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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"

20261 results found.

  1. GRB 251025A (sb25102501): stellar flare confirmed
  2. GRB 251025B: SVOM/VT optical observations with VHF data
  3. GRB 251025B: MASTER OT detection
  4. GRB 251025B: SVOM/C-GFT optical counterpart detection
  5. GRB 251025B: SVOM detection of a burst
  6. GRB 251025A (sb25102501): Likely a stellar flare by SVOM/VT
  7. GRB 251025A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  8. GRB 251025A: SVOM/VT VHF optical upper limit
  9. GRB 251025A: SVOM detection of a faint burst
  10. GRB 251003A: VLA Detection
  11. GRB 251024A: Enhanced Swift-XRT position
  12. GRB 251024A: LCOGT Optical Afterglow Detection
  13. GRB 251022A: KAIT optical observations
  14. GRB 251024A: Swift detection of a burst
  15. GRB 251023B / EP251023b: COLIBRÍ Confirmation of the Fading Nature of the Optical Candidate
  16. GRB 251022A: COLIBRÍ Further Multi-frequency Optical Observations
  17. EP251023a: MAO/AZT-22 optical observations
  18. EP251023b/GRB 251023B: JinShan optical observation
  19. GRB 251022A: Swift-XRT detection of GOTO25iym
  20. EP251023b/GRB 251023B : Einstein Probe detection of a fast X-ray transient
  21. GRB 251022A: GROWTH-India Telescope optical observations
  22. GRB 251023C: Swift/BAT-GUANO localization skymap of a burst
  23. EP251023a: GROWTH-India Telescope optical observations
  24. GRB 251022A: Fermi GBM Observation
  25. GRB 251022A: Swift/BAT-GUANO localization skymap of a burst
  26. EP251023a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm telescope at Teide Observatory
  27. GRB 251023B / EP#01709247298: COLIBRÍ optical counterpart candidate
  28. IPN triangulation of GRB 251016B
  29. EP251023a: COLIBRÍ optical observations
  30. GRB 251013C: further SAO RAS optical observations
  31. GRB 251022A: COLIBRÍ optical observations
  32. GRB 251013C: ISON-Castelgrande observatory optical observations
  33. GRB 251022A: MASTER OT detection
  34. GRB 251022A: DDOTI Optical Detection
  35. EP251021b/GRB 251021A: SVOM/VT optical candidate
  36. EP251023a: NOT optical counterpart detection
  37. EP251023a: Einstein Probe detection of an X-ray transient
  38. EP/WXT 01709247295: GOTO optical afterglow candidate.
  39. GRB 251022A: GOTO optical counterpart detection
  40. EP251021b: Einstein Probe detection of a fast X-ray transient
  41. GRB 251016A: SVOM/ECLAIRs refined analysis
  42. LIGO/Virgo/KAGRA S251021u: Identification of a GW compact binary merger candidate
  43. Fermi-LAT gamma-ray observations of IceCube-251018A
  44. GRB 251017A : RAPAS follow-up observations
  45. GRB 251017A: COLIBRÍ optical observations of a late plateau
  46. IceCube-251018A: DDOTI Optical Upper Limit
  47. GRB 251018A: BOOTES-5 and BOOTES-7 early optical detections
  48. GRB 251018A: Enhanced Swift-XRT position
  49. LIGO/Virgo/KAGRA S251018bi: Identification of a GW compact binary merger candidate
  50. GRB 251016A: Swift-XRT afterglow detection
  51. GRB 251017A: Swift/UVOT Detection
  52. GRB 251016A: Swift/UVOT Detection
  53. GRB 251018A: Swift/UVOT Detection
  54. GRB 251016A: VLT/FORS2 Optical Observation
  55. GRB 251017A: COLIBRÍ photometric redshift
  56. GRB 251018A: MASTER OT detection
  57. GRB 251018A: TRT optical afterglow detection
  58. GRB 251018A: Swift detection of a burst with an optical counterpart
  59. GRB 251017A: J-band detection with WINTER
  60. GRB 251013C: Liverpool Telescope observations
  61. GRB 251013C: Leavitt Observatory optical photometry
  62. GRB 251017A: JinShan observations of the optical afterglow
  63. GRB 251017A : MITSuME Akeno optical afterglow candidate detection
  64. GRB 251017A: Enhanced Swift-XRT position
  65. GRB 251017A: COLIBRÍ Early Afterglow Detection
  66. GRB 251017A: BOOTES-5/JGT early optical afterglow detection
  67. GRB 251017A: Swift detection of a burst with an optical counterpart
  68. GRB 251013C: JinShan observations of the non-thermal rebrightening of the optical counterpart
  69. GRB 251013C: SVOM/COLIBRÍ (FM-GFT) observations of a strong and late rebrightening of the optical counterpart
  70. sb25101602: Swift-XRT counterpart detection
  71. GRB 251016A: SVOM detection of a short burst
  72. GRB 251014A: Swift-XRT observations
  73. GRB 251014B: PRIME J-band upper limit
  74. GRB 251013C: Kilonova-Catcher optical afterglow detection
  75. GRB 251013D: Swift/UVOT Observations
  76. GRB 251013C: Swift/UVOT Detection
  77. Konus-Wind detection of GRB 251007A
  78. GRB 251013C: detection of a radio counterpart at 15.5GHz
  79. Swift Trigger 1404295: possible GRB 251015A
  80. GRB 251014B: Swift/UVOT Upper Limits
  81. GRB 251014B: VLT/FORS2 Optical Observation
  82. GRB 251014D: Swift/UVOT Upper Limits
  83. GRB 251014D: Swift-XRT afterglow detection
  84. GRB 251013C: MAO/AZT-22 optical observations
  85. GRB 251011B: SVOM/VT optical upper limit
  86. GRB 251013C: SVOM/COLIBRÍ (FM-GFT) further multi-band optical observations
  87. GRB 251013C: Calapai Observatory, Massa S. Giorgio (Messina), optical observation
  88. GRB 251014D: Swift detection of a burst
  89. GRB 251014A: PRIME near-infrared upper limits
  90. GRB 251014A: VLT/FORS2 Optical Observation
  91. GRB 251013C: MarSEC, optical afterglow photometry
  92. GRB 251013C: OHP/T193 optical afterglow photometry and spectroscopy
  93. GRB 251013D: LAST optical upper limit on Swift/BAT-GUANO localization
  94. GRB 251013C: Bassano Bresciano Observatory optical observations
  95. GRB 251013C: Early and late-time optical counterpart detection by LCO
  96. GRB 251013C: Fermi GBM Observation
  97. GRB 251014A: DDOTI Upper Limit
  98. GRB 251013C NUTTelA-TAO / BSTI Early Measurements
  99. LIGO/Virgo/KAGRA S251014cn: Identification of a GW compact binary merger candidate
  100. GRB 251013C: ULL-ASTRO-MASTER detection of the optical afterglow with the LCO 40-cm telescope at Sutherland Observatory

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