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"

21793 results found.

  1. GRB 260114A: Mondy optical observations
  2. GRB 260114A: GMG Optical Observation
  3. Fermi-LAT Gamma-ray Observations of IceCube-260111A
  4. EP-WXT trigger 01709251266: SVOM/C-GFT confirmation of a stellar flare
  5. Swift GRB260113.43: Global MASTER-Net observations report
  6. EP260110a: NOT and GTC Optical and Near-Infrared Observations
  7. EP260110a: TRT optical upper limits
  8. GRB 260111A: Swift-XRT observations
  9. GRB 260111A: GOTO optical upper limits
  10. GRB 260111A: Swift ToO observations
  11. GRB 251230A: Mondy Optical Observations
  12. GRB 260111A: Swift/BAT-GUANO arcminute localization of a burst
  13. IceCube Alert 260111A: Global MASTER-Net observations report
  14. EP260110a: Global MASTER-Net observations report
  15. Fermi GRB 260111A: Global MASTER-Net observations report
  16. EP260110a: refined analysis of the EP-WXT and EP-FXT observations
  17. EP 260110a: COLIBRÍ optical observations
  18. EP260110a: SVOM/C-GFT upper limit
  19. GRB 260109C: LCO optical upper limits
  20. GRB 260109C: Kilonova-Catcher optical upper limit
  21. EP260105b / GRB 260105C : Fermi-GBM Sub-Threshold Detection
  22. GRB 260102A: Swift-XRT afterglow detection
  23. Fermi GRB 260107A: Global MASTER-Net observations report
  24. GRB 260102A: AbAO optical observations
  25. EP260105b/EP-WXT trigger 01709251028: Einstein Probe detection of an X-ray transient
  26. Fermi GRB 260105A: Global MASTER-Net observations report
  27. EP260105a: FTW optical observations
  28. EP260104a: FTW optical observations
  29. Fermi GRB 260105B: Global MASTER-Net observations report
  30. EP260105a: refined analysis of the EP-WXT and EP-FXT observations
  31. EP260105a: LCO Optical Upper limit
  32. EP260104a: Global MASTER-Net observations report
  33. EP260104a: Einstein Probe detection of a fast X-ray transient
  34. EP260105a: Global MASTER-Net observations report
  35. Fermi GRB 260104B: Global MASTER-Net observations report
  36. Swift GRB 260104A: Global MASTER-Net observations report
  37. GRB 260101A: Swift/UVOT Detection
  38. Fermi-LAT Gamma-ray Observations of IceCube-251225A
  39. GRB 260101A: COLIBRÍ optical observations
  40. SVOM GRB260103.08: Global MASTER-Net observations report
  41. SVOM GRB260102A: Global MASTER-Net observations report
  42. Fermi GBM Sub-Threshold Detection of GRB 260102A
  43. EP260101a: Global MASTER-Net observations report
  44. GRB 260102A: Swift-XRT observations
  45. GRB 260102A: SVOM/COLIBRÍ (FM-GFT) optical observations
  46. GRB 260102A: Swift ToO observations
  47. EP260101a: refined analysis of the EP-WXT and EP-FXT observations
  48. GRB 260101A: NOT spectroscopic observations
  49. Swift GRB 260101A: Global MASTER-Net observations report
  50. GRB 260101A: LCO detection of the optical counterpart
  51. SVOM GRB251231.57: Global MASTER-Net observations report
  52. GRB 251230A / EP251230a: SVOM/VT optical continued observations and upper limit
  53. GRB 251230A: GRANDMA/TAROT Early Detection
  54. GRB 251230A / EP251230a: further NOT optical observations revealing shallower decay or possible rebrightening
  55. GRB 251230A/EP251230a: Optical upper limit with Kinder observations
  56. EP251229a: Optical upper limit with Kinder observations
  57. GRB 251230A: 1.3m DFOT optical upper limit
  58. GRB 251222A: Mondy Optical Observations
  59. EP251230a / GRB 251230A: refined analysis of the EP-WXT and EP-FXT observations
  60. GRB 251230A: Swift/UVOT detection
  61. GRB251230A: 7DT optical upper limits
  62. GRB 251230A / EP251230a: NOT observations and spectroscopic redshift upper limit z < 2.2
  63. EP251229a: BOOTES-2 early optical upper limit
  64. GRB 251230A: GOTO optical upper limit
  65. EP251229a: NOT optical upper limits
  66. EP251229a: refined analysis of the EP-WXT and EP-FXT observations
  67. GRB 251230A: Early optical counterpart detection by LCO.
  68. EP-WXT trigger 01709250662 Mephisto and 50cm telescope follow-up
  69. GRB 251230A: Optical Observations via Virtual Telescope Project, Italy
  70. GRB 251230A/EP#01709250693 (likely EP251230a): FTW optical and NIR observations
  71. LIGO/Virgo/KAGRA S251112cm: Candidates from the NSF-DOE Vera C. Rubin Observatory
  72. Swift GRB 251230A: Global MASTER-Net observations report
  73. EP251229a: Global MASTER-Net observations report
  74. GRB 251222A/EP251222b: 1.6m Mephisto optical followup
  75. GRB 251129A: redshift correction and SN detection at z = 0.505 with GTC
  76. Fermi GRB 251228A: Global MASTER-Net observations report
  77. SVOM GRB251227.07: Global MASTER-Net observations report
  78. IceCube Alert 251225.84: Global MASTER-Net observations report
  79. GRB 251222A: NUTTelA-TAO Early Measurements
  80. GRB 251222A/EP251222b: Optical detection with Kinder observations
  81. EP251222a: Optical upper limit with Kinder observations
  82. GRB 251222A/EP251222b: FTW optical and NIR observations
  83. EP251222a: FTW optical and NIR observations
  84. GRB 251205A: Kilonova-Catcher optical afterglow detection
  85. GRB 251222A: AbAO optical observations
  86. GRB 251222A / EP251222b: Kilonova-Catcher optical afterglow detection
  87. GRB 251129A / EP251129a: VLA detection of a radio counterpart
  88. EP251222a: VLT/FORS2 spectroscopic redshift z = 0.505
  89. GRB 251222A: ZTSH BVRI optical observations
  90. GRB 251222A: SVOM/COLIBRÍ (FM-GFT) optical observations
  91. GRB 251222A: Continued 1.3m DFOT optical observation
  92. EP251220a: 3.6m DOT optical afterglow detection
  93. EP251220a: CrAO ZTSh optical observations
  94. EP251221a: PRIME upper limit
  95. EP251222a: Global MASTER-Net observations report
  96. EP251222a: refined analysis of the EP-WXT and EP-FXT observations
  97. EP251222b/GRB 251222A: refined analysis of the EP-WXT and EP-FXT observations
  98. GRB 251222A: Swift-XRT afterglow detection
  99. GRB 251222A / EP251222b: LCO detection of the optical counterpart
  100. EP251222a: NTT/ULTRACAM optical observations

Advanced

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