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"

41894 results found.

  1. GRB 260610B / AT 2026owq: COLIBRÍ optical observations
  2. GRB 260610B / AT2026owq: Early ATLAS observations
  3. GRB 260610B: TRT optical observation
  4. EP260610a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  5. GRB 260611A: Fermi GBM Final Real-time Localization
  6. EP260610b: COLIBRÍ optical observations
  7. GRB 260610B: DDOTI optical observations
  8. EP260610b: MAO/AZT-22 optical observations
  9. GRB 260610B: GOTO optical counterpart candidate
  10. EP260610b: NOT optical observation
  11. GRB 260610B: Fermi GBM Final Localization
  12. EP260610b: SVOM/VT optical confirmation with blue color
  13. IceCube-260610A - IceCube observation of a high-energy neutrino candidate track-like event
  14. GRB 260515A: SOAR optical observations
  15. EP260610b: Gemini North optical counterpart candidate
  16. EP260610a: SVOM/VT optical upper limits
  17. EP260610b: Einstein Probe detection of an X-ray transient
  18. Konus-Wind detection of GRB 260601A
  19. GRB 260610A: Fermi GBM Final Real-time Localization
  20. EP260610a: COLIBRÍ optical upper limits
  21. EP260610a: Einstein Probe detection of a fast X-ray transient
  22. GRB 260609A: Fermi GBM Final Localization
  23. Konus-Wind detection of GRB 260604C
  24. GRB 260608A: Fermi GRB Observation
  25. GRB 260604C: AstroSat CZTI detection
  26. GRB 260604C: SVOM/ECLAIRs refined analysis
  27. GRB 260608A: SVOM/ECLAIRs refined analysis
  28. Konus-Wind detection of GRB 260607B
  29. GRB 260607B: GECAM-B observation
  30. GRB 260608C: Fermi GBM Final Real-time Localization
  31. GRB 260604C: further SAO RAS optical observations
  32. GRB 260607A: AT2026ong (GOTO26fqf) is a type-Ia SN
  33. GRB 260607A / GOTO26fqf / AT2026ong: COLIBRÍ optical observations
  34. GRB 260608B: Fermi GBM Final Localization
  35. GRB 260604C: SVOM/COLIBRÍ (FM-GFT) colour evolution and confirmation of the late rebrightening
  36. GRB 260604C: SVOM/C-GFT upper limit
  37. GRB 260607B: AstroSat CZTI detection
  38. GRB 260608A: SVOM detection of a burst
  39. GRB 260608A: Fermi GBM Final Real-time Localization
  40. EP260605a: EP-FXT follow-up observation
  41. GRB 260607A: TRT optical observations
  42. GRB 260604C: GRANDMA further observations
  43. GRB 260607A: GOTO tentative optical counterpart candidate GOTO26fqf / AT2026ong
  44. GRB 260604A: SVOM/GRM detection
  45. GRB 260604C: Mondy optical observations: evidence of a possible brightening
  46. GRB 260607B: Fermi GBM Observation
  47. GRB 260607B: Fermi-LAT detection
  48. GRB 260607B: Fermi GBM Final Localization Correction
  49. GRB 260604C: Simeiz Zeiss-1000 optical observations of the afterglow
  50. GRB 260604C: OPD1.6m - GRANDMA observations - detection
  51. GRB 260607A: Fermi GBM Final Real-time Localization
  52. GRB 260604C: GECAM-B observation
  53. GRB 260604C: 6 GHz VLA observations
  54. GRB 260604C: SAO RAS optical observations
  55. GRB 260604C: GRANDMA observations
  56. GRB 260604B: SVOM/GRM detection
  57. GRB 260605A: Insight-HXMT/HE detection
  58. GRB260603A: SVOM/ECLAIRs refined analysis
  59. EP260605a: Einstein Probe detection of a fast X-ray transient
  60. EP260603a: COLIBRÍ optical upper limit
  61. GRB 260604A: Glowbug gamma-ray detection
  62. GRB 260604C: LCO optical upper limit
  63. GRB 260604C: Liverpool Telescope optical detection
  64. The EP-WXT trigger 01709267001 is likely a flaring star
  65. EP260602d: EP-FXT follow-up observation
  66. EP260602c: EP-FXT follow-up observation
  67. GRB 260601B / EP260601a: AstroSat CZTI detection
  68. GRB 260527A/EP260527a: 6 GHz VLA observations
  69. GRB 260604C: GOTO detections of the optical afterglow
  70. GRB 260604C: Kilonova-Catcher optical afterglow detection
  71. GRB 260604C: SVOM/COLIBRÍ (FM-GFT) optical observations
  72. The EP-WXT trigger 01709266798 is likely a flaring star
  73. GRB 260604C: Jinshan optical observations
  74. GRB 260604C: Fermi GBM Observation
  75. EP260602d: J-band upper limit with WINTER
  76. EP260602b: J-band upper limit with WINTER
  77. GRB 260604C: LAST detection of optical counterpart candidate
  78. GRB 260604C: MASTER OT J145749.59+284903.0 optical counterpart discovery
  79. Fermi GRB 260604C: Global MASTER-Net observations report
  80. Fermi GRB 260604C: Global MASTER-Net observations report
  81. SVOM GRB260604.85: Global MASTER-Net observations report
  82. GRB 260604C: SVOM detection of a long burst
  83. GRB 260604C: Fermi GBM Final Real-time Localization
  84. GRB 260515A: SVOM/VT optical detection at about 18 days post trigger
  85. GRB 260603A: NOT optical observations
  86. GRB 260603A: Simeiz Zeiss-1000 optical upper limit
  87. GRB 260604B: Fermi GBM Final Real-time Localization
  88. GRB 260601A: CALET Gamma-Ray Burst Monitor detection
  89. EP260602a: EP-FXT follow-up observation
  90. EP260603a: Global MASTER-Net observations report
  91. EP260603a: Einstein Probe detection of a fast X-ray transient
  92. EP260602d: Optical Upper limits with kinder observations
  93. GRB 260604A: Fermi GBM Final Real-time Localization
  94. EP260602b: Liverpool Telescope observations
  95. EP260602a: Liverpool Telescope optical upper limits
  96. EP260602b: Liverpool Telescope and LCO observations
  97. GRB 260603B: Fermi GBM Final Localization
  98. EP260602a: GTC and Liverpool Telescope optical observations
  99. Konus-Wind detection of GRB 260601B/EP260601a
  100. GRB 260603A: EP-FXT follow-up observation

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