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"

43623 results found.

  1. GRB 251230A: Swift/UVOT detection
  2. GRB251230A: 7DT optical upper limits
  3. GRB 251230A / EP251230a: NOT observations and spectroscopic redshift upper limit z < 2.2
  4. EP251229a: BOOTES-2 early optical upper limit
  5. GRB 251230A: GOTO optical upper limit
  6. EP251229a: NOT optical upper limits
  7. GRB 251230A / EP251230a: SVOM/VT optical observation
  8. EP251229a: refined analysis of the EP-WXT and EP-FXT observations
  9. GRB 251230A: Enhanced Swift-XRT position
  10. GRB 251230A: Early optical counterpart detection by LCO.
  11. EP-WXT trigger 01709250662 Mephisto and 50cm telescope follow-up
  12. GRB 251230A: Optical Observations via Virtual Telescope Project, Italy
  13. EP251230a / GRB 251230A: Einstein Probe detection of an X-ray transient
  14. GRB 251230A/EP#01709250693 (likely EP251230a): FTW optical and NIR observations
  15. LIGO/Virgo/KAGRA S251112cm: Candidates from the NSF-DOE Vera C. Rubin Observatory
  16. Swift GRB 251230A: Global MASTER-Net observations report
  17. The EP-WXT trigger 01709250693/GRB 251230A: Las Cumbres detection of the optical counterpart
  18. EP251229a: Global MASTER-Net observations report
  19. EP251229a: Einstein Probe detection of an X-ray transient
  20. GRB 251230A: Swift detection of a burst with a bright optical counterpart
  21. GRB 251226A: Glowbug gamma-ray detection
  22. GRB 251222A/EP251222b: 1.6m Mephisto optical followup
  23. GRB 251129A: redshift correction and SN detection at z = 0.505 with GTC
  24. Fermi GRB 251228A: Global MASTER-Net observations report
  25. The EP-WXT trigger 01709250662 is likely a flaring star
  26. GRB 251228A: Fermi GBM Final Real-time Localization
  27. GRB 251226A: SVOM/GRM observation
  28. GRB 251226A: GECAM-B detection
  29. SVOM GRB251227.07: Global MASTER-Net observations report
  30. IceCube-251225A: Upper limits from a search for additional neutrino events in IceCube
  31. The EP-WXT trigger 01709250617 is likely a flaring star
  32. IceCube Alert 251225.84: Global MASTER-Net observations report
  33. IceCube-251225A - IceCube observation of a high-energy neutrino candidate track-like event
  34. Fermi Gamma-ray Burst Monitor trigger 788368008/251225630 is not a GRB
  35. GRB 251222A: NUTTelA-TAO Early Measurements
  36. GRB 251222A/EP251222b: Optical detection with Kinder observations
  37. EP251222a: Optical upper limit with Kinder observations
  38. GRB 251221A: Swift-BAT refined analysis
  39. GRB 251222A/EP251222b: FTW optical and NIR observations
  40. EP251222a: FTW optical and NIR observations
  41. GRB 251205A: Kilonova-Catcher optical afterglow detection
  42. GRB 251222A: AbAO optical observations
  43. GRB 251222A / EP251222b: Kilonova-Catcher optical afterglow detection
  44. GRB 251129A / EP251129a: VLA detection of a radio counterpart
  45. EP251222a: VLT/FORS2 spectroscopic redshift z = 0.505
  46. GRB 251222A: ZTSH BVRI optical observations
  47. GRB 251222A: SVOM/COLIBRÍ (FM-GFT) optical observations
  48. GRB 251222A: Continued 1.3m DFOT optical observation
  49. EP251220a: 3.6m DOT optical afterglow detection
  50. GRB 251222A: Fermi GBM Observation
  51. EP251220a: CrAO ZTSh optical observations
  52. EP251221a: PRIME upper limit
  53. EP251222a: Global MASTER-Net observations report
  54. GRB 251222A / EP251222b: GECAM-B observation
  55. EP251221a: Liverpool Telescope upper limits
  56. EP251222a: refined analysis of the EP-WXT and EP-FXT observations
  57. EP251222b/GRB 251222A: refined analysis of the EP-WXT and EP-FXT observations
  58. Konus-Wind detection of GRB 251222A / EP251222b
  59. GRB 251222A: Swift-XRT afterglow detection
  60. GRB 251222A / EP251222b: LCO detection of the optical counterpart
  61. EP251222a: NTT/ULTRACAM optical observations
  62. EP251222a: GOTO optical upper limit
  63. GRB 251222A / EP251222b: GOTO optical counterpart detection
  64. GRB 251222A / EP251222b: LCO optical observations
  65. GRB 251222A: 1.3m DFOT optical detection
  66. GRB251221A: 7DT optical upper limits
  67. EP251222a: GSP Optical Counterpart Detection
  68. GRB 251222A / EP251222b: VLT/X-shooter spectroscopic redshift z = 3.171
  69. GRB 251222A / EP251222b: SVOM/VT optical rebrightening
  70. EP251222b/GRB 251222A: SVOM/GRM observation
  71. EP251222b/GRB 251222A: Einstein Probe detection of an X-ray transient
  72. EP251222a: Einstein Probe detection of an X-ray transient
  73. The EP-WXT trigger 01709250397 is likely a flaring star
  74. EP251221a: Global MASTER-Net observations report
  75. GRB 251222A: PRIME near-infrared detection
  76. EP251221a: NOT optical upper limit
  77. GRB 251222A: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  78. GRB 251222A: NOT optical observations
  79. IceCube-251218A: No Candidate Transients from the Zwicky Transient Facility
  80. IPN triangulation of GRB 251220B (short)
  81. GRB 251222A: Swift ToO observations
  82. GRB 251222A: BALROG localization (Fermi Trigger / GRB 251222712)
  83. GRB 251222A: SVOM/VT optical candidate
  84. GRB 251222A: SVOM detection of a long burst
  85. SVOM GRB251222A: Global MASTER-Net observations report
  86. GRB 251222A: Fermi GBM Final Real-time Localization
  87. EP251220a: PRIME upper limit
  88. EP251220a: VLT/FORS2 spectroscopic redshift z = 2.375
  89. GRB 251221A: PRIME near-infrared observation
  90. EP251220a: NOT optical observations
  91. EP251220a: FTW optical and NIR observations
  92. GRB 251221A: UAFO and Mondy optical upper limit
  93. GRB 251221A: Swift-XRT refined Analysis
  94. EP251221a: Einstein Probe detection of a fast X-ray transient
  95. Fermi Gamma-ray Burst Monitor trigger 788028118/251221696 is not a GRB
  96. GRB 251221A: Enhanced Swift-XRT position
  97. GRB 251221A: Fermi GBM Observation
  98. GRB 251221B: Fermi GBM Final Real-time Localization
  99. EP251220a: EP-FXT follow-up observation
  100. GRB 251220B: SVOM/GRM observation of a short burst

Advanced

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