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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"

28055 results found.

  1. GRB260808B: MAO/AZT-22 optical observations
  2. GRB 250607A: SVOM/ECLAIRs detection through offline targeted search
  3. GRB 260809A: J-band upper limit with WINTER
  4. GRB 260806A: Glowbug gamma-ray detection
  5. GRB260809A/EPF_J234751.2+210212: EP-FXT follow-up observation
  6. GRB 260809A: SVOM/COLIBRÍ (FM-GFT) optical observation
  7. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) optical observation
  8. GRB 260809A: NOT optical observations
  9. GRB260809A: MAO/AZT-22 optical observations
  10. GRB260809A: OHP/T193 optical observations
  11. IceCube-260805A: Upper limits from a search for additional neutrino events in IceCube
  12. EP260809a: J-band upper limit with WINTER
  13. GRB 260808B: J-band upper limit with WINTER
  14. EP260809a:refined analysis of the EP-WXT and autonomous EP-FXT observation
  15. GRB 260809A: SVOM detection of a faint burst
  16. GRB 260808B: Liverpool Telescope optical observations
  17. GRB 260808B: NOT optical observations
  18. GRB 260808B: LCO optical observations
  19. GRB 260808A: NuSTAR detection of prompt emission
  20. EP260809a: COLIBRÍ optical observations
  21. EP260809a: LCO optical observation
  22. EP260809a: OHP/T193 optical observations
  23. GRB260808B: OHP/T193 optical observations
  24. GRB 260808B / EPF_J230056.0+082842: EP-FXT follow-up observation
  25. EP260809a: Einstein Probe detection of an X-ray transient
  26. GRB 260808B: SVOM/VT optical candidate from VHF data ( localization correction for GCN 45317 )
  27. GRB 260808B: SVOM/VT optical candidate from VHF data
  28. GRB 260808B: SVOM detection of a faint burst
  29. GRB 260808A: BALROG localization (Fermi Trigger 807850307 / GRB 260808119)
  30. Fermi GRB 260808A: Global MASTER-Net observations report
  31. IceCube Alert 260807A: Global MASTER-Net observations report
  32. GRB 260807A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  33. GRB 260807A: SVOM possible detection of a faint burst
  34. EP260806a: COLIBRÍ optical observations
  35. EP260806a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  36. EP260806a: SVOM/VT optical observation
  37. EP260806a: Liverpool Telescope observations of the counterpart show a blue colour
  38. EP260731a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  39. EP260806a: LCO likely optical counterpart
  40. EP260806a: Einstein Probe detection of an X-ray transient
  41. GRB 260715A: cubesat Avion detection
  42. GRB 260709A: cubesat Avion detection
  43. GRB 260708A: cubesat Avion detection
  44. GRB 260730B: Glowbug gamma-ray detection
  45. GRB 260805C: Glowbug gamma-ray detection
  46. GRB 260805B: Glowbug gamma-ray detection
  47. Fermi GRB 260805A: Global MASTER-Net observations report
  48. GRB 260804A: Glowbug gamma-ray detection
  49. GRB 260805B: BALROG localization (Fermi Trigger 807622617 / GRB 260805484)
  50. IceCube-Cascade 260801A: Upper limits from a search for additional neutrino events in IceCube
  51. GRB 260708A: LCO further optical observations show supernova features
  52. Fermi GRB 260802B: Global MASTER-Net observations report
  53. GRB 260802A / EP J223759.5+521421: EP-FXT follow-up observation
  54. GRB 260802A: SVOM/VT optical upper limits from VHF data
  55. GRB 260802A: LCO optical upper limits
  56. GRB 260802A / EP J223759.5+531421: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  57. GRB 260802A/EP J223759.5+531421: SVOM detection of a possible magnetar burst
  58. Fermi-LAT Gamma-ray Observations of IceCube-260722A
  59. EP260731a: COLIBRÍ optical upper limit
  60. EP260731a: NOT optical upper limit
  61. GRB 260730B: NuSTAR detection of prompt emission
  62. EP260731a: Einstein Probe detection of an X-ray transient
  63. EP260728a: COLIBRÍ optical upper limit
  64. EP260729a: Einstein Probe detection of an X-ray transient
  65. EP260727a: SAO RAS optical observations
  66. GRB 260727A: AbAO and SAO RAS optical observations
  67. EP260728a: EP-FXT follow-up observation
  68. GRB 260726A: EP-FXT follow-up observations
  69. EP260728a: Einstein Probe detection of a fast X-ray transient
  70. GRB 260726A: Fermi GBM Observation
  71. EP260727a: 1.5m OSN optical counterpart detection
  72. EP260727a:refined analysis of the EP-WXT and EP-FXT observation
  73. EP260727a: OHP/T193 optical observations
  74. GRB 260726A: Liverpool Telescope optical observations
  75. GRB 260727A: Liverpool Telescope optical upper limits
  76. EP260727a: Liverpool Telescope confirmation of optical counterpart
  77. EP260727a: Einstein Probe detection of an X-ray transient
  78. The EP-WXT trigger 01709276927 (EP260727a?): NOT likely optical counterpart
  79. GRB 260727A: Glowbug gamma-ray detection
  80. GRB 260726A: J-band upper limit with WINTER
  81. GRB 260727A: J-band upper limit with WINTER
  82. GRB 260727A / SVOM sb26072702: RAPAS optical non-detection
  83. EP260723a: SVOM/ECLAIRs Upper Limit
  84. GRB 260727A: AstroSat CZTI detection
  85. GRB 260727A: Kilonova-Catcher optical upper limit
  86. GRB 260727A: LCO optical upper limits
  87. Fermi GRB 260726A: Global MASTER-Net observations report
  88. GRB 260726A: SVOM detection of a burst
  89. IceCube-260722A: Classification of ZTF26abjbxfs/SN 2026vts as a Type Ia Supernova
  90. EP260723a: further EP-FXT follow-up observation
  91. EP260725a: EP-WXT detection of an X-ray transient
  92. GRB 260616A: cubesat Avion detection
  93. EP260723a: Continued Liverpool Telescope observations suggest hours long optical plateau or rebrightening
  94. GRB 260602B: cubesat Avion detection
  95. GRB 260601A: cubesat Avion detection
  96. EP260723a: SVOM/VT optical observation
  97. EP260723a: COLIBRÍ optical observations
  98. EP260723a: NOT optical conterpart confirmation
  99. EP260723a: Liverpool Telescope likely optical counterpart
  100. EP260723a: EP-WXT detection of a fast X-ray transient

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