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 260225A: SVOM/ECLAIRs refined analysis
  2. GRB 260303B: BALROG localization (Fermi Trigger 794237065 / GRB 260303559)
  3. GRB 260303B: Fermi GBM Final Real-time Localization
  4. EP260302a: analysis of the follow-up EP-FXT observation
  5. EP260227a: Gemini-South optical observations
  6. EP260302a: LCO observations
  7. EP260302a: BOOTES-7 optical counterpart detection at early times
  8. GRB 260303A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  9. GRB 260303A: SVOM detection of a burst
  10. GRB 260228A: EP-FXT follow-up observation
  11. EP260302a: Einstein Probe detection of an X-ray transient
  12. The EP-WXT trigger 01709258736: Las Cumbres discovery of the optical counterpart
  13. GRB 251130B: TERI Gamma-ray detection
  14. GRB 260208A: TERI Gamma-ray detection
  15. GRB 260302A: Fermi GBM Final Real-time Localization
  16. EP260227a: Mondy optical observations
  17. GRB 260228A: CAHA 2.2m telescope optical upper limit
  18. GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  19. EP260227a: Mephisto optical detection
  20. GRID detection of GRB 260225D
  21. EP-WXT trigger 01709258652: 50cm Telescope multi-band observations
  22. EP260227a: further LCO observations
  23. EP260227a: SVOM/VT optical observation
  24. GRB 260228A: SVOM/VT optical upper limits
  25. GRB 260225D: SVOM/GRM observation
  26. EP260227A: 3.6m DOT optical afterglow detection
  27. GRB 260225B: SVOM/GRM observation
  28. GRB 260228A: SVOM detection of a burst
  29. EP260227a: FTW optical and NIR observations
  30. EP260227a: Liverpool Telescope optical observations
  31. EP260227a: LCOGT Optical Observations
  32. GRB 260226A: Asiago r-band upper limit
  33. EP260227a: Thai National Telescope observations
  34. EP260227a: likely GTC/OSIRIS+ redshift z = 2.714
  35. EP260227a: Liverpool Telescope observations
  36. EP260227a: COLIBRÍ optical observations
  37. EP260227a: NOT optical observations
  38. GRB 260225A: SVOM/VT optical continued observations and upper limit
  39. GRID detection of GRB 260223A
  40. EP260227a: Global MASTER-Net observations report
  41. EP260227a: Einstein Probe detection of an X-ray transient and refined analysis
  42. The EP-WXT trigger 01709258681 (EP260227a?): Las Cumbres follow-up observation of the optical counterpart
  43. EP/WXT trigger 01709258681 (EP260227a?): LCO candidate afterglow
  44. IceCube cascade alert 142200_1517143 retraction
  45. GRB 260226A: Insight-HXMT/HE detection of the very bright burst
  46. Konus-Wind detection of GRB 260226A
  47. GRB 260223A: 7DT detection and Medium-band SED of Afterglow
  48. EP260214a: VLT/FORS2 optical observations
  49. GRB 260225A: WINTER J-band upper limit
  50. GRB 260226A: CALET Gamma-Ray Burst Monitor detection
  51. GRB 260226A: COLIBRÍ optical upper limits
  52. GRB 260226A: LCOGT Optical Upper Limit
  53. EP-WXT trigger 01709258652: SVOM/C-GFT confirmation of a stellar flare
  54. GRB 260225D: Glowbug gamma-ray detection of a likely short burst
  55. GRB 260226A: Glowbug gamma-ray detection
  56. GRB 260226A: NuSTAR detection of bright prompt emission
  57. GRB 260226A : GROWTH-India Telescope optical observations
  58. GRB 260226A: LAST optical upper limit
  59. GRB 260226A: Fermi GBM observation
  60. GRB 260226A: Fermi-LAT refined analysis
  61. The EP-WXT trigger 01709258652 is likely a flaring star
  62. LAT GRB260226.44: Global MASTER-Net observations report
  63. Fermi GRB 260226A: Global MASTER-Net observations report
  64. GRB 260226A: AstroSat CZTI detection of bright long burst
  65. EP260214a: VLA 6 GHz detection
  66. GRB 260226A: Fermi-LAT detection of a bright burst
  67. GRB 260226A???: BALROG localization (Fermi Trigger 793795080 / GRB 260226443)
  68. EP260224a: LCO optical upper limits
  69. GRB260225A: SVOM/ECLAIRs refined position
  70. GRB 260226A: Fermi GBM Final Real-time Localization
  71. GRB 260225A: EP-FXT follow-up observation
  72. GRB 260225A: SVOM/VT optical observation
  73. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) Detection of an Optical Counterpart Candidate
  74. GRB 260225C: Fermi GBM Final Real-time Localization
  75. GRB 260223A: Fermi GBM Observation
  76. GRB 260225A: SVOM/VT optical upper limits
  77. GRB 260225B: Fermi GBM Final Real-time Localization
  78. EP260126a: VLA 6 GHz detection
  79. EP260223a: Liverpool Telescope upper limits
  80. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  81. GRB 260225A: SVOM detection of a burst
  82. EP260224a: Einstein Probe detection of an X-ray transient
  83. EP 260225.148: COLIBRÍ Confirmation of flaring star
  84. EP260223a: Xinglong optical upper limit
  85. The EP-WXT trigger 01709258631 is likely a flaring star
  86. GRB 260223A: Glowbug gamma-ray detection
  87. EP260213a: Mephisto optical upper limits
  88. EP260223a: EP-FXT follow-up observation
  89. sb26021801: SVOM/VT optical upper limits
  90. GRB 260223A: COLIBRÍ optical afterglow decay confirmation
  91. sb26021801: SVOM/C-GFT upper limit
  92. EP260223a: COLIBRÍ optical upper limits
  93. EP260223a: Einstein Probe detection of an X-ray transient
  94. GRB 260223A: SVOM/VT optical observation
  95. GRB 260223A: SVOM/GRM observation
  96. GRB 260223A: COLIBRÍ further optical observations and a brightening
  97. EP260221a: Optical upper limit with Kinder observations
  98. GRB 260223A: COLIBRÍ optical observations
  99. GRB 260223A: DDOTI Optical Candidate
  100. GRB 260223A: BALROG localization (Fermi Trigger 793512674 / GRB 260223174)

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