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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"

45429 results found.

  1. EP260731a: COLIBRÍ optical upper limit
  2. EP260731a: NOT optical upper limit
  3. GRB 260730B: NuSTAR detection of prompt emission
  4. EP260731a: Einstein Probe detection of an X-ray transient
  5. GRB 260727A: SVOM/ECLAIRs refined analysis
  6. GRB 260726A: SVOM/ECLAIRs refined analysis
  7. GRB260730A: Fermi GBM Final Localization
  8. EP260728a: COLIBRÍ optical upper limit
  9. EP260727a: VLT/X-shooter spectroscopic redshift z = 2.817
  10. The EP-WXT trigger 01709277130 (EP260729a): refined EP-WXT analysis and association with a flaring star
  11. EP 260729a: Ondrejov D50 optical detection supports stellar flare origin
  12. EP260729a: Einstein Probe detection of an X-ray transient
  13. EP260727a: SAO RAS optical observations
  14. GRB 260727A: AbAO and SAO RAS optical observations
  15. EP260728a: EP-FXT follow-up observation
  16. GRB 260726A: EP-FXT follow-up observations
  17. EP260728a: Einstein Probe detection of a fast X-ray transient
  18. GRB 260727A: SVOM/GRM observation
  19. GRB 260726A: Fermi GBM Observation
  20. EP260727a: 1.5m OSN optical counterpart detection
  21. EP260727a:refined analysis of the EP-WXT and EP-FXT observation
  22. EP260727a: OHP/T193 optical observations
  23. Konus-Wind detection of GRB 260727A
  24. GRB 260726A: Liverpool Telescope optical observations
  25. GRB 260727A: Liverpool Telescope optical upper limits
  26. EP260727a: Liverpool Telescope confirmation of optical counterpart
  27. EP260727a: NUTTELA-TAO Early Optical Limits
  28. GRB 260728A: Fermi GBM Final Localization
  29. GRB 260727A: EP/FXT follow-up observations
  30. EP260727a: Einstein Probe detection of an X-ray transient
  31. The EP-WXT trigger 01709276927 (EP260727a?): NOT likely optical counterpart
  32. GRB 260727A: Glowbug gamma-ray detection
  33. GRB 260726A: J-band upper limit with WINTER
  34. GRB 260727A: J-band upper limit with WINTER
  35. GRB 260726A: SVOM/VT optical candidate
  36. GRB 260726A: SVOM ECLAIRs improved position and MXT possible detection of a counterpart
  37. GRB 260727A / SVOM sb26072702: RAPAS optical non-detection
  38. EP260723a: SVOM/ECLAIRs Upper Limit
  39. GRB 260727A: GOTO early optical upper limit
  40. GRB 260727A: AstroSat CZTI detection
  41. GRB 260727A: Kilonova-Catcher optical upper limit
  42. GRB 260727A: LCO optical upper limits
  43. GRB 260727B: Fermi GBM Final Real-time Localization
  44. Fermi GRB 260726A: Global MASTER-Net observations report
  45. GRB 260727A: SVOM detection of a bright long burst
  46. GRB 260726A: SVOM detection of a burst
  47. GRB 260726A: Fermi GBM Final Real-time Localization
  48. IceCube-260722A: Classification of ZTF26abjbxfs/SN 2026vts as a Type Ia Supernova
  49. EP260723a: further EP-FXT follow-up observation
  50. EP260725a: EP-FXT follow-up observation and association with a bright flaring star
  51. EP260725a: EP-WXT detection of an X-ray transient
  52. GRB 260616A: cubesat Avion detection
  53. EP260723a: Continued Liverpool Telescope observations suggest hours long optical plateau or rebrightening
  54. GRB 260602B: cubesat Avion detection
  55. GRB 260601A: cubesat Avion detection
  56. EP260723a: EP-FXT follow-up observation
  57. IPN triangulation of GRB 260706B
  58. GRB 260718A: SVOM/ECLAIRs refined analysis
  59. Fermi Gamma-ray Burst Monitor trigger 806592752 / 260724564 is not a GRB
  60. EP260723a: SVOM/VT optical observation
  61. EP260723a: COLIBRÍ optical observations
  62. EP260723a: NOT optical conterpart confirmation
  63. EP260723a: Liverpool Telescope likely optical counterpart
  64. EP260723a: EP-WXT detection of a fast X-ray transient
  65. GRB 260723A: Fermi GBM Final Localization
  66. IceCube-260722A: Upper limits from a search for additional neutrino events in IceCube
  67. IceCube-260722A: One candidate from the Zwicky Transient Facility (ZTF)
  68. IceCube Alert 260722A: Global MASTER-Net observations report
  69. Konus-Wind detection of GRB 260721A
  70. GRB 260722A: Fermi GBM Final Real-time Localization
  71. IceCube-260722A - IceCube observation of a high-energy neutrino candidate track-like event
  72. Fermi GBM trigger 806384210/260722151 is not a GRB
  73. GRB 260721A: NuSTAR detection of prompt emission
  74. Konus-Wind detection of GRB 260714B
  75. SVOM trigger sb26071506: SVOM/VT confirmation of a stellar flare
  76. GRB 260705A: Retraction of optical counterpart
  77. GRB 260714B: Insight-HXMT/HE detection
  78. GRB 260718A: EP-FXT follow-up observation
  79. Fermi trigger No 806104130: Global MASTER-Net observations report
  80. Fermi GRB 260718A: Global MASTER-Net observations report
  81. GRB 260718A: LCO optical upper limits
  82. GRB 260711A: SVOM/GRM observation
  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. IceCube-260708A: Follow-up studies of cosmic-ray origin of high-energy neutrino alert
  95. SVOM sb26071506: Global MASTER-Net observations report
  96. sb26071506: SVOM detection of a X-ray transient
  97. IceCube-260712A: No candidates with the Zwicky Transient Facility (ZTF)
  98. GRB 260715A: Fermi GBM Final Real-time Localization
  99. EP260703a: SVOM/ECLAIRs Upper Limit
  100. GRB 260710A: AstroSat CZTI detection

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