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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"

28052 results found.

  1. SVOM trigger sb26071506: SVOM/VT confirmation of a stellar flare
  2. Fermi trigger No 806104130: Global MASTER-Net observations report
  3. Fermi GRB 260718A: Global MASTER-Net observations report
  4. GRB 260718A: LCO optical upper limits
  5. GRB 260710A: SVOM/GRM observation
  6. GRB 260718A: Fermi GBM Observation
  7. GRB 260718A : GRANDMA and KNC upper limits
  8. GRB 260718A: SVOM/VT optical upper limits
  9. GRB 260718A: SVOM/VT optical upper limits from VHF data
  10. GRB 260714B: SVOM/GRM observation
  11. GRB 260310A / AT2026fgk: Late-time Chandra Detection
  12. GRB 260714B: COLIBRÍ optical counterpart candidate
  13. SVOM sb26071506: Global MASTER-Net observations report
  14. sb26071506: SVOM detection of a X-ray transient
  15. EP260703a: SVOM/ECLAIRs Upper Limit
  16. GRB 260710A: AstroSat CZTI detection
  17. GRB 260714B: Fermi GBM Detection
  18. GRB 260714B: BALROG localization (Fermi Trigger 805746211 / GRB 260714766)
  19. IceCube-260712A: Upper limits from a search for additional neutrino events in IceCube
  20. IceCube-260712A: LAST optical follow-up observations of the IceCube neutrino candidate
  21. EP260713a: Einstein Probe detection of an X-ray transient
  22. GRB 260619A: SVOM/VT continuous optical observations
  23. GRB 260708A: slowly decaying X-ray emission observed by EP/FXT
  24. EP260623a: KAIT optical observations
  25. GRB 260708A: GRANDMA Optical Observations
  26. Fermi-LAT Gamma-ray Observations of IceCube-260712A
  27. Fermi-LAT Gamma-ray Observations of IceCube-260708A
  28. Fermi-LAT Gamma-ray Observations of IceCube-260704A
  29. IceCube-260708A: Upper limits from a search for additional neutrino events in IceCube
  30. GRB 260708A: LCO optical observations
  31. EP260711a: Einstein Probe detection of an X-ray transient
  32. GRB 260709A: SVOM/GRM detection
  33. IceCube-260708A: Observations with the Vera C. Rubin Observatory
  34. EP-WXT trigger 0170924151 : RAPAS optical counterpart candidate detection
  35. GRB 260708A: Glowbug gamma-ray detection
  36. GRB 260706A : GRANDMA Upper limits
  37. GRB 260708A: Kilonova-Catcher optical afterglow detection
  38. IceCube-260708A: One candidate from the Zwicky Transient Facility
  39. GRB 260708A: Fermi-GBM observation
  40. Fermi LAT GRB 260708A: MASTER OT J150237.02-435307.7 optical counterpart detection
  41. IceCube Alert 260709A: Global MASTER-Net observations report
  42. LAT GRB260708.42: Global MASTER-Net observations report
  43. GRB260708B: MAXI/GSC detection
  44. GRB 260705B: SVOM/GRM observation
  45. GRB 260706A: Further EP-FXT follow-up observation
  46. EP260707a (by EP-FXT): NOT optical upper limit
  47. EP260707a is not a real source
  48. EP260707a: LCOGT Optical Upper Limit
  49. EP260707a: TRT optical upper limit
  50. EP260707a: Einstein Probe detection of an X-ray transient
  51. GRB 260705A: Candidate Optical Counterpart from SOAR and Gemini-South and Possible Association with GRB 260705B
  52. GRB 260705C: Glowbug gamma-ray detection of a short burst
  53. GRB 260704A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  54. GRB 260706A: REM optical/NIR observations
  55. GRB 260706A: LCO optical upper limit
  56. GRB 260706A: EP-FXT follow-up observation
  57. The EP-WXT trigger 01709274151 is likely a flaring star
  58. GRB 260706A: Fermi GBM Observation
  59. IceCube-260704A: Upper limits from a search for additional neutrino events in IceCube
  60. GRB 260706A: SVOM detection of a burst
  61. GRB 260705A: LCO optical upper limits
  62. GRB 260704A: NOT optical upper limits
  63. Fermi GBM Sub-Threshold Detection of GRB 260705A
  64. GRB 260704A: EP-FXT follow-up observation
  65. GRB 260629A: SVOM/GRM observation of a short burst
  66. GRB 260629A: AstroSat CZTI detection
  67. EP260703a: EP-FXT follow-up observation
  68. GRB 260704A: SVOM detection of a possible GRB
  69. EP260703a: EP-WXT detection of a fast X-ray transient
  70. EP260628b: EP-WXT detection of an X-ray transient and EP-FXT follow-up observation
  71. Fermi trigger No 804738310: Global MASTER-Net observations report
  72. Fermi GRB 260703A: Global MASTER-Net observations report
  73. GRB 260623A: Glowbug gamma-ray detection
  74. GRB 260610B / AT2026owq: SAO RAS, CrAO and INASAN further optical observations and light curve
  75. Fermi trigger No 804552016: Global MASTER-Net observations report
  76. GRB 260701A: Fermi GBM Final Real-time Localization
  77. Fermi-LAT Gamma-ray Observations of IceCube-260622A
  78. EP260628a: EP-FXT follow-up observation
  79. Fermi GRB 260628A: Global MASTER-Net observations report
  80. EP260628a: EP-WXT detection of a fast X-ray transient
  81. EP260626a: further Liverpool Telescope optical upper limits
  82. EP260626a: COLIBRÍ optical upper limit
  83. EP260626a: Liverpool Telescope upper limits
  84. EP260626a: EP-WXT detection of a fast X-ray transient
  85. EP260623a: TNG NIR afterglow detection
  86. GRB 260618A: Fermi GBM Observation
  87. GRB 260619A: SVOM/ECLAIRs refined analysis
  88. EP260623a: Liverpool Telescope optical observations
  89. EP260623a:refined analysis of the EP-WXT and EP-FXT observation
  90. EP260623a: WINTER J-band observations
  91. GRB 260617A: Glowbug gamma-ray detection of a short burst
  92. IceCube-260622A: Upper limits from a search for additional neutrino events in IceCube
  93. EP260623a: Optical follow-up observations with Kinder
  94. EP260623a: SVOM/VT optical observations
  95. EP260623a: TRT optical observations
  96. EP260623a: REM optical/NIR afterglow detection
  97. EP 260623a: COLIBRÍ optical observations
  98. GRB 260616B/EP260616a: Insight-HXMT/HE detection
  99. EP260623a: Las Cumbres discovery of the optical counterpart
  100. EP260623a: Einstein Probe detection of an X-ray transient

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