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"

19835 results found.

  1. EP260409a: Einstein Probe detection of an X-ray transient
  2. EP260321a: VLA radio detection
  3. GRB 260402A: SVOM/ECLAIRs refined analysis
  4. EP260402a / GRB 260402A: Mephisto optical upper limits
  5. EP-WXT01709259586: Xinglong optical upper limit
  6. EP260403a: Mephisto optical upper limits
  7. EP260402a/GRB 260402A: Xinglong optical upper limit
  8. GRID detection of GRB 260401A
  9. EP260405a: GMOS-N optical upper limits
  10. EP260405a: Einstein Probe detection of a fast X-ray transient
  11. EP260405a / EP-WXT 11900672904: COLIBRÍ optical upper limits
  12. EP260324A / AT 2026hir: COLIBRÍ further optical observations
  13. EP260403a: refined analysis of the EP-WXT and EP-FXT observations
  14. GRB 260330B: SVOM/VT further optical observation
  15. GRB 260330B: SVOM/ECLAIRs refined analysis
  16. EP260403a: LCO optical observations of the counterpart
  17. GRB 260310A/AT2026fgk: Kilonova-Catcher long term optical monitoring
  18. EP260403a: LCO optical counterpart detection
  19. EP260403a: COLIBRÍ optical counterpart candidate
  20. GRB 260330B: SVOM/VT optical candidate
  21. EP260403a: Einstein Probe detection of an X-ray transient
  22. GRB 260330B: EP-FXT follow-up and identification of candidate afterglow
  23. GRB 260403A: AstroSat CZTI detection
  24. EP260402a/GRB 260402A: refined analysis of the EP-WXT and EP-FXT observations
  25. EP260402a/GRB 260402A: Jinshan near-infrared upper limit
  26. GRB 260402C: AstroSat CZTI detection of a long burst
  27. EP260324A / AT 2026hir: COLIBRÍ optical observations
  28. GRB 260402A: WINTER J-band upper limit
  29. GRB260402A: GROWTH-India Telescope optical upper limit
  30. GRB 260402A / EP260402a: SVOM/VT optical upper limits
  31. EP260402a/GRB 260402A: SVOM/C-GFT upper limit
  32. GRB 260401A: SVOM/GRM observation
  33. EP260402a/GRB 260402A: Einstein Probe detection of an X-ray transient
  34. GRB 260402A: Kilonova-Catcher optical upper limit
  35. GRB 260402A: MASTER optical observations
  36. GRB 260402A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  37. GRB 260402A: SVOM/MXT candidate X-ray afterglow
  38. GRB 260402A: SVOM detection of a burst
  39. EP260329b: Mondy and Assy-Turgen optical upper limits
  40. GRB 260310A / AT2026fgk: Luminance-band optical follow-up with a 28cm telescope in Daocheng
  41. EP260321a :Xinglong optical observations
  42. EP260327a: Xinglong optical upper limit
  43. GRB 260330B: SVOM/VT optical upper limits
  44. GRB 260321A: SVOM/ECLAIRs refined analysis
  45. EP260329b: J-band upper limits with WINTER
  46. EP260329a: J-band upper limit with WINTER
  47. GRB 260310A: VLA Multi-frequency Radio Observations
  48. GRB 260330B: LCO optical upper limits
  49. EP260324a / AT2026hir: g- and r-band optical follow-up with the PKU 60cm Telescope
  50. EP260329b: refined analysis of the EP-WXT and EP-FXT observations
  51. EP260329a: COLIBRÍ optical upper limit
  52. EP260329a: EP-FXT follow up observation
  53. EP260329a: NOT optical counterpart candidate
  54. EP260329b: Optical follow-up with Kinder observations
  55. EP 260329b: COLIBRÍ optical observations
  56. EP260329a: Optical upper limit with Kinder observations
  57. EP260329b: LCO optical observations of the counterpart
  58. EP260329b: Einstein Probe detection of an X-ray transient
  59. EP260329a: Einstein Probe detection of an X-ray transient
  60. EP-WXT trigger 01709259209: TRT optical counterpart detection
  61. The EP-WXT trigger 01709259209 (EP260329b?): Las Cumbres discovery of the optical counterpart
  62. GRID detection of GRB 260326A
  63. EP260327a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  64. EP260327a: SVOM/VT optical upper limits
  65. EP260327a: WINTER J-band upper limit
  66. EP260327a: COLIBRÍ optical upper limits
  67. GRB 260327A: AstroSat CZTI detection of a long burst
  68. EP260327a: Gemini-North optical upper limits
  69. EP260324a: GROWTH-India Telescope optical observation
  70. EP260327a: Einstein Probe detection of an X-ray transient
  71. GRB 260310A / AT 2026fgk: COLIBRÍ photometric evidence of the emerging supernova
  72. GRB 260310A / AT2026fgk: Late-time infrared detection with MIRAGE on the MDM 1.3m telescope
  73. EP260324a: ZTF discovery of the optical counterpart ZTF26aapviim/AT2026hir
  74. GRB 260310A / AT2026fgk: R- and I-band observations with the PKU 60 cm optical telescope
  75. EP260321a: JinShan near-infrared observations
  76. EP260321a: Upper limits from a neutrino search with IceCube
  77. GRB 260310A/AT2026fgk: Kilonova-Catcher late optical afterglow detection at about 15 days post trigger time
  78. EP260321a: J-band observations by the SYSU 80 cm infrared telescope
  79. GRID detection of GRB 260320A
  80. GRB 260321A: SVOM/COLIBRÍ (FM-GFT) optical upper limits at the FXT positions
  81. EP260321a: COLIBRÍ further optical observations and brightening
  82. EP260321a: Continued brightening from Kinder follow-up of the emerging supernova candidate
  83. EP260214b: ATCA 6 GHz detection
  84. EP260321a: Early TRT rising followed by JinShan decaying and then re-rising
  85. The EP-WXT trigger 01709259045 is likely a flaring star
  86. EP260321a: GOTO detection of blue variable source
  87. EP260321a: VLT imaging and spectroscopy show the variable source to be at z = 0.0343
  88. EP260321a: further Kinder optical observations
  89. GRB 260321A: SVOM/VT optical upper limits
  90. EP260321a: Las Cumbres upper limit
  91. GRB 260321A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  92. EP260321a: COLIBRÍ optical upper limit on any supernova shock breakout emission
  93. EP260321a: refined analysis of the EP-WXT and EP-FXT observations, implying a possible supernova shock breakout candidate
  94. EP260321a: SVOM/VT optical upper limit
  95. EP260321a: Kinder observations detect a blue variable star and set limits on a source from the z =0.034 galaxy within the error circle
  96. EP260321a: Einstein Probe detection of an X-ray transient
  97. GRB 260310A / AT 2026fgk: KAIT optical observations
  98. GRB 260310A: no evidence of re-brightening up to 9.6 days in optical observation at Mondy
  99. GRB 260310A / AT 2026fgk: COLIBRÍ evidence of a late rebrightening
  100. GRB 260318A: SVOM/GRM observation

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