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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"

28082 results found.

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

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