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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"

28263 results found.

  1. GRB 250215A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow
  2. GRB 250215A: Fermi GBM Observation
  3. GRB 250215A/EP250215a: 1.6m Mephisto optical observation report
  4. GRB 250213A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow
  5. GRB 250215A: Swift-XRT refined Analysis
  6. GRB 250215A: SVOM/GRM observation
  7. EP250215a / GRB 250215A (potentially): NOT likely optical counterpart
  8. EP250215a: EP-WXT detection and FXT follow-up observation of an X-ray transient
  9. EP250207b: Xinglong optical upper limit
  10. EP250212a: Xinglong optical upper limit
  11. LIGO/Virgo/KAGRA S250206dm: DECam GW-MMADS candidates
  12. EP250212a: Global MASTER-Net observations report
  13. GRB 250205A: VIRT Optical Upper Limit
  14. GRB 250205A: Leavitt Observatory optical upper limit
  15. EP250207B: Chandra localization of the X-ray counterpart
  16. EP250212a: Liverpool Telescope optical upper limits
  17. GRB250101A: Radio upper limits from GMRT observations
  18. EP trigger 10202399251 (possibly EP250212a): NOT J-band upper limit
  19. EP250207B: GTC z-band Observations
  20. Fermi GRB 250212A: Global MASTER-Net observations report
  21. LIGO/Virgo/KAGRA S250206dm: NEWFIRM NIR Follow-up of AT2025ber
  22. GRB 250205A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  23. Fermi trigger No 760945500: Global MASTER-Net observations report
  24. EP250207b: NOT optical counterpart candidate
  25. GRB 250211B: A long GRB detected by INTEGRAL
  26. LIGO/Virgo/KAGRA S250206dm: GECKO Continued Observaiton with 7DT
  27. LIGO/Virgo/KAGRA S250206dm: AT 2025bbo observations with WFST
  28. LIGO/Virgo/KAGRA S250211be: Updated Sky localization
  29. GRB 250207A: Fermi GBM Observation
  30. GRB 250206A: Fermi GBM Observation
  31. GRB 250205A / EP250205A: radio detection with the VLA
  32. EP250207b: Tentative z-band brightening source
  33. LIGO/Virgo/KAGRA S250206dm: Kinder confirmation of a possible artefact in AT 2025bbo
  34. Konus-Wind detection of GRB 250206A
  35. GRB 250210A: SVOM/GRM observation of a long burst
  36. EP250207b: Liverpool Telescope possible optical counterpart
  37. LIGO/Virgo/KAGRA S250211be: Identification of a GW compact binary merger candidate
  38. LIGO/Virgo/KAGRA S250211aa: Updated Sky localization and EM Bright Classification
  39. LIGO/Virgo/KAGRA S250211aa: Identification of a GW compact binary merger candidate
  40. GRB 250207A: Skynet optical afterglow observations
  41. GRB 241128A: VIRT Optical Upper Limit
  42. EP250207b: Gemini GMOS-N z-band observations
  43. EP250207A: Upper limits from Fermi-GBM Observations
  44. EP250207b: a new X-ray transient detected by Einstein Probe
  45. GRB 250209A: MAXI/GSC detection (possible detection of an X-ray flare from 1RXS J145110.3+310648)
  46. LIGO/Virgo/KAGRA S250206dm: Upper limits from GECAM Observations
  47. IceCube-250207A: Upper limits from a search for additional neutrino events in IceCube
  48. LIGO/Virgo/KAGRA S250206dm: Global MASTER-Net observations report
  49. LIGO/Virgo/KAGRA S250206dm: COLIBRÍ/DDRAGO Observations of AT2025bbo and Galaxies in the Localization Volume
  50. LIGO/Virgo/KAGRA S250206dm: Observations from WINTER
  51. LIGO/Virgo/KAGRA S250206dm: Optical observations of candidate AT 2025bbo with Kinder
  52. Fermi-LAT Gamma-ray Observations of IceCube-250207A
  53. GRB 250207A: 1.3m DFOT Optical observations
  54. LIGO/Virgo/KAGRA S250206dm: WFST follow-up observations
  55. GRB 250206A: Swift-XRT observations
  56. GRB 250129A: GRANDMA Continued Afterglow Detection
  57. GRB 250207A: Swift-BAT refined analysis
  58. LIGO/Virgo/KAGRA S250206dm: further Pan-STARRS observations and one candidate AT2025bbo
  59. LIGO/Virgo/KAGRA S250207bg: Updated NED Galaxies in the Localization Volume
  60. LIGO/Virgo/KAGRA S250207bg: Updated Sky localization
  61. LIGO/Virgo/KAGRA S250206dm: GECKO Observation with 7DT and KMTNet
  62. GRB 250205A: 1.3m DFOT optical upper limit
  63. LIGO/Virgo/KAGRA S250118az: Updated Sky localization
  64. LIGO/Virgo/KAGRA S250208ad: Updated Sky localization
  65. GRB 250206A: EIRSAT-1 GMOD Detection
  66. LIGO/Virgo/KAGRA S250206dm: (Update-7) NED Galaxies in the Localization Volume
  67. LIGO/Virgo/KAGRA S250206dm: NEWFIRM NIR Observations
  68. GRB 250207B: Swift-XRT observations
  69. LIGO/Virgo/KAGRA S250206dm: Updated Sky localization and EM Bright Classification
  70. LIGO/Virgo/KAGRA S250206dm: COLIBRÍ/DDRAGO Observations of the DDOTI optical candidates
  71. LIGO/Virgo/KAGRA S250208ad: Identification of a GW compact binary merger candidate
  72. LIGO/Virgo/KAGRA S250206dm: MMT galaxy targeted observations
  73. GRB 250207A: Swift-XRT refined Analysis
  74. LIGO/Virgo/KAGRA S250206dm: FRB 20250206A & "Time Machine" Effect.
  75. EP trigger 01709131361 (possible EP250207a): NOT optical observations and flaring star
  76. GRB 250207A: Enhanced Swift-XRT position
  77. CHIME/FRB source FRB 20250206A detected less than 1 minute after LIGO-Virgo-Kagra (LVK) S250206dm, however the probability of spatial coincidence is order 0.1%
  78. GRB 250129A: ABObservatory SLOAN r’ afterglow detection
  79. GRB 250207A: REM IR afterglow detection
  80. LIGO/Virgo/KAGRA S250206dm: ATLAS observations of the skymap
  81. LIGO/Virgo/KAGRA S250206dm: Pan-STARRS survey of the skymap for optical transients
  82. LIGO/Virgo/KAGRA S250206dm: DDOTI Upper Limits
  83. LIGO/Virgo/KAGRA S250207bg: NED Galaxies in the Localization Volume
  84. IGO/Virgo/KAGRA S250206dm: Virtual Telescope Project upper limit for the Neutrino IceCube Candidate
  85. GRB 250207A: REM optical afterglow detection
  86. LIGO/Virgo/KAGRA S250207bg: Identification of a GW compact binary merger candidate
  87. LIGO/Virgo/KAGRA S250206dm:GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
  88. GRB 250207A: Swift/UVOT Detection
  89. LIGO/Virgo/KAGRA S250206dm: DDOTI Upper Limit for the Neutrino IceCube Candidate
  90. LIGO/Virgo/KAGRA S250206dm: GOTO observations of optical candidates AT 2025azn and AT 2025azm
  91. LIGO/Virgo/KAGRA S250206dm: Pan-STARRS observations of AT2025azm and AT2025azn
  92. LIGO/Virgo/KAGRA S250206dm: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  93. LIGO/Virgo/KAGRA S250206dm: COLIBRÍ/DDRAGO Observations of the AT 2025azn Optical Candidate
  94. GRB 250129A: Continued AbAO and Mondy optical observations
  95. LIGO/Virgo/KAGRA S250206dm: SAGUARO Detection of Two Potential Optical Counterparts
  96. GRB 250207B: MAXI/GSC detection
  97. GRB 250207A: COLIBRÍ/DDRAGO Optical Afterglow Detection
  98. LIGO/Virgo/KAGRA S250206dm: Updated-6 NED Galaxies in the Localization Volume
  99. LIGO/Virgo/KAGRA S250206dm: Updated Sky localization and EM Bright Classification
  100. LIGO/Virgo/KAGRA S250206dm: Upper limits from Fermi-GBM Observations

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