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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"

38354 results found.

  1. EP260707a is not a real source
  2. EP260707a: LCOGT Optical Upper Limit
  3. Fermi GBM trigger 805087514/260707142 (GRB 260707A) is not a GRB
  4. EP260707a: Einstein Probe detection of an X-ray transient
  5. Nova AT2026oyp (ASASSN-26dt): Pre-outburst Swift UVOT observation
  6. GRB 260705A: Candidate Optical Counterpart from SOAR and Gemini-South and Possible Association with GRB 260705B
  7. GRB 260705C: Glowbug gamma-ray detection of a short burst
  8. GRB 260706A: SVOM/ECLAIRs refined analysis
  9. GRB 260704A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  10. GRB 260706A: SVOM/GRM observation
  11. GRB 260706A: REM optical/NIR observations
  12. IceCube-260704A: No candidates from the Zwicky Transient Facility
  13. GRB 260706A: LCO optical upper limit
  14. GRB 260706A: EP-FXT follow-up observation
  15. GRB 260707A: Fermi GBM Final Real-time Localization
  16. The EP-WXT trigger 01709274151 is likely a flaring star
  17. The EP-WXT trigger 01709274141 is likely a flaring star
  18. GRB 260706A: Fermi GBM Observation
  19. IceCube-260704A: Upper limits from a search for additional neutrino events in IceCube
  20. IPN triangulation of GRB 260627A
  21. GRB 260705A: SVOM/ECLAIRs refined analysis
  22. GRB 260706A: SVOM detection of a burst
  23. GRB 260706A: Fermi GBM Final Real-time Localization
  24. The EP-WXT trigger 01709274014: KAIT confirmation of a stellar flare
  25. The EP-WXT trigger 01709274014 is likely a flaring star
  26. IceCube260704A: OHP/T193 optical observations
  27. GRB 260705A: LCO optical upper limits
  28. GRB 260704A: NOT optical upper limits
  29. GRB 260705C: Fermi GBM Final Localization
  30. GRB 260705B: Fermi GBM Final Real-time Localization
  31. Fermi GBM Sub-Threshold Detection of GRB 260705A
  32. GRB 260705A: SVOM detection of a burst
  33. GRB 260704A: EP-FXT follow-up observation
  34. GRB 260629A: SVOM/GRM observation of a short burst
  35. GRB 260629A: GECAM-A observation of a short burst
  36. IceCube-260704A - IceCube observation of a high-energy neutrino candidate track-like event
  37. GRB 260629A: AstroSat CZTI detection
  38. EP260703a: EP-FXT follow-up observation
  39. GRB 260704A: SVOM detection of a possible GRB
  40. GRB 260703B: Fermi GBM Final Localization
  41. EP260703a: EP-WXT detection of a fast X-ray transient
  42. EP260628b: EP-WXT detection of an X-ray transient and EP-FXT follow-up observation
  43. GRB 260703A: Fermi GBM Final Localization
  44. GRB 260610B: VLA detection
  45. GRB 260623A: Glowbug gamma-ray detection
  46. GRB 260614B: ATCA Radio Upper Limits
  47. GRB 260610B / AT2026owq: SAO RAS, CrAO and INASAN further optical observations and light curve
  48. GRB 260701A: Fermi GBM Final Real-time Localization
  49. Fermi GBM trigger 804552016/260630945 is not a GRB
  50. Fermi-LAT Gamma-ray Observations of IceCube-260622A
  51. EP260628a: EP-FXT follow-up observation
  52. GRB 260629A: Fermi GBM Final Real-time Localization
  53. EP260628a: EP-WXT detection of a fast X-ray transient
  54. GRB 260628A: Fermi GBM Final Real-time Localization
  55. The EP-WXT trigger 01709272671 is likely a flaring star
  56. EP260626a: further Liverpool Telescope optical upper limits
  57. EP260626a: EP-FXT follow-up observation
  58. EP260626a: COLIBRÍ optical upper limit
  59. EP260626a: Liverpool Telescope upper limits
  60. EP260626a: EP-WXT detection of a fast X-ray transient
  61. Konus-Wind detection of GRB 260623B / EP260623a
  62. EP260623a: TNG NIR afterglow detection
  63. GRB 260618A: Fermi GBM Observation
  64. MASS-Cube (GRID 2.0) detection of GRB 260616B
  65. GRB 260619A: SVOM/ECLAIRs refined analysis
  66. EP260623a: Liverpool Telescope optical observations
  67. Fermi GBM trigger 804010507/260624677 is not a GRB
  68. Konus-Wind detection of GRB 260618B
  69. GRB 260624A: Fermi GBM Final Real-time Localization
  70. EP260623a:refined analysis of the EP-WXT and EP-FXT observation
  71. GRB 260617A: Glowbug gamma-ray detection of a short burst
  72. IceCube-260622A: Upper limits from a search for additional neutrino events in IceCube
  73. IPN triangulation of GRB 260605A
  74. EP260623a: Optical follow-up observations with Kinder
  75. GRB 260623A: Fermi GBM Final Real-time Localization
  76. EP260623a: SVOM/VT optical observations
  77. EP260623a: TRT optical observations
  78. EP260623a: REM optical/NIR afterglow detection
  79. EP 260623a: COLIBRÍ optical observations
  80. GRB 260616B/EP260616a: Insight-HXMT/HE detection
  81. EP260623a: OSIRIS+/GTC redshift z = 0.703
  82. EP260623a: Einstein Probe detection of an X-ray transient
  83. GRB 260614B: EP-FXT follow-up observation
  84. IceCube-260622A - IceCube observation of a high-energy neutrino candidate track-like event
  85. GRB 260618C: SVOM/ECLAIRs detection of a possible burst through on-ground search
  86. EP260618a: Liverpool Telescope optical observations
  87. GRB 260619A: NOT optical observations
  88. GRB 260618B: LCO optical observations
  89. The EP-WXT trigger 01709271197 is likely a flaring star
  90. GRB 260616B/EP260616a: SVOM/GRM detection of a burst
  91. GRB 260618B: Fermi GBM Observation
  92. IceCube-Cascade 260618A: Upper limits from a search for additional neutrino events in IceCube
  93. GRB 260619A: TRT optical counterpart confirmation
  94. GRB 260610B: Further GRANDMA Optical Observations and re-brightening detection
  95. GRB 260604B: 239Alferov CubeSat detection
  96. GRB 260604A: 239Alferov CubeSat detection
  97. GRB 260610B: VLT/FORS2 spectroscopic observation suggests the non-thermal nature of the optical rebrightening
  98. GRB 260619A: SVOM/VT optical counterpart confirmation
  99. Fermi-LAT Gamma-ray Observations of IceCube-260610A
  100. GRB 260618B: SVOM/VT optical candidate

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