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"

11528 results found.

  1. GRB 260829A: Fermi GBM Final Real-time Localization
  2. Fermi GBM trigger 809666623/260829141 is not a GRB
  3. IceCube-260827A - IceCube observation of a high-energy neutrino candidate track-like event
  4. GRB 260827A: Fermi GBM Final Real-time Localization
  5. GRB 260809A: SVOM/ECLAIRs refined analysis
  6. GRB 260825A: Fermi GBM Final Real-time Localization
  7. IceCube-260825A - IceCube observation of a high-energy neutrino candidate track-like event
  8. GRB260822B: Fermi GBM Final Localization
  9. Fermi-LAT Gamma-ray Observations of IceCube-260821A
  10. Fermi-LAT Gamma-ray Observations of IceCube-260807A
  11. GRB 260820A: Insight-HXMT/HE detection
  12. IceCube-260821A - IceCube observation of a high-energy neutrino candidate track-like event
  13. GRB260820A: Fermi GBM Final Real-Time Localization
  14. GRB 260805D: SVOM/GRM detection of a possible magnetar burst
  15. GRB 260813A: BALROG localization (Fermi Trigger 808341387 / GRB 260813803)
  16. GRB 260813A: Fermi GBM Final Real-time Localization
  17. GRB 260808A: SVOM/GRM observation
  18. Fermi GBM Sub-Threshold Detection of GRB 260809A
  19. GRB 260317A: SVOM/ECLAIRs detection through offline targeted search and its possible association to magnetar 1E 1841-04.5
  20. GRB 260808A: GECAM-B observation
  21. GRB 250607A: SVOM/ECLAIRs detection through offline targeted search
  22. GRB 260808A: CALET Gamma-Ray Burst Monitor detection
  23. GRB 260804A: CALET Gamma-Ray Burst Monitor detection
  24. GRB 260808A: NuSTAR detection of prompt emission
  25. GRB 260808C: Fermi GBM Final Real-time Localization
  26. GRB 260808A: BALROG localization (Fermi Trigger 807850307 / GRB 260808119)
  27. Fermi GRB 260808A: Global MASTER-Net observations report
  28. GRB 260808A: Fermi GBM Final Real-time Localization
  29. IceCube-260807A - IceCube observation of a high-energy neutrino candidate track-like event
  30. GRB 260715A: cubesat Avion detection
  31. GRB 260709A: cubesat Avion detection
  32. GRB 260708A: cubesat Avion detection
  33. SN 2026stf / GRB 260708A: ATLAS forced photometry
  34. IceCube-260805A - IceCube observation of a high-energy neutrino candidate track-like event
  35. GRB 260805B: Glowbug gamma-ray detection
  36. Fermi GRB 260805A: Global MASTER-Net observations report
  37. GRB 260805B: Fermi GBM Final Localization
  38. GRB 260804A: Glowbug gamma-ray detection
  39. GRB 260805B: BALROG localization (Fermi Trigger 807622617 / GRB 260805484)
  40. GRB 260805A: Fermi GBM Final Localization
  41. GRB 260708A / SN 2026stf: Spectroscopic host redshift z = 0.055 and confirmation of an associated type Ic-BL supernova
  42. GRB 260804A: Fermi GBM Final Real-time Localization
  43. GRB 260708A: LCO further optical observations show supernova features
  44. GRB 260803A: Fermi GBM Final Real-time Localization
  45. Fermi GRB 260802B: Global MASTER-Net observations report
  46. GRB 260802B: Fermi GBM Final Localization
  47. GRB 260618B: SVOM/VT continued optical observations indicated a steeper and redder decay
  48. Fermi-LAT Gamma-ray Observations of IceCube-260722A
  49. GRB 260726A: SVOM/ECLAIRs refined analysis
  50. GRB260730A: Fermi GBM Final Localization
  51. GRB 260726A: EP-FXT follow-up observations
  52. GRB 260726A: Fermi GBM Observation
  53. GRB 260726A: Liverpool Telescope optical observations
  54. GRB 260728A: Fermi GBM Final Localization
  55. GRB 260726A: J-band upper limit with WINTER
  56. GRB 260726A: SVOM/VT optical candidate
  57. GRB 260727B: Fermi GBM Final Real-time Localization
  58. Fermi GRB 260726A: Global MASTER-Net observations report
  59. GRB 260726A: SVOM detection of a burst
  60. GRB 260726A: Fermi GBM Final Real-time Localization
  61. GRB 260616A: cubesat Avion detection
  62. GRB 260602B: cubesat Avion detection
  63. GRB 260601A: cubesat Avion detection
  64. GRB 260718A: SVOM/ECLAIRs refined analysis
  65. Fermi Gamma-ray Burst Monitor trigger 806592752 / 260724564 is not a GRB
  66. GRB 260723A: Fermi GBM Final Localization
  67. GRB 260722A: Fermi GBM Final Real-time Localization
  68. IceCube-260722A - IceCube observation of a high-energy neutrino candidate track-like event
  69. Fermi GBM trigger 806384210/260722151 is not a GRB
  70. Konus-Wind detection of GRB 260714B
  71. GRB 260714B: Insight-HXMT/HE detection
  72. GRB 260718A: EP-FXT follow-up observation
  73. Fermi trigger No 806104130: Global MASTER-Net observations report
  74. Fermi GRB 260718A: Global MASTER-Net observations report
  75. GRB 260718A: LCO optical upper limits
  76. GRB 260710A: SVOM/GRM observation
  77. GRB 260718A: Fermi GBM Observation
  78. GRB 260714B: SVOM/GRM observation
  79. GRB 260310A / AT2026fgk: Late-time Chandra Detection
  80. GRB 260714B: GECAM-B observation of a burst
  81. GRB 260618B: EP-FXT follow-up observation upper limit
  82. GRB 260714B: COLIBRÍ optical counterpart candidate
  83. GRB 260715A: Fermi GBM Final Real-time Localization
  84. GRB 260710A: AstroSat CZTI detection
  85. GRB 260709A: AstroSat CZTI detection
  86. GRB 260714B: AstroSat CZTI detection
  87. GRB 260714B: Fermi-LAT detection
  88. GRB 260714B: Fermi GBM Detection
  89. GRB 260714B: BALROG localization (Fermi Trigger 805746211 / GRB 260714766)
  90. GRB 260714B: Fermi GBM Final Real-time Localization
  91. GRB 260706A: ATCA detection of possible radio counterpart
  92. GRB 260705A: ATCA radio observations
  93. GRB 260714A: Fermi GBM Final Real-time Localization
  94. GRB 260619A: SVOM/VT continuous optical observations
  95. GRB 260618B: SVOM/VT optical observations indicate shallow decay and reddening
  96. GRB 260708A: slowly decaying X-ray emission observed by EP/FXT
  97. GRB 260708A: GRANDMA Optical Observations
  98. Fermi-LAT Gamma-ray Observations of IceCube-260712A
  99. Fermi-LAT Gamma-ray Observations of IceCube-260708A
  100. GRB 260710A: Insight-HXMT/HE detection

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