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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"

32510 results found.

  1. GRB 251106A: MASTER optical observations
  2. GRB 251103B: AstroSat CZTI detection
  3. GRB 251025C: TERI Gamma-ray detection
  4. GRB 251016B: TERI Gamma-ray detection
  5. GRB 251016A: TERI Gamma-ray detection of a short burst
  6. GRB 250920C: TERI Gamma-ray detection
  7. EP251102a: Xinglong 2.16-m clear-band observations of the optical counterpart
  8. GRB 251105A: Fermi GBM Observation
  9. GRB 251105A: Swift/BAT-GUANO localization skymap of a burst
  10. GRB 251104A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  11. GRB 251105B: AstroSat CZTI detection of a short burst with extended emission
  12. GRB 251023A: SVOM/ECLAIRs detection of a burst through targeted search
  13. Fermi GBM Sub-Threshold Detection of GRB 251105B
  14. GRB 251103B: Swift/UVOT Upper Limits
  15. LIGO/Virgo/KAGRA S251105aj: Identification of a GW compact binary merger candidate
  16. Fermi GRB 251105A: Global MASTER-Net observations report
  17. GRB 251103B: Fermi GBM observation
  18. GRB 251028A: Insight-HXMT/HE detection
  19. GRB 251103A: Optical afterglow detection by ZTF’s public survey
  20. EP251102a: FTW optical and NIR observations
  21. GRB 251103A: WFST optical observations
  22. EP251102a: update of EP-FXT follow-up observation
  23. EP251102a: OHP/T193 optical observations
  24. GRB 251103A: OHP/T193 optical observations
  25. GRB 251103A: Xinglong 2.16m optical detection
  26. GRB 251103A: Insight-HXMT detection
  27. GRB 251103A: KAIT optical observations
  28. GRB 251103B: Nanshan/HMT optical upper limit
  29. GRB 251013C: 7DT detection and Medium-band SED of Afterglow
  30. GRB 251103B: MITSuME Akeno optical upper limits
  31. Fermi GRB 251103A: Global MASTER-Net observations report
  32. LIGO/Virgo/KAGRA S251103f: Identification of a GW compact binary merger candidate
  33. EP251102a: NIR observations with WINTER
  34. GRB 251103A: J-band detection with WINTER
  35. Swift GRB 251103B: Global MASTER-Net observations report
  36. GRB 251103B: GROWTH-India Telescope optical upper limits
  37. GRB 251103A: Kilonova-Catcher optical afterglow detection
  38. GRB 251103A: Swift/UVOT Detection
  39. GRB 251103A: Fermi GBM Observation
  40. GRB 251103A: SVOM/GRM observation
  41. GRB 251103A: Swift-XRT afterglow detection
  42. LIGO/Virgo/KAGRA S251031cq: Updated Sky localization
  43. GRB 251103A: SVOM/COLIBRÍ (FM-GFT) optical observations
  44. EP251102a: Einstein Probe detection of a fast X-ray transient
  45. GRB 251025B: OHP/T193 optical upper limit
  46. EP251102a (WXT 11900459650): LCO observations confirm COLIBRÍ candidate
  47. GRB 251103A: LCO optical observation
  48. GRB 251103A: GOTO optical afterglow detection
  49. GRB 251102A: AstroSat CZTI detection
  50. GRB 251026A: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical counterpart
  51. GRB 251103A: NOT spectroscopic redshift z = 0.76
  52. GRB 251103A: LCO optical afterglow detection
  53. GRB 251103A: NOT optical afterglow candidate (duplicate submission)
  54. GRB 251103A: NOT optical afterglow candidate
  55. Fermi GRB 251102A: Global MASTER-Net observations report
  56. GRB 251031A: Fermi GBM Observation
  57. LIGO/Virgo/KAGRA S251031cq: Identification of a GW compact binary merger candidate
  58. GRB 251031A: Swift/BAT-GUANO localization skymap of a burst
  59. Konus-Wind detection of GRB 251028A
  60. GRB 251025C: SVOM/GRM observation
  61. GRB 251028A: GECAM-B detection
  62. GRB 251028A: SVOM/GRM observation
  63. IceCube-251025A: Two Transient Candidates from the Zwicky Transient Facility
  64. GRB 251028A: Fermi GBM Observation
  65. GRB 251026B: SOAR Classification of GOTO25jgl/SN2025absf as a Type Ia supernova
  66. GRB 251022A: Swift-XRT confirmation of fading
  67. GRB 251026B: LBT near-infrared observations
  68. GRB 250926B: VZLUSAT-2 detection
  69. GRB 250926A: VZLUSAT-2 detection
  70. GRB 250925A: VZLUSAT-2 detection
  71. GRB 251026A/EP251026a: SVOM/VT optical counterpart
  72. GRB 251026A/EP251026a: EP-FXT follow-up observation
  73. GRB 251028B: Fermi/GBM observation
  74. GRB 251028B: Swift/BAT-GUANO localization skymap of a burst
  75. GRB 251028B: Glowbug gamma-ray detection
  76. GRB 251028A: Glowbug gamma-ray detection
  77. GRB 251028B: CALET Gamma-Ray Burst Monitor detection
  78. Fermi GRB 251028B: Global MASTER-Net observations report
  79. GRB 251025B: GROWTH-India Telescope continued multiband optical observations and rebrightening
  80. GRB251026B: PRIME H-band upper limit
  81. GRB251025B: 3.6m DOT Optical Observations
  82. SVOM trigger sb25102702/GRB 251027A is not a GRB
  83. IceCube-251025A: Upper limits from a search for additional neutrino events in IceCube
  84. GRB 251025B: Swift-XRT confirmation of fading
  85. GRB 251013C : 3.4-m telescope of Iranian National Observatory (INO340) optical observations
  86. GRB 251026B: Swift-XRT observations of GOTO25jgl/AT2025absf
  87. GRB 251025C: Glowbug gamma-ray detection
  88. Fermi-LAT Gamma-ray Observations of IceCube-251025A
  89. GRB 251023B: Swift-UVOT Upper Limits
  90. Konus-Wind detection of GRB 251022A
  91. GRB 251022A: SVOM/GRM observation
  92. GRB 251026B: Swift ToO observations
  93. GRB 251026A/EP251026a: Einstein Probe detection of a fast X-ray transient
  94. GRB 251027A: LCO optical upper limit
  95. GRB 251027A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  96. GRB 251017A: Mondy AZT-33IK and Koshka Zeiss-1000 optical observations
  97. GRB 251023B / EP251023b: Mondy optical upper limit
  98. GRB 251017A: INASAN-Kislovodsk optical observations
  99. GRB 251026A: Mondy optical upper limit
  100. GRB 251025B: Mondy optical observations

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