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"
  1. GRB 260115A: AstroSat CZTI detection
  2. EP260119a: LCO optical observations
  3. GRB 260117A: ZTSh optical upper limit
  4. EP260119a: COLIBRÍ optical counterpart candidate
  5. EP260119a: preliminary result from the EP-FXT observation
  6. GRB 260110A: SVOM detection of a burst through offline search
  7. EP260119a: EP-WXT detection of a fast X-ray transient
  8. Swift GRB260118.48: Global MASTER-Net observations report
  9. GRB 260117A: SVOM/COLIBRÍ (FM-GFT) optical observations
  10. SVOM GRB260117.82: Global MASTER-Net observations report
  11. Fermi-LAT Gamma-ray Observations of IceCube-260115A
  12. Swift trigger on the HMXB 1A 1118-61
  13. GRB 260117A: SVOM/VT optical candidate
  14. GRB 260117A: SVOM/C-GFT upper limit
  15. GRB 260117A: Swift-XRT observations
  16. GRB 260117A: Swift ToO observations
  17. GRB 260117A: SVOM detection of a long faint burst
  18. EP 260116a: COLIBRÍ optical upper limit
  19. Swift triggered on the HMXB 1A 1118-61
  20. GRB 260115A: GECAM-B observation
  21. FRB 20251229A: COLIBRÍ further inspection of the updated localization
  22. EP260116a: Liverpool Telescope upper limits
  23. FRB 20251229A: Updated CHIME/FRB Baseband Localization of FRB 20251229A
  24. EP260116A: 1.3m DFOT optical upper limit
  25. GRB 260114A: VLT/MUSE spectroscopic observations
  26. IceCube-260115A: Upper limits from a search for additional neutrino events in IceCube
  27. EP260116a: Global MASTER-Net observations report
  28. GRB 260111A: COLIBRÍ fading of the optical counterpart candidate
  29. EP260116a: Xinglong optical upper limit
  30. EP260116a: Einstein Probe detection of an X-ray transient
  31. GRB 260114A: VLT/HAWK-I further near-infrared upper limits
  32. IceCube Alert 260115.73: Global MASTER-Net observations report
  33. IceCube-260115A - IceCube observation of a high-energy neutrino candidate track-like event
  34. GRB 260115A: BALROG localization (Fermi Trigger 790192010 / GRB 260115741)
  35. IceCube: GCN Notices for high-energy track alerts now streamed via Kafka
  36. Fermi GRB 260115A: Global MASTER-Net observations report
  37. GRB 260115A: Fermi GBM Final Real-time Localization
  38. GRB260114A: STEP/T80S optical limits
  39. GRB 251222A: radio detection with the VLA
  40. GRB 260114A: VLT/HAWK-I near-infrared upper limits
  41. Konus-Wind detection of GRB 260114A
  42. GRB 260114A: Swift-XRT refined Analysis
  43. GRB 260114A: 6 GHz VLA observations
  44. GRB 260114A: VLT/X-shooter redshift of the putative host galaxy
  45. GRB 260114A : MITSuME Akeno optical upper limits
  46. GRB 260114A: COLIBRÍ optical upper limits
  47. GRB 260114A: TNG NIR upper limit
  48. GRB 260114A: NOT optical observations
  49. Konus-Wind detection of GRB 251230A / EP251230a
  50. GRB 260114A: SVOM/GRM observation of a short burst
  51. Swift GRB 260114A: Global MASTER-Net observations report
  52. GRB 260114A: GECAM-B observation of a short burst
  53. GRB 260114A: Mondy optical observations
  54. GRB 260114A: Fermi GBM observation
  55. GRB 260112B: GECAM-B observation
  56. GRB 260114A: GMG Optical Observation
  57. Fermi-LAT Gamma-ray Observations of IceCube-260111A
  58. GRB 260114A: Swift detection of a short burst
  59. GRB 260114A: Fermi GBM Final Real-time Localization
  60. EP-WXT trigger 01709251266: SVOM/C-GFT confirmation of a stellar flare
  61. IceCube-260111A: Upper limits from a search for additional neutrino events in IceCube
  62. Swift GRB260113.43: Global MASTER-Net observations report
  63. EP260110a: NOT and GTC Optical and Near-Infrared Observations
  64. EP260110a: TRT optical upper limits
  65. Konus-Wind detection of GRB 260101A
  66. GRB 260111A: Swift-XRT observations
  67. Swift Trigger 1439093: is probably not GRB 260113A
  68. GRB 260111A: COLIBRÍ optical afterglow candidate
  69. GRB 260111A: GECAM-B observation of a burst
  70. GRB 260111A: Fermi GBM Observation
  71. The EP-WXT trigger 01709251266 is likely a flaring star
  72. Swift Trigger 1434591 is not a GRB
  73. GRB 260111A: GOTO optical upper limits
  74. GRB 260112B: Fermi GBM Final Real-time Localization
  75. GRB 260111A: Swift ToO observations
  76. GRB 251230A: Mondy Optical Observations
  77. GRB 260111A: Swift/BAT-GUANO arcminute localization of a burst
  78. GRB 260112A: Fermi GBM Final Real-time Localization
  79. EP260110a: SVOM/VT optical upper limits
  80. IceCube-260111A - IceCube observation of a high-energy neutrino candidate track-like event
  81. IceCube Alert 260111A: Global MASTER-Net observations report
  82. EP260110a: Global MASTER-Net observations report
  83. Fermi GRB 260111A: Global MASTER-Net observations report
  84. GRB 260111A: Fermi GBM Final Real-time Localization
  85. Swift trigger 1436759 is not an astrophysical event
  86. EP260110a: KAIT optical upper limit
  87. EP260110a: refined analysis of the EP-WXT and EP-FXT observations
  88. EP 260110a: COLIBRÍ optical observations
  89. EP260110a: SVOM/C-GFT upper limit
  90. EP260110a: BOOTES-5/JGU optical upper limit
  91. EP260110a: Einstein Probe detection of an X-ray transient
  92. GRB 260109C: LCO optical upper limits
  93. GRB 260109C: Kilonova-Catcher optical upper limit
  94. EP260105b / GRB 260105C : Fermi-GBM Sub-Threshold Detection
  95. Swift Trigger 1434591: possible GRB 260109C
  96. GRB 260109B: Fermi GBM Final Real-time Localization
  97. GRB 260102A: Swift-XRT afterglow detection
  98. GRB 260109A: Fermi GBM Final Real-time Localization
  99. GRB 260104A: Swift-BAT refined analysis
  100. GRB 260101A: Swift-BAT refined analysis

Advanced

Download all Circulars as a .tar.gz archive (updated once a day):
Questions or comments?
Contact GCN directly.
Have you found a bug in GCN?
Open an issue.
Want to contribute code to GCN?
Get involved on GitHub.

gcn.nasa.gov

A service of the Astrophysics Science Division at NASA Goddard Space Flight Center

Looking for U.S. government information and services? Visit USA.gov