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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.

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

20365 results found.

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

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