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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').
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"

23578 results found.

  1. GRB 250219A: NUTTelA-TAO / BSTI Optical Limits
  2. GRB 250221A: GRANDMA/TAROT Detection
  3. GRB 250221A: Swift-XRT refined Analysis
  4. GRB 250221A: 1.6m Mephisto optical detection
  5. GRB 250221A: AKO Optical Upper Limit
  6. GRB 250221A: Swift/UVOT Detection
  7. EP250220a: Liverpool Telescope upper limits
  8. GRB 250219A: GRANDMA/Kilonova-Catcher upper limits
  9. GRB 250221A: REM optical/NIR afterglow detection
  10. GRB 250221A: Enhanced Swift-XRT position
  11. EP250220a: 1.6m Mephisto observations
  12. EP250220a: Liverpool Telescope optical upper limits
  13. EP250220a: Optical upper limit with Kinder observations
  14. SVOM trigger sb25022102 is not an astrophysical event
  15. GRB 250221A: COLIBRÍ/DDRAGO Confirmation of a Bright Optical Counterpart
  16. GRB 250221A: Swift detection of a burst with an optical counterpart
  17. EP250220a: Xinglong optical upper limit
  18. GRB 250219A: Swift/UVOT Upper Limits
  19. GRB 250219A: OHP/T193 optical upper limit
  20. GRB 250219A: NOT optical observations
  21. GRB 250219A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  22. GRB 250219A: 1.6m Mephisto optical upper limits
  23. GRB 250219A: Swift-XRT observations
  24. LIGO/Virgo/KAGRA S250206dm: Upper limits from MSU cubesats observations
  25. SVOM/sb25021804: COLIBRÍ/DDRAGO Confirmation of Variability
  26. GRB 250217C: Swift-XRT observations
  27. SVOM/sb25021804: QSO variability in Liverpool Telescope observations
  28. GRB 250217C: COLIBRÍ/DDRAGO Upper Limits on the Optical Counterpart
  29. GRB 250217C: DDOTI Upper Limits on the Optical Afterglow
  30. GRB 250217C: SVOM/GRM observation
  31. GRB 250217C: Fermi GBM Observation
  32. GRB 250215A / EP250215A: Encouraging Follow-up Observations of a BdHN I with a Rest-Frame Duration 2.3 s at z=4.61
  33. IPN triangulation of GRB 250217C (short)
  34. Transient SVOM/sb25021804: COLIBRÍ/DDRAGO Optical Upper Limits on the Optical Counterpart
  35. GRB 250213A: Swift-XRT observations
  36. LIGO/Virgo/KAGRA S250206dm: AZT-33IK Target Optical Observations
  37. LIGO/Virgo/KAGRA S250206dm: observation in AbAO, optical transient near NED/GLADE+ galaxy WISEA J021210.14+514821.7
  38. GRANDMA/OPD observations of GRB250215A
  39. GRB 250215A / EP250215a: LCO detection of the afterglow
  40. EP250212a: FTW optical and NIR upper limits
  41. GRB 250215A: Swift/UVOT Upper Limits
  42. GRB 250215A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow
  43. GRB 250215A/EP250215a: 1.6m Mephisto optical observation report
  44. GRB 250213A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow
  45. GRB 250215A: SVOM/GRM observation
  46. EP250215a / GRB 250215A (potentially): NOT likely optical counterpart
  47. EP250215a: EP-WXT detection and FXT follow-up observation of an X-ray transient
  48. EP250207b: Xinglong optical upper limit
  49. EP250212a: Xinglong optical upper limit
  50. LIGO/Virgo/KAGRA S250206dm: DECam GW-MMADS candidates
  51. GRB 250205A: VIRT Optical Upper Limit
  52. GRB 250205A: Leavitt Observatory optical upper limit
  53. EP250207B: Chandra localization of the X-ray counterpart
  54. LIGO/Virgo/KAGRA S250206dm: FTW observations of counterpart candidates AT2025bbo and AT2025bcx, and of NED galaxies
  55. EP250207b: VLA radio upper limits
  56. EP250212a: Liverpool Telescope optical upper limits
  57. GRB250101A: Radio upper limits from GMRT observations
  58. EP trigger 10202399251 (possibly EP250212a): NOT J-band upper limit
  59. EP250207B: GTC z-band Observations
  60. LIGO/Virgo/KAGRA S250206dm: NEWFIRM NIR Follow-up of AT2025ber
  61. GRB 250205A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  62. EP250207b: NOT optical counterpart candidate
  63. LIGO/Virgo/KAGRA S250206dm: GECKO Continued Observaiton with 7DT
  64. LIGO/Virgo/KAGRA S250206dm: AT 2025bbo observations with WFST
  65. GRB 250205A / EP250205A: radio detection with the VLA
  66. EP250207b: Tentative z-band brightening source
  67. LIGO/Virgo/KAGRA S250206dm: continued in SOAR galaxy targeted observations and identification of one possible transient
  68. LIGO/Virgo/KAGRA S250206dm: Kinder confirmation of a possible artefact in AT 2025bbo
  69. GRB 250210A: SVOM/GRM observation of a long burst
  70. EP250207b: Liverpool Telescope possible optical counterpart
  71. LIGO/Virgo/KAGRA S250211be: Identification of a GW compact binary merger candidate
  72. LIGO/Virgo/KAGRA S250211aa: Updated Sky localization and EM Bright Classification
  73. LIGO/Virgo/KAGRA S250211aa: Identification of a GW compact binary merger candidate
  74. GRB 250207A: Skynet optical afterglow observations
  75. GRB 241128A: VIRT Optical Upper Limit
  76. EP250207b: Gemini GMOS-N z-band observations
  77. EP250207b: a new X-ray transient detected by Einstein Probe
  78. LIGO/Virgo/KAGRA S250206dm: Upper limits from GECAM Observations
  79. LIGO/Virgo/KAGRA S250206dm: Global MASTER-Net observations report
  80. LIGO/Virgo/KAGRA S250206dm: COLIBRÍ/DDRAGO Observations of AT2025bbo and Galaxies in the Localization Volume
  81. LIGO/Virgo/KAGRA S250206dm: Observations from WINTER
  82. LIGO/Virgo/KAGRA S250206dm: Optical observations of candidate AT 2025bbo with Kinder
  83. GRB 250207A: 1.3m DFOT Optical observations
  84. LIGO/Virgo/KAGRA S250206dm: WFST follow-up observations
  85. GRB 250206A: Swift-XRT observations
  86. GRB 250129A: GRANDMA Continued Afterglow Detection
  87. LIGO/Virgo/KAGRA S250206dm: GECKO Observation with 7DT and KMTNet
  88. GRB 250205A: 1.3m DFOT optical upper limit
  89. LIGO/Virgo/KAGRA S250206dm: NEWFIRM NIR Observations
  90. GRB 250207B: Swift-XRT observations
  91. LIGO/Virgo/KAGRA S250206dm: Updated Sky localization and EM Bright Classification
  92. LIGO/Virgo/KAGRA S250206dm: COLIBRÍ/DDRAGO Observations of the DDOTI optical candidates
  93. LIGO/Virgo/KAGRA S250208ad: Identification of a GW compact binary merger candidate
  94. EP trigger 01709131361 (possible EP250207a): NOT optical observations and flaring star
  95. GRB 250207A: Enhanced Swift-XRT position
  96. 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%
  97. EP-WXT trigger 01709131361 / LIGO/Virgo/KAGRA S250206dm: FTW optical and NIR observations
  98. GRB 250129A: ABObservatory SLOAN r’ afterglow detection
  99. GRB 250207A: REM IR afterglow detection
  100. LIGO/Virgo/KAGRA S250206dm: Pan-STARRS survey of the skymap for optical transients

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