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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"

20366 results found.

  1. GRB 251116B: LCO optical upper limits
  2. GRB 251116C: LCO optical upper limits
  3. IceCube-Cascade 251112A: Upper limits from a search for additional neutrino events in IceCube
  4. LIGO/Virgo/KAGRA S251112cm: GRANDMA observations of the skymap
  5. GRB 251013C: joint SVOM/ECLAIRs-GRM refined analysis
  6. LIGO/Virgo/KAGRA S251112cm: NED Galaxies in the 4-Update Localization Volume
  7. LIGO/Virgo/KAGRA S251112cm: DECam GW-MMADS candidates
  8. LIGO/Virgo/KAGRA S251112cm: Updated Sky localization and false alarm rate estimate
  9. GRB 251113A: AstroSat CZTI detection
  10. LIGO/Virgo/KAGRA S251112cm: ATLAS targeted observations of the skymap
  11. LIGO/Virgo/KAGRA S251112cm: Swift XRT observations, 20 X-ray sources
  12. The EP-WXT trigger 01709248221 is likely a flaring star
  13. LIGO/Virgo/KAGRA S251112cm: FTW observations of galaxies within localization region
  14. GRB 251111A: SVOM/ECLAIRs refined analysis
  15. GRB 251025B: SVOM/ECLAIRs refined analysis
  16. GRB 251112A: Swift/UVOT Upper Limits
  17. GRB 251108C: AstroSat CZTI detection
  18. LIGO/Virgo/KAGRA S251112cm: Coverage and upper limits from MAXI/GSC observations
  19. Swift Trigger 1413695: a possible GRB 251112A
  20. GRB251111A: 1.3m DFOT optical upper limit
  21. GRB 251111A: Swift-XRT afterglow detection
  22. GRB 251111A: SVOM/VT optical observations with X-band data
  23. GRB 251111A: SVOM/VT optical observations with VHF data
  24. GRB 251111A: LCO optical observation
  25. GRB 251111A: SVOM/COLIBRÍ (FM-GFT) optical counterpart detection
  26. GRB 251106A: Swift/UVOT Upper Limits
  27. LIGO/Virgo/KAGRA S251108fi: DDOTI Optical Candidate
  28. LIGO/Virgo/KAGRA S251108fi: One counterpart neutrino candidate from IceCube neutrino searches
  29. IceCube-Cascade 251107A: Upper limits from a search for additional neutrino events in IceCube
  30. LIGO/Virgo/KAGRA S251108fi: Identification of a GW compact binary merger candidate
  31. GRB 251102B: SVOM/GRM observation
  32. LIGO/Virgo/KAGRA S251108dn: Identification of a GW compact binary merger candidate
  33. The EP-WXT trigger 01709248051 is likely a flaring star
  34. GRB 251106A: SVOM/COLIBRÍ (FM-GFT) fading of the optical counterpart
  35. GRB 251106A: Swift-XRT afterglow detection
  36. GRB 251106A: Kilonova-Catcher optical upper limit
  37. GRB 251106A: SVOM/COLIBRÍ (FM-GFT) detection of a likely optical counterpart
  38. GRB 251106A: MASTER optical observations
  39. GRB 251103B: AstroSat CZTI detection
  40. EP251102a: Xinglong 2.16-m clear-band observations of the optical counterpart
  41. GRB 251105A: Swift/BAT-GUANO localization skymap of a burst
  42. GRB 251104A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  43. GRB 251023A: SVOM/ECLAIRs detection of a burst through targeted search
  44. GRB 251103B: Swift/UVOT Upper Limits
  45. LIGO/Virgo/KAGRA S251105aj: Identification of a GW compact binary merger candidate
  46. GRB 251103A: WFST optical observations
  47. GRB 251103A: OHP/T193 optical observations
  48. GRB 251103A: Xinglong 2.16m optical detection
  49. GRB 251103A: KAIT optical observations
  50. GRB 251103B: Nanshan/HMT optical upper limit
  51. GRB 251013C: 7DT detection and Medium-band SED of Afterglow
  52. GRB 251103B: MITSuME Akeno optical upper limits
  53. LIGO/Virgo/KAGRA S251103f: Identification of a GW compact binary merger candidate
  54. EP251102a: NIR observations with WINTER
  55. GRB 251103A: J-band detection with WINTER
  56. GRB 251103B: GROWTH-India Telescope optical upper limits
  57. GRB 251103A: Kilonova-Catcher optical afterglow detection
  58. GRB 251103B: Enhanced Swift-XRT position
  59. GRB 251103B: Swift detection of a burst
  60. GRB 251103A: Swift/UVOT Detection
  61. GRB 251103A: Fermi GBM Observation
  62. GRB 251103A: Swift-XRT afterglow detection
  63. GRB 251103A: SVOM/COLIBRÍ (FM-GFT) optical observations
  64. EP251102a: Einstein Probe detection of a fast X-ray transient
  65. EP251102a (WXT 11900459650): LCO observations confirm COLIBRÍ candidate
  66. GRB 251103A: LCO optical observation
  67. EP251102.890: COLIBRÍ optical counterpart candidate
  68. GRB 251102A: AstroSat CZTI detection
  69. GRB 251026A: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical counterpart
  70. GRB 251103A: NOT spectroscopic redshift z = 0.76
  71. GRB 251103A: LCO optical afterglow detection
  72. GRB 251103A: NOT optical afterglow candidate
  73. LIGO/Virgo/KAGRA S251031cq: Identification of a GW compact binary merger candidate
  74. GRB 251031A: Swift/BAT-GUANO localization skymap of a burst
  75. GRB 251025C: SVOM/GRM observation
  76. GRB 251028A: GECAM-B detection
  77. GRB 251028A: SVOM/GRM observation
  78. GRB 251022A: Swift-XRT confirmation of fading
  79. GRB 251026A/EP251026a: SVOM/VT optical counterpart
  80. GRB 251028B: Swift/BAT-GUANO localization skymap of a burst
  81. GRB 251025B: GROWTH-India Telescope continued multiband optical observations and rebrightening
  82. GRB251026B: PRIME H-band upper limit
  83. GRB251025B: 3.6m DOT Optical Observations
  84. SVOM trigger sb25102702/GRB 251027A is not a GRB
  85. IceCube-251025A: Upper limits from a search for additional neutrino events in IceCube
  86. GRB 251013C : 3.4-m telescope of Iranian National Observatory (INO340) optical observations
  87. GRB 251026B: Swift-XRT observations of GOTO25jgl/AT2025absf
  88. Fermi-LAT Gamma-ray Observations of IceCube-251025A
  89. GRB 251027A: Swift-XRT observations
  90. EP251027.145: COLIBRÍ optical upper limits
  91. GRB 251022A: SVOM/GRM observation
  92. GRB 251026A/EP251026a: Einstein Probe detection of a fast X-ray transient
  93. GRB 251027A: LCO optical upper limit
  94. GRB 251027A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  95. GRB 251023B / EP251023b: Mondy optical upper limit
  96. GRB 251017A: INASAN-Kislovodsk optical observations
  97. GRB 251026A: Mondy optical upper limit
  98. GRB 251025B: Mondy optical observations
  99. GRB 251025B: Kilonova-Catcher optical afterglow detection
  100. GRB 251025B: VLT/MUSE spectroscopic redshift z = 2.003

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