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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"

28089 results found.

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

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