Skip to main content
Updates to LVK & CHIME Notices, Schema v7.2.3! 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"

28055 results found.

  1. EP260602d: J-band upper limit with WINTER
  2. EP260602b: J-band upper limit with WINTER
  3. GRB 260604C: LAST detection of optical counterpart candidate
  4. Fermi GRB 260604C: Global MASTER-Net observations report
  5. Fermi GRB 260604C: Global MASTER-Net observations report
  6. SVOM GRB260604.85: Global MASTER-Net observations report
  7. GRB 260603A: Simeiz Zeiss-1000 optical upper limit
  8. GRB 260601A: CALET Gamma-Ray Burst Monitor detection
  9. EP260602a: EP-FXT follow-up observation
  10. EP260603a: Global MASTER-Net observations report
  11. EP260603a: Einstein Probe detection of a fast X-ray transient
  12. EP260602d: Optical Upper limits with kinder observations
  13. EP260602b: Liverpool Telescope observations
  14. EP260602a: Liverpool Telescope optical upper limits
  15. EP260602b: Liverpool Telescope and LCO observations
  16. EP260602a: GTC and Liverpool Telescope optical observations
  17. EP260601a/GRB 260601B: EP-FXT follow-up observation
  18. GRB 260601B / EP260601a: Mondy optical upper limit
  19. EP260602b: EP-FXT follow-up observation
  20. GRB 260601B/EP260601a: Glowbug gamma-ray detection
  21. GRB 260603A: Kilonova-Catcher optical upper limit
  22. GRB 260603A: SVOM/VT optical observations
  23. EP260602a: NOT NIR J-band observations
  24. GRB 260603A: SVOM/COLIBRÍ (FM-GFT) photometric redshift z = 3.57
  25. EP260602d: Einstein Probe detection of a fast X-ray transient
  26. Fermi trigger No 802141998: Global MASTER-Net observations report
  27. GRB 260601A: SVOM/GRM observation of a short burst
  28. EP260602c: Einstein Probe detection of a fast X-ray transient
  29. GRB 260603A: SVOM/COLIBRÍ (GFT-FM) optical counterpart candidate
  30. EP260602a: COLIBRÍ optical observations
  31. GRB260601B/EP260601a: NOT near-infrared observations
  32. SVOM GRB260603.23: Global MASTER-Net observations report
  33. GRB 260603A: SVOM detection of a burst
  34. EP260602b: Einstein Probe detection of a fast X-ray transient
  35. Fermi GRB 260602B: Global MASTER-Net observations report
  36. Fermi GRB 260602B: Global MASTER-Net observations report
  37. EP260530a: Xinglong optical spectroscopy of EP260530a / AT 2026nwl
  38. EP260602a: SVOM/VT optical candidate
  39. EP-WXT trigger 01709266414 (EP260602b): JinShan optical counterpart detection
  40. GRB 260601B/EP260601a: J-band upper limit with WINTER
  41. EP260530a/AT 2026nwl: COLIBRÍ optical follow up
  42. EP260530a/AT 2026nwl: KAIT optical observations
  43. GRB 260601B: CALET Gamma-Ray Burst Monitor detection
  44. EP260602a: Optical upper limits with Kinder observations
  45. GRB 260601B / EP260601a: NuSTAR detection of prompt emission
  46. EP260602a: Einstein Probe detection of a fast X-ray transient
  47. GRB 260601B/EP260601a: SVOM/VT optical observations
  48. GRB 260601B/EP260601a: GECAM-B analysis suggests a possible long duration Type I burst
  49. GRB 260601B: GECAM-B detection of a burst probably associated with EP260601a
  50. EP260601a: Einstein Probe detection of an X-ray transient
  51. EP-WXT trigger 01709266307 (EP260601a): COLIBRÍ optical observations
  52. EP-WXT trigger 01709266307 (EP260601a): JinShan optical counterpart detection
  53. GRB 260601A: Glowbug gamma-ray detection of a short burst
  54. GRB 260531B: Glowbug gamma-ray detection
  55. GRB 260601A: Fermi GBM Observation
  56. EP260530a/AT 2026nwl: COLIBRÍ optical observations
  57. GRB 260527A/EP260527a: Glowbug gamma-ray detection
  58. Fermi GRB 260601A: Global MASTER-Net observations report
  59. GRB 260601A: Fermi GBM Final Real-time Localization
  60. The EP-WXT trigger 01709266272 is likely a flaring star
  61. AT2026nik: EP-FXT X-ray counterpart
  62. Fermi trigger No 801900520: Global MASTER-Net observations report
  63. GRB 260531A: MAXI/GSC detection
  64. AT 2026nuz: COLIBRÍ optical observations
  65. EP260527a/GRB 260527A: optical upper limit with Kinder observations
  66. GRB 260429B / EP260429a: COLIBRÍ optical counterpart candidate
  67. GRB 260527A/EP260527a: VLT/X-shooter tentative redshift
  68. Fermi GRB 260529A: Global MASTER-Net observations report
  69. EP260526a: SVOM/VT optical upper limits
  70. EP260527a / GRB 260527A: VLT detection of the optical and nIR counterpart
  71. EP260527a/GRB 260527A: Infrared J upper limit with MDM/MIRAGE
  72. EP260527a/GRB 260527A: EP-FXT follow-up observation
  73. GRB 260527A: GECAM-B detection of a short burst probably associated with EP260527a
  74. EP260527a: SVOM/VT optical observation
  75. EP260527a: COLIBRÍ optical detection
  76. EP260527a: Einstein Probe detection of a fast X-ray transient
  77. Fermi trigger No 801580882: Global MASTER-Net observations report
  78. EP260526a: LCO optical upper limits
  79. EP260526a: Einstein Probe detection of a fast X-ray transient
  80. EP260526.405: COLIBRÍ optical upper limits
  81. The EP-WXT trigger 01709266106 is not a real source
  82. Fermi GRB 260526A: Global MASTER-Net observations report
  83. EP01709266106 (EP260526a?): Liverpool Telescope upper limits
  84. EP-WXT 01709266106: NOT optical upper limits
  85. Fermi GRB 260525A: Global MASTER-Net observations report
  86. GRB 260523B: AstroSat CZTI detection
  87. Fermi GRB 260523A: Global MASTER-Net observations report
  88. GRB 260522A: Fermi GBM Observation
  89. GRB 260522B: NuSTAR detection of prompt emission
  90. EP260518a (AT2026ndp): LCO observations and Gemini-South Redshift z = 2.28
  91. Fermi trigger No 801135305: Global MASTER-Net observations report
  92. Fermi GRB 260522A: Global MASTER-Net observations report
  93. EP260518a: Einstein Probe detection of an sub-threshold X-ray transient with counterpart AT 2026ndp
  94. GRB 260511A: iTelescope T-75 optical detection
  95. GRB 260520B: SVOM/GRM observation
  96. GRB 260411B: TERI Gamma-ray detection
  97. GRB 260407A: TERI Gamma-ray detection
  98. GRB 260307A: TERI Gamma-ray detection
  99. GRB 260225D: TERI Gamma-ray detection
  100. GRB 251118A: TERI Gamma-ray detection

Advanced

Download all Circulars as a .tar.gz archive (updated once a day):
Looking for U.S. government information and services? Visit USA.gov