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"

18332 results found.

  1. The EP-WXT trigger 01709269176 is likely a flaring star
  2. EP260610b: refined analysis of the EP-WXT and follow-up EP-FXT observations
  3. GRB 260610B / AT 2026owq: COLIBRÍ optical observations
  4. GRB 260610B: TRT optical observation
  5. EP260610a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  6. EP260610b: COLIBRÍ optical observations
  7. GRB 260610B: DDOTI optical observations
  8. EP260610b: MAO/AZT-22 optical observations
  9. EP260610b: NOT optical observation
  10. EP260610b: SVOM/VT optical confirmation with blue color
  11. GRB 260515A: SOAR optical observations
  12. EP260610a: SVOM/VT optical upper limits
  13. EP260610b: Einstein Probe detection of an X-ray transient
  14. EP260610a: COLIBRÍ optical upper limits
  15. EP260610a: Einstein Probe detection of a fast X-ray transient
  16. GRB 260604C: further SAO RAS optical observations
  17. GRB 260607A / GOTO26fqf / AT2026ong: COLIBRÍ optical observations
  18. GRB 260608B: Fermi GBM Final Localization
  19. GRB 260604C: SVOM/COLIBRÍ (FM-GFT) colour evolution and confirmation of the late rebrightening
  20. GRB 260604C: SVOM/C-GFT upper limit
  21. EP260605a: EP-FXT follow-up observation
  22. GRB 260607A: TRT optical observations
  23. GRB 260604A: SVOM/GRM detection
  24. GRB 260604C: Mondy optical observations: evidence of a possible brightening
  25. GRB 260604C: Simeiz Zeiss-1000 optical observations of the afterglow
  26. GRB 260604C: OPD1.6m - GRANDMA observations - detection
  27. GRB 260604C: 6 GHz VLA observations
  28. GRB 260604C: SAO RAS optical observations
  29. GRB 260604B: SVOM/GRM detection
  30. EP260605a: Einstein Probe detection of a fast X-ray transient
  31. EP260603a: COLIBRÍ optical upper limit
  32. GRB 260604C: LCO optical upper limit
  33. The EP-WXT trigger 01709267001 is likely a flaring star
  34. EP260602d: EP-FXT follow-up observation
  35. EP260602c: EP-FXT follow-up observation
  36. GRB 260527A/EP260527a: 6 GHz VLA observations
  37. GRB 260604C: Kilonova-Catcher optical afterglow detection
  38. GRB 260604C: SVOM/COLIBRÍ (FM-GFT) optical observations
  39. The EP-WXT trigger 01709266798 is likely a flaring star
  40. GRB 260604C: Jinshan optical observations
  41. EP260602d: J-band upper limit with WINTER
  42. EP260602b: J-band upper limit with WINTER
  43. GRB 260604C: LAST detection of optical counterpart candidate
  44. GRB 260603A: Simeiz Zeiss-1000 optical upper limit
  45. EP260602a: EP-FXT follow-up observation
  46. EP260603a: Einstein Probe detection of a fast X-ray transient
  47. EP260602d: Optical Upper limits with kinder observations
  48. EP260602b: Liverpool Telescope observations
  49. EP260602a: Liverpool Telescope optical upper limits
  50. EP260602b: Liverpool Telescope and LCO observations
  51. EP260602a: GTC and Liverpool Telescope optical observations
  52. GRB 260603A: EP-FXT follow-up observation
  53. EP260601a/GRB 260601B: EP-FXT follow-up observation
  54. GRB 260601B / EP260601a: Mondy optical upper limit
  55. EP260602b: EP-FXT follow-up observation
  56. GRB 260603A: Kilonova-Catcher optical upper limit
  57. GRB 260603A: SVOM/VT optical observations
  58. EP260602a: NOT NIR J-band observations
  59. GRB 260603A: SVOM/COLIBRÍ (FM-GFT) photometric redshift z = 3.57
  60. EP260602d: Einstein Probe detection of a fast X-ray transient
  61. GRB 260601A: SVOM/GRM observation of a short burst
  62. EP260602c: Einstein Probe detection of a fast X-ray transient
  63. GRB 260603A: SVOM/COLIBRÍ (GFT-FM) optical counterpart candidate
  64. EP260602a: COLIBRÍ optical observations
  65. GRB260601B/EP260601a: NOT near-infrared observations
  66. SVOM GRB260603.23: Global MASTER-Net observations report
  67. EP260602b: Einstein Probe detection of a fast X-ray transient
  68. EP260602a: SVOM/VT optical candidate
  69. EP-WXT trigger 01709266414 (EP260602b): JinShan optical counterpart detection
  70. GRB 260601B/EP260601a: J-band upper limit with WINTER
  71. EP260530a/AT 2026nwl: COLIBRÍ optical follow up
  72. EP260530a/AT 2026nwl: KAIT optical observations
  73. EP260602a: Optical upper limits with Kinder observations
  74. EP260602a: Einstein Probe detection of a fast X-ray transient
  75. GRB 260601B/EP260601a: SVOM/VT optical observations
  76. EP260601a: Einstein Probe detection of an X-ray transient
  77. EP-WXT trigger 01709266307 (EP260601a): COLIBRÍ optical observations
  78. EP-WXT trigger 01709266307 (EP260601a): JinShan optical counterpart detection
  79. EP260530a/AT 2026nwl: COLIBRÍ optical observations
  80. The EP-WXT trigger 01709266272 is likely a flaring star
  81. AT2026nik: EP-FXT X-ray counterpart
  82. AT 2026nuz: COLIBRÍ optical observations
  83. EP260527a/GRB 260527A: optical upper limit with Kinder observations
  84. GRB 260429B / EP260429a: COLIBRÍ optical counterpart candidate
  85. GRB 260527A/EP260527a: VLT/X-shooter tentative redshift
  86. EP260526a: SVOM/VT optical upper limits
  87. EP260527a / GRB 260527A: VLT detection of the optical and nIR counterpart
  88. EP260527a/GRB 260527A: Infrared J upper limit with MDM/MIRAGE
  89. EP260527a/GRB 260527A: EP-FXT follow-up observation
  90. EP260526a: EP-FXT follow-up observation
  91. EP260527a: SVOM/VT optical observation
  92. EP260527a: COLIBRÍ optical detection
  93. EP260527a: Einstein Probe detection of a fast X-ray transient
  94. The EP-WXT trigger 01709266172 is likely a flaring star
  95. The EP-WXT trigger 01709266147 is likely a flaring star
  96. EP260526a: LCO optical upper limits
  97. EP260526a: Einstein Probe detection of a fast X-ray transient
  98. EP260526.405: COLIBRÍ optical upper limits
  99. The EP-WXT trigger 01709266106 is not a real source
  100. EP01709266106 (EP260526a?): Liverpool Telescope upper limits

Advanced

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