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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"

4252 results found.

  1. EP-WXT trigger 01709133021: Optical upper limit through Kinder observations
  2. FRB 250316A: DDOTI Continued Optical Observations
  3. GRB 250322A: MASTER optical observation
  4. FRB 20250316A: detection of a candidate associated X-ray source EP J120944.2+585060 by Einstein Probe
  5. EP250321a: SVOM/VT optical observation
  6. GRB 250320B: AstroSat CZTI detection
  7. Fermi GRB 250320B: Global MASTER-Net observations report
  8. GRB 250321A: GOTO optical upper limits
  9. GRB 250319B: Fermi GBM Final Localization
  10. Fermi trigger No 763933627: Global MASTER-Net observations report
  11. GRB 250316A: Swift/UVOT Upper Limits
  12. GRB 250317A: Fermi GBM Final Real-time Localization
  13. Fermi GRB 250313A: Global MASTER-Net observations report
  14. EP250311a/GRB 250311A: EP-FXT follow-up observation
  15. Fermi GRB 250312B: Global MASTER-Net observations report
  16. IceCube-250309A: MITSuME Akeno and Seimei/TriCCS optical observations
  17. GRB 250309B / AT2025dws: SAO RAS optical observations
  18. IceCube Alert 250309.32: Global MASTER-Net observations report
  19. EP250304A: Upper limits from Fermi-GBM Observations
  20. GRB 250219A: SVOM/C-GFT optical upper limit at early phase
  21. IceCube-250302A: Upper limits from a search for additional neutrino events in IceCube
  22. EP250304a: refined analysis of the EP-WXT and EP-FXT observations
  23. EP250302a: Mondy Continued Optical Observations
  24. Fermi GRB 250302A: Global MASTER-Net observations report
  25. Fermi GRB 250225A: Global MASTER-Net observations report
  26. GRB 250225B: Swift detection of a burst
  27. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: AstroSat CZTI non-detection and upper limits
  28. EP250223a: REM NIR upper limit
  29. GRB 250223B: Fermi GBM Final Localization
  30. Fermi trigger No 762020305: Global MASTER-Net observations report
  31. GRB 250221A: continued Assy optical observations, brightening afterglow confirmation
  32. GRB 250221A: continued Mondy optical observations, brightening afterglow
  33. GRB 250213A: Swift-XRT observations
  34. Fermi GRB 250217A: Global MASTER-Net observations report
  35. EP250215a: Global MASTER-Net observations report
  36. Fermi trigger No 761206993: Global MASTER-Net observations report
  37. EP250212a: Xinglong optical upper limit
  38. EP250207b: VLA radio upper limits
  39. Fermi GRB 250212A: Global MASTER-Net observations report
  40. Fermi trigger No 760945500: Global MASTER-Net observations report
  41. LIGO/Virgo/KAGRA S250206dm: continued in SOAR galaxy targeted observations and identification of one possible transient
  42. LIGO/VIRGO/KAGRA S250206dm: AT 2025bbo spectroscopic observations with NIRES on Keck II
  43. GRB 241128A: VIRT Optical Upper Limit
  44. GRB 250210A: AstroSat CZTI detection
  45. GRB 250209A: MAXI/GSC detection (possible detection of an X-ray flare from 1RXS J145110.3+310648)
  46. Fermi GRB 250210A: Global MASTER-Net observations report
  47. LIGO/Virgo/KAGRA S250206dm: Global MASTER-Net observations report
  48. IceCube Alert 250207.09: Global MASTER-Net observations report
  49. LIGO/Virgo/KAGRA S250206dm & FRB 20250206A: MASTER observations and possible mother galaxy
  50. LIGO/Virgo/KAGRA S250206dm: GECKO Observation with 7DT and KMTNet
  51. LIGO/Virgo/KAGRA S250206dm: Candidates from the Zwicky Transient Facility
  52. EP250207a: EP-WXT detection and XRT follow-up observation
  53. LIGO/Virgo/KAGRA S250206dm: DDOTI Upper Limits
  54. LIGO/Virgo/KAGRA S250207bg: Identification of a GW compact binary merger candidate
  55. LIGO/Virgo/KAGRA S250206dm: SOAR galaxy targeted observations
  56. GRB 250207B: MAXI/GSC detection
  57. GRB 250202B: Fermi GBM Detection
  58. The EP-WXT trigger 01709131196 is likely a flaring star
  59. Swift GRB250129A: MASTER 4 days observations report
  60. GRB 250129A: optical photometry from Konkoly
  61. GRB 250128B: VLA possible radio detection
  62. GRB 250129A: AKO Optical Afterglow Detection
  63. GRB 250127A: EP-FXT second observation epoch and confirmation of the x-ray afterglow fading
  64. GRB 250128B: SAO RAS Zeiss-1000 and CrAO ZTSh optical upper limits
  65. GRB 250128B: VLA radio upper limit
  66. GRB 250129A: Skynet optical observations
  67. GRB 250128B: Gemini-North optical extended source detection
  68. GRB 250128B: TNG optical upper limit
  69. GRB 250129A: REM optical/NIR afterglow detection
  70. GRB 250129A: Early afterglow detection by LCO.
  71. GRB 250129A: LCO optical observations
  72. GRB 250129A: GOTO optical observations show brightening afterglow
  73. Swift GRB 250129A: Global MASTER-Net observations report
  74. The EP-WXT trigger 01709131085 is likely a flaring star
  75. Fermi GRB 250128B: Global MASTER-Net observations report
  76. Swift GRB 250129A: Global MASTER-Net OT detection
  77. GRB 250127A: EP-FXT afterglow detection
  78. Fermi GRB 250127B: Global MASTER-Net observations report
  79. GRB 250126A: MAXI/GSC detection
  80. GECAM-A detection of a bright burst from SGR 1E1841-045
  81. Konus-Wind detection of a bright burst from SGR 1E1841-045 on 2025 January 23
  82. IPN triangulation of a bright burst from SGR 1E1841-045
  83. IPN triangulation of GRB 250119B
  84. EP250108a / SN2025kg: Gemini GMOS-S confirmation of an associated broad-lined SN Ic
  85. LIGO/Virgo/KAGRA S250118az: Identification of a GW compact binary merger candidate
  86. GRB 250116A: GECAM-B detection of a long burst
  87. GRB 250114B: OHP/T193 optical upper limit
  88. EP250111a: Global MASTER-Net observations report
  89. EP250108a / AT 2025kg (the "kangaroo”): VLT/X-shooter spectroscopic redshift z = 0.176 and LFBOT classification
  90. GRB 250109A / EP250109a: Swift detection of the X-ray afterglow
  91. IPN triangulation of GRB 250107D (short/hard)
  92. EP250109a: SVOM/VT optical candidate
  93. GRB 250106A: SVOM detection of a long burst
  94. Fermi trigger No 757753930: Global MASTER-Net observations report
  95. LIGO/Virgo/KAGRA S250104v: Identification of a GW compact binary merger candidate
  96. Swift GRB 250103B: Global MASTER-Net observations report
  97. EP241231b and EP250101a: EP-WXT detection of two X-ray transients
  98. Fermi GRB 250101B: Global MASTER-Net observations report
  99. GRB 250101A: SAO RAS optical observations
  100. LIGO/Virgo/KAGRA S241231bg: Identification of a GW compact binary merger candidate

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