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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"

25999 results found.

  1. GRB 251025B: ULL-ASTRO-MASTER optical counterpart detection with IAC80 telescope at Teide Observatory
  2. GRB 251025B: GROWTH-India Telescope optical observations
  3. GRB 251024A: Swift/UVOT Upper Limits
  4. GRB 251025B: Swift-XRT afterglow detection
  5. GRB 251024A: Swift-BAT refined analysis
  6. GRB 251024A: Swift-XRT refined Analysis
  7. GRB 251025A (sb25102501): stellar flare confirmed
  8. GRB 251025B: SVOM/VT optical observations with VHF data
  9. GRB 251025B: MASTER OT detection
  10. GRB 251025B: SVOM/C-GFT optical counterpart detection
  11. GRB 251025B: SVOM detection of a burst
  12. GRB 251025A (sb25102501): Likely a stellar flare by SVOM/VT
  13. GRB 251025A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  14. GRB 251025A: SVOM/VT VHF optical upper limit
  15. GRB 251025A: SVOM detection of a faint burst
  16. GRB 251003A: VLA Detection
  17. GRB 251024A: Enhanced Swift-XRT position
  18. GRB 251023C: Glowbug gamma-ray detection
  19. GRB 251024A: LCOGT Optical Afterglow Detection
  20. GRB 251022A: KAIT optical observations
  21. GRB 251024A: Swift detection of a burst
  22. GRB 251023B / EP251023b: COLIBRÍ Confirmation of the Fading Nature of the Optical Candidate
  23. GRB 251022A: COLIBRÍ Further Multi-frequency Optical Observations
  24. EP251023a: MAO/AZT-22 optical observations
  25. GRB 251023C: AstroSat CZTI detection
  26. EP251023b/GRB 251023B: JinShan optical observation
  27. GRB 251022A: Swift-XRT detection of GOTO25iym
  28. EP251023b/GRB 251023B : Einstein Probe detection of a fast X-ray transient
  29. GRB 251022A: GROWTH-India Telescope optical observations
  30. GRB 251023C: Swift/BAT-GUANO localization skymap of a burst
  31. EP251023a: GROWTH-India Telescope optical observations
  32. GRB 251022A: Fermi GBM Observation
  33. GRB 251022A: Swift/BAT-GUANO localization skymap of a burst
  34. GRB 251023A: Glowbug gamma-ray detection
  35. GRB 251023B: Glowbug gamma-ray detection
  36. EP251023a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm telescope at Teide Observatory
  37. GRB 251023B / EP#01709247298: COLIBRÍ optical counterpart candidate
  38. IPN triangulation of GRB 251016B
  39. EP#01709247298: Swift-XRT counterpart detection
  40. EP251023a: COLIBRÍ optical observations
  41. GRB 251013C: further SAO RAS optical observations
  42. GRB 251022A: COLIBRÍ optical observations
  43. GRB 251013C: ISON-Castelgrande observatory optical observations
  44. GRB 251022A: MASTER OT detection
  45. GRB 251022A: DDOTI Optical Detection
  46. EP251021b/GRB 251021A: SVOM/VT optical candidate
  47. GRB 251023B / MAXI J0451+122: MAXI/GSC detection
  48. EP251023a: NOT optical counterpart detection
  49. EP251023a: GSP Optical Counterpart Detection
  50. EP251023a: Einstein Probe detection of an X-ray transient
  51. GRB 251016B: Fermi GBM Detection
  52. GRB 251021A/EP251021b: Fermi-GBM Sub-Threshold Detection
  53. EP251021b: Einstein Probe detection of a fast X-ray transient
  54. LIGO/Virgo/KAGRA S251021u: Updated Sky localization
  55. LIGO/Virgo/KAGRA S251021u: Identification of a GW compact binary merger candidate
  56. LIGO/Virgo/KAGRA S251018bi: Updated Sky localization
  57. Fermi-LAT gamma-ray observations of IceCube-251018A
  58. GRB 251017A : RAPAS follow-up observations
  59. IceCube-251018A: Upper limits from a search for additional neutrino events in IceCube
  60. GRB 251017A: COLIBRÍ optical observations of a late plateau
  61. IceCube-251018A: DDOTI Optical Upper Limit
  62. GRB 251017A: Swift-BAT refined analysis
  63. GRB 251018A: Fermi GBM Observation
  64. GRB 251018A: BOOTES-5 and BOOTES-7 early optical detections
  65. GRB 251018A: Swift-XRT refined Analysis
  66. GRB 251018A: Enhanced Swift-XRT position
  67. LIGO/Virgo/KAGRA S251018bi: Identification of a GW compact binary merger candidate
  68. GRB 251016A: Swift-XRT afterglow detection
  69. GRB 251017A: Swift/UVOT Detection
  70. GRB 251016A: Swift/UVOT Detection
  71. GRB 251018A: Swift/UVOT Detection
  72. GRB 251016A: VLT/FORS2 Optical Observation
  73. GRB 251017A: COLIBRÍ photometric redshift
  74. GRB 251017A: Swift-XRT refined Analysis
  75. GRB 251018A: MASTER OT detection
  76. GRB 251018A: TRT optical afterglow detection
  77. GRB 251018A: Swift detection of a burst with an optical counterpart
  78. GRB 251011A: Fermi GBM Observation
  79. GRB 251017A: J-band detection with WINTER
  80. GRB 251017A: Glowbug gamma-ray detection
  81. GRB 251013C: Liverpool Telescope observations
  82. GRB 251013C: Leavitt Observatory optical photometry
  83. GRB 251017A: JinShan observations of the optical afterglow
  84. GRB 251017A : MITSuME Akeno optical afterglow candidate detection
  85. GRB 251016A: AstroSat CZTI detection of a short burst
  86. GRB 251017A: Enhanced Swift-XRT position
  87. GRB 251017A: COLIBRÍ Early Afterglow Detection
  88. GRB 251017A: BOOTES-5/JGT early optical afterglow detection
  89. GRB 251017A: Swift detection of a burst with an optical counterpart
  90. GRB 251013C: JinShan observations of the non-thermal rebrightening of the optical counterpart
  91. GRB 251013C: SVOM/COLIBRÍ (FM-GFT) observations of a strong and late rebrightening of the optical counterpart
  92. GRB 251007B: Swift-BAT refined analysis
  93. GRB 251014D: Swift-BAT refined analysis
  94. GRB 251016A: BOOTES-6/DPRT optical upper limit
  95. GRB 251016A: Glowbug gamma-ray detection of a short burst
  96. sb25101602: Swift-XRT counterpart detection
  97. GRB 251014A: Swift-XRT observations
  98. LIGO/Virgo/KAGRA S251014cn: Updated Sky localization
  99. GRB 251014B: PRIME J-band upper limit
  100. Upper limits from a search for additional neutrino events in IceCube

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