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"

26491 results found.

  1. GRB 260807A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  2. GRB 260807A: SVOM possible detection of a faint burst
  3. EP260806a: COLIBRÍ optical observations
  4. EP260806a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  5. EP260806a: SVOM/VT optical observation
  6. EP260806a: Liverpool Telescope observations of the counterpart show a blue colour
  7. EP260731a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  8. EP260806a: LCO likely optical counterpart
  9. EP260806a: Einstein Probe detection of an X-ray transient
  10. GRB 260715A: cubesat Avion detection
  11. GRB 260709A: cubesat Avion detection
  12. GRB 260708A: cubesat Avion detection
  13. GRB 260730B: Glowbug gamma-ray detection
  14. GRB 260805C: Glowbug gamma-ray detection
  15. GRB 260805B: Glowbug gamma-ray detection
  16. GRB 260804A: Glowbug gamma-ray detection
  17. GRB 260805B: BALROG localization (Fermi Trigger 807622617 / GRB 260805484)
  18. AT 2026wki: EP/FXT follow-up observations
  19. IceCube-Cascade 260801A: Upper limits from a search for additional neutrino events in IceCube
  20. GRB 260802A / EP J223759.5+521421: EP-FXT follow-up observation
  21. GRB 260802A: SVOM/VT optical upper limits from VHF data
  22. GRB 260802A: LCO optical upper limits
  23. GRB 260802A / EP J223759.5+531421: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  24. The EP-WXT trigger 01709277420 is likely a flaring star
  25. GRB 260802A/EP J223759.5+531421: SVOM detection of a possible magnetar burst
  26. GRB 260727A: EP-FXT further follow-up observations and candidate afterglow
  27. GRB 260731A: AstroSat CZTI detection of a long burst
  28. Fermi-LAT Gamma-ray Observations of IceCube-260722A
  29. EP260731a: COLIBRÍ optical upper limit
  30. EP260731a: NOT optical upper limit
  31. EP260731a: Einstein Probe detection of an X-ray transient
  32. GRB 260727A: SVOM/ECLAIRs refined analysis
  33. GRB 260726A: SVOM/ECLAIRs refined analysis
  34. EP260728a: COLIBRÍ optical upper limit
  35. The EP-WXT trigger 01709277130 (EP260729a): refined EP-WXT analysis and association with a flaring star
  36. EP260729a: Einstein Probe detection of an X-ray transient
  37. EP260727a: SAO RAS optical observations
  38. GRB 260727A: AbAO and SAO RAS optical observations
  39. EP260728a: EP-FXT follow-up observation
  40. GRB 260726A: EP-FXT follow-up observations
  41. EP260728a: Einstein Probe detection of a fast X-ray transient
  42. GRB 260727A: SVOM/GRM observation
  43. GRB 260726A: Fermi GBM Observation
  44. EP260727a:refined analysis of the EP-WXT and EP-FXT observation
  45. EP260727a: OHP/T193 optical observations
  46. Konus-Wind detection of GRB 260727A
  47. GRB 260726A: Liverpool Telescope optical observations
  48. GRB 260727A: Liverpool Telescope optical upper limits
  49. EP260727a: Liverpool Telescope confirmation of optical counterpart
  50. GRB 260727A: EP/FXT follow-up observations
  51. EP260727a: Einstein Probe detection of an X-ray transient
  52. The EP-WXT trigger 01709276927 (EP260727a?): NOT likely optical counterpart
  53. GRB 260727A: Glowbug gamma-ray detection
  54. GRB 260726A: J-band upper limit with WINTER
  55. GRB 260727A: J-band upper limit with WINTER
  56. GRB 260727A / SVOM sb26072702: RAPAS optical non-detection
  57. EP260723a: SVOM/ECLAIRs Upper Limit
  58. GRB 260727A: AstroSat CZTI detection
  59. GRB 260727A: Kilonova-Catcher optical upper limit
  60. GRB 260727A: LCO optical upper limits
  61. GRB 260727A: SVOM detection of a bright long burst
  62. GRB 260726A: SVOM detection of a burst
  63. EP260723a: further EP-FXT follow-up observation
  64. EP260725a: EP-FXT follow-up observation and association with a bright flaring star
  65. EP260725a: EP-WXT detection of an X-ray transient
  66. GRB 260616A: cubesat Avion detection
  67. EP260723a: Continued Liverpool Telescope observations suggest hours long optical plateau or rebrightening
  68. GRB 260602B: cubesat Avion detection
  69. GRB 260601A: cubesat Avion detection
  70. GRB 260718A: SVOM/ECLAIRs refined analysis
  71. EP260723a: SVOM/VT optical observation
  72. EP260723a: COLIBRÍ optical observations
  73. EP260723a: NOT optical conterpart confirmation
  74. EP260723a: Liverpool Telescope likely optical counterpart
  75. EP260723a: EP-WXT detection of a fast X-ray transient
  76. IceCube-260722A: Upper limits from a search for additional neutrino events in IceCube
  77. IceCube-260722A: One candidate from the Zwicky Transient Facility (ZTF)
  78. Konus-Wind detection of GRB 260721A
  79. Konus-Wind detection of GRB 260714B
  80. SVOM trigger sb26071506: SVOM/VT confirmation of a stellar flare
  81. GRB 260718A: EP-FXT follow-up observation
  82. GRB 260718A: LCO optical upper limits
  83. GRB 260710A: SVOM/GRM observation
  84. GRB 260718A: Fermi GBM Observation
  85. GRB 260718A : GRANDMA and KNC upper limits
  86. GRB 260718A: SVOM/VT optical upper limits
  87. GRB 260718A: SVOM/VT optical upper limits from VHF data
  88. GRB 260718A: SVOM detection of a burst
  89. GRB 260714B: SVOM/GRM observation
  90. GRB 260310A / AT2026fgk: Late-time Chandra Detection
  91. GRB 260714B: GECAM-B observation of a burst
  92. GRB 260618B: EP-FXT follow-up observation upper limit
  93. GRB 260714B: COLIBRÍ optical counterpart candidate
  94. sb26071506: SVOM detection of a X-ray transient
  95. EP260703a: SVOM/ECLAIRs Upper Limit
  96. GRB 260709A: AstroSat CZTI detection
  97. GRB 260714B: Fermi GBM Detection
  98. IceCube-260712A: Upper limits from a search for additional neutrino events in IceCube
  99. IceCube-260712A: LAST optical follow-up observations of the IceCube neutrino candidate
  100. GRB 260706A: ATCA detection of possible radio counterpart

Advanced

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