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"

17904 results found.

  1. GRB 260604B: SVOM/GRM detection
  2. EP260605a: Einstein Probe detection of a fast X-ray transient
  3. EP260603a: COLIBRÍ optical upper limit
  4. GRB 260604C: LCO optical upper limit
  5. The EP-WXT trigger 01709267001 is likely a flaring star
  6. EP260602d: EP-FXT follow-up observation
  7. EP260602c: EP-FXT follow-up observation
  8. GRB 260527A/EP260527a: 6 GHz VLA observations
  9. GRB 260604C: Kilonova-Catcher optical afterglow detection
  10. GRB 260604C: SVOM/COLIBRÍ (FM-GFT) optical observations
  11. The EP-WXT trigger 01709266798 is likely a flaring star
  12. GRB 260604C: Jinshan optical observations
  13. EP260602d: J-band upper limit with WINTER
  14. EP260602b: J-band upper limit with WINTER
  15. GRB 260604C: LAST detection of optical counterpart candidate
  16. GRB 260603A: Simeiz Zeiss-1000 optical upper limit
  17. EP260602a: EP-FXT follow-up observation
  18. EP260603a: Einstein Probe detection of a fast X-ray transient
  19. EP260602d: Optical Upper limits with kinder observations
  20. EP260602b: Liverpool Telescope observations
  21. EP260602a: Liverpool Telescope optical upper limits
  22. EP260602b: Liverpool Telescope and LCO observations
  23. EP260602a: GTC and Liverpool Telescope optical observations
  24. GRB 260603A: EP-FXT follow-up observation
  25. EP260601a/GRB 260601B: EP-FXT follow-up observation
  26. GRB 260601B / EP260601a: Mondy optical upper limit
  27. EP260602b: EP-FXT follow-up observation
  28. GRB 260603A: Kilonova-Catcher optical upper limit
  29. GRB 260603A: SVOM/VT optical observations
  30. EP260602a: NOT NIR J-band observations
  31. GRB 260603A: SVOM/COLIBRÍ (FM-GFT) photometric redshift z = 3.57
  32. EP260602d: Einstein Probe detection of a fast X-ray transient
  33. GRB 260601A: SVOM/GRM observation of a short burst
  34. EP260602c: Einstein Probe detection of a fast X-ray transient
  35. GRB 260603A: SVOM/COLIBRÍ (GFT-FM) optical counterpart candidate
  36. EP260602a: COLIBRÍ optical observations
  37. GRB260601B/EP260601a: NOT near-infrared observations
  38. SVOM GRB260603.23: Global MASTER-Net observations report
  39. EP260602b: Einstein Probe detection of a fast X-ray transient
  40. EP260602a: SVOM/VT optical candidate
  41. EP-WXT trigger 01709266414 (EP260602b): JinShan optical counterpart detection
  42. GRB 260601B/EP260601a: J-band upper limit with WINTER
  43. EP260530a/AT 2026nwl: COLIBRÍ optical follow up
  44. EP260530a/AT 2026nwl: KAIT optical observations
  45. EP260602a: Optical upper limits with Kinder observations
  46. EP260602a: Einstein Probe detection of a fast X-ray transient
  47. GRB 260601B/EP260601a: SVOM/VT optical observations
  48. EP260601a: Einstein Probe detection of an X-ray transient
  49. EP-WXT trigger 01709266307 (EP260601a): COLIBRÍ optical observations
  50. EP-WXT trigger 01709266307 (EP260601a): JinShan optical counterpart detection
  51. EP260530a/AT 2026nwl: COLIBRÍ optical observations
  52. The EP-WXT trigger 01709266272 is likely a flaring star
  53. AT2026nik: EP-FXT X-ray counterpart
  54. AT 2026nuz: COLIBRÍ optical observations
  55. EP260527a/GRB 260527A: optical upper limit with Kinder observations
  56. GRB 260429B / EP260429a: COLIBRÍ optical counterpart candidate
  57. GRB 260527A/EP260527a: VLT/X-shooter tentative redshift
  58. EP260526a: SVOM/VT optical upper limits
  59. EP260527a / GRB 260527A: VLT detection of the optical and nIR counterpart
  60. EP260527a/GRB 260527A: Infrared J upper limit with MDM/MIRAGE
  61. EP260527a/GRB 260527A: EP-FXT follow-up observation
  62. EP260526a: EP-FXT follow-up observation
  63. EP260527a: SVOM/VT optical observation
  64. EP260527a: COLIBRÍ optical detection
  65. EP260527a: Einstein Probe detection of a fast X-ray transient
  66. The EP-WXT trigger 01709266172 is likely a flaring star
  67. The EP-WXT trigger 01709266147 is likely a flaring star
  68. EP260526a: LCO optical upper limits
  69. EP260526a: Einstein Probe detection of a fast X-ray transient
  70. EP260526.405: COLIBRÍ optical upper limits
  71. The EP-WXT trigger 01709266106 is not a real source
  72. EP01709266106 (EP260526a?): Liverpool Telescope upper limits
  73. EP-WXT 01709266106: NOT optical upper limits
  74. Fermi trigger No 801135305: Global MASTER-Net observations report
  75. EP260518a: Einstein Probe detection of an sub-threshold X-ray transient with counterpart AT 2026ndp
  76. GRB 260511A: iTelescope T-75 optical detection
  77. GRB 260520B: SVOM/GRM observation
  78. Konus-Wind detection of GRB 260518A
  79. GRB 260518A: AstroSat CZTI detection of a long burst
  80. GRB 260421B: radio detection with the VLA
  81. GRB 260509A: CrAO ZTSh optical upper limit
  82. GRB 260516D: EP-FXT follow-up observation
  83. GRB 260516D: GOTO optical counterpart detection
  84. GRB 260516D: LCO optical observations
  85. GRB 260515A: further Liverpool Telescope observations
  86. GRB 260516D: SVOM/COLIBRÍ (FM-GFT) optical observations
  87. GRB 260516D: GROWTH-India Telescope optical detection
  88. GRB 260516D: SVOM/VT optical bright candidate
  89. GRB 260515A: CrAO ZTSh BVRI optical observations
  90. Konus-Wind detection of GRB 260515A
  91. GRB 260515A: LCO optical counterpart detection
  92. GRB 260515A: SVOM/COLIBRÍ (FM-GFT) optical observations
  93. GRB 260515A: EP-FXT follow-up observation
  94. EP260514a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  95. EP260514a: NOT optical counterpart confirmation
  96. EP260514a: TRT optical counterpart candidate
  97. EP260514a: SVOM/VT optical candidate
  98. GRB 260515A: OHP/T193 optical observations
  99. EP260514a: COLIBRÍ optical upper limits
  100. GRB 260515A: LCO optical observations

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