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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"

27687 results found.

  1. GRB 260726A: Fermi GBM Observation
  2. EP260727a: 1.5m OSN optical counterpart detection
  3. EP260727a:refined analysis of the EP-WXT and EP-FXT observation
  4. EP260727a: OHP/T193 optical observations
  5. GRB 260726A: Liverpool Telescope optical observations
  6. GRB 260727A: Liverpool Telescope optical upper limits
  7. EP260727a: Liverpool Telescope confirmation of optical counterpart
  8. EP260727a: Einstein Probe detection of an X-ray transient
  9. The EP-WXT trigger 01709276927 (EP260727a?): NOT likely optical counterpart
  10. GRB 260727A: Glowbug gamma-ray detection
  11. GRB 260726A: J-band upper limit with WINTER
  12. GRB 260727A: J-band upper limit with WINTER
  13. GRB 260727A / SVOM sb26072702: RAPAS optical non-detection
  14. EP260723a: SVOM/ECLAIRs Upper Limit
  15. GRB 260727A: AstroSat CZTI detection
  16. GRB 260727A: Kilonova-Catcher optical upper limit
  17. GRB 260727A: LCO optical upper limits
  18. Fermi GRB 260726A: Global MASTER-Net observations report
  19. GRB 260726A: SVOM detection of a burst
  20. IceCube-260722A: Classification of ZTF26abjbxfs/SN 2026vts as a Type Ia Supernova
  21. EP260723a: further EP-FXT follow-up observation
  22. EP260725a: EP-WXT detection of an X-ray transient
  23. GRB 260616A: cubesat Avion detection
  24. EP260723a: Continued Liverpool Telescope observations suggest hours long optical plateau or rebrightening
  25. GRB 260602B: cubesat Avion detection
  26. GRB 260601A: cubesat Avion detection
  27. EP260723a: SVOM/VT optical observation
  28. EP260723a: COLIBRÍ optical observations
  29. EP260723a: NOT optical conterpart confirmation
  30. EP260723a: Liverpool Telescope likely optical counterpart
  31. EP260723a: EP-WXT detection of a fast X-ray transient
  32. IceCube-260722A: Upper limits from a search for additional neutrino events in IceCube
  33. IceCube-260722A: One candidate from the Zwicky Transient Facility (ZTF)
  34. IceCube Alert 260722A: Global MASTER-Net observations report
  35. GRB 260721A: NuSTAR detection of prompt emission
  36. SVOM trigger sb26071506: SVOM/VT confirmation of a stellar flare
  37. Fermi trigger No 806104130: Global MASTER-Net observations report
  38. Fermi GRB 260718A: Global MASTER-Net observations report
  39. GRB 260718A: LCO optical upper limits
  40. GRB 260710A: SVOM/GRM observation
  41. GRB 260718A: Fermi GBM Observation
  42. GRB 260718A : GRANDMA and KNC upper limits
  43. GRB 260718A: SVOM/VT optical upper limits
  44. GRB 260718A: SVOM/VT optical upper limits from VHF data
  45. GRB 260714B: SVOM/GRM observation
  46. GRB 260310A / AT2026fgk: Late-time Chandra Detection
  47. GRB 260714B: COLIBRÍ optical counterpart candidate
  48. SVOM sb26071506: Global MASTER-Net observations report
  49. sb26071506: SVOM detection of a X-ray transient
  50. EP260703a: SVOM/ECLAIRs Upper Limit
  51. GRB 260710A: AstroSat CZTI detection
  52. GRB 260714B: Fermi GBM Detection
  53. GRB 260714B: BALROG localization (Fermi Trigger 805746211 / GRB 260714766)
  54. IceCube-260712A: Upper limits from a search for additional neutrino events in IceCube
  55. IceCube-260712A: LAST optical follow-up observations of the IceCube neutrino candidate
  56. EP260713a: Einstein Probe detection of an X-ray transient
  57. GRB 260619A: SVOM/VT continuous optical observations
  58. GRB 260708A: slowly decaying X-ray emission observed by EP/FXT
  59. EP260623a: KAIT optical observations
  60. GRB 260708A: GRANDMA Optical Observations
  61. Fermi-LAT Gamma-ray Observations of IceCube-260712A
  62. Fermi-LAT Gamma-ray Observations of IceCube-260708A
  63. Fermi-LAT Gamma-ray Observations of IceCube-260704A
  64. IceCube-260708A: Upper limits from a search for additional neutrino events in IceCube
  65. GRB 260708A: LCO optical observations
  66. EP260711a: Einstein Probe detection of an X-ray transient
  67. GRB 260709A: SVOM/GRM detection
  68. IceCube-260708A: Observations with the Vera C. Rubin Observatory
  69. EP-WXT trigger 0170924151 : RAPAS optical counterpart candidate detection
  70. GRB 260708A: Glowbug gamma-ray detection
  71. GRB 260706A : GRANDMA Upper limits
  72. GRB 260708A: Kilonova-Catcher optical afterglow detection
  73. IceCube-260708A: One candidate from the Zwicky Transient Facility
  74. GRB 260708A: Fermi-GBM observation
  75. Fermi LAT GRB 260708A: MASTER OT J150237.02-435307.7 optical counterpart detection
  76. IceCube Alert 260709A: Global MASTER-Net observations report
  77. LAT GRB260708.42: Global MASTER-Net observations report
  78. GRB260708B: MAXI/GSC detection
  79. GRB 260705B: SVOM/GRM observation
  80. GRB 260706A: Further EP-FXT follow-up observation
  81. EP260707a (by EP-FXT): NOT optical upper limit
  82. EP260707a is not a real source
  83. EP260707a: LCOGT Optical Upper Limit
  84. EP260707a: TRT optical upper limit
  85. EP260707a: Einstein Probe detection of an X-ray transient
  86. GRB 260705A: Candidate Optical Counterpart from SOAR and Gemini-South and Possible Association with GRB 260705B
  87. GRB 260705C: Glowbug gamma-ray detection of a short burst
  88. GRB 260704A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  89. GRB 260706A: REM optical/NIR observations
  90. GRB 260706A: LCO optical upper limit
  91. GRB 260706A: EP-FXT follow-up observation
  92. The EP-WXT trigger 01709274151 is likely a flaring star
  93. GRB 260706A: Fermi GBM Observation
  94. IceCube-260704A: Upper limits from a search for additional neutrino events in IceCube
  95. GRB 260706A: SVOM detection of a burst
  96. GRB 260705A: LCO optical upper limits
  97. GRB 260704A: NOT optical upper limits
  98. Fermi GBM Sub-Threshold Detection of GRB 260705A
  99. GRB 260704A: EP-FXT follow-up observation
  100. GRB 260629A: SVOM/GRM observation of a short burst

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