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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"

27887 results found.

  1. EP260728a: Einstein Probe detection of a fast X-ray transient
  2. GRB 260726A: Fermi GBM Observation
  3. EP260727a: 1.5m OSN optical counterpart detection
  4. EP260727a:refined analysis of the EP-WXT and EP-FXT observation
  5. EP260727a: OHP/T193 optical observations
  6. GRB 260726A: Liverpool Telescope optical observations
  7. GRB 260727A: Liverpool Telescope optical upper limits
  8. EP260727a: Liverpool Telescope confirmation of optical counterpart
  9. EP260727a: Einstein Probe detection of an X-ray transient
  10. The EP-WXT trigger 01709276927 (EP260727a?): NOT likely optical counterpart
  11. GRB 260727A: Glowbug gamma-ray detection
  12. GRB 260726A: J-band upper limit with WINTER
  13. GRB 260727A: J-band upper limit with WINTER
  14. GRB 260727A / SVOM sb26072702: RAPAS optical non-detection
  15. EP260723a: SVOM/ECLAIRs Upper Limit
  16. GRB 260727A: AstroSat CZTI detection
  17. GRB 260727A: Kilonova-Catcher optical upper limit
  18. GRB 260727A: LCO optical upper limits
  19. Fermi GRB 260726A: Global MASTER-Net observations report
  20. GRB 260726A: SVOM detection of a burst
  21. IceCube-260722A: Classification of ZTF26abjbxfs/SN 2026vts as a Type Ia Supernova
  22. EP260723a: further EP-FXT follow-up observation
  23. EP260725a: EP-WXT detection of an X-ray transient
  24. GRB 260616A: cubesat Avion detection
  25. EP260723a: Continued Liverpool Telescope observations suggest hours long optical plateau or rebrightening
  26. GRB 260602B: cubesat Avion detection
  27. GRB 260601A: cubesat Avion detection
  28. EP260723a: SVOM/VT optical observation
  29. EP260723a: COLIBRÍ optical observations
  30. EP260723a: NOT optical conterpart confirmation
  31. EP260723a: Liverpool Telescope likely optical counterpart
  32. EP260723a: EP-WXT detection of a fast X-ray transient
  33. IceCube-260722A: Upper limits from a search for additional neutrino events in IceCube
  34. IceCube-260722A: One candidate from the Zwicky Transient Facility (ZTF)
  35. IceCube Alert 260722A: Global MASTER-Net observations report
  36. GRB 260721A: NuSTAR detection of prompt emission
  37. SVOM trigger sb26071506: SVOM/VT confirmation of a stellar flare
  38. Fermi trigger No 806104130: Global MASTER-Net observations report
  39. Fermi GRB 260718A: Global MASTER-Net observations report
  40. GRB 260718A: LCO optical upper limits
  41. GRB 260710A: SVOM/GRM observation
  42. GRB 260718A: Fermi GBM Observation
  43. GRB 260718A : GRANDMA and KNC upper limits
  44. GRB 260718A: SVOM/VT optical upper limits
  45. GRB 260718A: SVOM/VT optical upper limits from VHF data
  46. GRB 260714B: SVOM/GRM observation
  47. GRB 260310A / AT2026fgk: Late-time Chandra Detection
  48. GRB 260714B: COLIBRÍ optical counterpart candidate
  49. SVOM sb26071506: Global MASTER-Net observations report
  50. sb26071506: SVOM detection of a X-ray transient
  51. EP260703a: SVOM/ECLAIRs Upper Limit
  52. GRB 260710A: AstroSat CZTI detection
  53. GRB 260714B: Fermi GBM Detection
  54. GRB 260714B: BALROG localization (Fermi Trigger 805746211 / GRB 260714766)
  55. IceCube-260712A: Upper limits from a search for additional neutrino events in IceCube
  56. IceCube-260712A: LAST optical follow-up observations of the IceCube neutrino candidate
  57. EP260713a: Einstein Probe detection of an X-ray transient
  58. GRB 260619A: SVOM/VT continuous optical observations
  59. GRB 260708A: slowly decaying X-ray emission observed by EP/FXT
  60. EP260623a: KAIT optical observations
  61. GRB 260708A: GRANDMA Optical Observations
  62. Fermi-LAT Gamma-ray Observations of IceCube-260712A
  63. Fermi-LAT Gamma-ray Observations of IceCube-260708A
  64. Fermi-LAT Gamma-ray Observations of IceCube-260704A
  65. IceCube-260708A: Upper limits from a search for additional neutrino events in IceCube
  66. GRB 260708A: LCO optical observations
  67. EP260711a: Einstein Probe detection of an X-ray transient
  68. GRB 260709A: SVOM/GRM detection
  69. IceCube-260708A: Observations with the Vera C. Rubin Observatory
  70. EP-WXT trigger 0170924151 : RAPAS optical counterpart candidate detection
  71. GRB 260708A: Glowbug gamma-ray detection
  72. GRB 260706A : GRANDMA Upper limits
  73. GRB 260708A: Kilonova-Catcher optical afterglow detection
  74. IceCube-260708A: One candidate from the Zwicky Transient Facility
  75. GRB 260708A: Fermi-GBM observation
  76. Fermi LAT GRB 260708A: MASTER OT J150237.02-435307.7 optical counterpart detection
  77. IceCube Alert 260709A: Global MASTER-Net observations report
  78. LAT GRB260708.42: Global MASTER-Net observations report
  79. GRB260708B: MAXI/GSC detection
  80. GRB 260705B: SVOM/GRM observation
  81. GRB 260706A: Further EP-FXT follow-up observation
  82. EP260707a (by EP-FXT): NOT optical upper limit
  83. EP260707a is not a real source
  84. EP260707a: LCOGT Optical Upper Limit
  85. EP260707a: TRT optical upper limit
  86. EP260707a: Einstein Probe detection of an X-ray transient
  87. GRB 260705A: Candidate Optical Counterpart from SOAR and Gemini-South and Possible Association with GRB 260705B
  88. GRB 260705C: Glowbug gamma-ray detection of a short burst
  89. GRB 260704A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  90. GRB 260706A: REM optical/NIR observations
  91. GRB 260706A: LCO optical upper limit
  92. GRB 260706A: EP-FXT follow-up observation
  93. The EP-WXT trigger 01709274151 is likely a flaring star
  94. GRB 260706A: Fermi GBM Observation
  95. IceCube-260704A: Upper limits from a search for additional neutrino events in IceCube
  96. GRB 260706A: SVOM detection of a burst
  97. GRB 260705A: LCO optical upper limits
  98. GRB 260704A: NOT optical upper limits
  99. Fermi GBM Sub-Threshold Detection of GRB 260705A
  100. GRB 260704A: EP-FXT follow-up observation

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