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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"

22912 results found.

  1. GRB 251117A: Swift-XRT observations
  2. GRB 251118C: SVOM/GRM observation of a possible gamma-ray counterpart of EP251118a
  3. GRB 251119A: SVOM trigger sb25111901 is not a GRB
  4. EP251118a: VLT near-infrared observation
  5. GRB 251116D: SVOM/GRM observation of a long GRB
  6. GRB 251119A: SVOM detection of a possible burst
  7. EP251118a: NOT candidate optical counterpart
  8. EP251118a: Einstein Probe detected of a fast X-ray transient
  9. LIGO/Virgo/KAGRA S251112cm: Upper limits from Glowbug gamma-ray observations
  10. GRB 251117A: FTW Observations of Swift candidate X-ray sources
  11. GRB 251115A: Swift-XRT observations
  12. GRB 251117A: Swift/BAT-GUANO localization skymap of a short burst
  13. GRB 251117A: SVOM/GRM observation of a short burst
  14. LIGO/Virgo/KAGRA S251117dq: Identification of a GW compact binary merger candidate
  15. GRB 251116C: Swift/BAT arcminute localization of a burst
  16. LIGO/Virgo/KAGRA S251112cm: J-GEM follow-up observations
  17. GRB 251116B: SVOM/VT optical upper limit
  18. LIGO/Virgo/KAGRA S251112cm: WFST follow-up observations and preliminary results
  19. GRB 251116C: Swift-XRT observations
  20. GRB 251116D: Glowbug gamma-ray detection
  21. EP251023a: Assy AZT-20 optical observations
  22. EP251023a: UAFO and AbAO optical observations
  23. GRB 251116D: AstroSat CZTI detection
  24. The EP-WXT trigger 01709247588: more evidence of flaring star from Mondy optical observations
  25. GRB 251116C: SVOM/VT optical upper limit
  26. GRB 251025B: further Mondy optical observations
  27. GRB 251111A: Mondy optical upper limit
  28. LIGO/Virgo/KAGRA S251116en: Identification of a GW compact binary merger candidate
  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. IceCube-Cascade 251112A: Upper limits from a search for additional neutrino events in IceCube
  34. LIGO/Virgo/KAGRA S251112cm: GRANDMA observations of the skymap
  35. LIGO/Virgo/KAGRA S251112cm: DECam GW-MMADS candidates
  36. GRB 251113A: Glowbug gamma-ray detection
  37. LIGO/Virgo/KAGRA S251112cm: ATLAS targeted observations of the skymap
  38. LIGO/Virgo/KAGRA S251112cm: Swift XRT observations, 20 X-ray sources
  39. IPN triangulation of GRB 251108C
  40. LIGO/Virgo/KAGRA S251112cm: FTW observations of galaxies within localization region
  41. GRB 251112A: Swift/UVOT Upper Limits
  42. GRB 251108C: AstroSat CZTI detection
  43. LIGO/Virgo/KAGRA S251112cm: Coverage and upper limits from MAXI/GSC observations
  44. GRB 251108B: Glowbug gamma-ray detection
  45. Swift Trigger 1413695: a possible GRB 251112A
  46. LIGO/Virgo/KAGRA S251112cm: Upper limits from Fermi-GBM Observations
  47. LIGO/Virgo/KAGRA S251112cm: NED Galaxies in the 3-Initial Localization Volume
  48. GRB251111A: 1.3m DFOT optical upper limit
  49. LIGO/Virgo/KAGRA S251112cm: Identification of a GW compact binary merger candidate
  50. GRB 251106B: Glowbug gamma-ray detection of a likely short burst
  51. GRB 251111A: Swift-XRT afterglow detection
  52. GRB 251111A: SVOM/VT optical observations with X-band data
  53. GRB 251111A: Swift-XRT observations
  54. GRB 251111A: SVOM/VT optical observations with VHF data
  55. GRB 251111A: KAIT optical upper limit
  56. GRB 251111A: LCO optical observation
  57. GRB 251111A: SVOM/COLIBRÍ (FM-GFT) optical counterpart detection
  58. GRB 251106A: Swift/UVOT Upper Limits
  59. LIGO/Virgo/KAGRA S251108fi: DDOTI Optical Candidate
  60. GRB 251105A: AstroSat CZTI detection
  61. LIGO/Virgo/KAGRA S251108fi: One counterpart neutrino candidate from IceCube neutrino searches
  62. LIGO/Virgo/KAGRA S251108fi: Identification of a GW compact binary merger candidate
  63. GRB 251102B: SVOM/GRM observation
  64. LIGO/Virgo/KAGRA S251108dn: Identification of a GW compact binary merger candidate
  65. IPN triangulation of GRB 251105B (possible sGRB with EE)
  66. GRB 251106A: SVOM/COLIBRÍ (FM-GFT) fading of the optical counterpart
  67. GRB 251106A: Swift-XRT afterglow detection
  68. GRB 251106A: Kilonova-Catcher optical upper limit
  69. GRB 251106A: Swift/BAT arcminute localization of a burst
  70. GRB 251106A: SVOM/COLIBRÍ (FM-GFT) detection of a likely optical counterpart
  71. GRB 251106A: MASTER optical observations
  72. GRB 251025C: TERI Gamma-ray detection
  73. GRB 251016B: TERI Gamma-ray detection
  74. GRB 251016A: TERI Gamma-ray detection of a short burst
  75. GRB 250920C: TERI Gamma-ray detection
  76. EP251102a: Xinglong 2.16-m clear-band observations of the optical counterpart
  77. GRB 251105A: Swift/BAT-GUANO localization skymap of a burst
  78. GRB 251104A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  79. GRB 251103B: Swift/UVOT Upper Limits
  80. LIGO/Virgo/KAGRA S251105aj: Identification of a GW compact binary merger candidate
  81. GRB 251103A: WFST optical observations
  82. GRB 251103A: Xinglong 2.16m optical detection
  83. GRB 251103A: KAIT optical observations
  84. GRB 251103B: Nanshan/HMT optical upper limit
  85. GRB 251013C: 7DT detection and Medium-band SED of Afterglow
  86. GRB 251103B: MITSuME Akeno optical upper limits
  87. LIGO/Virgo/KAGRA S251103f: Identification of a GW compact binary merger candidate
  88. EP251102a: NIR observations with WINTER
  89. GRB 251103A: J-band detection with WINTER
  90. GRB 251103B: GROWTH-India Telescope optical upper limits
  91. GRB 251103A: Kilonova-Catcher optical afterglow detection
  92. GRB 251103B: Enhanced Swift-XRT position
  93. GRB 251103B: Swift detection of a burst
  94. GRB 251103B: Fermi GBM Final Real-time Localization
  95. GRB 251103A: Swift/UVOT Detection
  96. GRB 251103A: Fermi GBM Observation
  97. GRB 251103A: Swift-XRT afterglow detection
  98. GRB 251103A: SVOM/COLIBRÍ (FM-GFT) optical observations
  99. EP251102a: Einstein Probe detection of a fast X-ray transient
  100. GRB 251025B: OHP/T193 optical upper limit

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