Skip to main content
New! BOOM Notices and Schema v7.0.0. 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"

2993 results found.

  1. EP260321a: VLT imaging and spectroscopy show the variable source to be at z = 0.0343
  2. EP260321a: further Kinder optical observations
  3. EP260321a: Las Cumbres upper limit
  4. EP260321a: COLIBRÍ optical upper limit on any supernova shock breakout emission
  5. EP260321a: refined analysis of the EP-WXT and EP-FXT observations, implying a possible supernova shock breakout candidate
  6. EP260321a: SVOM/VT optical upper limit
  7. EP260321a: Kinder observations detect a blue variable star and set limits on a source from the z =0.034 galaxy within the error circle
  8. EP260321a: Global MASTER-Net observations report
  9. EP260321a: Einstein Probe detection of an X-ray transient
  10. EP-WXT trigger 01709258989: KAIT confirmation of a stellar flare
  11. EP-WXT trigger 01709258989: confirmation of a stellar flare by BOOTES-7
  12. The EP-WXT trigger 01709258989 is likely a flaring star
  13. GRB 260310A: classification as long GRB based on Eiso, Ep, and T_90
  14. IceCube-260315A/AT2026fpm: EP-FXT follow-up observation
  15. EP260316a: COLIBRÍ faint optical counterpart candidate
  16. EP260316a: refined analysis of the EP-WXT and EP-FXT observations
  17. EP260316a: Xinglong optical upper limit
  18. EP260316a: optical upper limit with Kinder observations
  19. EP260316a / GRB 260316A : Fermi-GBM Sub-Threshold Detection
  20. The EP-WXT trigger 00199258890 (EP260316a): a correction to the trigger time and FXT automatic follow-up
  21. EP260314a: Xinglong optical upper limit
  22. EP260314a: optical upper limit with Kinder observations
  23. EP260314a: refined analysis of the EP-WXT and EP-FXT observations
  24. EP260314a: Global MASTER-Net observations report
  25. EP260314a: SVOM/VT optical candidate
  26. EP260314a: Einstein Probe detection of an X-ray transient
  27. The EP-WXT trigger 01709258851: Las Cumbres upper limit
  28. GRB 260310A: Einstein Probe Follow-up X-ray Telescope (FXT) Detection
  29. GRB 260310A / AT 2026fgk: Location in the Epeak - Eiso diagram
  30. The EP-WXT trigger 01709258843 is not a real source
  31. EP260306a: refined analysis of the EP-WXT and EP-FXT observations
  32. EP260302a: SVOM/VT optical observation
  33. EP260306a: Gemini-North redshift z = 4.773
  34. EP260306a: SVOM/VT optical observation
  35. EP260302a: Gemini-South redshift z = 1.535
  36. EP260306a: Einstein Probe detection of an X-ray transient
  37. The EP-WXT trigger 01709258759: Las Cumbres discovery of the optical counterpart
  38. EP260302a: Optical afterglow rebrightening
  39. GRB 260228A: further EP-FXT observations and X-ray afterglow confirmation
  40. EP260214b: ATCA 6 GHz observations
  41. EP260302a: Global MASTER-Net observations report
  42. EP260302a: analysis of the follow-up EP-FXT observation
  43. EP260302a: LCO observations
  44. EP260302a: BOOTES-7 optical counterpart detection at early times
  45. GRB 260228A: EP-FXT follow-up observation
  46. EP260302a: Einstein Probe detection of an X-ray transient
  47. The EP-WXT trigger 01709258736: Las Cumbres discovery of the optical counterpart
  48. EP-WXT trigger 01709258652: 50cm Telescope multi-band observations
  49. EP260227a: SVOM/VT optical observation
  50. EP260227A: 3.6m DOT optical afterglow detection
  51. EP260227a: FTW optical and NIR observations
  52. GRB 260225A: SVOM/VT optical continued observations and upper limit
  53. EP260227a: Global MASTER-Net observations report
  54. EP260227a: Einstein Probe detection of an X-ray transient and refined analysis
  55. The EP-WXT trigger 01709258681 (EP260227a?): Las Cumbres follow-up observation of the optical counterpart
  56. EP/WXT trigger 01709258681 (EP260227a?): LCO candidate afterglow
  57. Konus-Wind detection of GRB 260226A
  58. EP260214a: VLT/FORS2 optical observations
  59. GRB 260225A: WINTER J-band upper limit
  60. EP-WXT trigger 01709258652: SVOM/C-GFT confirmation of a stellar flare
  61. The EP-WXT trigger 01709258652 is likely a flaring star
  62. EP260214a: VLA 6 GHz detection
  63. EP260224a: LCO optical upper limits
  64. GRB260225A: SVOM/ECLAIRs refined position
  65. GRB 260225A: EP-FXT follow-up observation
  66. EP260126a: VLA 6 GHz detection
  67. EP260223a: Liverpool Telescope upper limits
  68. EP260224a: Einstein Probe detection of an X-ray transient
  69. EP 260225.148: COLIBRÍ Confirmation of flaring star
  70. EP260223a: Xinglong optical upper limit
  71. The EP-WXT trigger 01709258631 is likely a flaring star
  72. EP260213a: Mephisto optical upper limits
  73. EP260223a: EP-FXT follow-up observation
  74. EP260223a: Einstein Probe detection of an X-ray transient
  75. EP260221a: Optical upper limit with Kinder observations
  76. EP260221a: Liverpool Telescope detection of COLIBRÍ counterpart candidate
  77. EP260221a: COLIBRÍ optical counterpart candidate
  78. EP260221a: Gemini South z-band upper limit
  79. EP260221a: Global MASTER-Net observations report
  80. EP260221a: EP-FXT follow-up observation
  81. EP-WXT01709258519: Xinglong optical upper limit
  82. EP260221a: Xinglong optical upper limit
  83. EP260221a: GOTO optical upper limit
  84. EP260221a: COLIBRÍ optical upper limit
  85. EP260221a: Einstein Probe detection of an X-ray transient
  86. The EP-WXT trigger 01709258519 is likely caused by Mrk 421
  87. GRB 260214B/EP260214b: SVOM/ECLAIRs detection through targeted search
  88. The EP-WXT trigger 01709258455 is likely a flaring star
  89. EP-WXT 01709258455: NOT optical upper limits
  90. EP260214b: 1.3m DFOT optical upper limit
  91. EP260210a: Mondy optical upper limits
  92. Konus-Wind detection of GRB 260212A
  93. EP260214b: Liverpool Telescope optical observations
  94. EP260214b: Optical upper limit with Kinder observations
  95. EP260214a: Optical upper limits with Kinder observations
  96. EP260214b: EP-FXT follow-up observation
  97. EP260214a / GRB 260214A: Fermi-GBM Sub-Threshold Detection
  98. EP260214b: GROWTH-India Telescope optical upper limit
  99. EP260214a: VLT near-infrared observation
  100. EP260214a: NOT optical upper limits

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