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"

45758 results found.

  1. Fermi GRB 260412A: Global MASTER-Net observations report
  2. GRB 260412A: Fermi GBM Observation
  3. GRB 260310A / AT2026fgk: NuSTAR detection of the rebrightening
  4. GRB 260411B: Fermi-LAT detection
  5. GRB 260412A: SVOM detection of a long burst
  6. GRB 260412A: Fermi GBM Final Real-time Localization
  7. GRB 260411B: COLIBRÍ optical observations
  8. GRB 260410B: Fermi GBM Observation
  9. GRB 260411B: Ondrejov D50 optical afterglow detection
  10. GRB260411B: 3.6m DOT optical observation
  11. GRB 260411A: SVOM/GRM observation
  12. GRB 260407B: SVOM/GRM detection of a possible magnetar X-ray burst
  13. GRB 260411B: SVOM/GRM observation of a long burst
  14. GRB 260409A: Insight-HXMT/HE detection
  15. GRB 260411B: Fermi GBM Detection
  16. GRB 260411B: GOTO optical counterpart candidate
  17. EP260409a: Gemini/FLAMINGOS2 J-band counterpart
  18. GRB 260411B: BALROG localization (Fermi Trigger 797587480 / GRB 260411337)
  19. GRB 260411B: Fermi GBM Final Real-time Localization
  20. GRB 260411A: Fermi GBM Final Real-time Localization
  21. GRB 260410A: COLIBRÍ optical upper limit
  22. EP-WXT01709259790: Optical Upper limits with kinder observations
  23. GRB 260410A: Fermi GBM Observation
  24. GRB 260410B: SVOM/GRM detection of a short faint burst
  25. The EP-WXT trigger 01709259790 is likely a flaring star
  26. GRB 260410B: Fermi GBM Final Real-time Localization
  27. EP-WXT01709259790: Xinglong optical upper limit
  28. GRB 260410A: Fermi-LAT detection
  29. GRB 260410A: Fermi GBM Final Real-time Localization
  30. EP260409a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  31. EP260321a: Chandra X-ray Non-detection
  32. GRB 260409A: Fermi GBM Final Real-time Localization
  33. GRB 260310A/AT2026fgk: Kilonova-Catcher SN peak identification
  34. The EP-WXT trigger 01709259773 is likely a flaring star
  35. GRB 260407A: GECAM-A detection
  36. GRB 260407A: Insight-HXMT/HE detection
  37. EP260409a: SVOM/VT optical upper limits
  38. EP260409a: COLIBRÍ optical upper limits
  39. GRB 260407A: CALET Gamma-Ray Burst Monitor detection
  40. EP260409a: Global MASTER-Net observations report
  41. EP260409a: Einstein Probe detection of an X-ray transient
  42. EP260321a: VLA radio detection
  43. GRB 260404A: Fermi GBM Final Localization
  44. GRB 260407A: Glowbug gamma-ray detection
  45. GRB 260402A: SVOM/ECLAIRs refined analysis
  46. GRB 260310A: Continued VLA Multi-frequency Radio Observations
  47. GRB 260310A / AT2026fgk: X-ray rebrightening
  48. EP260402a / GRB 260402A: Mephisto optical upper limits
  49. EP-WXT01709259586: Xinglong optical upper limit
  50. EP260403a: Mephisto optical upper limits
  51. EP260402a/GRB 260402A: Xinglong optical upper limit
  52. EP260321a: Upper limits from VLA radio observations
  53. GRID detection of GRB 260401A
  54. EP260321a: uGMRT observations
  55. GRB 260407A: Fermi GBM Final Real-time Localization
  56. EP260405a: GMOS-N optical upper limits
  57. EP260405a: SVOM/VT optical upper limits
  58. EP260405a: Global MASTER-Net observations report
  59. EP260405a: Einstein Probe detection of a fast X-ray transient
  60. The EP-WXT trigger 01709259621 is likely a flaring star
  61. EP260405a / EP-WXT 11900672904: COLIBRÍ optical upper limits
  62. The EP-WXT trigger 01709259615 is likely a flaring star
  63. Fermi trigger No 797039833: Global MASTER-Net observations report
  64. GRB 260403A: GECAM-B observation of a long burst
  65. EP260324A / AT 2026hir: COLIBRÍ further optical observations
  66. Fermi Gamma-ray Burst Monitor trigger 796972356/260404217 is not a GRB
  67. EP260403a: refined analysis of the EP-WXT and EP-FXT observations
  68. The EP-WXT trigger 01709259586 is likely a flaring star
  69. GRB 260330B: SVOM/VT further optical observation
  70. Fermi Gamma-ray Burst Monitor trigger 796931884/260403749 is not a GRB
  71. GRB 260330B: SVOM/ECLAIRs refined analysis
  72. EP260403a: LCO optical observations of the counterpart
  73. GRB 260310A/AT2026fgk: Kilonova-Catcher long term optical monitoring
  74. EP260403a: LCO optical counterpart detection
  75. EP260403a: COLIBRÍ optical counterpart candidate
  76. GRB 260330B: SVOM/VT optical candidate
  77. EP260403a: Einstein Probe detection of an X-ray transient
  78. GRB 260330B: EP-FXT follow-up and identification of candidate afterglow
  79. GRB 260403A: AstroSat CZTI detection
  80. EP260402a/GRB 260402A: refined analysis of the EP-WXT and EP-FXT observations
  81. GRB 260402B: GECAM-B observation
  82. EP260402a/GRB 260402A: Jinshan near-infrared upper limit
  83. GRB 260402C: NuSTAR detection of prompt emission
  84. GRB 260402C: AstroSat CZTI detection of a long burst
  85. EP260324A / AT 2026hir: COLIBRÍ optical observations
  86. GRB 260403A: Fermi GBM Final Real-time Localization
  87. EP260324A / AT 2026hir: Spectroscopic Observations with the Next Generation Palomar Spectrograph
  88. GRB 260402B: Fermi GBM Final Real-time Localization
  89. GRB 260402A: WINTER J-band upper limit
  90. GRB260402A: GROWTH-India Telescope optical upper limit
  91. GRB 260402A / EP260402a: SVOM/VT optical upper limits
  92. EP260402a/GRB 260402A: SVOM/C-GFT upper limit
  93. GRB 260401A: SVOM/GRM observation
  94. GRB 260401A: GECAM-B observation
  95. EP260402a/GRB 260402A: Einstein Probe detection of an X-ray transient
  96. GRB 260402A: Kilonova-Catcher optical upper limit
  97. GRB 260402A: MASTER optical observations
  98. GRB 260402A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  99. GRB 260402A: SVOM/MXT candidate X-ray afterglow
  100. GRB 260402A: SVOM detection of a burst

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