Skip to main content
New! CHIME and DSA-110 FRB Notices, IceCube Notices and Schema v6.1.1. 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. FRB 20251229A: Updated CHIME/FRB Baseband Localization of FRB 20251229A
  2. EP260116A: 1.3m DFOT optical upper limit
  3. GRB 260114A: VLT/MUSE spectroscopic observations
  4. IceCube-260115A: Upper limits from a search for additional neutrino events in IceCube
  5. EP260116a: Global MASTER-Net observations report
  6. GRB 260111A: COLIBRÍ fading of the optical counterpart candidate
  7. EP260116a: Xinglong optical upper limit
  8. EP260116a: Einstein Probe detection of an X-ray transient
  9. GRB 260114A: VLT/HAWK-I further near-infrared upper limits
  10. IceCube Alert 260115.73: Global MASTER-Net observations report
  11. IceCube-260115A - IceCube observation of a high-energy neutrino candidate track-like event
  12. GRB 260115A: BALROG localization (Fermi Trigger 790192010 / GRB 260115741)
  13. IceCube: GCN Notices for high-energy track alerts now streamed via Kafka
  14. Fermi GRB 260115A: Global MASTER-Net observations report
  15. GRB 260115A: Fermi GBM Final Real-time Localization
  16. GRB260114A: STEP/T80S optical limits
  17. GRB 251222A: radio detection with the VLA
  18. GRB 260114A: VLT/HAWK-I near-infrared upper limits
  19. Konus-Wind detection of GRB 260114A
  20. GRB 260114A: Swift-XRT refined Analysis
  21. GRB 260114A: 6 GHz VLA observations
  22. GRB 260114A: VLT/X-shooter redshift of the putative host galaxy
  23. GRB 260114A : MITSuME Akeno optical upper limits
  24. GRB 260114A: COLIBRÍ optical upper limits
  25. GRB 260114A: TNG NIR upper limit
  26. GRB 260114A: NOT optical observations
  27. Konus-Wind detection of GRB 251230A / EP251230a
  28. GRB 260114A: SVOM/GRM observation of a short burst
  29. Swift GRB 260114A: Global MASTER-Net observations report
  30. GRB 260114A: GECAM-B observation of a short burst
  31. GRB 260114A: Mondy optical observations
  32. GRB 260114A: Fermi GBM observation
  33. GRB 260112B: GECAM-B observation
  34. GRB 260114A: GMG Optical Observation
  35. Fermi-LAT Gamma-ray Observations of IceCube-260111A
  36. GRB 260114A: Swift detection of a short burst
  37. GRB 260114A: Fermi GBM Final Real-time Localization
  38. EP-WXT trigger 01709251266: SVOM/C-GFT confirmation of a stellar flare
  39. IceCube-260111A: Upper limits from a search for additional neutrino events in IceCube
  40. Swift GRB260113.43: Global MASTER-Net observations report
  41. EP260110a: NOT and GTC Optical and Near-Infrared Observations
  42. EP260110a: TRT optical upper limits
  43. Konus-Wind detection of GRB 260101A
  44. GRB 260111A: Swift-XRT observations
  45. Swift Trigger 1439093: is probably not GRB 260113A
  46. GRB 260111A: COLIBRÍ optical afterglow candidate
  47. GRB 260111A: GECAM-B observation of a burst
  48. GRB 260111A: Fermi GBM Observation
  49. The EP-WXT trigger 01709251266 is likely a flaring star
  50. Swift Trigger 1434591 is not a GRB
  51. GRB 260111A: GOTO optical upper limits
  52. GRB 260112B: Fermi GBM Final Real-time Localization
  53. GRB 260111A: Swift ToO observations
  54. GRB 251230A: Mondy Optical Observations
  55. GRB 260111A: Swift/BAT-GUANO arcminute localization of a burst
  56. GRB 260112A: Fermi GBM Final Real-time Localization
  57. EP260110a: SVOM/VT optical upper limits
  58. IceCube-260111A - IceCube observation of a high-energy neutrino candidate track-like event
  59. IceCube Alert 260111A: Global MASTER-Net observations report
  60. EP260110a: Global MASTER-Net observations report
  61. Fermi GRB 260111A: Global MASTER-Net observations report
  62. GRB 260111A: Fermi GBM Final Real-time Localization
  63. Swift trigger 1436759 is not an astrophysical event
  64. EP260110a: KAIT optical upper limit
  65. EP260110a: refined analysis of the EP-WXT and EP-FXT observations
  66. EP 260110a: COLIBRÍ optical observations
  67. EP260110a: SVOM/C-GFT upper limit
  68. EP260110a: BOOTES-5/JGU optical upper limit
  69. EP260110a: Einstein Probe detection of an X-ray transient
  70. GRB 260109C: LCO optical upper limits
  71. GRB 260109C: Kilonova-Catcher optical upper limit
  72. EP260105b / GRB 260105C : Fermi-GBM Sub-Threshold Detection
  73. Swift Trigger 1434591: possible GRB 260109C
  74. GRB 260109B: Fermi GBM Final Real-time Localization
  75. GRB 260102A: Swift-XRT afterglow detection
  76. GRB 260109A: Fermi GBM Final Real-time Localization
  77. GRB 260104A: Swift-BAT refined analysis
  78. GRB 260101A: Swift-BAT refined analysis
  79. Swift GRB 251230A: Global MASTER-Net OT detection
  80. Fermi GRB 260107A: Global MASTER-Net observations report
  81. GRB 260102A: AbAO optical observations
  82. GRB 260107A: Fermi GBM Final Real-time Localization
  83. EP260105b/EP-WXT trigger 01709251028: Einstein Probe detection of an X-ray transient
  84. The EP-WXT trigger 01709251112 is likely a flaring star
  85. Fermi GRB 260105A: Global MASTER-Net observations report
  86. GRB 260105B: Fermi GBM Detection
  87. EP260105a: FTW optical observations
  88. EP260104a: FTW optical observations
  89. GRB 260105B: BALROG localization (Fermi Trigger 789348101 / GRB 260105973)
  90. GRB 260105A: SVOM/GRM observation
  91. GRB 260105B: SVOM/GRM observation
  92. The EP-WXT trigger 01709251028 is likely a flaring star
  93. FRB 20251229A: COLIBRÍ optical upper limits
  94. Fermi GRB 260105B: Global MASTER-Net observations report
  95. EP260105a: SVOM/VT optical upperlimit
  96. GRB 260105B: Fermi GBM Final Real-time Localization
  97. GRB 260105A: Fermi GBM Final Real-time Localization
  98. FRB 20251229A: A potentially hyperactive repeating fast radio burst source
  99. EP260105a: refined analysis of the EP-WXT and EP-FXT observations
  100. EP260105a: LCO Optical Upper limit

Advanced

Download all Circulars as a .tar.gz archive:
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