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"

28041 results found.

  1. EP260416a: KAIT optical upper limit
  2. EP260416a: COLIBRÍ confirmation of the optical rebrightening
  3. EP260416a: WFST optical observations and rebrightening
  4. GOTO26djh/AT2026jpw: ZTSh R,I bands observations of the transient
  5. GOTO26djh/AT2026jpw: SVOM/VT optical observation
  6. GRB 260415B: Glowbug gamma-ray detection
  7. GRB 260411B: Glowbug gamma-ray detection
  8. EP260416a: COLIBRÍ optical counterpart candidate
  9. COLIBRI optical observations of the transient GOTO26djh/AT2026jpw
  10. EP260416a: Global MASTER-Net observations report
  11. EP260416a: Einstein Probe detection of an X-ray transient
  12. GOTO26djh/AT2026jpw : MASTER OT observation
  13. GOTO26djh/AT2026jpw transient: SAO RAS optical observations
  14. NOT r-band observations of the transient GOTO26djh/AT2026jpw
  15. GRB 260415B: NuSTAR detection of long prompt emission
  16. GOTO discovery of fast-fading transient GOTO26djh/AT2026jpw, a candidate orphan afterglow
  17. Fermi trigger No 797912738: Global MASTER-Net observations report
  18. GRB 260414A: Glowbug gamma-ray detection
  19. EP260409a: Early NIR limits from MIRAGE on the MDM 1.3m telescope
  20. EP260321a: CMO SAI J,K observations
  21. Fermi GRB 260413A: Global MASTER-Net observations report
  22. GRB 260410A: Glowbug gamma-ray detection of a short burst
  23. Fermi GRB 260412A: Global MASTER-Net observations report
  24. GRB 260412A: Fermi GBM Observation
  25. GRB 260411B: Fermi-LAT detection
  26. GRB 260411B: COLIBRÍ optical observations
  27. GRB 260410B: Fermi GBM Observation
  28. GRB260411B: 3.6m DOT optical observation
  29. GRB 260411A: SVOM/GRM observation
  30. GRB 260411B: SVOM/GRM observation of a long burst
  31. GRB 260409A: Insight-HXMT/HE detection
  32. GRB 260411B: Fermi GBM Detection
  33. EP260409a: Gemini/FLAMINGOS2 J-band counterpart
  34. GRB 260411B: BALROG localization (Fermi Trigger 797587480 / GRB 260411337)
  35. GRB 260410A: COLIBRÍ optical upper limit
  36. EP-WXT01709259790: Optical Upper limits with kinder observations
  37. GRB 260410A: Fermi GBM Observation
  38. GRB 260410B: SVOM/GRM detection of a short faint burst
  39. EP-WXT01709259790: Xinglong optical upper limit
  40. EP260409a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  41. GRB 260310A/AT2026fgk: Kilonova-Catcher SN peak identification
  42. EP260409a: COLIBRÍ optical upper limits
  43. EP260409a: Global MASTER-Net observations report
  44. EP260409a: Einstein Probe detection of an X-ray transient
  45. EP260321a: VLA radio detection
  46. GRB 260407A: Glowbug gamma-ray detection
  47. GRB 260402A: SVOM/ECLAIRs refined analysis
  48. GRB 260310A: Continued VLA Multi-frequency Radio Observations
  49. EP260402a / GRB 260402A: Mephisto optical upper limits
  50. EP-WXT01709259586: Xinglong optical upper limit
  51. EP260403a: Mephisto optical upper limits
  52. EP260402a/GRB 260402A: Xinglong optical upper limit
  53. EP260405a: GMOS-N optical upper limits
  54. EP260405a: Global MASTER-Net observations report
  55. EP260405a: Einstein Probe detection of a fast X-ray transient
  56. EP260405a / EP-WXT 11900672904: COLIBRÍ optical upper limits
  57. Fermi trigger No 797039833: Global MASTER-Net observations report
  58. EP260324A / AT 2026hir: COLIBRÍ further optical observations
  59. EP260403a: refined analysis of the EP-WXT and EP-FXT observations
  60. The EP-WXT trigger 01709259586 is likely a flaring star
  61. GRB 260330B: SVOM/VT further optical observation
  62. EP260403a: LCO optical observations of the counterpart
  63. GRB 260310A/AT2026fgk: Kilonova-Catcher long term optical monitoring
  64. EP260403a: LCO optical counterpart detection
  65. EP260403a: COLIBRÍ optical counterpart candidate
  66. GRB 260330B: SVOM/VT optical candidate
  67. EP260403a: Einstein Probe detection of an X-ray transient
  68. GRB 260330B: EP-FXT follow-up and identification of candidate afterglow
  69. EP260402a/GRB 260402A: refined analysis of the EP-WXT and EP-FXT observations
  70. EP260402a/GRB 260402A: Jinshan near-infrared upper limit
  71. GRB 260402C: NuSTAR detection of prompt emission
  72. GRB 260402C: AstroSat CZTI detection of a long burst
  73. EP260324A / AT 2026hir: COLIBRÍ optical observations
  74. GRB 260402A: WINTER J-band upper limit
  75. GRB260402A: GROWTH-India Telescope optical upper limit
  76. GRB 260402A / EP260402a: SVOM/VT optical upper limits
  77. EP260402a/GRB 260402A: SVOM/C-GFT upper limit
  78. GRB 260401A: SVOM/GRM observation
  79. EP260402a/GRB 260402A: Einstein Probe detection of an X-ray transient
  80. GRB 260402A: Kilonova-Catcher optical upper limit
  81. GRB 260402A: MASTER optical observations
  82. GRB 260402A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  83. GRB 260402A: SVOM/MXT candidate X-ray afterglow
  84. GRB 260402A: SVOM detection of a burst
  85. Fermi GRB 260401A: Global MASTER-Net observations report
  86. GRB 260401A: Fermi GBM Observation
  87. GRB 260401A: NuSTAR detection of prompt emission
  88. GRB 260401A: CALET Gamma-Ray Burst Monitor detection
  89. GRB 260401A: MAXI/GSC detection
  90. GRB 260401A: BALROG localization (Fermi Trigger 796733611 / GRB 260401454)
  91. GRB 260401A: Fermi GBM Final Real-time Localization
  92. EP260329b: Mondy and Assy-Turgen optical upper limits
  93. GRB 260310A / AT2026fgk: Luminance-band optical follow-up with a 28cm telescope in Daocheng
  94. EP260321a :Xinglong optical observations
  95. EP260327a: Xinglong optical upper limit
  96. GRB 260330B: SVOM/VT optical upper limits
  97. Konus-Wind detection of GRB 260320A
  98. GRB 260321A: SVOM/ECLAIRs refined analysis
  99. EP260329b: J-band upper limits with WINTER
  100. EP260329a: J-band upper limit with WINTER

Advanced

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