Skip to main content
New! BOOM Notices and Schema v7.0.0. 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"

27397 results found.

  1. GRB 260402A: SVOM/ECLAIRs refined analysis
  2. GRB 260310A: Continued VLA Multi-frequency Radio Observations
  3. EP260402a / GRB 260402A: Mephisto optical upper limits
  4. EP-WXT01709259586: Xinglong optical upper limit
  5. EP260403a: Mephisto optical upper limits
  6. EP260402a/GRB 260402A: Xinglong optical upper limit
  7. EP260405a: GMOS-N optical upper limits
  8. EP260405a: Global MASTER-Net observations report
  9. EP260405a: Einstein Probe detection of a fast X-ray transient
  10. EP260405a / EP-WXT 11900672904: COLIBRÍ optical upper limits
  11. Fermi trigger No 797039833: Global MASTER-Net observations report
  12. EP260324A / AT 2026hir: COLIBRÍ further optical observations
  13. EP260403a: refined analysis of the EP-WXT and EP-FXT observations
  14. The EP-WXT trigger 01709259586 is likely a flaring star
  15. GRB 260330B: SVOM/VT further optical observation
  16. EP260403a: LCO optical observations of the counterpart
  17. GRB 260310A/AT2026fgk: Kilonova-Catcher long term optical monitoring
  18. EP260403a: LCO optical counterpart detection
  19. EP260403a: COLIBRÍ optical counterpart candidate
  20. GRB 260330B: SVOM/VT optical candidate
  21. EP260403a: Einstein Probe detection of an X-ray transient
  22. GRB 260330B: EP-FXT follow-up and identification of candidate afterglow
  23. EP260402a/GRB 260402A: refined analysis of the EP-WXT and EP-FXT observations
  24. EP260402a/GRB 260402A: Jinshan near-infrared upper limit
  25. GRB 260402C: NuSTAR detection of prompt emission
  26. GRB 260402C: AstroSat CZTI detection of a long burst
  27. EP260324A / AT 2026hir: COLIBRÍ optical observations
  28. GRB 260402A: WINTER J-band upper limit
  29. GRB260402A: GROWTH-India Telescope optical upper limit
  30. GRB 260402A / EP260402a: SVOM/VT optical upper limits
  31. EP260402a/GRB 260402A: SVOM/C-GFT upper limit
  32. GRB 260401A: SVOM/GRM observation
  33. EP260402a/GRB 260402A: Einstein Probe detection of an X-ray transient
  34. GRB 260402A: Kilonova-Catcher optical upper limit
  35. GRB 260402A: MASTER optical observations
  36. GRB 260402A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  37. GRB 260402A: SVOM/MXT candidate X-ray afterglow
  38. GRB 260402A: SVOM detection of a burst
  39. Fermi GRB 260401A: Global MASTER-Net observations report
  40. GRB 260401A: Fermi GBM Observation
  41. GRB 260401A: NuSTAR detection of prompt emission
  42. GRB 260401A: CALET Gamma-Ray Burst Monitor detection
  43. GRB 260401A: MAXI/GSC detection
  44. GRB 260401A: BALROG localization (Fermi Trigger 796733611 / GRB 260401454)
  45. GRB 260401A: Fermi GBM Final Real-time Localization
  46. EP260329b: Mondy and Assy-Turgen optical upper limits
  47. GRB 260310A / AT2026fgk: Luminance-band optical follow-up with a 28cm telescope in Daocheng
  48. EP260321a :Xinglong optical observations
  49. EP260327a: Xinglong optical upper limit
  50. GRB 260330B: SVOM/VT optical upper limits
  51. Konus-Wind detection of GRB 260320A
  52. GRB 260321A: SVOM/ECLAIRs refined analysis
  53. EP260329b: J-band upper limits with WINTER
  54. EP260329a: J-band upper limit with WINTER
  55. GRB 260330A: Glowbug gamma-ray detection
  56. Fermi GBM Sub-Threshold Detection of GRB 260330B
  57. GRB 260330B: LCO optical upper limits
  58. EP260324a / AT2026hir: g- and r-band optical follow-up with the PKU 60cm Telescope
  59. EP260329b: refined analysis of the EP-WXT and EP-FXT observations
  60. EP260329a: COLIBRÍ optical upper limit
  61. EP260329a: EP-FXT follow up observation
  62. EP260329a: NOT optical counterpart candidate
  63. EP260329b: Global MASTER-Net observations report
  64. Fermi trigger No 796485221: Global MASTER-Net observations report
  65. GRB 260327A: Insight-HXMT/HE detection
  66. EP260329b: Optical follow-up with Kinder observations
  67. EP 260329b: COLIBRÍ optical observations
  68. EP260329a: Optical upper limit with Kinder observations
  69. EP260329b: LCO optical observations of the counterpart
  70. GRB 260326A: Insight-HXMT/HE detection
  71. EP260329b: Einstein Probe detection of an X-ray transient
  72. EP260329a: Einstein Probe detection of an X-ray transient
  73. EP-WXT trigger 01709259209: TRT optical counterpart detection
  74. The EP-WXT trigger 01709259209 (EP260329b?): Las Cumbres discovery of the optical counterpart
  75. EP260327a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  76. EP260327a: SVOM/VT optical upper limits
  77. EP260327a: WINTER J-band upper limit
  78. EP260327a: COLIBRÍ optical upper limits
  79. EP260327a: Gemini-North optical upper limits
  80. EP260324a: GROWTH-India Telescope optical observation
  81. EP260327a: Global MASTER-Net observations report
  82. EP260327a: Einstein Probe detection of an X-ray transient
  83. GRB 260310A / AT 2026fgk: COLIBRÍ photometric evidence of the emerging supernova
  84. GRB 260310A / AT2026fgk: Late-time infrared detection with MIRAGE on the MDM 1.3m telescope
  85. EP260324a: ZTF discovery of the optical counterpart ZTF26aapviim/AT2026hir
  86. GRB 260310A / AT2026fgk: R- and I-band observations with the PKU 60 cm optical telescope
  87. GRB 260326A: Fermi GBM Detection
  88. EP260321a: JinShan near-infrared observations
  89. EP260321a: Upper limits from a neutrino search with IceCube
  90. GRB 260310A/AT2026fgk: Kilonova-Catcher late optical afterglow detection at about 15 days post trigger time
  91. EP260321a: J-band observations by the SYSU 80 cm infrared telescope
  92. GRB 260321A: SVOM/COLIBRÍ (FM-GFT) optical upper limits at the FXT positions
  93. EP-WXT trigger 01709259112: confirmation of a stellar flare by BOOTES-5 & BOOTES-7
  94. Fermi GRB 260323A: Global MASTER-Net observations report
  95. GRB260310A: Palomar 60-inch photometry of an extremely bright late-time afterglow with a temporal break at 8 days
  96. GRB 260320A: Glowbug gamma-ray detection
  97. EP260321a: COLIBRÍ further optical observations and brightening
  98. EP260321a: Continued brightening from Kinder follow-up of the emerging supernova candidate
  99. EP260321a: Early TRT rising followed by JinShan decaying and then re-rising
  100. GRB 260321A: EP-FXT follow-up observation

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