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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"

16977 results found.

  1. LIGO/Virgo/KAGRA S251108fi: DDOTI Optical Candidate
  2. GRB 251102B: SVOM/GRM observation
  3. The EP-WXT trigger 01709248051 is likely a flaring star
  4. GRB 251106A: SVOM/COLIBRÍ (FM-GFT) fading of the optical counterpart
  5. GRB 251106A: Swift-XRT afterglow detection
  6. GRB 251106A: Kilonova-Catcher optical upper limit
  7. GRB 251106A: SVOM/COLIBRÍ (FM-GFT) detection of a likely optical counterpart
  8. EP251102a: Xinglong 2.16-m clear-band observations of the optical counterpart
  9. LIGO/Virgo/KAGRA S251031dw: Candidates from the Zwicky Transient Facility
  10. GRB 251105A: Swift/BAT-GUANO localization skymap of a burst
  11. GRB 251104A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  12. GRB 251105B: AstroSat CZTI detection of a short burst with extended emission
  13. GRB 251103B: Swift/UVOT Upper Limits
  14. LIGO/Virgo/KAGRA S251105aj: Identification of a GW compact binary merger candidate
  15. GRB 251103A: WFST optical observations
  16. EP251102a: update of EP-FXT follow-up observation
  17. GRB 251103A: Xinglong 2.16m optical detection
  18. GRB 251103A: KAIT optical observations
  19. GRB 251103B: Nanshan/HMT optical upper limit
  20. GRB 251013C: 7DT detection and Medium-band SED of Afterglow
  21. GRB 251103B: MITSuME Akeno optical upper limits
  22. GRB 251103B: Swift-XRT refined Analysis
  23. LIGO/Virgo/KAGRA S251103f: Identification of a GW compact binary merger candidate
  24. EP251102a: NIR observations with WINTER
  25. GRB 251103A: J-band detection with WINTER
  26. GRB 251103B: GROWTH-India Telescope optical upper limits
  27. GRB 251103A: Kilonova-Catcher optical afterglow detection
  28. GRB 251103B: Enhanced Swift-XRT position
  29. GRB 251103B: Swift detection of a burst
  30. GRB 251103A: Swift/UVOT Detection
  31. GRB 251103A: Swift-XRT afterglow detection
  32. GRB 251103A: SVOM/COLIBRÍ (FM-GFT) optical observations
  33. EP251102a: Einstein Probe detection of a fast X-ray transient
  34. EP251102a (WXT 11900459650): LCO observations confirm COLIBRÍ candidate
  35. GRB 251103A: LCO optical observation
  36. EP251102.890: COLIBRÍ optical counterpart candidate
  37. GRB 251026A: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical counterpart
  38. GRB 251103A: LCO optical afterglow detection
  39. GRB 251103A: NOT optical afterglow candidate
  40. LIGO/Virgo/KAGRA S251031cq: Identification of a GW compact binary merger candidate
  41. GRB 251031A: Swift/BAT-GUANO localization skymap of a burst
  42. GRB 251025C: SVOM/GRM observation
  43. GRB 251028A: SVOM/GRM observation
  44. GRB 251022A: Swift-XRT confirmation of fading
  45. GRB 251026A/EP251026a: SVOM/VT optical counterpart
  46. GRB 251026A/EP251026a: EP-FXT follow-up observation
  47. The EP-WXT trigger 01709247588 is likely a flaring star
  48. GRB 251028B: Swift/BAT-GUANO localization skymap of a burst
  49. GRB 251025B: GROWTH-India Telescope continued multiband optical observations and rebrightening
  50. GRB251026B: PRIME H-band upper limit
  51. GRB251025B: 3.6m DOT Optical Observations
  52. SVOM trigger sb25102702/GRB 251027A is not a GRB
  53. GRB 251013C : 3.4-m telescope of Iranian National Observatory (INO340) optical observations
  54. GRB 251026B: Swift-XRT observations of GOTO25jgl/AT2025absf
  55. EP251027.145: COLIBRÍ optical upper limits
  56. GRB 251022A: SVOM/GRM observation
  57. GRB 251026A/EP251026a: Einstein Probe detection of a fast X-ray transient
  58. GRB 251027A: LCO optical upper limit
  59. GRB 251027A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  60. GRB 251023B / EP251023b: Mondy optical upper limit
  61. GRB 251017A: INASAN-Kislovodsk optical observations
  62. GRB 251026A: Mondy optical upper limit
  63. GRB 251025B: Mondy optical observations
  64. GRB 251025B: Kilonova-Catcher optical afterglow detection
  65. GRB 251025B: VLT/MUSE spectroscopic redshift z = 2.003
  66. EP251023a: Mondy optical observations
  67. GRB 251025B: MAO/AZT-22 optical observations
  68. LIGO/Virgo/KAGRA S251026bn: Identification of a GW compact binary merger candidate
  69. GRB 251025B: J-band detection with WINTER
  70. GRB 251026A: SVOM/C-GFT upper limit
  71. IceCube-251025A: DDOTI Optical Upper Limit
  72. GRB 251026A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  73. GRB 251026A: SVOM detection of a long burst
  74. GRB 251025B: SVOM/COLIBRÍ (FM-GFT) strong rebrightening of the optical counterpart
  75. GRB 251023A: SVOM/GRM observation
  76. GRB 251025B: ULL-ASTRO-MASTER optical counterpart detection with IAC80 telescope at Teide Observatory
  77. GRB 251025B: GROWTH-India Telescope optical observations
  78. GRB 251024A: Swift/UVOT Upper Limits
  79. GRB 251025B: Swift-XRT afterglow detection
  80. GRB 251025A (sb25102501): stellar flare confirmed
  81. GRB 251025B: SVOM/VT optical observations with VHF data
  82. GRB 251025B: SVOM/C-GFT optical counterpart detection
  83. GRB 251025B: SVOM detection of a burst
  84. GRB 251025A (sb25102501): Likely a stellar flare by SVOM/VT
  85. GRB 251025A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  86. GRB 251025A: SVOM/VT VHF optical upper limit
  87. GRB 251025A: SVOM detection of a faint burst
  88. GRB 251003A: VLA Detection
  89. GRB 251024A: Enhanced Swift-XRT position
  90. GRB 251024A: LCOGT Optical Afterglow Detection
  91. GRB 251022A: KAIT optical observations
  92. GRB 251024A: Swift detection of a burst
  93. GRB 251023B / EP251023b: COLIBRÍ Confirmation of the Fading Nature of the Optical Candidate
  94. GRB 251022A: COLIBRÍ Further Multi-frequency Optical Observations
  95. EP251023a: MAO/AZT-22 optical observations
  96. EP251023b/GRB 251023B: JinShan optical observation
  97. GRB 251022A: Swift-XRT detection of GOTO25iym
  98. EP251023b/GRB 251023B : Einstein Probe detection of a fast X-ray transient
  99. GRB 251022A: GROWTH-India Telescope optical observations
  100. GRB 251023C: Swift/BAT-GUANO localization skymap of a burst

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