBM Final Real-time Localization
  90. EP251220a: Global MASTER-Net observations report
  91. EP251220a: EP detection of a fast X-ray transient
  92. SVOM GRB251220.98: Global MASTER-Net observations report
  93. GRB 251220B: Fermi GBM Final Real-time Localization
  94. GRB 251219A: SVOM/GRM observation of a short burst
  95. GRB 251219A: GECAM-B detection of a possible magnetar X-ray burst from SGR 1830-0645
  96. IceCube-251218A: COLIBRÍ optical upper limits
  97. SVOM GRB251219.11: Global MASTER-Net observations report
  98. IceCube Alert 251218.85: Global MASTER-Net observations report
  99. Fermi trigger No 787736968: Global MASTER-Net observations report
  100. Fermi GRB 251217A: Global MASTER-Net observations report

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