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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"

38349 results found.

  1. EP260725a: EP-FXT follow-up observation and association with a bright flaring star
  2. EP260725a: EP-WXT detection of an X-ray transient
  3. GRB 260616A: cubesat Avion detection
  4. EP260723a: Continued Liverpool Telescope observations suggest hours long optical plateau or rebrightening
  5. GRB 260602B: cubesat Avion detection
  6. GRB 260601A: cubesat Avion detection
  7. EP260723a: EP-FXT follow-up observation
  8. IPN triangulation of GRB 260706B
  9. GRB 260718A: SVOM/ECLAIRs refined analysis
  10. Fermi Gamma-ray Burst Monitor trigger 806592752 / 260724564 is not a GRB
  11. EP260723a: SVOM/VT optical observation
  12. EP260723a: COLIBRÍ optical observations
  13. EP260723a: Liverpool Telescope likely optical counterpart
  14. EP260723a: EP-WXT detection of a fast X-ray transient
  15. GRB 260723A: Fermi GBM Final Localization
  16. IceCube-260722A: Upper limits from a search for additional neutrino events in IceCube
  17. IceCube-260722A: One candidate from the Zwicky Transient Facility (ZTF)
  18. Konus-Wind detection of GRB 260721A
  19. GRB 260722A: Fermi GBM Final Real-time Localization
  20. IceCube-260722A - IceCube observation of a high-energy neutrino candidate track-like event
  21. Fermi GBM trigger 806384210/260722151 is not a GRB
  22. GRB 260721A: NuSTAR detection of prompt emission
  23. Konus-Wind detection of GRB 260714B
  24. SVOM trigger sb26071506: SVOM/VT confirmation of a stellar flare
  25. GRB 260705A: Retraction of optical counterpart
  26. GRB 260714B: Insight-HXMT/HE detection
  27. GRB 260718A: EP-FXT follow-up observation
  28. GRB 260718A: LCO optical upper limits
  29. GRB 260711A: SVOM/GRM observation
  30. GRB 260710A: SVOM/GRM observation
  31. GRB 260718A: Fermi GBM Observation
  32. GRB 260718A : GRANDMA and KNC upper limits
  33. GRB 260718A: SVOM/VT optical upper limits
  34. GRB 260718A: SVOM/VT optical upper limits from VHF data
  35. GRB 260718A: SVOM detection of a burst
  36. GRB 260714B: SVOM/GRM observation
  37. GRB 260714B: GECAM-B observation of a burst
  38. GRB 260618B: EP-FXT follow-up observation upper limit
  39. GRB 260714B: COLIBRÍ optical counterpart candidate
  40. IceCube-260708A: Follow-up studies of cosmic-ray origin of high-energy neutrino alert
  41. SVOM sb26071506: Global MASTER-Net observations report
  42. sb26071506: SVOM detection of a X-ray transient
  43. IceCube-260712A: No candidates with the Zwicky Transient Facility (ZTF)
  44. GRB 260715A: Fermi GBM Final Real-time Localization
  45. EP260703a: SVOM/ECLAIRs Upper Limit
  46. GRB 260710A: AstroSat CZTI detection
  47. GRB 260709A: AstroSat CZTI detection
  48. GRB 260714B: AstroSat CZTI detection
  49. GRB 260714B: Fermi-LAT detection
  50. GRB 260714B: Fermi GBM Detection
  51. GRB 260714B: BALROG localization (Fermi Trigger 805746211 / GRB 260714766)
  52. IceCube-260712A: Upper limits from a search for additional neutrino events in IceCube
  53. GRB 260714B: Fermi GBM Final Real-time Localization
  54. IceCube-260712A: LAST optical follow-up observations of the IceCube neutrino candidate
  55. GRB 260706A: ATCA detection of possible radio counterpart
  56. GRB 260705A: ATCA radio observations
  57. GRB 260714A: Fermi GBM Final Real-time Localization
  58. EP260713a: Einstein Probe detection of an X-ray transient
  59. GRB 260619A: SVOM/VT continuous optical observations
  60. GRB 260618B: SVOM/VT optical observations indicate shallow decay and reddening
  61. GRB 260708A: slowly decaying X-ray emission observed by EP/FXT
  62. EP260623a: KAIT optical observations
  63. EP260711a: EP-FXT follow-up observation
  64. GRB 260708A: GRANDMA Optical Observations
  65. Fermi-LAT Gamma-ray Observations of IceCube-260712A
  66. Fermi-LAT Gamma-ray Observations of IceCube-260708A
  67. GRB 260710A: Insight-HXMT/HE detection
  68. Fermi-LAT Gamma-ray Observations of IceCube-260704A
  69. IceCube-260708A: Upper limits from a search for additional neutrino events in IceCube
  70. IceCube-260712A - IceCube observation of a high-energy neutrino candidate track-like event
  71. GRB 260708A: LCO optical observations
  72. EP260711a: Einstein Probe detection of an X-ray transient
  73. GRB 260710A: Fermi GBM Detection
  74. GRB 260709A: SVOM/GRM detection
  75. GRB 260709A: GECAM-B observation
  76. The EP-WXT trigger 01709274666 is likely a new outburst of the CV SS Cyg
  77. IceCube-260708A: Observations with the Vera C. Rubin Observatory
  78. EP-WXT trigger 0170924151 : RAPAS optical counterpart candidate detection
  79. GRB 260705C: AstroSat CZTI detection
  80. GRB 260710A: Fermi GBM Final Real-time Localization
  81. GRB 260708A: Glowbug gamma-ray detection
  82. GRB 260704A: SVOM/ECLAIRs refined analysis
  83. GRB 260706A : GRANDMA Upper limits
  84. GRB 260708A: Kilonova-Catcher optical afterglow detection
  85. GRB 260708A: GECAM-B observation of a burst
  86. IceCube-260708A: One candidate from the Zwicky Transient Facility
  87. GRB 260708A: Fermi-GBM observation
  88. GRB 260709A: Fermi GBM Final Real-time Localization
  89. IceCube-260708A - IceCube observation of a high-energy neutrino candidate track-like event
  90. GRB260708B: MAXI/GSC detection
  91. GRB 260708A: Fermi-LAT detection
  92. GRB 260705B: SVOM/GRM observation
  93. GRB 260708A: Fermi-GBM detection
  94. GRB 260706A: Further EP-FXT follow-up observation
  95. GRB 260706A: SVOM/VT optical upper limits
  96. EP260707a is not a real source
  97. EP260707a: LCOGT Optical Upper Limit
  98. Fermi GBM trigger 805087514/260707142 (GRB 260707A) is not a GRB
  99. EP260707a: Einstein Probe detection of an X-ray transient
  100. Nova AT2026oyp (ASASSN-26dt): Pre-outburst Swift UVOT observation

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