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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"

28035 results found.

  1. GRB 260808B / EPF_J230056.0+082842: EP-FXT follow-up observation
  2. EP260809a: Einstein Probe detection of an X-ray transient
  3. GRB 260808B: SVOM/VT optical candidate from VHF data ( localization correction for GCN 45317 )
  4. GRB 260808B: SVOM/VT optical candidate from VHF data
  5. GRB 260808B: SVOM detection of a faint burst
  6. GRB 260808A: BALROG localization (Fermi Trigger 807850307 / GRB 260808119)
  7. Fermi GRB 260808A: Global MASTER-Net observations report
  8. IceCube Alert 260807A: Global MASTER-Net observations report
  9. GRB 260807A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  10. GRB 260807A: SVOM possible detection of a faint burst
  11. EP260806a: COLIBRÍ optical observations
  12. EP260806a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  13. EP260806a: SVOM/VT optical observation
  14. EP260806a: Liverpool Telescope observations of the counterpart show a blue colour
  15. EP260731a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  16. EP260806a: LCO likely optical counterpart
  17. EP260806a: Einstein Probe detection of an X-ray transient
  18. GRB 260715A: cubesat Avion detection
  19. GRB 260709A: cubesat Avion detection
  20. GRB 260708A: cubesat Avion detection
  21. GRB 260730B: Glowbug gamma-ray detection
  22. GRB 260805C: Glowbug gamma-ray detection
  23. GRB 260805B: Glowbug gamma-ray detection
  24. Fermi GRB 260805A: Global MASTER-Net observations report
  25. GRB 260804A: Glowbug gamma-ray detection
  26. GRB 260805B: BALROG localization (Fermi Trigger 807622617 / GRB 260805484)
  27. IceCube-Cascade 260801A: Upper limits from a search for additional neutrino events in IceCube
  28. GRB 260708A: LCO further optical observations show supernova features
  29. Fermi GRB 260802B: Global MASTER-Net observations report
  30. GRB 260802A / EP J223759.5+521421: EP-FXT follow-up observation
  31. GRB 260802A: SVOM/VT optical upper limits from VHF data
  32. GRB 260802A: LCO optical upper limits
  33. GRB 260802A / EP J223759.5+531421: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  34. GRB 260802A/EP J223759.5+531421: SVOM detection of a possible magnetar burst
  35. Fermi-LAT Gamma-ray Observations of IceCube-260722A
  36. EP260731a: COLIBRÍ optical upper limit
  37. EP260731a: NOT optical upper limit
  38. GRB 260730B: NuSTAR detection of prompt emission
  39. EP260731a: Einstein Probe detection of an X-ray transient
  40. EP260728a: COLIBRÍ optical upper limit
  41. EP260729a: Einstein Probe detection of an X-ray transient
  42. EP260727a: SAO RAS optical observations
  43. GRB 260727A: AbAO and SAO RAS optical observations
  44. EP260728a: EP-FXT follow-up observation
  45. GRB 260726A: EP-FXT follow-up observations
  46. EP260728a: Einstein Probe detection of a fast X-ray transient
  47. GRB 260726A: Fermi GBM Observation
  48. EP260727a: 1.5m OSN optical counterpart detection
  49. EP260727a:refined analysis of the EP-WXT and EP-FXT observation
  50. EP260727a: OHP/T193 optical observations
  51. GRB 260726A: Liverpool Telescope optical observations
  52. GRB 260727A: Liverpool Telescope optical upper limits
  53. EP260727a: Liverpool Telescope confirmation of optical counterpart
  54. EP260727a: Einstein Probe detection of an X-ray transient
  55. The EP-WXT trigger 01709276927 (EP260727a?): NOT likely optical counterpart
  56. GRB 260727A: Glowbug gamma-ray detection
  57. GRB 260726A: J-band upper limit with WINTER
  58. GRB 260727A: J-band upper limit with WINTER
  59. GRB 260727A / SVOM sb26072702: RAPAS optical non-detection
  60. EP260723a: SVOM/ECLAIRs Upper Limit
  61. GRB 260727A: AstroSat CZTI detection
  62. GRB 260727A: Kilonova-Catcher optical upper limit
  63. GRB 260727A: LCO optical upper limits
  64. Fermi GRB 260726A: Global MASTER-Net observations report
  65. GRB 260726A: SVOM detection of a burst
  66. IceCube-260722A: Classification of ZTF26abjbxfs/SN 2026vts as a Type Ia Supernova
  67. EP260723a: further EP-FXT follow-up observation
  68. EP260725a: EP-WXT detection of an X-ray transient
  69. GRB 260616A: cubesat Avion detection
  70. EP260723a: Continued Liverpool Telescope observations suggest hours long optical plateau or rebrightening
  71. GRB 260602B: cubesat Avion detection
  72. GRB 260601A: cubesat Avion detection
  73. EP260723a: SVOM/VT optical observation
  74. EP260723a: COLIBRÍ optical observations
  75. EP260723a: NOT optical conterpart confirmation
  76. EP260723a: Liverpool Telescope likely optical counterpart
  77. EP260723a: EP-WXT detection of a fast X-ray transient
  78. IceCube-260722A: Upper limits from a search for additional neutrino events in IceCube
  79. IceCube-260722A: One candidate from the Zwicky Transient Facility (ZTF)
  80. IceCube Alert 260722A: Global MASTER-Net observations report
  81. GRB 260721A: NuSTAR detection of prompt emission
  82. SVOM trigger sb26071506: SVOM/VT confirmation of a stellar flare
  83. Fermi trigger No 806104130: Global MASTER-Net observations report
  84. Fermi GRB 260718A: Global MASTER-Net observations report
  85. GRB 260718A: LCO optical upper limits
  86. GRB 260710A: SVOM/GRM observation
  87. GRB 260718A: Fermi GBM Observation
  88. GRB 260718A : GRANDMA and KNC upper limits
  89. GRB 260718A: SVOM/VT optical upper limits
  90. GRB 260718A: SVOM/VT optical upper limits from VHF data
  91. GRB 260714B: SVOM/GRM observation
  92. GRB 260310A / AT2026fgk: Late-time Chandra Detection
  93. GRB 260714B: COLIBRÍ optical counterpart candidate
  94. SVOM sb26071506: Global MASTER-Net observations report
  95. sb26071506: SVOM detection of a X-ray transient
  96. EP260703a: SVOM/ECLAIRs Upper Limit
  97. GRB 260710A: AstroSat CZTI detection
  98. GRB 260714B: Fermi GBM Detection
  99. GRB 260714B: BALROG localization (Fermi Trigger 805746211 / GRB 260714766)
  100. IceCube-260712A: Upper limits from a search for additional neutrino events in IceCube

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