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"

42254 results found.

  1. GRB 260603B: Fermi GBM Final Localization
  2. EP260602a: GTC and Liverpool Telescope optical observations
  3. Konus-Wind detection of GRB 260601B/EP260601a
  4. GRB 260603A: EP-FXT follow-up observation
  5. EP260601a/GRB 260601B: EP-FXT follow-up observation
  6. GRB 260601B / EP260601a: Mondy optical upper limit
  7. EP260602b: EP-FXT follow-up observation
  8. GRB 260601B/EP260601a: Glowbug gamma-ray detection
  9. GRB 260603A: Kilonova-Catcher optical upper limit
  10. GRB 260603A: SVOM/VT optical observations
  11. EP260602a: NOT NIR J-band observations
  12. GRB 260603A: SVOM/COLIBRÍ (FM-GFT) photometric redshift z = 3.57
  13. EP260602d: Einstein Probe detection of a fast X-ray transient
  14. Fermi trigger No 802141998: Global MASTER-Net observations report
  15. EP260602a: SVOM/VT optical magnitudes correction
  16. GRB 260601A: SVOM/GRM observation of a short burst
  17. EP260602c: Einstein Probe detection of a fast X-ray transient
  18. GRB 260603A: SVOM/COLIBRÍ (GFT-FM) optical counterpart candidate
  19. EP260602a: COLIBRÍ optical observations
  20. GRB260601B/EP260601a: NOT near-infrared observations
  21. SVOM GRB260603.23: Global MASTER-Net observations report
  22. GRB 260603A: SVOM detection of a burst
  23. EP260602b: Einstein Probe detection of a fast X-ray transient
  24. GRB 260601B/EP260601a: Insight-HXMT detection
  25. Fermi GRB 260602B: Global MASTER-Net observations report
  26. Fermi GRB 260602B: Global MASTER-Net observations report
  27. EP260530a: Xinglong optical spectroscopy of EP260530a / AT 2026nwl
  28. EP260602a: SVOM/VT optical candidate
  29. EP-WXT trigger 01709266414 (EP260602b): JinShan optical counterpart detection
  30. GRB 260602B: Fermi GBM Final Localization
  31. GRB 260601A: GECAM-B observation of a short burst
  32. GRB 260601B/EP260601a: J-band upper limit with WINTER
  33. EP260530a/AT 2026nwl: COLIBRÍ optical follow up
  34. EP260530a/AT 2026nwl: KAIT optical observations
  35. GRB 260602A: Fermi GBM Final Real-time Localization
  36. GRB 260601B: CALET Gamma-Ray Burst Monitor detection
  37. EP260602a: Optical upper limits with Kinder observations
  38. GRB 260601B / EP260601a: NuSTAR detection of prompt emission
  39. EP260602a: Einstein Probe detection of a fast X-ray transient
  40. GRB 260601B/EP260601a: SVOM/VT optical observations
  41. GRB 260601B/EP260601a: GECAM-B analysis suggests a possible long duration Type I burst
  42. GRB 260601B: GECAM-B detection of a burst probably associated with EP260601a
  43. EP260601a: Einstein Probe detection of an X-ray transient
  44. EP-WXT trigger 01709266307 (EP260601a): COLIBRÍ optical observations
  45. EP-WXT trigger 01709266307 (EP260601a): JinShan optical counterpart detection
  46. GRB 260601A: Glowbug gamma-ray detection of a short burst
  47. GRB 260531B: Glowbug gamma-ray detection
  48. GRB 260516D: VLA radio detection
  49. GRB 260601A: Fermi GBM Observation
  50. EP260530a/AT 2026nwl: COLIBRÍ optical observations
  51. GRB 260530C: SVOM/ECLAIRs detection of a burst through on-ground search
  52. GRB 260527A/EP260527a: Glowbug gamma-ray detection
  53. Fermi GRB 260601A: Global MASTER-Net observations report
  54. GRB 260601A: Fermi GBM Final Real-time Localization
  55. GRB 260531B: GECAM-B observation
  56. GRB 260518B: SVOM/ECLAIRs detection of a soft burst possibly associated with EP 260518a and AT 2026ndp
  57. The EP-WXT trigger 01709266272 is likely a flaring star
  58. GRB 260531C: Fermi GBM Final Localization Correction
  59. AT2026nik: EP-FXT X-ray counterpart
  60. Fermi trigger No 801900520: Global MASTER-Net observations report
  61. GRB 260531B: Fermi GBM Final Real-time Localization
  62. GRB 260531A: MAXI/GSC detection
  63. AT 2026nuz: COLIBRÍ optical observations
  64. EP260527a/GRB 260527A: further FTW optical and NIR observations
  65. GRB 260530B: SVOM/GRM detection of a possible bright short GRB
  66. GRB 260530A: Fermi GBM Final Real-time Localization
  67. GRB 260527A / EP260527a: VLA radio detection
  68. EP260527a/GRB 260527A: optical upper limit with Kinder observations
  69. GRB 260429B / EP260429a: COLIBRÍ optical counterpart candidate
  70. GRB 260529A: GOTO tentative optical afterglow candidate
  71. GRB 260527A/EP260527a: VLT/X-shooter tentative redshift
  72. GRB 260527A/EP260527a: Insight-HXMT detection
  73. Fermi GRB 260529A: Global MASTER-Net observations report
  74. GRB 260529A: Fermi GBM Final Real-time Localization
  75. EP260526a: SVOM/VT optical upper limits
  76. GRB 260527A/EP260527a: Gemini GMOS-S Optical Observations
  77. EP260527a / GRB 260527A: VLT detection of the optical and nIR counterpart
  78. EP260527a / GRB 260527A: NOT optical observations
  79. GRB 260527A/EP260527a: FTW optical and NIR observations
  80. EP260527a/GRB 260527A: Infrared J upper limit with MDM/MIRAGE
  81. GRB 260527A: CALET Gamma-Ray Burst Monitor detection
  82. EP260527a/GRB 260527A: EP-FXT follow-up observation
  83. GRB 260527A: GECAM-B detection of a short burst probably associated with EP260527a
  84. GRB 260526A: GECAM-B observation
  85. Konus-Wind detection of GRB 260527A (short/hard) ~4 min before EP260527a
  86. EP260526a: EP-FXT follow-up observation
  87. EP260527a: SVOM/VT optical observation
  88. EP260527a: COLIBRÍ optical detection
  89. EP260527a: Einstein Probe detection of a fast X-ray transient
  90. The EP-WXT trigger 01709266172 is likely a flaring star
  91. The EP-WXT trigger 01709266147 is likely a flaring star
  92. Fermi trigger No 801580882: Global MASTER-Net observations report
  93. GRB 260524A: SVOM/ECLAIRs detection of a burst through on-ground search
  94. EP260526a: LCO optical upper limits
  95. EP260526a: Einstein Probe detection of a fast X-ray transient
  96. GRB 260525A: AstroSat CZTI detection
  97. EP260526.405: COLIBRÍ optical upper limits
  98. Fermi GRB 260526A: Global MASTER-Net observations report
  99. GRB 260526A: Fermi GBM Final Real-time Localization
  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