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"

8474 results found.

  1. GRB 260731A: AstroSat CZTI detection of a long burst
  2. GRB 260730B: AstroSat CZTI detection
  3. EP260727a: SAO RAS optical observations
  4. GRB 260727A: AbAO and SAO RAS optical observations
  5. EP260727a: 1.5m OSN optical counterpart detection
  6. EP260727a: OHP/T193 optical observations
  7. GRB 260726A: Liverpool Telescope optical observations
  8. GRB 260726A: J-band upper limit with WINTER
  9. GRB 260726A: SVOM/VT optical candidate
  10. GRB 260727A: AstroSat CZTI detection
  11. IceCube-260722A: Upper limits from a search for additional neutrino events in IceCube
  12. IceCube-260722A: One candidate from the Zwicky Transient Facility (ZTF)
  13. IceCube-260722A - IceCube observation of a high-energy neutrino candidate track-like event
  14. GRB 260618B: EP-FXT follow-up observation upper limit
  15. GRB 260714B: COLIBRÍ optical counterpart candidate
  16. IceCube-260712A: No candidates with the Zwicky Transient Facility (ZTF)
  17. GRB 260710A: AstroSat CZTI detection
  18. GRB 260709A: AstroSat CZTI detection
  19. GRB 260714B: AstroSat CZTI detection
  20. IceCube-260712A: Upper limits from a search for additional neutrino events in IceCube
  21. IceCube-260712A: LAST optical follow-up observations of the IceCube neutrino candidate
  22. GRB 260705A: ATCA radio observations
  23. GRB 260619A: SVOM/VT continuous optical observations
  24. GRB 260618B: SVOM/VT optical observations indicate shallow decay and reddening
  25. GRB 260708A: GRANDMA Optical Observations
  26. Fermi-LAT Gamma-ray Observations of IceCube-260708A
  27. IceCube-260708A: Upper limits from a search for additional neutrino events in IceCube
  28. IceCube-260712A - IceCube observation of a high-energy neutrino candidate track-like event
  29. EP-WXT trigger 0170924151 : RAPAS optical counterpart candidate detection
  30. GRB 260705C: AstroSat CZTI detection
  31. GRB 260708A: Kilonova-Catcher optical afterglow detection
  32. IceCube-260708A: One candidate from the Zwicky Transient Facility
  33. IceCube-260708A - IceCube observation of a high-energy neutrino candidate track-like event
  34. EP260707a is not a real source
  35. GRB 260705A: Candidate Optical Counterpart from SOAR and Gemini-South and Possible Association with GRB 260705B
  36. GRB 260704A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  37. IceCube-260704A: No candidates from the Zwicky Transient Facility
  38. The EP-WXT trigger 01709274151 is likely a flaring star
  39. IceCube-260704A: Upper limits from a search for additional neutrino events in IceCube
  40. Fermi GBM Sub-Threshold Detection of GRB 260705A
  41. IceCube-260704A - IceCube observation of a high-energy neutrino candidate track-like event
  42. GRB 260629A: AstroSat CZTI detection
  43. IceCube-260622A: Upper limits from a search for additional neutrino events in IceCube
  44. IceCube-260622A - IceCube observation of a high-energy neutrino candidate track-like event
  45. IceCube-Cascade 260618A: Upper limits from a search for additional neutrino events in IceCube
  46. GRB 260619A: SVOM/VT optical counterpart confirmation
  47. GRB 260618B: SVOM/VT optical candidate
  48. GRB 260618B: SVOM/VT optical candidate (duplicate Submission of 45001)
  49. GRB 260619A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  50. GRB 260616B: AstroSat CZTI detection
  51. GRB 260616A: AstroSat CZTI detection
  52. EP260618a: COLIBRÍ optical counterpart candidate
  53. IceCube-260610A: Upper limits from a search for additional neutrino events in IceCube
  54. GRB 260614A: AstroSat CZTI detection
  55. GRB 260610B / AT 2026owq: Possible re-brightening identified from Pan-STARRS observations
  56. GRB 260614B: SVOM/VT optical candidate from VHF data
  57. GRB 260603C: AstroSat CZTI detection
  58. GRB 260610B / AT2026owq: GRANDMA optical observations
  59. IceCube-260610A: No candidates from the Zwicky Transient Facility
  60. IceCube-260610A: EP-FXT follow-up observation
  61. GRB 260610B: DDOTI optical observations
  62. GRB 260610B: GOTO optical counterpart candidate
  63. IceCube-260610A - IceCube observation of a high-energy neutrino candidate track-like event
  64. EP260610b: Gemini North optical counterpart candidate
  65. GRB 260604C: AstroSat CZTI detection
  66. GRB 260607A / GOTO26fqf / AT2026ong: COLIBRÍ optical observations
  67. GRB 260607B: AstroSat CZTI detection
  68. GRB 260607A: TRT optical observations
  69. GRB 260607A: GOTO tentative optical counterpart candidate GOTO26fqf / AT2026ong
  70. GRB 260601B / EP260601a: AstroSat CZTI detection
  71. GRB 260604C: Correction to GCN 44828
  72. GRB 260604C: LAST detection of optical counterpart candidate
  73. EP260602a: NOT NIR J-band observations
  74. GRB 260603A: SVOM/COLIBRÍ (FM-GFT) photometric redshift z = 3.57
  75. GRB 260603A: SVOM/COLIBRÍ (GFT-FM) optical counterpart candidate
  76. EP260530a: Xinglong optical spectroscopy of EP260530a / AT 2026nwl
  77. EP260602a: SVOM/VT optical candidate
  78. GRB 260601B/EP260601a: GECAM-B analysis suggests a possible long duration Type I burst
  79. EP260530a/AT 2026nwl: COLIBRÍ optical observations
  80. GRB 260518B: SVOM/ECLAIRs detection of a soft burst possibly associated with EP 260518a and AT 2026ndp
  81. The EP-WXT trigger 01709266272 is likely a flaring star
  82. EP260527a/GRB 260527A: optical upper limit with Kinder observations
  83. GRB 260429B / EP260429a: COLIBRÍ optical counterpart candidate
  84. GRB 260529A: GOTO tentative optical afterglow candidate
  85. GRB 260527A/EP260527a: FTW optical and NIR observations
  86. The EP-WXT trigger 01709266147 is likely a flaring star
  87. GRB 260525A: AstroSat CZTI detection
  88. GRB 260523B: AstroSat CZTI detection
  89. EP260518a (AT2026ndp): LCO observations and Gemini-South Redshift z = 2.28
  90. EP260518a: Einstein Probe detection of an sub-threshold X-ray transient with counterpart AT 2026ndp
  91. GRB 260518A: AstroSat CZTI detection of a long burst
  92. GRB 260516D: SVOM/ECLAIRs refined analysis
  93. GRB 260515A: SVOM/ECLAIRs refined analysis
  94. GRB 260421B: radio detection with the VLA
  95. GRB 260516D: GOTO optical counterpart detection
  96. GRB 260516D: SVOM/VT optical bright candidate
  97. EP260514a: NOT optical counterpart confirmation
  98. EP260514a: TRT optical counterpart candidate
  99. EP260514a: SVOM/VT optical candidate
  100. GRB 260515A: SVOM/VT optical candidate from VHF data

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