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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"

16202 results found.

  1. EP250215a: EP-WXT detection and FXT follow-up observation of an X-ray transient
  2. EP250207b: Xinglong optical upper limit
  3. EP250212a: Xinglong optical upper limit
  4. LIGO/Virgo/KAGRA S250206dm: DECam GW-MMADS candidates
  5. GRB 250205A: VIRT Optical Upper Limit
  6. GRB 250205A: Leavitt Observatory optical upper limit
  7. EP250207B: Chandra localization of the X-ray counterpart
  8. EP250212a: Liverpool Telescope optical upper limits
  9. EP250212a: EP-WXT detection and FXT follow-up observation of a fast X-ray transient
  10. GRB250101A: Radio upper limits from GMRT observations
  11. EP trigger 10202399251 (possibly EP250212a): NOT J-band upper limit
  12. EP250207B: GTC z-band Observations
  13. LIGO/Virgo/KAGRA S250206dm: NEWFIRM NIR Follow-up of AT2025ber
  14. GRB 250205A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  15. EP250207b: NOT optical counterpart candidate
  16. LIGO/Virgo/KAGRA S250206dm: GECKO Continued Observaiton with 7DT
  17. LIGO/Virgo/KAGRA S250206dm: AT 2025bbo observations with WFST
  18. GRB 250205A / EP250205A: radio detection with the VLA
  19. EP250207b: Tentative z-band brightening source
  20. LIGO/Virgo/KAGRA S250206dm: Kinder confirmation of a possible artefact in AT 2025bbo
  21. Konus-Wind detection of GRB 250206A
  22. GRB 250210A: SVOM/GRM observation of a long burst
  23. EP250207b: Liverpool Telescope possible optical counterpart
  24. LIGO/Virgo/KAGRA S250211be: Identification of a GW compact binary merger candidate
  25. GRB 250207A: Skynet optical afterglow observations
  26. GRB 241128A: VIRT Optical Upper Limit
  27. EP250207b: Gemini GMOS-N z-band observations
  28. EP250207b: a new X-ray transient detected by Einstein Probe
  29. GRB 250209A: MAXI/GSC detection (possible detection of an X-ray flare from 1RXS J145110.3+310648)
  30. LIGO/Virgo/KAGRA S250206dm: COLIBRÍ/DDRAGO Observations of AT2025bbo and Galaxies in the Localization Volume
  31. LIGO/Virgo/KAGRA S250206dm: Observations from WINTER
  32. LIGO/Virgo/KAGRA S250206dm: Optical observations of candidate AT 2025bbo with Kinder
  33. GRB 250207A: 1.3m DFOT Optical observations
  34. LIGO/Virgo/KAGRA S250206dm: WFST follow-up observations
  35. GRB 250129A: GRANDMA Continued Afterglow Detection
  36. LIGO/Virgo/KAGRA S250206dm: GECKO Observation with 7DT and KMTNet
  37. GRB 250205A: 1.3m DFOT optical upper limit
  38. LIGO/Virgo/KAGRA S250206dm: NEWFIRM NIR Observations
  39. GRB 250207B: Swift-XRT observations
  40. LIGO/Virgo/KAGRA S250206dm: COLIBRÍ/DDRAGO Observations of the DDOTI optical candidates
  41. EP250207a: EP-WXT detection and XRT follow-up observation
  42. LIGO/Virgo/KAGRA S250208ad: Identification of a GW compact binary merger candidate
  43. EP trigger 01709131361 (possible EP250207a): NOT optical observations and flaring star
  44. GRB 250207A: Enhanced Swift-XRT position
  45. GRB 250129A: ABObservatory SLOAN r’ afterglow detection
  46. GRB 250207A: REM IR afterglow detection
  47. LIGO/Virgo/KAGRA S250206dm: DDOTI Upper Limits
  48. IGO/Virgo/KAGRA S250206dm: Virtual Telescope Project upper limit for the Neutrino IceCube Candidate
  49. GRB 250207A: REM optical afterglow detection
  50. GRB 250207A: Swift/UVOT Detection
  51. LIGO/Virgo/KAGRA S250206dm: DDOTI Upper Limit for the Neutrino IceCube Candidate
  52. LIGO/Virgo/KAGRA S250206dm: GOTO observations of optical candidates AT 2025azn and AT 2025azm
  53. LIGO/Virgo/KAGRA S250206dm: COLIBRÍ/DDRAGO Observations of the AT 2025azn Optical Candidate
  54. GRB 250129A: Continued AbAO and Mondy optical observations
  55. LIGO/Virgo/KAGRA S250206dm: SAGUARO Detection of Two Potential Optical Counterparts
  56. The EP-WXT trigger 01709131347 is likely a flaring star
  57. The EP-WXT trigger 01709131332 is likely a flaring star
  58. The EP-WXT trigger 01709131290 is likely a flaring star
  59. GRB 250207A: COLIBRÍ/DDRAGO Optical Afterglow Detection
  60. GRB 250207A: Swift detection of a burst with optical counterpart
  61. Fermi-LAT Gamma-ray Observations of IceCube-250203A
  62. GRB 250205A: REM NIR upper limit
  63. GRB 250205A: Swift/UVOT Upper Limits
  64. EP250205a/GRB 250205A: Einstein Probe observation
  65. GRB 250127C: SVOM/GRM observation of a burst
  66. GRB 250204B: SVOM/GRM observation of a likely short burst
  67. GRB 250205A: COLIBRÍ/DDRAGO Optical Afterglow Detection
  68. GRB 250205A: Redshift from OSIRIS+/GTC z = 3.55
  69. GRB250205A: SVOM/VT optical afterglow detection
  70. GRB 250205A: OHP/T193 optical counterpart candidate
  71. GRB 250205A: SVOM detection of a burst
  72. IPN triangulation of GRB 250201A
  73. Konus-Wind detection of GRB 250202B
  74. IPN triangulation of GRB 250202B
  75. GRB 250129A: LCO late afterglow detection
  76. GRB 250129A: AbAO AS-32 and Mondy AZT-33IK optical observations
  77. GRB 250129A: COLIBRÍ/DDRAGO Afterglow Detection
  78. GRB 250129a: Liverpool Telescope optical follow-up
  79. GRB 240129A: further SAO RAS optical observations
  80. GRB 250129A: 7DT Detection and Medium-band SED of Afterglow
  81. The EP-WXT trigger 01709131196 is likely a flaring star
  82. GRB 250129A: SVOM/C-GFT optical observations
  83. Swift GRB250129A: MASTER 4 days observations report
  84. GRB 250129A: 1.3m DFOT Optical observations
  85. GRB 250129A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations
  86. GRB 250129A: SAO RAS optical observations
  87. GRB 250129A: COLIBRÍ Continuing Detection of the Afterglow
  88. GRB 250129A: COLIBRÍ Optical Observations
  89. GRB 250129A: iTelescope optical observation
  90. GRB 250129a: Liverpool Telescope optical follow-up
  91. GRB 250129A: TNG NIR afterglow detection
  92. GRB 250129A: AKO Optical Afterglow Detection
  93. GRB 250129A: GRANDMA/TAROT optical afterglow detection
  94. GRB 250127A: EP-FXT second observation epoch and confirmation of the x-ray afterglow fading
  95. GRB 250128B: SAO RAS Zeiss-1000 and CrAO ZTSh optical upper limits
  96. GRB 250128B: VLA radio upper limit
  97. Ep250125A: 1.3m DFOT optical upper limit
  98. GRB 250129A: Skynet optical observations
  99. GRB 250128B: TNG optical upper limit
  100. GRB 250129A: Swift/UVOT Detection

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