Skip to main content
Retirement of GCN Classic VOEvent Brokers. 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"
  1. GRB 260303A: 1.3m DFOT optical upper limit
  2. EP260214b: ATCA 6 GHz observations
  3. GRB 260211A: SVOM/VT optical rebrightening at 20 days after the burst, SN candidate
  4. GRB 260303A: SVOM/ECLAIRs refined analysis
  5. Fermi GRB 260305A: Global MASTER-Net observations report
  6. GRB 260305A: Fermi GBM Final Real-time Localization
  7. GRB 260303B: AstroSat CZTI detection
  8. GRB 260304A: AstroSat CZTI detection of a long burst
  9. SVOM/sb26030408: SVOM detection of an X-ray transient likely associated with Beta Persei
  10. GRB 260303A: SVOM/VT optical observations
  11. GRB 260303A: J-band observations with WINTER
  12. GRB 260303B: NuSTAR detection of prompt emission
  13. EP260302a: Global MASTER-Net observations report
  14. Fermi GRB 260303B: Global MASTER-Net observations report
  15. IceCube-260217A: No Candidate Transients from the Zwicky Transient Facility
  16. GRB 260228A: SVOM/ECLAIRs refined analysis
  17. GRB 260225A: SVOM/ECLAIRs refined analysis
  18. GRB 260303B: BALROG localization (Fermi Trigger 794237065 / GRB 260303559)
  19. GRB 260303B: Fermi GBM Final Real-time Localization
  20. EP260302a: analysis of the follow-up EP-FXT observation
  21. EP260227a: Gemini-South optical observations
  22. EP260302a: LCO observations
  23. EP260302a: BOOTES-7 optical counterpart detection at early times
  24. GRB 260303A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  25. GRB 260303A: SVOM detection of a burst
  26. GRB 260228A: EP-FXT follow-up observation
  27. EP260302a: Einstein Probe detection of an X-ray transient
  28. The EP-WXT trigger 01709258736: Las Cumbres discovery of the optical counterpart
  29. GRB 251130B: TERI Gamma-ray detection
  30. GRB 260208A: TERI Gamma-ray detection
  31. GRB 260302A: Fermi GBM Final Real-time Localization
  32. EP260227a: Mondy optical observations
  33. GRB 260228A: CAHA 2.2m telescope optical upper limit
  34. GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  35. EP260227a: Mephisto optical detection
  36. GRID detection of GRB 260225D
  37. EP-WXT trigger 01709258652: 50cm Telescope multi-band observations
  38. EP260227a: further LCO observations
  39. EP260227a: SVOM/VT optical observation
  40. GRB 260228A: SVOM/VT optical upper limits
  41. GRB 260225D: SVOM/GRM observation
  42. EP260227A: 3.6m DOT optical afterglow detection
  43. GRB 260225B: SVOM/GRM observation
  44. GRB 260228A: SVOM detection of a burst
  45. EP260227a: FTW optical and NIR observations
  46. EP260227a: Liverpool Telescope optical observations
  47. EP260227a: LCOGT Optical Observations
  48. GRB 260226A: Asiago r-band upper limit
  49. EP260227a: Thai National Telescope observations
  50. EP260227a: likely GTC/OSIRIS+ redshift z = 2.714
  51. EP260227a: Liverpool Telescope observations
  52. EP260227a: COLIBRÍ optical observations
  53. EP260227a: NOT optical observations
  54. GRB 260225A: SVOM/VT optical continued observations and upper limit
  55. GRID detection of GRB 260223A
  56. EP260227a: Global MASTER-Net observations report
  57. EP260227a: Einstein Probe detection of an X-ray transient and refined analysis
  58. The EP-WXT trigger 01709258681 (EP260227a?): Las Cumbres follow-up observation of the optical counterpart
  59. EP/WXT trigger 01709258681 (EP260227a?): LCO candidate afterglow
  60. IceCube cascade alert 142200_1517143 retraction
  61. GRB 260226A: Insight-HXMT/HE detection of the very bright burst
  62. Konus-Wind detection of GRB 260226A
  63. GRB 260223A: 7DT detection and Medium-band SED of Afterglow
  64. EP260214a: VLT/FORS2 optical observations
  65. GRB 260225A: WINTER J-band upper limit
  66. GRB 260226A: CALET Gamma-Ray Burst Monitor detection
  67. GRB 260226A: COLIBRÍ optical upper limits
  68. GRB 260226A: LCOGT Optical Upper Limit
  69. EP-WXT trigger 01709258652: SVOM/C-GFT confirmation of a stellar flare
  70. GRB 260225D: Glowbug gamma-ray detection of a likely short burst
  71. GRB 260226A: Glowbug gamma-ray detection
  72. GRB 260226A: NuSTAR detection of bright prompt emission
  73. GRB 260226A : GROWTH-India Telescope optical observations
  74. GRB 260226A: LAST optical upper limit
  75. GRB 260226A: Fermi GBM observation
  76. GRB 260226A: Fermi-LAT refined analysis
  77. The EP-WXT trigger 01709258652 is likely a flaring star
  78. LAT GRB260226.44: Global MASTER-Net observations report
  79. Fermi GRB 260226A: Global MASTER-Net observations report
  80. GRB 260226A: AstroSat CZTI detection of bright long burst
  81. EP260214a: VLA 6 GHz detection
  82. GRB 260226A: Fermi-LAT detection of a bright burst
  83. GRB 260226A???: BALROG localization (Fermi Trigger 793795080 / GRB 260226443)
  84. EP260224a: LCO optical upper limits
  85. GRB260225A: SVOM/ECLAIRs refined position
  86. GRB 260226A: Fermi GBM Final Real-time Localization
  87. GRB 260225A: EP-FXT follow-up observation
  88. GRB 260225A: SVOM/VT optical observation
  89. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) Detection of an Optical Counterpart Candidate
  90. GRB 260225C: Fermi GBM Final Real-time Localization
  91. GRB 260223A: Fermi GBM Observation
  92. GRB 260225A: SVOM/VT optical upper limits
  93. GRB 260225B: Fermi GBM Final Real-time Localization
  94. EP260126a: VLA 6 GHz detection
  95. EP260223a: Liverpool Telescope upper limits
  96. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  97. GRB 260225A: SVOM detection of a burst
  98. EP260224a: Einstein Probe detection of an X-ray transient
  99. EP 260225.148: COLIBRÍ Confirmation of flaring star
  100. EP260223a: Xinglong optical upper limit

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