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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"

28051 results found.

  1. GRB260809A/EPF_J234751.2+210212: EP-FXT follow-up observation
  2. GRB 260809A: SVOM/COLIBRÍ (FM-GFT) optical observation
  3. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) optical observation
  4. GRB 260809A: NOT optical observations
  5. GRB260809A: MAO/AZT-22 optical observations
  6. GRB260809A: OHP/T193 optical observations
  7. IceCube-260805A: Upper limits from a search for additional neutrino events in IceCube
  8. EP260809a: J-band upper limit with WINTER
  9. GRB 260808B: J-band upper limit with WINTER
  10. EP260809a:refined analysis of the EP-WXT and autonomous EP-FXT observation
  11. GRB 260809A: SVOM detection of a faint burst
  12. GRB 260808B: Liverpool Telescope optical observations
  13. GRB 260808B: NOT optical observations
  14. GRB 260808B: LCO optical observations
  15. GRB 260808A: NuSTAR detection of prompt emission
  16. EP260809a: COLIBRÍ optical observations
  17. EP260809a: LCO optical observation
  18. EP260809a: OHP/T193 optical observations
  19. GRB260808B: OHP/T193 optical observations
  20. GRB 260808B / EPF_J230056.0+082842: EP-FXT follow-up observation
  21. EP260809a: Einstein Probe detection of an X-ray transient
  22. GRB 260808B: SVOM/VT optical candidate from VHF data ( localization correction for GCN 45317 )
  23. GRB 260808B: SVOM/VT optical candidate from VHF data
  24. GRB 260808B: SVOM detection of a faint burst
  25. GRB 260808A: BALROG localization (Fermi Trigger 807850307 / GRB 260808119)
  26. Fermi GRB 260808A: Global MASTER-Net observations report
  27. IceCube Alert 260807A: Global MASTER-Net observations report
  28. GRB 260807A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  29. GRB 260807A: SVOM possible detection of a faint burst
  30. EP260806a: COLIBRÍ optical observations
  31. EP260806a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  32. EP260806a: SVOM/VT optical observation
  33. EP260806a: Liverpool Telescope observations of the counterpart show a blue colour
  34. EP260731a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  35. EP260806a: LCO likely optical counterpart
  36. EP260806a: Einstein Probe detection of an X-ray transient
  37. GRB 260715A: cubesat Avion detection
  38. GRB 260709A: cubesat Avion detection
  39. GRB 260708A: cubesat Avion detection
  40. GRB 260730B: Glowbug gamma-ray detection
  41. GRB 260805C: Glowbug gamma-ray detection
  42. GRB 260805B: Glowbug gamma-ray detection
  43. Fermi GRB 260805A: Global MASTER-Net observations report
  44. GRB 260804A: Glowbug gamma-ray detection
  45. GRB 260805B: BALROG localization (Fermi Trigger 807622617 / GRB 260805484)
  46. IceCube-Cascade 260801A: Upper limits from a search for additional neutrino events in IceCube
  47. GRB 260708A: LCO further optical observations show supernova features
  48. Fermi GRB 260802B: Global MASTER-Net observations report
  49. GRB 260802A / EP J223759.5+521421: EP-FXT follow-up observation
  50. GRB 260802A: SVOM/VT optical upper limits from VHF data
  51. GRB 260802A: LCO optical upper limits
  52. GRB 260802A / EP J223759.5+531421: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  53. GRB 260802A/EP J223759.5+531421: SVOM detection of a possible magnetar burst
  54. Fermi-LAT Gamma-ray Observations of IceCube-260722A
  55. EP260731a: COLIBRÍ optical upper limit
  56. EP260731a: NOT optical upper limit
  57. GRB 260730B: NuSTAR detection of prompt emission
  58. EP260731a: Einstein Probe detection of an X-ray transient
  59. EP260728a: COLIBRÍ optical upper limit
  60. EP260729a: Einstein Probe detection of an X-ray transient
  61. EP260727a: SAO RAS optical observations
  62. GRB 260727A: AbAO and SAO RAS optical observations
  63. EP260728a: EP-FXT follow-up observation
  64. GRB 260726A: EP-FXT follow-up observations
  65. EP260728a: Einstein Probe detection of a fast X-ray transient
  66. GRB 260726A: Fermi GBM Observation
  67. EP260727a: 1.5m OSN optical counterpart detection
  68. EP260727a:refined analysis of the EP-WXT and EP-FXT observation
  69. EP260727a: OHP/T193 optical observations
  70. GRB 260726A: Liverpool Telescope optical observations
  71. GRB 260727A: Liverpool Telescope optical upper limits
  72. EP260727a: Liverpool Telescope confirmation of optical counterpart
  73. EP260727a: Einstein Probe detection of an X-ray transient
  74. The EP-WXT trigger 01709276927 (EP260727a?): NOT likely optical counterpart
  75. GRB 260727A: Glowbug gamma-ray detection
  76. GRB 260726A: J-band upper limit with WINTER
  77. GRB 260727A: J-band upper limit with WINTER
  78. GRB 260727A / SVOM sb26072702: RAPAS optical non-detection
  79. EP260723a: SVOM/ECLAIRs Upper Limit
  80. GRB 260727A: AstroSat CZTI detection
  81. GRB 260727A: Kilonova-Catcher optical upper limit
  82. GRB 260727A: LCO optical upper limits
  83. Fermi GRB 260726A: Global MASTER-Net observations report
  84. GRB 260726A: SVOM detection of a burst
  85. IceCube-260722A: Classification of ZTF26abjbxfs/SN 2026vts as a Type Ia Supernova
  86. EP260723a: further EP-FXT follow-up observation
  87. EP260725a: EP-WXT detection of an X-ray transient
  88. GRB 260616A: cubesat Avion detection
  89. EP260723a: Continued Liverpool Telescope observations suggest hours long optical plateau or rebrightening
  90. GRB 260602B: cubesat Avion detection
  91. GRB 260601A: cubesat Avion detection
  92. EP260723a: SVOM/VT optical observation
  93. EP260723a: COLIBRÍ optical observations
  94. EP260723a: NOT optical conterpart confirmation
  95. EP260723a: Liverpool Telescope likely optical counterpart
  96. EP260723a: EP-WXT detection of a fast X-ray transient
  97. IceCube-260722A: Upper limits from a search for additional neutrino events in IceCube
  98. IceCube-260722A: One candidate from the Zwicky Transient Facility (ZTF)
  99. IceCube Alert 260722A: Global MASTER-Net observations report
  100. GRB 260721A: NuSTAR detection of prompt emission

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