Skip to main content
Updates to LVK & CHIME Notices, Schema v7.2.3! See news and announcements

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"

26922 results found.

  1. GRB 251230A / EP251230a: NOT observations and spectroscopic redshift upper limit z < 2.2
  2. GRB 251230A: GOTO optical upper limit
  3. EP251229a: NOT optical upper limits
  4. GRB 251230A / EP251230a: SVOM/VT optical observation
  5. EP251229a: refined analysis of the EP-WXT and EP-FXT observations
  6. GRB 251230A: Early optical counterpart detection by LCO.
  7. EP-WXT trigger 01709250662 Mephisto and 50cm telescope follow-up
  8. EP251230a / GRB 251230A: Einstein Probe detection of an X-ray transient
  9. GRB 251230A/EP#01709250693 (likely EP251230a): FTW optical and NIR observations
  10. Swift GRB 251230A: Global MASTER-Net observations report
  11. The EP-WXT trigger 01709250693/GRB 251230A: Las Cumbres detection of the optical counterpart
  12. EP251229a: Global MASTER-Net observations report
  13. EP251229a: Einstein Probe detection of an X-ray transient
  14. GRB 251230A: Swift detection of a burst with a bright optical counterpart
  15. GRB 251222A/EP251222b: 1.6m Mephisto optical followup
  16. Fermi GRB 251228A: Global MASTER-Net observations report
  17. The EP-WXT trigger 01709250662 is likely a flaring star
  18. GRB 251228A: Fermi GBM Final Real-time Localization
  19. GRB 251226A: SVOM/GRM observation
  20. GRB 251226A: GECAM-B detection
  21. SVOM GRB251227.07: Global MASTER-Net observations report
  22. The EP-WXT trigger 01709250617 is likely a flaring star
  23. IceCube Alert 251225.84: Global MASTER-Net observations report
  24. Fermi Gamma-ray Burst Monitor trigger 788368008/251225630 is not a GRB
  25. GRB 251222A: NUTTelA-TAO Early Measurements
  26. EP251222a: Optical upper limit with Kinder observations
  27. GRB 251221A: Swift-BAT refined analysis
  28. GRB 251222A/EP251222b: FTW optical and NIR observations
  29. EP251222a: FTW optical and NIR observations
  30. GRB 251205A: Kilonova-Catcher optical afterglow detection
  31. GRB 251222A: AbAO optical observations
  32. GRB 251222A / EP251222b: Kilonova-Catcher optical afterglow detection
  33. GRB 251129A / EP251129a: VLA detection of a radio counterpart
  34. EP251222a: VLT/FORS2 spectroscopic redshift z = 0.505
  35. GRB 251222A: ZTSH BVRI optical observations
  36. GRB 251222A: SVOM/COLIBRÍ (FM-GFT) optical observations
  37. GRB 251222A: Continued 1.3m DFOT optical observation
  38. EP251220a: 3.6m DOT optical afterglow detection
  39. GRB 251222A: Fermi GBM Observation
  40. EP251220a: CrAO ZTSh optical observations
  41. EP251221a: PRIME upper limit
  42. EP251222a: Global MASTER-Net observations report
  43. GRB 251222A / EP251222b: GECAM-B observation
  44. EP251221a: Liverpool Telescope upper limits
  45. EP251222a: refined analysis of the EP-WXT and EP-FXT observations
  46. EP251222b/GRB 251222A: refined analysis of the EP-WXT and EP-FXT observations
  47. EP251222a: NTT/ULTRACAM optical observations
  48. EP251222a: GOTO optical upper limit
  49. GRB 251222A / EP251222b: GOTO optical counterpart detection
  50. GRB 251222A / EP251222b: LCO optical observations
  51. GRB 251222A: 1.3m DFOT optical detection
  52. GRB251221A: 7DT optical upper limits
  53. EP251222a: GSP Optical Counterpart Detection
  54. GRB 251222A / EP251222b: VLT/X-shooter spectroscopic redshift z = 3.171
  55. GRB 251222A / EP251222b: SVOM/VT optical rebrightening
  56. EP251222b/GRB 251222A: SVOM/GRM observation
  57. EP251222b/GRB 251222A: Einstein Probe detection of an X-ray transient
  58. EP251222a: Einstein Probe detection of an X-ray transient
  59. The EP-WXT trigger 01709250397 is likely a flaring star
  60. EP251221a: Global MASTER-Net observations report
  61. EP251221a: NOT optical upper limit
  62. GRB 251222A: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  63. GRB 251222A: NOT optical observations
  64. IPN triangulation of GRB 251220B (short)
  65. GRB 251222A: BALROG localization (Fermi Trigger / GRB 251222712)
  66. GRB 251222A: SVOM/VT optical candidate
  67. GRB 251222A: SVOM detection of a long burst
  68. SVOM GRB251222A: Global MASTER-Net observations report
  69. GRB 251222A: Fermi GBM Final Real-time Localization
  70. EP251220a: PRIME upper limit
  71. EP251220a: VLT/FORS2 spectroscopic redshift z = 2.375
  72. GRB 251221A: PRIME near-infrared observation
  73. EP251220a: NOT optical observations
  74. EP251220a: FTW optical and NIR observations
  75. GRB 251221A: UAFO and Mondy optical upper limit
  76. GRB 251221A: Swift-XRT refined Analysis
  77. EP251221a: Einstein Probe detection of a fast X-ray transient
  78. GRB 251221A: Swift/UVOT Upper Limits
  79. Fermi Gamma-ray Burst Monitor trigger 788028118/251221696 is not a GRB
  80. GRB 251221A: Fermi GBM Observation
  81. GRB 251221B: Fermi GBM Final Real-time Localization
  82. EP251220a: EP-FXT follow-up observation
  83. GRB 251220B: SVOM/GRM observation of a short burst
  84. EP251220a: COLIBRÍ confirmation of fading and photometric redshift upper limit of z < 3.4
  85. EP 251220a: GOTO optical counterpart detection
  86. GRB 251221A: COLIBRÍ detection of the optical counterpart
  87. EP 251220a: COLIBRÍ detection of the optical counterpart
  88. GRB 251221A: Swift detection of a burst
  89. Swift GRB251221A: Global MASTER-Net observations report
  90. GRB 251221A: Fermi GBM Final Real-time Localization
  91. EP251220a: Global MASTER-Net observations report
  92. EP251220a: EP detection of a fast X-ray transient
  93. SVOM GRB251220.98: Global MASTER-Net observations report
  94. GRB 251220B: Fermi GBM Final Real-time Localization
  95. GRB 251219A: SVOM/GRM observation of a short burst
  96. GRB 251219A: GECAM-B detection of a possible magnetar X-ray burst from SGR 1830-0645
  97. IceCube-251218A: COLIBRÍ optical upper limits
  98. SVOM GRB251219.11: Global MASTER-Net observations report
  99. IceCube Alert 251218.85: Global MASTER-Net observations report
  100. Fermi trigger No 787736968: Global MASTER-Net observations report

Advanced

Download all Circulars as a .tar.gz archive (updated once a day):
Looking for U.S. government information and services? Visit USA.gov