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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

28290 results found.

  1. EP250220a: Liverpool Telescope optical upper limits
  2. EP250220a: Optical upper limit with Kinder observations
  3. SVOM trigger sb25022102 is not an astrophysical event
  4. GRB 250221A: COLIBRÍ/DDRAGO Confirmation of a Bright Optical Counterpart
  5. GRB 250221A: Swift detection of a burst with an optical counterpart
  6. Swift GRB250221.15: Global MASTER-Net OT detection
  7. EP250220a: Xinglong optical upper limit
  8. GRB 250219A: Swift/UVOT Upper Limits
  9. GRB 250219A: OHP/T193 optical upper limit
  10. GRB 250219A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  11. GRB 250219A: 1.6m Mephisto optical upper limits
  12. GRB 250219A: Swift-XRT observations
  13. LIGO/Virgo/KAGRA S250206dm: Upper limits from MSU cubesats observations
  14. Konus-Wind detection of GRB 250215A / EP250215a
  15. SVOM/sb25021804: COLIBRÍ/DDRAGO Confirmation of Variability
  16. GRB 250217C: Swift-XRT observations
  17. SVOM/sb25021804: QSO variability in Liverpool Telescope observations
  18. GRB 250217C: COLIBRÍ/DDRAGO Upper Limits on the Optical Counterpart
  19. GRB 250217C: DDOTI Upper Limits on the Optical Afterglow
  20. GRB 250217C: SVOM/GRM observation
  21. Transient SVOM/sb25021804: COLIBRÍ/DDRAGO Optical Upper Limits on the Optical Counterpart
  22. SVOM/sb25021804: SVOM detection of a long X-ray transient
  23. GRB 250213A: Swift-XRT observations
  24. GRB 250216A: AstroSat CZTI detection
  25. GRB 250217C: AstroSat CZTI detection of a short burst
  26. IceCube-Cascade 250215A: Upper limits from a search for additional neutrino events in IceCube
  27. GRANDMA/OPD observations of GRB250215A
  28. GRB 250215A / EP250215a: LCO detection of the afterglow
  29. GRB 250215A: Swift/UVOT Upper Limits
  30. GRB 250215A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow
  31. GRB 250215A: Fermi GBM Observation
  32. GRB 250215A/EP250215a: 1.6m Mephisto optical observation report
  33. GRB 250213A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow
  34. GRB 250215A: Swift-XRT refined Analysis
  35. GRB 250215A: SVOM/GRM observation
  36. EP250215a / GRB 250215A (potentially): NOT likely optical counterpart
  37. EP250215a: EP-WXT detection and FXT follow-up observation of an X-ray transient
  38. EP250207b: Xinglong optical upper limit
  39. EP250212a: Xinglong optical upper limit
  40. LIGO/Virgo/KAGRA S250206dm: DECam GW-MMADS candidates
  41. EP250212a: Global MASTER-Net observations report
  42. GRB 250205A: VIRT Optical Upper Limit
  43. GRB 250205A: Leavitt Observatory optical upper limit
  44. EP250207B: Chandra localization of the X-ray counterpart
  45. EP250212a: Liverpool Telescope optical upper limits
  46. GRB250101A: Radio upper limits from GMRT observations
  47. EP trigger 10202399251 (possibly EP250212a): NOT J-band upper limit
  48. EP250207B: GTC z-band Observations
  49. Fermi GRB 250212A: Global MASTER-Net observations report
  50. LIGO/Virgo/KAGRA S250206dm: NEWFIRM NIR Follow-up of AT2025ber
  51. GRB 250205A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  52. Fermi trigger No 760945500: Global MASTER-Net observations report
  53. EP250207b: NOT optical counterpart candidate
  54. GRB 250211B: A long GRB detected by INTEGRAL
  55. LIGO/Virgo/KAGRA S250206dm: GECKO Continued Observaiton with 7DT
  56. LIGO/Virgo/KAGRA S250206dm: AT 2025bbo observations with WFST
  57. LIGO/Virgo/KAGRA S250211be: Updated Sky localization
  58. GRB 250207A: Fermi GBM Observation
  59. GRB 250206A: Fermi GBM Observation
  60. GRB 250205A / EP250205A: radio detection with the VLA
  61. EP250207b: Tentative z-band brightening source
  62. LIGO/Virgo/KAGRA S250206dm: Kinder confirmation of a possible artefact in AT 2025bbo
  63. Konus-Wind detection of GRB 250206A
  64. GRB 250210A: SVOM/GRM observation of a long burst
  65. EP250207b: Liverpool Telescope possible optical counterpart
  66. LIGO/Virgo/KAGRA S250211be: Identification of a GW compact binary merger candidate
  67. LIGO/Virgo/KAGRA S250211aa: Updated Sky localization and EM Bright Classification
  68. LIGO/Virgo/KAGRA S250211aa: Identification of a GW compact binary merger candidate
  69. GRB 250207A: Skynet optical afterglow observations
  70. GRB 241128A: VIRT Optical Upper Limit
  71. EP250207b: Gemini GMOS-N z-band observations
  72. EP250207A: Upper limits from Fermi-GBM Observations
  73. EP250207b: a new X-ray transient detected by Einstein Probe
  74. GRB 250209A: MAXI/GSC detection (possible detection of an X-ray flare from 1RXS J145110.3+310648)
  75. LIGO/Virgo/KAGRA S250206dm: Upper limits from GECAM Observations
  76. IceCube-250207A: Upper limits from a search for additional neutrino events in IceCube
  77. LIGO/Virgo/KAGRA S250206dm: Global MASTER-Net observations report
  78. LIGO/Virgo/KAGRA S250206dm: COLIBRÍ/DDRAGO Observations of AT2025bbo and Galaxies in the Localization Volume
  79. LIGO/Virgo/KAGRA S250206dm: Observations from WINTER
  80. LIGO/Virgo/KAGRA S250206dm: Optical observations of candidate AT 2025bbo with Kinder
  81. Fermi-LAT Gamma-ray Observations of IceCube-250207A
  82. GRB 250207A: 1.3m DFOT Optical observations
  83. LIGO/Virgo/KAGRA S250206dm: WFST follow-up observations
  84. GRB 250206A: Swift-XRT observations
  85. GRB 250129A: GRANDMA Continued Afterglow Detection
  86. GRB 250207A: Swift-BAT refined analysis
  87. LIGO/Virgo/KAGRA S250206dm: further Pan-STARRS observations and one candidate AT2025bbo
  88. LIGO/Virgo/KAGRA S250207bg: Updated NED Galaxies in the Localization Volume
  89. LIGO/Virgo/KAGRA S250207bg: Updated Sky localization
  90. LIGO/Virgo/KAGRA S250206dm: GECKO Observation with 7DT and KMTNet
  91. GRB 250205A: 1.3m DFOT optical upper limit
  92. LIGO/Virgo/KAGRA S250118az: Updated Sky localization
  93. LIGO/Virgo/KAGRA S250208ad: Updated Sky localization
  94. GRB 250206A: EIRSAT-1 GMOD Detection
  95. LIGO/Virgo/KAGRA S250206dm: (Update-7) NED Galaxies in the Localization Volume
  96. LIGO/Virgo/KAGRA S250206dm: NEWFIRM NIR Observations
  97. GRB 250207B: Swift-XRT observations
  98. LIGO/Virgo/KAGRA S250206dm: Updated Sky localization and EM Bright Classification
  99. LIGO/Virgo/KAGRA S250206dm: COLIBRÍ/DDRAGO Observations of the DDOTI optical candidates
  100. LIGO/Virgo/KAGRA S250208ad: Identification of a GW compact binary merger candidate

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