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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"

28036 results found.

  1. GRB 260710A: AstroSat CZTI detection
  2. GRB 260714B: Fermi GBM Detection
  3. GRB 260714B: BALROG localization (Fermi Trigger 805746211 / GRB 260714766)
  4. IceCube-260712A: Upper limits from a search for additional neutrino events in IceCube
  5. IceCube-260712A: LAST optical follow-up observations of the IceCube neutrino candidate
  6. EP260713a: Einstein Probe detection of an X-ray transient
  7. GRB 260619A: SVOM/VT continuous optical observations
  8. GRB 260708A: slowly decaying X-ray emission observed by EP/FXT
  9. EP260623a: KAIT optical observations
  10. GRB 260708A: GRANDMA Optical Observations
  11. Fermi-LAT Gamma-ray Observations of IceCube-260712A
  12. Fermi-LAT Gamma-ray Observations of IceCube-260708A
  13. Fermi-LAT Gamma-ray Observations of IceCube-260704A
  14. IceCube-260708A: Upper limits from a search for additional neutrino events in IceCube
  15. GRB 260708A: LCO optical observations
  16. EP260711a: Einstein Probe detection of an X-ray transient
  17. GRB 260709A: SVOM/GRM detection
  18. IceCube-260708A: Observations with the Vera C. Rubin Observatory
  19. EP-WXT trigger 0170924151 : RAPAS optical counterpart candidate detection
  20. GRB 260708A: Glowbug gamma-ray detection
  21. GRB 260706A : GRANDMA Upper limits
  22. GRB 260708A: Kilonova-Catcher optical afterglow detection
  23. IceCube-260708A: One candidate from the Zwicky Transient Facility
  24. GRB 260708A: Fermi-GBM observation
  25. Fermi LAT GRB 260708A: MASTER OT J150237.02-435307.7 optical counterpart detection
  26. IceCube Alert 260709A: Global MASTER-Net observations report
  27. LAT GRB260708.42: Global MASTER-Net observations report
  28. GRB260708B: MAXI/GSC detection
  29. GRB 260705B: SVOM/GRM observation
  30. GRB 260706A: Further EP-FXT follow-up observation
  31. EP260707a (by EP-FXT): NOT optical upper limit
  32. EP260707a is not a real source
  33. EP260707a: LCOGT Optical Upper Limit
  34. EP260707a: TRT optical upper limit
  35. EP260707a: Einstein Probe detection of an X-ray transient
  36. GRB 260705A: Candidate Optical Counterpart from SOAR and Gemini-South and Possible Association with GRB 260705B
  37. GRB 260705C: Glowbug gamma-ray detection of a short burst
  38. GRB 260704A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  39. GRB 260706A: REM optical/NIR observations
  40. GRB 260706A: LCO optical upper limit
  41. GRB 260706A: EP-FXT follow-up observation
  42. The EP-WXT trigger 01709274151 is likely a flaring star
  43. GRB 260706A: Fermi GBM Observation
  44. IceCube-260704A: Upper limits from a search for additional neutrino events in IceCube
  45. GRB 260706A: SVOM detection of a burst
  46. GRB 260705A: LCO optical upper limits
  47. GRB 260704A: NOT optical upper limits
  48. Fermi GBM Sub-Threshold Detection of GRB 260705A
  49. GRB 260704A: EP-FXT follow-up observation
  50. GRB 260629A: SVOM/GRM observation of a short burst
  51. GRB 260629A: AstroSat CZTI detection
  52. EP260703a: EP-FXT follow-up observation
  53. GRB 260704A: SVOM detection of a possible GRB
  54. EP260703a: EP-WXT detection of a fast X-ray transient
  55. EP260628b: EP-WXT detection of an X-ray transient and EP-FXT follow-up observation
  56. Fermi trigger No 804738310: Global MASTER-Net observations report
  57. Fermi GRB 260703A: Global MASTER-Net observations report
  58. GRB 260623A: Glowbug gamma-ray detection
  59. GRB 260610B / AT2026owq: SAO RAS, CrAO and INASAN further optical observations and light curve
  60. Fermi trigger No 804552016: Global MASTER-Net observations report
  61. GRB 260701A: Fermi GBM Final Real-time Localization
  62. Fermi-LAT Gamma-ray Observations of IceCube-260622A
  63. EP260628a: EP-FXT follow-up observation
  64. Fermi GRB 260628A: Global MASTER-Net observations report
  65. EP260628a: EP-WXT detection of a fast X-ray transient
  66. EP260626a: further Liverpool Telescope optical upper limits
  67. EP260626a: COLIBRÍ optical upper limit
  68. EP260626a: Liverpool Telescope upper limits
  69. EP260626a: EP-WXT detection of a fast X-ray transient
  70. EP260623a: TNG NIR afterglow detection
  71. GRB 260618A: Fermi GBM Observation
  72. GRB 260619A: SVOM/ECLAIRs refined analysis
  73. EP260623a: Liverpool Telescope optical observations
  74. EP260623a:refined analysis of the EP-WXT and EP-FXT observation
  75. EP260623a: WINTER J-band observations
  76. GRB 260617A: Glowbug gamma-ray detection of a short burst
  77. IceCube-260622A: Upper limits from a search for additional neutrino events in IceCube
  78. EP260623a: Optical follow-up observations with Kinder
  79. EP260623a: SVOM/VT optical observations
  80. EP260623a: TRT optical observations
  81. EP260623a: REM optical/NIR afterglow detection
  82. EP 260623a: COLIBRÍ optical observations
  83. GRB 260616B/EP260616a: Insight-HXMT/HE detection
  84. EP260623a: Las Cumbres discovery of the optical counterpart
  85. EP260623a: Einstein Probe detection of an X-ray transient
  86. GRB 260614B: EP-FXT follow-up observation
  87. GRB 260618C: SVOM/ECLAIRs detection of a possible burst through on-ground search
  88. EP260618a: Liverpool Telescope optical observations
  89. GRB 260618B: LCO optical observations
  90. EP260618a: JinShan optical observations
  91. GRB 260616B/EP260616a: SVOM/GRM detection of a burst
  92. GRB 260618B: Fermi GBM Observation
  93. IceCube-Cascade 260618A: Upper limits from a search for additional neutrino events in IceCube
  94. GRB 260619A: TRT optical counterpart confirmation
  95. GRB 260610B: Further GRANDMA Optical Observations and re-brightening detection
  96. Fermi-LAT Gamma-ray Observations of IceCube-260610A
  97. GRB 260619A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  98. GRB 260616B: AstroSat CZTI detection
  99. GRB 260616A: AstroSat CZTI detection
  100. GRB 260616A: SVOM/GRM observation

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