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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').
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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.

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subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

32509 results found.

  1. Konus-Wind detection of GRB 251016A (short/hard)
  2. GRB 251025B: VLT/MUSE spectroscopic redshift z = 2.003
  3. GRB 251026B: Tentative GOTO optical counterpart candidate
  4. GRB 251025C: AstroSat CZTI detection
  5. EP251023a: Mondy optical observations
  6. GRB 251025C: CALET Gamma-Ray Burst Monitor detection
  7. GRB 251025B: MAO/AZT-22 optical observations
  8. LIGO/Virgo/KAGRA S251026bn: Updated Sky localization
  9. Fermi GRB 251026B: Global MASTER-Net observations report
  10. Fermi GRB 251025C: Global MASTER-Net observations report
  11. LIGO/Virgo/KAGRA S251026bn: Identification of a GW compact binary merger candidate
  12. GRB 251026A: Swift-XRT observations
  13. GRB 251025B: OHP/T193 optical detection
  14. GRB 251025B: J-band detection with WINTER
  15. GRB 251026A: SVOM/C-GFT upper limit
  16. IceCube-251025A: DDOTI Optical Upper Limit
  17. GRB 251026A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  18. GRB 251025B: SVOM/VT optical bump
  19. GRB 251025B: SVOM/COLIBRÍ (FM-GFT) strong rebrightening of the optical counterpart
  20. GRB 251023A: SVOM/GRM observation
  21. GRB 251025B: ULL-ASTRO-MASTER optical counterpart detection with IAC80 telescope at Teide Observatory
  22. Konus-Wind detection of GRB 251016B
  23. GRB 251025B: GROWTH-India Telescope optical observations
  24. GRB 251024A: Swift/UVOT Upper Limits
  25. GRB 251025B: Swift-XRT afterglow detection
  26. GRB 251024A: Swift-BAT refined analysis
  27. GRB 251025A (sb25102501): stellar flare confirmed
  28. GRB 251025B: SVOM/VT optical observations with VHF data
  29. GRB 251025B: MASTER OT detection
  30. GRB 251025B: SVOM/C-GFT optical counterpart detection
  31. GRB 251025A (sb25102501): Likely a stellar flare by SVOM/VT
  32. GRB 251025A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  33. GRB 251025A: SVOM/VT VHF optical upper limit
  34. GRB 251003A: VLA Detection
  35. GRB 251023C: Glowbug gamma-ray detection
  36. GRB 251024A: LCOGT Optical Afterglow Detection
  37. GRB 251022A: KAIT optical observations
  38. GRB 251023B / EP251023b: COLIBRÍ Confirmation of the Fading Nature of the Optical Candidate
  39. GRB 251022A: COLIBRÍ Further Multi-frequency Optical Observations
  40. EP251023a: MAO/AZT-22 optical observations
  41. GRB 251023B: OHP/T193 optical observations
  42. EP251023a: OHP/T193 optical observations
  43. GRB 251023C: AstroSat CZTI detection
  44. EP251023b/GRB 251023B: JinShan optical observation
  45. GRB 251022A: Swift-XRT detection of GOTO25iym
  46. EP251023b: Global MASTER-Net observations report
  47. EP251023b/GRB 251023B : Einstein Probe detection of a fast X-ray transient
  48. GRB 251023C: CALET Gamma-Ray Burst Monitor detection
  49. GRB 251022A: GROWTH-India Telescope optical observations
  50. EP251023a: GROWTH-India Telescope optical observations
  51. GRB 251022A: Fermi GBM Observation
  52. GRB 251022A: Swift/BAT-GUANO localization skymap of a burst
  53. GRB 251023A: Glowbug gamma-ray detection
  54. GRB 251023B: Glowbug gamma-ray detection
  55. EP251023a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm telescope at Teide Observatory
  56. EP251023a: Global MASTER-Net observations report
  57. GRB 251023B / EP#01709247298: COLIBRÍ optical counterpart candidate
  58. IPN triangulation of GRB 251016B
  59. GRB 251023B: CALET Gamma-Ray Burst Monitor detection
  60. EP#01709247298: Swift-XRT counterpart detection
  61. EP251023a: COLIBRÍ optical observations
  62. GRB 251013C: further SAO RAS optical observations
  63. EP251023a: Keck/LRIS spectroscopic redshift z=2.232
  64. GRB 251022A: COLIBRÍ optical observations
  65. GRB 251013C: ISON-Castelgrande observatory optical observations
  66. GRB 251022A: MASTER OT detection
  67. GRB 251022A: DDOTI Optical Detection
  68. EP251021b/GRB 251021A: SVOM/VT optical candidate
  69. EP251023a: NOT optical counterpart detection
  70. Fermi GRB 251023A: Global MASTER-Net observations report
  71. EP251023a: GSP Optical Counterpart Detection
  72. EP251023a: Einstein Probe detection of an X-ray transient
  73. GRB 251022A: GOTO optical counterpart detection
  74. GRB 251022A: Fermi-LAT detection
  75. GRB 251022A: Tiled Swift observations
  76. GRB 251021A/EP251021b: Fermi-GBM Sub-Threshold Detection
  77. EP251021b: BOOTES-7 optical upper limit
  78. GRB 250911A: MAXI/GSC detection
  79. LIGO/Virgo/KAGRA S251021u: Updated Sky localization
  80. GRB 251016A: SVOM/ECLAIRs refined analysis
  81. LIGO/Virgo/KAGRA S251021u: Identification of a GW compact binary merger candidate
  82. LIGO/Virgo/KAGRA S251018bi: Updated Sky localization
  83. Fermi-LAT gamma-ray observations of IceCube-251018A
  84. GRB 251017A : RAPAS follow-up observations
  85. IceCube-251018A: Upper limits from a search for additional neutrino events in IceCube
  86. GRB 251017A: COLIBRÍ optical observations of a late plateau
  87. IceCube-251018A: DDOTI Optical Upper Limit
  88. GRB 251017A: Swift-BAT refined analysis
  89. GRB 251016A: Fermi GBM Observation
  90. GRB 251018A: Fermi GBM Observation
  91. GRB 251018A: BOOTES-5 and BOOTES-7 early optical detections
  92. GRB 251016A: HXMT/HE detection
  93. LIGO/Virgo/KAGRA S251018bi: Identification of a GW compact binary merger candidate
  94. GRB 251017A: Swift/UVOT Detection
  95. GRB 251016A: Swift/UVOT Detection
  96. GRB 251018A: Swift/UVOT Detection
  97. IceCube-251018A - IceCube observation of a high-energy neutrino candidate track-like event (duplicate submission)
  98. GRB 251017A: VLT/MUSE spectroscopic redshift z = 4.327
  99. GRB 251016A: VLT/FORS2 Optical Observation
  100. GRB 251017A: COLIBRÍ photometric redshift

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