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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"

28037 results found.

  1. GRB 260808A: NuSTAR detection of prompt emission
  2. EP260809a: COLIBRÍ optical observations
  3. EP260809a: LCO optical observation
  4. EP260809a: OHP/T193 optical observations
  5. GRB260808B: OHP/T193 optical observations
  6. GRB 260808B / EPF_J230056.0+082842: EP-FXT follow-up observation
  7. EP260809a: Einstein Probe detection of an X-ray transient
  8. GRB 260808B: SVOM/VT optical candidate from VHF data ( localization correction for GCN 45317 )
  9. GRB 260808B: SVOM/VT optical candidate from VHF data
  10. GRB 260808B: SVOM detection of a faint burst
  11. GRB 260808A: BALROG localization (Fermi Trigger 807850307 / GRB 260808119)
  12. Fermi GRB 260808A: Global MASTER-Net observations report
  13. IceCube Alert 260807A: Global MASTER-Net observations report
  14. GRB 260807A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  15. GRB 260807A: SVOM possible detection of a faint burst
  16. EP260806a: COLIBRÍ optical observations
  17. EP260806a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  18. EP260806a: SVOM/VT optical observation
  19. EP260806a: Liverpool Telescope observations of the counterpart show a blue colour
  20. EP260731a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  21. EP260806a: LCO likely optical counterpart
  22. EP260806a: Einstein Probe detection of an X-ray transient
  23. GRB 260715A: cubesat Avion detection
  24. GRB 260709A: cubesat Avion detection
  25. GRB 260708A: cubesat Avion detection
  26. GRB 260730B: Glowbug gamma-ray detection
  27. GRB 260805C: Glowbug gamma-ray detection
  28. GRB 260805B: Glowbug gamma-ray detection
  29. Fermi GRB 260805A: Global MASTER-Net observations report
  30. GRB 260804A: Glowbug gamma-ray detection
  31. GRB 260805B: BALROG localization (Fermi Trigger 807622617 / GRB 260805484)
  32. IceCube-Cascade 260801A: Upper limits from a search for additional neutrino events in IceCube
  33. GRB 260708A: LCO further optical observations show supernova features
  34. Fermi GRB 260802B: Global MASTER-Net observations report
  35. GRB 260802A / EP J223759.5+521421: EP-FXT follow-up observation
  36. GRB 260802A: SVOM/VT optical upper limits from VHF data
  37. GRB 260802A: LCO optical upper limits
  38. GRB 260802A / EP J223759.5+531421: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  39. GRB 260802A/EP J223759.5+531421: SVOM detection of a possible magnetar burst
  40. Fermi-LAT Gamma-ray Observations of IceCube-260722A
  41. EP260731a: COLIBRÍ optical upper limit
  42. EP260731a: NOT optical upper limit
  43. GRB 260730B: NuSTAR detection of prompt emission
  44. EP260731a: Einstein Probe detection of an X-ray transient
  45. EP260728a: COLIBRÍ optical upper limit
  46. EP260729a: Einstein Probe detection of an X-ray transient
  47. EP260727a: SAO RAS optical observations
  48. GRB 260727A: AbAO and SAO RAS optical observations
  49. EP260728a: EP-FXT follow-up observation
  50. GRB 260726A: EP-FXT follow-up observations
  51. EP260728a: Einstein Probe detection of a fast X-ray transient
  52. GRB 260726A: Fermi GBM Observation
  53. EP260727a: 1.5m OSN optical counterpart detection
  54. EP260727a:refined analysis of the EP-WXT and EP-FXT observation
  55. EP260727a: OHP/T193 optical observations
  56. GRB 260726A: Liverpool Telescope optical observations
  57. GRB 260727A: Liverpool Telescope optical upper limits
  58. EP260727a: Liverpool Telescope confirmation of optical counterpart
  59. EP260727a: Einstein Probe detection of an X-ray transient
  60. The EP-WXT trigger 01709276927 (EP260727a?): NOT likely optical counterpart
  61. GRB 260727A: Glowbug gamma-ray detection
  62. GRB 260726A: J-band upper limit with WINTER
  63. GRB 260727A: J-band upper limit with WINTER
  64. GRB 260727A / SVOM sb26072702: RAPAS optical non-detection
  65. EP260723a: SVOM/ECLAIRs Upper Limit
  66. GRB 260727A: AstroSat CZTI detection
  67. GRB 260727A: Kilonova-Catcher optical upper limit
  68. GRB 260727A: LCO optical upper limits
  69. Fermi GRB 260726A: Global MASTER-Net observations report
  70. GRB 260726A: SVOM detection of a burst
  71. IceCube-260722A: Classification of ZTF26abjbxfs/SN 2026vts as a Type Ia Supernova
  72. EP260723a: further EP-FXT follow-up observation
  73. EP260725a: EP-WXT detection of an X-ray transient
  74. GRB 260616A: cubesat Avion detection
  75. EP260723a: Continued Liverpool Telescope observations suggest hours long optical plateau or rebrightening
  76. GRB 260602B: cubesat Avion detection
  77. GRB 260601A: cubesat Avion detection
  78. EP260723a: SVOM/VT optical observation
  79. EP260723a: COLIBRÍ optical observations
  80. EP260723a: NOT optical conterpart confirmation
  81. EP260723a: Liverpool Telescope likely optical counterpart
  82. EP260723a: EP-WXT detection of a fast X-ray transient
  83. IceCube-260722A: Upper limits from a search for additional neutrino events in IceCube
  84. IceCube-260722A: One candidate from the Zwicky Transient Facility (ZTF)
  85. IceCube Alert 260722A: Global MASTER-Net observations report
  86. GRB 260721A: NuSTAR detection of prompt emission
  87. SVOM trigger sb26071506: SVOM/VT confirmation of a stellar flare
  88. Fermi trigger No 806104130: Global MASTER-Net observations report
  89. Fermi GRB 260718A: Global MASTER-Net observations report
  90. GRB 260718A: LCO optical upper limits
  91. GRB 260710A: SVOM/GRM observation
  92. GRB 260718A: Fermi GBM Observation
  93. GRB 260718A : GRANDMA and KNC upper limits
  94. GRB 260718A: SVOM/VT optical upper limits
  95. GRB 260718A: SVOM/VT optical upper limits from VHF data
  96. GRB 260714B: SVOM/GRM observation
  97. GRB 260310A / AT2026fgk: Late-time Chandra Detection
  98. GRB 260714B: COLIBRÍ optical counterpart candidate
  99. SVOM sb26071506: Global MASTER-Net observations report
  100. sb26071506: SVOM detection of a X-ray transient

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