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"

14822 results found.

  1. GRB 250926A: AstroSat CZTI detection
  2. GRB 250925A: COLIBRÍ photometric redshift
  3. IceCube-250926A - IceCube observation of a high-energy neutrino candidate track-like event
  4. GRB 250925A/EP250925a: EP-WXT detection
  5. GRB 250925A: 1.5m OSN optical detection and redshift with the 10.4m GTC/OSIRIS+
  6. GRB 250919A / EP250919a: Global MASTER Net before, during and after trigger optical observations
  7. GRB 250926A: Fermi GBM Final Real-time Localization
  8. GRB250925A: Liverpool Telescope optical observations
  9. GRB 250925A: Swift detection of a burst
  10. GRB 250924A: AstroSat CZTI detection
  11. GRB 250914A: AstroSat CZTI detection
  12. GRB 250920B: AstroSat CZTI detection
  13. GRB 250924A: Swift/UVOT Detection
  14. GRB 250924A: J-band detection with WINTER
  15. GRB 250924A: Mondy optical observations, afterglow fading
  16. GRB 250924A: Kilonova-Catcher optical afterglow detection
  17. GRB 250920C: Kilonova-Catcher optical afterglow detection
  18. GRB 250920C: TRT optical observation
  19. GRB 250924B: Fermi GBM Final Localization
  20. GRB 250924A: DDOTI Detection of the Optical Counterpart
  21. GRB 250924A: Swift detection of a burst with an optical counterpart
  22. Konus-Wind detection of GRB 250920C
  23. GRB 250920C: VLT redshift confirmation z = 1.399
  24. GRB 250922C: AstroSat CZTI detection of a short burst
  25. GRB 250922B: Fermi GBM Final Real-time Localization
  26. GRB 250920C: PRIME near-infrared detection
  27. Konus-Wind detection of GRB 250920B
  28. Konus-Wind detection of GRB 250920A
  29. IPN triangulation of GRB 250920A (long/bright)
  30. Konus-Wind detection of GRB 250911A
  31. GRB 250916A: Swift/UVOT Detection
  32. GRB 250920B: Glowbug gamma-ray detection
  33. GRB 250922A: Fermi GBM Final Localization
  34. GRB 250920C: GTC/OSIRIS+ spectroscopic redshift z = 1.40
  35. GRB 250920A: NuSTAR detection of bright prompt emission
  36. GRB 250920C: Swift/UVOT Detection
  37. GRB 250920A: Fermi GBM Detection
  38. GRB 250920B: Swift/UVOT Detection
  39. GRB 250920C: Optical counterpart detection by LCO
  40. GRB250920C: LCOGT Optical Detection
  41. GRB 250919A / EP250919a: LCO optical observation
  42. Konus-Wind detection of GRB 250919A
  43. GRB 250920C: Swift detection of a burst
  44. GRB 250920C: Fermi GBM Final Real-time Localization
  45. GRB 250919A / EP250919a: Insight-HXMT detection
  46. GRB 250920A: AstroSat CZTI detection
  47. GRB 250920B: Swift detection of a burst with a bright optical counterpart.
  48. GRB 250920B: Fermi GBM Final Real-time Localization
  49. GRB 250920A: Fermi GBM Final Localization
  50. GRB 250919A / EP250919a: MASTER bright afterglow detection 24h after GRB time
  51. GRB 250919A: Glowbug gamma-ray detection
  52. GRB 250919A / EP250919a: NuSTAR detection of bright prompt emission
  53. GRB 250919A/EP250919A: Swift/UVOT afterglow detection
  54. GRB 250919A: Swift-XRT afterglow detection
  55. GRB 250919A: Fermi-LAT detection
  56. EP250919a: Einstein Probe detection of an X-ray transient
  57. GRB 250919A: Fermi GBM Final Real-time Localization
  58. GRB 250916A: NuSTAR detection of the prompt emission
  59. GRB 250918A: Fermi GBM Final Real-time Localization
  60. EP250916a: EP-FXT follow-up observation
  61. GRB 250916A: Glowbug gamma-ray detection
  62. GRB250917B: WFST optical observations
  63. GRB 250917B: Swift detection of a short burst
  64. GRB 250916A: GOTO optical counterpart candidate
  65. GRB 250917B: Fermi GBM Final Real-time Localization
  66. GRB 250917A: Fermi GBM Final Real-time Localization
  67. GRB 250916A: AstroSat CZTI detection of a bright long burst
  68. EP250916a: Einstein Probe detection of an X-ray transient
  69. GRB 250916A: Fermi GBM Final Real-time Localization
  70. SVOM/sb25091517: SVOM detection of an X-ray transient
  71. GRB 250912A: VLT observations
  72. GRB 250911A: Insight-HXMT detection
  73. GRB 250912A: SVOM detection of a burst
  74. GRB 250912A: Fermi GBM Final Real-time Localization
  75. GRB 250911A: GECAM-B detection
  76. EP250911a: GTC/OSIRIS+ spectroscopic redshift z = 3.84
  77. GRB 250910C: Fermi GBM Final Localization Correction
  78. EP250911a: Optical detection with Kinder observations
  79. GRB 250911A: Swift/UVOT Detection
  80. GRB 250910A / EP250910a: Swift-XRT afterglow detection
  81. GRB 250909B: Insight-HXMT detection
  82. GRB 250910A / EP250910a : VLT/HAWK-I NIR counterpart discovery
  83. EP250911a: LCO optical counterpart discovery
  84. EP250911a: Einstein Probe detection of an X-ray transient
  85. GRB 250911A: Swift detection of a burst
  86. GRB 250910B: Fermi GBM Final Real-time Localization
  87. EP250910a/GRB 250910A: EP-WXT detection of a fast X-ray transient
  88. GRB 250909B: AstroSat CZTI detection of a long burst
  89. GRB 250909A: AstroSat CZTI detection
  90. GRB 250910A: SVOM/MXT possible afterglow detection
  91. GRB 250910A: SVOM detection of a faint burst
  92. LIGO/Virgo/KAGRA S250910b: Retraction of GW compact binary merger candidate
  93. EP250908b/EP#01709240653: Swift/UVOT Detection
  94. GRB 250907A: CALET Gamma-Ray Burst Monitor detection
  95. EP250908c: Einstein Probe detection of an X-ray transient
  96. GRB 250909A: Fermi GBM Final Real-time Localization
  97. EP250908b: EP-WXT detection of a fast X-ray transient and EP-FXT observation
  98. GRB 250907A: GECAM-B detection
  99. GRB 250903A: Swift-XRT afterglow detection
  100. SVOM/sb25090605: detection of an X-ray transient from the LMXB 4U 0513-40

Advanced

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