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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"

16153 results found.

  1. EP251118A: 1.3m DFOT optical afterglow detection
  2. EP251118a / GRB 251118C: SAO RAS optical observations
  3. EP251118a: Optical detection with Kinder observations
  4. LIGO/Virgo/KAGRA S251112cm: SVOM/VT optical observations and preliminary results
  5. EP251118a / GRB 251118C: SVOM/VT optical observation
  6. EP251118a / GRB 251118C: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at CTIO
  7. GRB 251116C: NOT optical observations
  8. GRB 251018A: FRAM-Auger optical detection
  9. EP251118A / GRB 251118C : MASTER optical counterpart observations
  10. GRB 251118C: SVOM/GRM observation of a possible gamma-ray counterpart of EP251118a
  11. EP251118a: FTW optical and NIR observations
  12. EP251118a: VLT near-infrared observation
  13. GRB 251116D: SVOM/GRM observation of a long GRB
  14. EP251118a: GOTO optical afterglow detection
  15. EP251118a: NOT spectroscopic redshift of z = 1.216
  16. EP251118a: preliminary result of EP-FXT follow-up observation
  17. EP251118a: NOT candidate optical counterpart
  18. GRB 251013C: Koshka, SAO RAS, Mondy, and CrAO optical observations, possible SN detection
  19. GRB 251117A: SVOM/GRM observation of a short burst
  20. LIGO/Virgo/KAGRA S251112cm: J-GEM follow-up observations
  21. LIGO/Virgo/KAGRA S251112cm: Classification of reported candidates with SOAR/Goodman
  22. GRB 251116B: SVOM/VT optical upper limit
  23. EP251023a: Assy AZT-20 optical observations
  24. EP251023a: UAFO and AbAO optical observations
  25. The EP-WXT trigger 01709247588: more evidence of flaring star from Mondy optical observations
  26. GRB 251116C: SVOM/VT optical upper limit
  27. GRB 251025B: further Mondy optical observations
  28. GRB 251111A: Mondy optical upper limit
  29. LIGO/Virgo/KAGRA S251112cm: Observations with the NSF-DOE Vera C. Rubin Observatory
  30. GRB 251116B: LCO optical upper limits
  31. GRB 251116C: LCO optical upper limits
  32. GRB 251116C: SVOM detection of a burst
  33. LIGO/Virgo/KAGRA S251112cm: ATLAS targeted observations of the skymap
  34. LIGO/Virgo/KAGRA S251112cm: Candidates from the Zwicky Transient Facility
  35. LIGO/Virgo/KAGRA S251112cm: TROVE Vetting of TNS Candidates
  36. GRB 251112A: Swift/UVOT Upper Limits
  37. LIGO/Virgo/KAGRA S251112cm: ATLAS pre-detections of AT2025adgp and AT2025adgq
  38. LIGO/Virgo/KAGRA S251112cm: Initial GOTO-South observations
  39. GRB251111A: 1.3m DFOT optical upper limit
  40. GRB 251111A: SVOM/VT optical observations with X-band data
  41. GRB 251111A: Swift-XRT observations
  42. GRB 251111A: EP-FXT counterpart detection
  43. GRB 251111A: SVOM/VT optical observations with VHF data
  44. GRB 251111A: KAIT optical upper limit
  45. GRB 251111A: LCO optical observation
  46. GRB 251111A: SVOM/COLIBRÍ (FM-GFT) optical counterpart detection
  47. GRB 251106A: Swift/UVOT Upper Limits
  48. LIGO/Virgo/KAGRA S251108fi: DDOTI Optical Candidate
  49. GRB 251102B: SVOM/GRM observation
  50. GRB 251106A: SVOM/COLIBRÍ (FM-GFT) fading of the optical counterpart
  51. GRB 251106A: Swift-XRT afterglow detection
  52. GRB 251106A: Kilonova-Catcher optical upper limit
  53. GRB 251106A: SVOM/COLIBRÍ (FM-GFT) detection of a likely optical counterpart
  54. GRB 251106A: MASTER optical observations
  55. GRB 251106A: SVOM detection of a burst
  56. EP251102a: Xinglong 2.16-m clear-band observations of the optical counterpart
  57. LIGO/Virgo/KAGRA S251031dw: Candidates from the Zwicky Transient Facility
  58. GRB 251104A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  59. GRB 251103B: Swift/UVOT Upper Limits
  60. GRB 251104A: SVOM detection of a burst
  61. GRB 251103A: Optical afterglow detection by ZTF’s public survey
  62. EP251102a: FTW optical and NIR observations
  63. GRB 251103A: WFST optical observations
  64. EP251102a: OHP/T193 optical observations
  65. GRB 251103A: OHP/T193 optical observations
  66. GRB 251103A: Xinglong 2.16m optical detection
  67. GRB 251103A: KAIT optical observations
  68. GRB 251103B: Nanshan/HMT optical upper limit
  69. GRB 251013C: 7DT detection and Medium-band SED of Afterglow
  70. GRB 251103B: MITSuME Akeno optical upper limits
  71. EP251102a: NIR observations with WINTER
  72. GRB 251103A: J-band detection with WINTER
  73. GRB 251103B: GROWTH-India Telescope optical upper limits
  74. GRB 251103A: Kilonova-Catcher optical afterglow detection
  75. GRB 251103A: Swift/UVOT Detection
  76. GRB 251103A: SVOM/GRM observation
  77. GRB 251103A: Swift-XRT afterglow detection
  78. GRB 251103A: SVOM/COLIBRÍ (FM-GFT) optical observations
  79. EP251102a: Einstein Probe detection of a fast X-ray transient
  80. GRB 251025B: OHP/T193 optical upper limit
  81. GRB 251103A: LCO optical observation
  82. EP251102.890: COLIBRÍ optical counterpart candidate
  83. GRB 251103A: GOTO optical afterglow detection
  84. GRB 251026A: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical counterpart
  85. GRB 251103A: NOT spectroscopic redshift z = 0.76
  86. GRB 251103A: BOOTES-2/TELMA optical afterglow
  87. GRB 251103A: LCO optical afterglow detection
  88. GRB 251103A: NOT optical afterglow candidate (duplicate submission)
  89. GRB 251103A: NOT optical afterglow candidate
  90. GRB 251103A: SVOM detection of a bright burst
  91. GRB 251025C: SVOM/GRM observation
  92. GRB 251028A: SVOM/GRM observation
  93. GRB 251026B: SOAR Classification of GOTO25jgl/SN2025absf as a Type Ia supernova
  94. GRB 251026B: LBT near-infrared observations
  95. GRB 251026A/EP251026a: SVOM/VT optical counterpart
  96. GRB 251025B: GROWTH-India Telescope continued multiband optical observations and rebrightening
  97. GRB251026B: PRIME H-band upper limit
  98. GRB251025B: 3.6m DOT Optical Observations
  99. GRB 251013C : 3.4-m telescope of Iranian National Observatory (INO340) optical observations
  100. GRB 251026B: Swift-XRT observations of GOTO25jgl/AT2025absf

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