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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"

28045 results found.

  1. IceCube-260805A: Upper limits from a search for additional neutrino events in IceCube
  2. EP260809a: J-band upper limit with WINTER
  3. GRB 260808B: J-band upper limit with WINTER
  4. EP260809a:refined analysis of the EP-WXT and autonomous EP-FXT observation
  5. GRB 260809A: SVOM detection of a faint burst
  6. GRB 260808B: Liverpool Telescope optical observations
  7. GRB 260808B: NOT optical observations
  8. GRB 260808B: LCO optical observations
  9. GRB 260808A: NuSTAR detection of prompt emission
  10. EP260809a: COLIBRÍ optical observations
  11. EP260809a: LCO optical observation
  12. EP260809a: OHP/T193 optical observations
  13. GRB260808B: OHP/T193 optical observations
  14. GRB 260808B / EPF_J230056.0+082842: EP-FXT follow-up observation
  15. EP260809a: Einstein Probe detection of an X-ray transient
  16. GRB 260808B: SVOM/VT optical candidate from VHF data ( localization correction for GCN 45317 )
  17. GRB 260808B: SVOM/VT optical candidate from VHF data
  18. GRB 260808B: SVOM detection of a faint burst
  19. GRB 260808A: BALROG localization (Fermi Trigger 807850307 / GRB 260808119)
  20. Fermi GRB 260808A: Global MASTER-Net observations report
  21. IceCube Alert 260807A: Global MASTER-Net observations report
  22. GRB 260807A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  23. GRB 260807A: SVOM possible detection of a faint burst
  24. EP260806a: COLIBRÍ optical observations
  25. EP260806a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  26. EP260806a: SVOM/VT optical observation
  27. EP260806a: Liverpool Telescope observations of the counterpart show a blue colour
  28. EP260731a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  29. EP260806a: LCO likely optical counterpart
  30. EP260806a: Einstein Probe detection of an X-ray transient
  31. GRB 260715A: cubesat Avion detection
  32. GRB 260709A: cubesat Avion detection
  33. GRB 260708A: cubesat Avion detection
  34. GRB 260730B: Glowbug gamma-ray detection
  35. GRB 260805C: Glowbug gamma-ray detection
  36. GRB 260805B: Glowbug gamma-ray detection
  37. Fermi GRB 260805A: Global MASTER-Net observations report
  38. GRB 260804A: Glowbug gamma-ray detection
  39. GRB 260805B: BALROG localization (Fermi Trigger 807622617 / GRB 260805484)
  40. IceCube-Cascade 260801A: Upper limits from a search for additional neutrino events in IceCube
  41. GRB 260708A: LCO further optical observations show supernova features
  42. Fermi GRB 260802B: Global MASTER-Net observations report
  43. GRB 260802A / EP J223759.5+521421: EP-FXT follow-up observation
  44. GRB 260802A: SVOM/VT optical upper limits from VHF data
  45. GRB 260802A: LCO optical upper limits
  46. GRB 260802A / EP J223759.5+531421: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  47. GRB 260802A/EP J223759.5+531421: SVOM detection of a possible magnetar burst
  48. Fermi-LAT Gamma-ray Observations of IceCube-260722A
  49. EP260731a: COLIBRÍ optical upper limit
  50. EP260731a: NOT optical upper limit
  51. GRB 260730B: NuSTAR detection of prompt emission
  52. EP260731a: Einstein Probe detection of an X-ray transient
  53. EP260728a: COLIBRÍ optical upper limit
  54. EP260729a: Einstein Probe detection of an X-ray transient
  55. EP260727a: SAO RAS optical observations
  56. GRB 260727A: AbAO and SAO RAS optical observations
  57. EP260728a: EP-FXT follow-up observation
  58. GRB 260726A: EP-FXT follow-up observations
  59. EP260728a: Einstein Probe detection of a fast X-ray transient
  60. GRB 260726A: Fermi GBM Observation
  61. EP260727a: 1.5m OSN optical counterpart detection
  62. EP260727a:refined analysis of the EP-WXT and EP-FXT observation
  63. EP260727a: OHP/T193 optical observations
  64. GRB 260726A: Liverpool Telescope optical observations
  65. GRB 260727A: Liverpool Telescope optical upper limits
  66. EP260727a: Liverpool Telescope confirmation of optical counterpart
  67. EP260727a: Einstein Probe detection of an X-ray transient
  68. The EP-WXT trigger 01709276927 (EP260727a?): NOT likely optical counterpart
  69. GRB 260727A: Glowbug gamma-ray detection
  70. GRB 260726A: J-band upper limit with WINTER
  71. GRB 260727A: J-band upper limit with WINTER
  72. GRB 260727A / SVOM sb26072702: RAPAS optical non-detection
  73. EP260723a: SVOM/ECLAIRs Upper Limit
  74. GRB 260727A: AstroSat CZTI detection
  75. GRB 260727A: Kilonova-Catcher optical upper limit
  76. GRB 260727A: LCO optical upper limits
  77. Fermi GRB 260726A: Global MASTER-Net observations report
  78. GRB 260726A: SVOM detection of a burst
  79. IceCube-260722A: Classification of ZTF26abjbxfs/SN 2026vts as a Type Ia Supernova
  80. EP260723a: further EP-FXT follow-up observation
  81. EP260725a: EP-WXT detection of an X-ray transient
  82. GRB 260616A: cubesat Avion detection
  83. EP260723a: Continued Liverpool Telescope observations suggest hours long optical plateau or rebrightening
  84. GRB 260602B: cubesat Avion detection
  85. GRB 260601A: cubesat Avion detection
  86. EP260723a: SVOM/VT optical observation
  87. EP260723a: COLIBRÍ optical observations
  88. EP260723a: NOT optical conterpart confirmation
  89. EP260723a: Liverpool Telescope likely optical counterpart
  90. EP260723a: EP-WXT detection of a fast X-ray transient
  91. IceCube-260722A: Upper limits from a search for additional neutrino events in IceCube
  92. IceCube-260722A: One candidate from the Zwicky Transient Facility (ZTF)
  93. IceCube Alert 260722A: Global MASTER-Net observations report
  94. GRB 260721A: NuSTAR detection of prompt emission
  95. SVOM trigger sb26071506: SVOM/VT confirmation of a stellar flare
  96. Fermi trigger No 806104130: Global MASTER-Net observations report
  97. Fermi GRB 260718A: Global MASTER-Net observations report
  98. GRB 260718A: LCO optical upper limits
  99. GRB 260710A: SVOM/GRM observation
  100. GRB 260718A: Fermi GBM Observation

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