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"

26496 results found.

  1. GRB 260604C: SVOM/COLIBRÍ (FM-GFT) optical observations
  2. The EP-WXT trigger 01709266798 is likely a flaring star
  3. GRB 260604C: Jinshan optical observations
  4. GRB 260604C: Fermi GBM Observation
  5. EP260602d: J-band upper limit with WINTER
  6. EP260602b: J-band upper limit with WINTER
  7. GRB 260604C: LAST detection of optical counterpart candidate
  8. GRB 260604C: SVOM detection of a long burst
  9. GRB 260603A: Simeiz Zeiss-1000 optical upper limit
  10. EP260602a: EP-FXT follow-up observation
  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. GRB 260603A: EP-FXT follow-up observation
  18. EP260601a/GRB 260601B: EP-FXT follow-up observation
  19. GRB 260601B / EP260601a: Mondy optical upper limit
  20. EP260602b: EP-FXT follow-up observation
  21. GRB 260601B/EP260601a: Glowbug gamma-ray detection
  22. GRB 260603A: Kilonova-Catcher optical upper limit
  23. GRB 260603A: SVOM/VT optical observations
  24. EP260602a: NOT NIR J-band observations
  25. GRB 260603A: SVOM/COLIBRÍ (FM-GFT) photometric redshift z = 3.57
  26. EP260602d: Einstein Probe detection of a fast X-ray transient
  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. GRB 260603A: SVOM detection of a burst
  33. EP260602b: Einstein Probe detection of a fast X-ray transient
  34. EP260602a: SVOM/VT optical candidate
  35. EP-WXT trigger 01709266414 (EP260602b): JinShan optical counterpart detection
  36. GRB 260601B/EP260601a: J-band upper limit with WINTER
  37. EP260530a/AT 2026nwl: COLIBRÍ optical follow up
  38. EP260530a/AT 2026nwl: KAIT optical observations
  39. GRB 260602A: Fermi GBM Final Real-time Localization
  40. EP260602a: Optical upper limits with Kinder observations
  41. EP260602a: Einstein Probe detection of a fast X-ray transient
  42. GRB 260601B/EP260601a: SVOM/VT optical observations
  43. GRB 260601B/EP260601a: GECAM-B analysis suggests a possible long duration Type I burst
  44. EP260601a: Einstein Probe detection of an X-ray transient
  45. EP-WXT trigger 01709266307 (EP260601a): COLIBRÍ optical observations
  46. EP-WXT trigger 01709266307 (EP260601a): JinShan optical counterpart detection
  47. GRB 260601A: Glowbug gamma-ray detection of a short burst
  48. GRB 260531B: Glowbug gamma-ray 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. GRB 260518B: SVOM/ECLAIRs detection of a soft burst possibly associated with EP 260518a and AT 2026ndp
  54. The EP-WXT trigger 01709266272 is likely a flaring star
  55. AT2026nik: EP-FXT X-ray counterpart
  56. AT 2026nuz: COLIBRÍ optical observations
  57. EP260527a/GRB 260527A: optical upper limit with Kinder observations
  58. GRB 260429B / EP260429a: COLIBRÍ optical counterpart candidate
  59. GRB 260527A/EP260527a: VLT/X-shooter tentative redshift
  60. EP260526a: SVOM/VT optical upper limits
  61. EP260527a / GRB 260527A: VLT detection of the optical and nIR counterpart
  62. EP260527a/GRB 260527A: Infrared J upper limit with MDM/MIRAGE
  63. EP260527a/GRB 260527A: EP-FXT follow-up observation
  64. Konus-Wind detection of GRB 260527A (short/hard) ~4 min before EP260527a
  65. EP260526a: EP-FXT follow-up observation
  66. EP260527a: SVOM/VT optical observation
  67. EP260527a: COLIBRÍ optical detection
  68. EP260527a: Einstein Probe detection of a fast X-ray transient
  69. The EP-WXT trigger 01709266172 is likely a flaring star
  70. The EP-WXT trigger 01709266147 is likely a flaring star
  71. EP260526a: LCO optical upper limits
  72. EP260526a: Einstein Probe detection of a fast X-ray transient
  73. GRB 260525A: AstroSat CZTI detection
  74. EP260526.405: COLIBRÍ optical upper limits
  75. The EP-WXT trigger 01709266106 is not a real source
  76. EP01709266106 (EP260526a?): Liverpool Telescope upper limits
  77. EP-WXT 01709266106: NOT optical upper limits
  78. GRB 260522A: Fermi GBM Observation
  79. EP260518a (AT2026ndp): LCO observations and Gemini-South Redshift z = 2.28
  80. EP260518a: Einstein Probe detection of an sub-threshold X-ray transient with counterpart AT 2026ndp
  81. GRB 260519C: SVOM/GRM observation
  82. GRB 260511A: iTelescope T-75 optical detection
  83. GRB 260520B: SVOM/GRM observation
  84. Konus-Wind detection of GRB 260519C
  85. GRB 260509A: SVOM/ECLAIRs refined analysis
  86. Konus-Wind detection of GRB 260518A
  87. GRB 260518A: AstroSat CZTI detection of a long burst
  88. GRB 260421B: radio detection with the VLA
  89. GRB 260509A: CrAO ZTSh optical upper limit
  90. GRB 260516D: EP-FXT follow-up observation
  91. GRB 260516D: GOTO optical counterpart detection
  92. GRB 260516D: LCO optical observations
  93. GRB 260515A: further Liverpool Telescope observations
  94. GRB 260516D: SVOM/COLIBRÍ (FM-GFT) optical observations
  95. GRB 260516D: GROWTH-India Telescope optical detection
  96. GRB 260516D: SVOM/VT optical bright candidate
  97. GRB 260515A: CrAO ZTSh BVRI optical observations
  98. GRB 260516D: SVOM possible detection of a burst
  99. Konus-Wind detection of GRB 260515A
  100. GRB 260515A: LCO optical counterpart 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