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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"

28042 results found.

  1. GRB 260809A: SVOM detection of a faint burst
  2. GRB 260808B: Liverpool Telescope optical observations
  3. GRB 260808B: NOT optical observations
  4. GRB 260808B: LCO optical observations
  5. GRB 260808A: NuSTAR detection of prompt emission
  6. EP260809a: COLIBRÍ optical observations
  7. EP260809a: LCO optical observation
  8. EP260809a: OHP/T193 optical observations
  9. GRB260808B: OHP/T193 optical observations
  10. GRB 260808B / EPF_J230056.0+082842: EP-FXT follow-up observation
  11. EP260809a: Einstein Probe detection of an X-ray transient
  12. GRB 260808B: SVOM/VT optical candidate from VHF data ( localization correction for GCN 45317 )
  13. GRB 260808B: SVOM/VT optical candidate from VHF data
  14. GRB 260808B: SVOM detection of a faint burst
  15. GRB 260808A: BALROG localization (Fermi Trigger 807850307 / GRB 260808119)
  16. Fermi GRB 260808A: Global MASTER-Net observations report
  17. IceCube Alert 260807A: Global MASTER-Net observations report
  18. GRB 260807A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  19. GRB 260807A: SVOM possible detection of a faint burst
  20. EP260806a: COLIBRÍ optical observations
  21. EP260806a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  22. EP260806a: SVOM/VT optical observation
  23. EP260806a: Liverpool Telescope observations of the counterpart show a blue colour
  24. EP260731a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  25. EP260806a: LCO likely optical counterpart
  26. EP260806a: Einstein Probe detection of an X-ray transient
  27. GRB 260715A: cubesat Avion detection
  28. GRB 260709A: cubesat Avion detection
  29. GRB 260708A: cubesat Avion detection
  30. GRB 260730B: Glowbug gamma-ray detection
  31. GRB 260805C: Glowbug gamma-ray detection
  32. GRB 260805B: Glowbug gamma-ray detection
  33. Fermi GRB 260805A: Global MASTER-Net observations report
  34. GRB 260804A: Glowbug gamma-ray detection
  35. GRB 260805B: BALROG localization (Fermi Trigger 807622617 / GRB 260805484)
  36. IceCube-Cascade 260801A: Upper limits from a search for additional neutrino events in IceCube
  37. GRB 260708A: LCO further optical observations show supernova features
  38. Fermi GRB 260802B: Global MASTER-Net observations report
  39. GRB 260802A / EP J223759.5+521421: EP-FXT follow-up observation
  40. GRB 260802A: SVOM/VT optical upper limits from VHF data
  41. GRB 260802A: LCO optical upper limits
  42. GRB 260802A / EP J223759.5+531421: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  43. GRB 260802A/EP J223759.5+531421: SVOM detection of a possible magnetar burst
  44. Fermi-LAT Gamma-ray Observations of IceCube-260722A
  45. EP260731a: COLIBRÍ optical upper limit
  46. EP260731a: NOT optical upper limit
  47. GRB 260730B: NuSTAR detection of prompt emission
  48. EP260731a: Einstein Probe detection of an X-ray transient
  49. EP260728a: COLIBRÍ optical upper limit
  50. EP260729a: Einstein Probe detection of an X-ray transient
  51. EP260727a: SAO RAS optical observations
  52. GRB 260727A: AbAO and SAO RAS optical observations
  53. EP260728a: EP-FXT follow-up observation
  54. GRB 260726A: EP-FXT follow-up observations
  55. EP260728a: Einstein Probe detection of a fast X-ray transient
  56. GRB 260726A: Fermi GBM Observation
  57. EP260727a: 1.5m OSN optical counterpart detection
  58. EP260727a:refined analysis of the EP-WXT and EP-FXT observation
  59. EP260727a: OHP/T193 optical observations
  60. GRB 260726A: Liverpool Telescope optical observations
  61. GRB 260727A: Liverpool Telescope optical upper limits
  62. EP260727a: Liverpool Telescope confirmation of optical counterpart
  63. EP260727a: Einstein Probe detection of an X-ray transient
  64. The EP-WXT trigger 01709276927 (EP260727a?): NOT likely optical counterpart
  65. GRB 260727A: Glowbug gamma-ray detection
  66. GRB 260726A: J-band upper limit with WINTER
  67. GRB 260727A: J-band upper limit with WINTER
  68. GRB 260727A / SVOM sb26072702: RAPAS optical non-detection
  69. EP260723a: SVOM/ECLAIRs Upper Limit
  70. GRB 260727A: AstroSat CZTI detection
  71. GRB 260727A: Kilonova-Catcher optical upper limit
  72. GRB 260727A: LCO optical upper limits
  73. Fermi GRB 260726A: Global MASTER-Net observations report
  74. GRB 260726A: SVOM detection of a burst
  75. IceCube-260722A: Classification of ZTF26abjbxfs/SN 2026vts as a Type Ia Supernova
  76. EP260723a: further EP-FXT follow-up observation
  77. EP260725a: EP-WXT detection of an X-ray transient
  78. GRB 260616A: cubesat Avion detection
  79. EP260723a: Continued Liverpool Telescope observations suggest hours long optical plateau or rebrightening
  80. GRB 260602B: cubesat Avion detection
  81. GRB 260601A: cubesat Avion detection
  82. EP260723a: SVOM/VT optical observation
  83. EP260723a: COLIBRÍ optical observations
  84. EP260723a: NOT optical conterpart confirmation
  85. EP260723a: Liverpool Telescope likely optical counterpart
  86. EP260723a: EP-WXT detection of a fast X-ray transient
  87. IceCube-260722A: Upper limits from a search for additional neutrino events in IceCube
  88. IceCube-260722A: One candidate from the Zwicky Transient Facility (ZTF)
  89. IceCube Alert 260722A: Global MASTER-Net observations report
  90. GRB 260721A: NuSTAR detection of prompt emission
  91. SVOM trigger sb26071506: SVOM/VT confirmation of a stellar flare
  92. Fermi trigger No 806104130: Global MASTER-Net observations report
  93. Fermi GRB 260718A: Global MASTER-Net observations report
  94. GRB 260718A: LCO optical upper limits
  95. GRB 260710A: SVOM/GRM observation
  96. GRB 260718A: Fermi GBM Observation
  97. GRB 260718A : GRANDMA and KNC upper limits
  98. GRB 260718A: SVOM/VT optical upper limits
  99. GRB 260718A: SVOM/VT optical upper limits from VHF data
  100. GRB 260714B: SVOM/GRM observation

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