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"

5154 results found.

  1. Fermi GRB 260601A: Global MASTER-Net observations report
  2. Fermi trigger No 801900520: Global MASTER-Net observations report
  3. GRB 260531B: Fermi GBM Final Real-time Localization
  4. IPN triangulation of GRB 260527A / EP260527a
  5. EP260527a/GRB 260527A: optical upper limit with Kinder observations
  6. Fermi trigger No 801580882: Global MASTER-Net observations report
  7. Fermi GRB 260526A: Global MASTER-Net observations report
  8. Fermi GRB 260522A: Global MASTER-Net observations report
  9. GRB 260511A: iTelescope T-75 optical detection
  10. GRB 260520A: Fermi GBM Final Localization
  11. Konus-Wind detection of GRB 260518A
  12. GRB 260421B: radio detection with the VLA
  13. Fermi GRB 260516C: Global MASTER-Net observations report
  14. Fermi GRB 260516B: Global MASTER-Net observations report
  15. SVOM GRB 260515A: Global MASTER-Net observations report
  16. EP260514a: Global MASTER-Net observations report
  17. GRB 260513A: Fermi GBM Final Real-time Localization
  18. Konus-Wind detection of GRB 260511B
  19. GRB 260511B: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  20. GRB 260511B: SAO RAS optical observations
  21. GRB 260511B: SVOM/COLIBRÍ (FM-GFT) optical observations
  22. GRB 260510C: AstroSat CZTI detection
  23. Fermi GRB 260511A: Global MASTER-Net observations report
  24. GRB 260511A: LCO optical afterglow detection
  25. GRB 260510C: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  26. GRB 260510C: MAXI/GSC detection
  27. SVOM GRB 260509A: MASTER-OAFA optical observation
  28. Fermi GRB 260510A: Global MASTER-Net observations report
  29. GRB 260509A: SVOM/COLIBRÍ (FM-GFT) observations
  30. EP260502a is likely a flaring star
  31. GRB 260421B: radio observation with the VLA
  32. IPN triangulation of GRB 260429A
  33. EP260502a: BOOTES-7 observations of a fading catalogued source close to the X-ray position
  34. GRB 260429A: SVOM/GRM observation of a short burst
  35. SN 2026kid: Optical follow-up with small-aperture telescopes in Spain and China
  36. GRB 260424B: AstroSat CZTI detection
  37. GRB 260429A: Fermi GBM Detection
  38. GRB 260429A: Fermi GBM Final Real-time Localization
  39. IceCube-260425A: Upper limits from a search for additional neutrino events in IceCube
  40. GRB 260424B: Glowbug gamma-ray detection of a short burst
  41. Konus-Wind detection of GRB 260424B
  42. GRB 260424C: Fermi GBM Final Localization
  43. IPN triangulation of GRB 260424B (short)
  44. GRB 260401A: cubesat Avion detection
  45. GRB 260424A: AstroSat CZTI detection of a long burst
  46. GRB 260421B: 3.6m DOT optical observation
  47. EP-WXT trigger 01709260362: FRAM-ORM optical observations confirm flaring star G 151-9
  48. Fermi GRB 260421C: Global MASTER-Net observations report
  49. Fermi GRB 260421B: Global MASTER-Net observations report
  50. EP260416a: Optical follow-up observations with Kinder
  51. Fermi GRB 260417B: Global MASTER-Net observations report
  52. EP260417a: Global MASTER-Net observations report
  53. EP260417a/GRB 260417A: refined analysis of the EP-WXT and follow-up EP-FXT observations
  54. Fermi GRB 260417A: Global MASTER-Net observations report
  55. EP260416a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  56. GRB 260411B: COLIBRÍ optical observations
  57. EP260405a: Global MASTER-Net observations report
  58. The EP-WXT trigger 01709259621 is likely a flaring star
  59. Fermi trigger No 797039833: Global MASTER-Net observations report
  60. GRB 260401A: SVOM/GRM observation
  61. GRB 260402A: SVOM/MXT candidate X-ray afterglow
  62. EP260329b: Mondy and Assy-Turgen optical upper limits
  63. GRB 260310A / AT2026fgk: Luminance-band optical follow-up with a 28cm telescope in Daocheng
  64. Fermi trigger No 796485221: Global MASTER-Net observations report
  65. EP260327a: COLIBRÍ optical upper limits
  66. EP260327a: Global MASTER-Net observations report
  67. IPN triangulation of GRB 260316B
  68. EP260321a: J-band observations by the SYSU 80 cm infrared telescope
  69. Fermi Gamma-ray Burst Monitor trigger 796060650/260324665 is not a GRB
  70. EP260321a: VLT/FORS2 spectroscopy confirmation of an associated type Ic-BL supernova SN 2026gzf
  71. GRB 260321A: SVOM/COLIBRÍ (FM-GFT) optical upper limits at the FXT positions
  72. EP-WXT trigger 01709259112: confirmation of a stellar flare by BOOTES-5 & BOOTES-7
  73. Fermi GRB 260323A: Global MASTER-Net observations report
  74. EP260321a: COLIBRÍ optical upper limit on any supernova shock breakout emission
  75. IceCube-260315A: COLIBRÍ optical observations
  76. Fermi trigger No 795185313: Global MASTER-Net observations report
  77. IceCube Alert 260315A: Global MASTER-Net observations report
  78. Fermi GRB 260314A: Global MASTER-Net observations report
  79. Fermi GRB 260313A: Global MASTER-Net observations report
  80. GRB 260310A: potential optical counterpart
  81. Fermi GRB 260311B: Global MASTER-Net observations report
  82. GRB 260311B: Fermi GBM Final Real-time Localization
  83. EP260306a: Mondy optical upper limit
  84. Fermi GRB 260310B: Global MASTER-Net observations report
  85. GRB 260307B: SVOM/ECLAIRs refined analysis
  86. GRB 260208A: radio detection with the VLA
  87. GRB 260207A: TESS Detection and Possible VLA Counterpart
  88. GRB 260303B: AstroSat CZTI detection
  89. GRB 260304A: AstroSat CZTI detection of a long burst
  90. GRB 260303B: NuSTAR detection of prompt emission
  91. GRB 260303B: BALROG localization (Fermi Trigger 794237065 / GRB 260303559)
  92. GRB 260303B: Fermi GBM Final Real-time Localization
  93. GRB 260303A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  94. EP260227A: 3.6m DOT optical afterglow detection
  95. EP/WXT trigger 01709258681 (EP260227a?): LCO candidate afterglow
  96. LAT GRB260226.44: Global MASTER-Net observations report
  97. EP260214a: VLA 6 GHz detection
  98. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) Detection of an Optical Counterpart Candidate
  99. EP260126a: VLA 6 GHz detection
  100. EP260223a: Liverpool Telescope upper limits

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