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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"

20265 results found.

  1. Konus-Wind detection of GRB 251016B
  2. GRB 251025B: GROWTH-India Telescope optical observations
  3. GRB 251024A: Swift/UVOT Upper Limits
  4. GRB 251025B: Swift-XRT afterglow detection
  5. GRB 251025A (sb25102501): stellar flare confirmed
  6. GRB 251025B: SVOM/VT optical observations with VHF data
  7. GRB 251025B: MASTER OT detection
  8. GRB 251025B: SVOM/C-GFT optical counterpart detection
  9. GRB 251025B: SVOM detection of a burst
  10. GRB 251025A (sb25102501): Likely a stellar flare by SVOM/VT
  11. GRB 251025A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  12. GRB 251025A: SVOM/VT VHF optical upper limit
  13. GRB 251025A: SVOM detection of a faint burst
  14. GRB 251003A: VLA Detection
  15. GRB 251024A: Enhanced Swift-XRT position
  16. GRB 251024A: LCOGT Optical Afterglow Detection
  17. GRB 251022A: KAIT optical observations
  18. GRB 251024A: Swift detection of a burst
  19. GRB 251023B / EP251023b: COLIBRÍ Confirmation of the Fading Nature of the Optical Candidate
  20. GRB 251022A: COLIBRÍ Further Multi-frequency Optical Observations
  21. EP251023a: MAO/AZT-22 optical observations
  22. EP251023b/GRB 251023B: JinShan optical observation
  23. GRB 251022A: Swift-XRT detection of GOTO25iym
  24. EP251023b/GRB 251023B : Einstein Probe detection of a fast X-ray transient
  25. GRB 251022A: GROWTH-India Telescope optical observations
  26. GRB 251023C: Swift/BAT-GUANO localization skymap of a burst
  27. EP251023a: GROWTH-India Telescope optical observations
  28. GRB 251022A: Fermi GBM Observation
  29. GRB 251022A: Swift/BAT-GUANO localization skymap of a burst
  30. EP251023a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm telescope at Teide Observatory
  31. GRB 251023B / EP#01709247298: COLIBRÍ optical counterpart candidate
  32. IPN triangulation of GRB 251016B
  33. EP251023a: COLIBRÍ optical observations
  34. GRB 251013C: further SAO RAS optical observations
  35. GRB 251022A: COLIBRÍ optical observations
  36. GRB 251013C: ISON-Castelgrande observatory optical observations
  37. GRB 251022A: MASTER OT detection
  38. GRB 251022A: DDOTI Optical Detection
  39. EP251021b/GRB 251021A: SVOM/VT optical candidate
  40. EP251023a: NOT optical counterpart detection
  41. EP251023a: Einstein Probe detection of an X-ray transient
  42. EP/WXT 01709247295: GOTO optical afterglow candidate.
  43. GRB 251022A: GOTO optical counterpart detection
  44. EP251021b: Einstein Probe detection of a fast X-ray transient
  45. GRB 251016A: SVOM/ECLAIRs refined analysis
  46. LIGO/Virgo/KAGRA S251021u: Identification of a GW compact binary merger candidate
  47. Fermi-LAT gamma-ray observations of IceCube-251018A
  48. GRB 251017A : RAPAS follow-up observations
  49. GRB 251017A: COLIBRÍ optical observations of a late plateau
  50. IceCube-251018A: DDOTI Optical Upper Limit
  51. GRB 251018A: BOOTES-5 and BOOTES-7 early optical detections
  52. GRB 251018A: Enhanced Swift-XRT position
  53. LIGO/Virgo/KAGRA S251018bi: Identification of a GW compact binary merger candidate
  54. GRB 251016A: Swift-XRT afterglow detection
  55. GRB 251017A: Swift/UVOT Detection
  56. GRB 251016A: Swift/UVOT Detection
  57. GRB 251018A: Swift/UVOT Detection
  58. GRB 251016A: VLT/FORS2 Optical Observation
  59. GRB 251017A: COLIBRÍ photometric redshift
  60. GRB 251018A: MASTER OT detection
  61. GRB 251018A: TRT optical afterglow detection
  62. GRB 251018A: Swift detection of a burst with an optical counterpart
  63. GRB 251017A: J-band detection with WINTER
  64. GRB 251013C: Liverpool Telescope observations
  65. GRB 251013C: Leavitt Observatory optical photometry
  66. GRB 251017A: JinShan observations of the optical afterglow
  67. GRB 251017A : MITSuME Akeno optical afterglow candidate detection
  68. GRB 251017A: Enhanced Swift-XRT position
  69. GRB 251017A: COLIBRÍ Early Afterglow Detection
  70. GRB 251017A: BOOTES-5/JGT early optical afterglow detection
  71. GRB 251017A: Swift detection of a burst with an optical counterpart
  72. GRB 251013C: JinShan observations of the non-thermal rebrightening of the optical counterpart
  73. GRB 251013C: SVOM/COLIBRÍ (FM-GFT) observations of a strong and late rebrightening of the optical counterpart
  74. sb25101602: Swift-XRT counterpart detection
  75. GRB 251016A: SVOM detection of a short burst
  76. GRB 251014A: Swift-XRT observations
  77. GRB 251014B: PRIME J-band upper limit
  78. GRB 251013C: Kilonova-Catcher optical afterglow detection
  79. GRB 251013D: Swift/UVOT Observations
  80. GRB 251013C: Swift/UVOT Detection
  81. Konus-Wind detection of GRB 251007A
  82. GRB 251013C: detection of a radio counterpart at 15.5GHz
  83. Swift Trigger 1404295: possible GRB 251015A
  84. GRB 251014B: Swift/UVOT Upper Limits
  85. GRB 251014B: VLT/FORS2 Optical Observation
  86. GRB 251014D: Swift/UVOT Upper Limits
  87. GRB 251014D: Swift-XRT afterglow detection
  88. GRB 251013C: MAO/AZT-22 optical observations
  89. GRB 251011B: SVOM/VT optical upper limit
  90. GRB 251013C: SVOM/COLIBRÍ (FM-GFT) further multi-band optical observations
  91. GRB 251013C: Calapai Observatory, Massa S. Giorgio (Messina), optical observation
  92. GRB 251014D: Swift detection of a burst
  93. GRB 251014A: PRIME near-infrared upper limits
  94. GRB 251014A: VLT/FORS2 Optical Observation
  95. GRB 251013C: MarSEC, optical afterglow photometry
  96. GRB 251013C: OHP/T193 optical afterglow photometry and spectroscopy
  97. GRB 251013D: LAST optical upper limit on Swift/BAT-GUANO localization
  98. GRB 251013C: Bassano Bresciano Observatory optical observations
  99. GRB 251013C: Early and late-time optical counterpart detection by LCO
  100. GRB 251013C: Fermi GBM Observation

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