Skip to main content
JSON Notices via Email, Kafka Cron Jobs, Submitter Profile, GCN is Hiring. See news and announcements

GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

45706 results found.

  1. EP260409a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  2. EP260321a: Chandra X-ray Non-detection
  3. GRB 260409A: Fermi GBM Final Real-time Localization
  4. GRB 260310A/AT2026fgk: Kilonova-Catcher SN peak identification
  5. The EP-WXT trigger 01709259773 is likely a flaring star
  6. GRB 260407A: GECAM-A detection
  7. GRB 260407A: Insight-HXMT/HE detection
  8. EP260409a: SVOM/VT optical upper limits
  9. EP260409a: COLIBRÍ optical upper limits
  10. GRB 260407A: CALET Gamma-Ray Burst Monitor detection
  11. EP260409a: Global MASTER-Net observations report
  12. EP260409a: Einstein Probe detection of an X-ray transient
  13. EP260321a: VLA radio detection
  14. GRB 260404A: Fermi GBM Final Localization
  15. GRB 260407A: Glowbug gamma-ray detection
  16. GRB 260402A: SVOM/ECLAIRs refined analysis
  17. GRB 260310A: Continued VLA Multi-frequency Radio Observations
  18. GRB 260310A / AT2026fgk: X-ray rebrightening
  19. EP260402a / GRB 260402A: Mephisto optical upper limits
  20. EP-WXT01709259586: Xinglong optical upper limit
  21. EP260403a: Mephisto optical upper limits
  22. EP260402a/GRB 260402A: Xinglong optical upper limit
  23. EP260321a: Upper limits from VLA radio observations
  24. GRID detection of GRB 260401A
  25. EP260321a: uGMRT observations
  26. GRB 260407A: Fermi GBM Final Real-time Localization
  27. EP260405a: GMOS-N optical upper limits
  28. EP260405a: SVOM/VT optical upper limits
  29. EP260405a: Global MASTER-Net observations report
  30. EP260405a: Einstein Probe detection of a fast X-ray transient
  31. The EP-WXT trigger 01709259621 is likely a flaring star
  32. EP260405a / EP-WXT 11900672904: COLIBRÍ optical upper limits
  33. The EP-WXT trigger 01709259615 is likely a flaring star
  34. Fermi trigger No 797039833: Global MASTER-Net observations report
  35. GRB 260403A: GECAM-B observation of a long burst
  36. EP260324A / AT 2026hir: COLIBRÍ further optical observations
  37. Fermi Gamma-ray Burst Monitor trigger 796972356/260404217 is not a GRB
  38. EP260403a: refined analysis of the EP-WXT and EP-FXT observations
  39. The EP-WXT trigger 01709259586 is likely a flaring star
  40. GRB 260330B: SVOM/VT further optical observation
  41. Fermi Gamma-ray Burst Monitor trigger 796931884/260403749 is not a GRB
  42. GRB 260330B: SVOM/ECLAIRs refined analysis
  43. EP260403a: LCO optical observations of the counterpart
  44. GRB 260310A/AT2026fgk: Kilonova-Catcher long term optical monitoring
  45. EP260403a: LCO optical counterpart detection
  46. EP260403a: COLIBRÍ optical counterpart candidate
  47. GRB 260330B: SVOM/VT optical candidate
  48. EP260403a: Einstein Probe detection of an X-ray transient
  49. GRB 260330B: EP-FXT follow-up and identification of candidate afterglow
  50. GRB 260403A: AstroSat CZTI detection
  51. EP260402a/GRB 260402A: refined analysis of the EP-WXT and EP-FXT observations
  52. GRB 260402B: GECAM-B observation
  53. EP260402a/GRB 260402A: Jinshan near-infrared upper limit
  54. GRB 260402C: NuSTAR detection of prompt emission
  55. GRB 260402C: AstroSat CZTI detection of a long burst
  56. EP260324A / AT 2026hir: COLIBRÍ optical observations
  57. GRB 260403A: Fermi GBM Final Real-time Localization
  58. EP260324A / AT 2026hir: Spectroscopic Observations with the Next Generation Palomar Spectrograph
  59. GRB 260402B: Fermi GBM Final Real-time Localization
  60. GRB 260402A: WINTER J-band upper limit
  61. GRB260402A: GROWTH-India Telescope optical upper limit
  62. GRB 260402A / EP260402a: SVOM/VT optical upper limits
  63. EP260402a/GRB 260402A: SVOM/C-GFT upper limit
  64. GRB 260401A: SVOM/GRM observation
  65. GRB 260401A: GECAM-B observation
  66. EP260402a/GRB 260402A: Einstein Probe detection of an X-ray transient
  67. GRB 260402A: Kilonova-Catcher optical upper limit
  68. GRB 260402A: MASTER optical observations
  69. GRB 260402A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  70. GRB 260402A: SVOM/MXT candidate X-ray afterglow
  71. GRB 260402A: SVOM detection of a burst
  72. Fermi GRB 260401A: Global MASTER-Net observations report
  73. GRB 260401A: Fermi GBM Observation
  74. GRB 260401A: NuSTAR detection of prompt emission
  75. GRB 260401A: CALET Gamma-Ray Burst Monitor detection
  76. GRB 260401A: MAXI/GSC detection
  77. GRB 260401A: BALROG localization (Fermi Trigger 796733611 / GRB 260401454)
  78. GRB 260401A: Fermi GBM Final Real-time Localization
  79. EP260329b: Mondy and Assy-Turgen optical upper limits
  80. GRB 260310A / AT2026fgk: Luminance-band optical follow-up with a 28cm telescope in Daocheng
  81. EP260321a :Xinglong optical observations
  82. EP260327a: Xinglong optical upper limit
  83. EP260329b: GOTO detection of optical counterpart
  84. GRB 260330B: SVOM/VT optical upper limits
  85. Konus-Wind detection of GRB 260320A
  86. Konus-Wind detection of GRB 260316B (duplicate submission)
  87. Konus-Wind detection of GRB 260316B
  88. GRB 260321A: SVOM/ECLAIRs refined analysis
  89. EP260329b: J-band upper limits with WINTER
  90. EP260329a: J-band upper limit with WINTER
  91. GRB 260330A: Glowbug gamma-ray detection
  92. GRB 260310A: VLA Multi-frequency Radio Observations
  93. Fermi GBM Sub-Threshold Detection of GRB 260330B
  94. GRB 260330B: LCO optical upper limits
  95. GRB 260330B: SVOM detection of a burst
  96. EP260324a / AT2026hir: g- and r-band optical follow-up with the PKU 60cm Telescope
  97. EP260329b: refined analysis of the EP-WXT and EP-FXT observations
  98. EP260329a: COLIBRÍ optical upper limit
  99. EP260329a: EP-FXT follow up observation
  100. EP260329a: NOT optical counterpart candidate

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