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"

32531 results found.

  1. GRB 260117A: Swift-XRT afterglow detection
  2. EP260119a: COLIBRÍ photometric redshift z ≈ 5.6
  3. EP260119a: Global MASTER-Net observations report
  4. GRB 260115A: AstroSat CZTI detection
  5. EP260119a: LCO optical observations
  6. GRB 260117A: ZTSh optical upper limit
  7. EP260119a: COLIBRÍ optical counterpart candidate
  8. EP260119a: preliminary result from the EP-FXT observation
  9. GRB 260117A: SVOM/COLIBRÍ (FM-GFT) optical observations
  10. Fermi-LAT Gamma-ray Observations of IceCube-260115A
  11. Swift trigger on the HMXB 1A 1118-61
  12. GRB 260117A: SVOM/VT optical candidate
  13. GRB 260117A: SVOM/C-GFT upper limit
  14. GRB 260117A: Swift ToO observations
  15. EP 260116a: COLIBRÍ optical upper limit
  16. GRB 260115A: GECAM-B observation
  17. FRB 20251229A: COLIBRÍ further inspection of the updated localization
  18. EP260116a: Liverpool Telescope upper limits
  19. FRB 20251229A: Updated CHIME/FRB Baseband Localization of FRB 20251229A
  20. EP260116A: 1.3m DFOT optical upper limit
  21. GRB 260114A: VLT/MUSE spectroscopic observations
  22. IceCube-260115A: Upper limits from a search for additional neutrino events in IceCube
  23. EP260116a: Global MASTER-Net observations report
  24. GRB 260111A: COLIBRÍ fading of the optical counterpart candidate
  25. EP260116a: Xinglong optical upper limit
  26. GRB 260114A: VLT/HAWK-I further near-infrared upper limits
  27. IceCube-260115A - IceCube observation of a high-energy neutrino candidate track-like event
  28. IceCube: GCN Notices for high-energy track alerts now streamed via Kafka
  29. Fermi GRB 260115A: Global MASTER-Net observations report
  30. GRB260114A: STEP/T80S optical limits
  31. GRB 251222A: radio detection with the VLA
  32. GRB 260114A: VLT/HAWK-I near-infrared upper limits
  33. Konus-Wind detection of GRB 260114A
  34. GRB 260114A: 6 GHz VLA observations
  35. GRB 260114A: VLT/X-shooter redshift of the putative host galaxy
  36. GRB 260114A : MITSuME Akeno optical upper limits
  37. GRB 260114A: COLIBRÍ optical upper limits
  38. GRB 260114A: TNG NIR upper limit
  39. GRB 260114A: NOT optical observations
  40. Konus-Wind detection of GRB 251230A / EP251230a
  41. GRB 260114A: SVOM/GRM observation of a short burst
  42. Swift GRB 260114A: Global MASTER-Net observations report
  43. GRB 260114A: GECAM-B observation of a short burst
  44. GRB 260114A: Mondy optical observations
  45. GRB 260114A: Fermi GBM observation
  46. GRB 260112B: GECAM-B observation
  47. GRB 260114A: GMG Optical Observation
  48. Fermi-LAT Gamma-ray Observations of IceCube-260111A
  49. EP-WXT trigger 01709251266: SVOM/C-GFT confirmation of a stellar flare
  50. IceCube-260111A: Upper limits from a search for additional neutrino events in IceCube
  51. EP260110a: NOT and GTC Optical and Near-Infrared Observations
  52. EP260110a: TRT optical upper limits
  53. Konus-Wind detection of GRB 260101A
  54. GRB 260111A: Swift-XRT observations
  55. GRB 260111A: COLIBRÍ optical afterglow candidate
  56. GRB 260111A: GECAM-B observation of a burst
  57. GRB 260111A: Fermi GBM Observation
  58. Swift Trigger 1434591 is not a GRB
  59. GRB 260111A: GOTO optical upper limits
  60. GRB 260111A: Swift ToO observations
  61. GRB 251230A: Mondy Optical Observations
  62. GRB 260111A: Swift/BAT-GUANO arcminute localization of a burst
  63. EP260110a: SVOM/VT optical upper limits
  64. EP260110a: Global MASTER-Net observations report
  65. Fermi GRB 260111A: Global MASTER-Net observations report
  66. EP260110a: KAIT optical upper limit
  67. EP260110a: refined analysis of the EP-WXT and EP-FXT observations
  68. EP 260110a: COLIBRÍ optical observations
  69. EP260110a: SVOM/C-GFT upper limit
  70. EP260110a: BOOTES-5/JGU optical upper limit
  71. GRB 260109C: LCO optical upper limits
  72. GRB 260109C: Kilonova-Catcher optical upper limit
  73. EP260105b / GRB 260105C : Fermi-GBM Sub-Threshold Detection
  74. GRB 260104A: Swift-BAT refined analysis
  75. GRB 260101A: Swift-BAT refined analysis
  76. Swift GRB 251230A: Global MASTER-Net OT detection
  77. Fermi GRB 260107A: Global MASTER-Net observations report
  78. GRB 260102A: AbAO optical observations
  79. EP260105b/EP-WXT trigger 01709251028: Einstein Probe detection of an X-ray transient
  80. Fermi GRB 260105A: Global MASTER-Net observations report
  81. EP260105a: FTW optical observations
  82. EP260104a: FTW optical observations
  83. GRB 260105A: SVOM/GRM observation
  84. GRB 260105B: SVOM/GRM observation
  85. FRB 20251229A: COLIBRÍ optical upper limits
  86. Fermi GRB 260105B: Global MASTER-Net observations report
  87. EP260105a: SVOM/VT optical upperlimit
  88. EP260105a: refined analysis of the EP-WXT and EP-FXT observations
  89. EP260105a: LCO Optical Upper limit
  90. EP260104a: Global MASTER-Net observations report
  91. GRB 260101A: COLIBRÍ optical upper limits
  92. EP260105a: Global MASTER-Net observations report
  93. GRB 260103A: Insight-HXMT/HE detection
  94. GRB 260104A: COLIBRÍ optical upper limits
  95. Fermi GRB 260104B: Global MASTER-Net observations report
  96. Swift GRB 260104A: Global MASTER-Net observations report
  97. GRB 251230A/EP-WXT trigger 01709250693: Mephisto optical upper limits
  98. GRB 260101A: Swift/UVOT Detection
  99. GRB 260103A: GECAM-B observation of a burst
  100. Fermi-LAT Gamma-ray Observations of IceCube-251225A

Advanced

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