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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"

24392 results found.

  1. Integral GRB250211.89: Global MASTER-Net observations report
  2. GRB 250212A: Fermi GBM Final Real-time Localization
  3. LIGO/Virgo/KAGRA S250211be: Updated Sky localization
  4. GRB 250207A: Fermi GBM Observation
  5. GRB 250206A: Fermi GBM Observation
  6. IceCube-250207A: One candidate from the Zwicky Transient Facility
  7. EP250207b: Tentative z-band brightening source
  8. LIGO/Virgo/KAGRA S250206dm: continued in SOAR galaxy targeted observations and identification of one possible transient
  9. Konus-Wind detection of GRB 250207A
  10. Konus-Wind detection of GRB 250206A
  11. EP250207b: Global MASTER-Net observations report
  12. Gemini-South spectroscopic redshift of EP250207b host galaxy candidate (z=0.082)
  13. LIGO/Virgo/KAGRA S250211be: Identification of a GW compact binary merger candidate
  14. LIGO/Virgo/KAGRA S250211aa: Updated Sky localization and EM Bright Classification
  15. LIGO/Virgo/KAGRA S250211aa: Identification of a GW compact binary merger candidate
  16. EP250207b: Gemini GMOS-N z-band observations
  17. EP250207A: Upper limits from Fermi-GBM Observations
  18. EP250207b: a new X-ray transient detected by Einstein Probe
  19. Fermi GRB 250210A: Global MASTER-Net observations report
  20. GRB 250210A: Fermi GBM Final Real-time Localization
  21. LIGO/Virgo/KAGRA S250206dm: Upper limits from GECAM Observations
  22. IceCube-250207A: Upper limits from a search for additional neutrino events in IceCube
  23. LIGO/Virgo/KAGRA S250206dm: Global MASTER-Net observations report
  24. LIGO/Virgo/KAGRA S250206dm: COLIBRÍ/DDRAGO Observations of AT2025bbo and Galaxies in the Localization Volume
  25. IceCube Alert 250207.09: Global MASTER-Net observations report
  26. LIGO/Virgo/KAGRA S250206dm: Observations from WINTER
  27. GRB 250204B: GRBAlpha detection
  28. GRB 250204A: GRBAlpha detection
  29. LIGO/Virgo/KAGRA S250206dm & FRB 20250206A: MASTER observations and possible mother galaxy
  30. Fermi-LAT Gamma-ray Observations of IceCube-250207A
  31. GRB 250207A: 1.3m DFOT Optical observations
  32. LIGO/Virgo/KAGRA S250206dm: WFST follow-up observations
  33. GRB 250206A: Swift-XRT observations
  34. GRB 250207A: Swift-BAT refined analysis
  35. LIGO/Virgo/KAGRA S250206dm: further Pan-STARRS observations and one candidate AT2025bbo
  36. LIGO/Virgo/KAGRA S250207bg: Updated NED Galaxies in the Localization Volume
  37. LIGO/Virgo/KAGRA S250207bg: Updated Sky localization
  38. GRB 250205A: 1.3m DFOT optical upper limit
  39. LIGO/Virgo/KAGRA S250118az: Updated Sky localization
  40. LIGO/Virgo/KAGRA S250208ad: Updated Sky localization
  41. GRB 250206A: EIRSAT-1 GMOD Detection
  42. LIGO/Virgo/KAGRA S250206dm: (Update-7) NED Galaxies in the Localization Volume
  43. LIGO/Virgo/KAGRA S250206dm: NEWFIRM NIR Observations
  44. GRB 250206A: Fermi-LAT detection
  45. GRB 250207B: Swift-XRT observations
  46. LIGO/Virgo/KAGRA S250206dm: Updated Sky localization and EM Bright Classification
  47. IceCube-250203A: No transient candidates from the Zwicky Transient Facility
  48. LIGO/Virgo/KAGRA S250206dm: Spectroscopic Classification of AT2025bay and AT2025baz with Keck I/LRIS
  49. LIGO/Virgo/KAGRA S250206dm: Candidates from the Zwicky Transient Facility
  50. GRB 250208A: Fermi GBM Final Real-time Localization
  51. EP250207a: EP-WXT detection and XRT follow-up observation
  52. LIGO/Virgo/KAGRA S250208ad: Identification of a GW compact binary merger candidate
  53. LIGO/Virgo/KAGRA S250206dm: MMT galaxy targeted observations
  54. GRB 250207A: Swift-XRT refined Analysis
  55. LIGO/Virgo/KAGRA S250206dm: FRB 20250206A & "Time Machine" Effect.
  56. 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%
  57. LIGO/Virgo/KAGRA S250206dm: GOTO counterpart search update - AT2025bar
  58. EP-WXT trigger 01709131361 / LIGO/Virgo/KAGRA S250206dm: FTW optical and NIR observations
  59. GRB 250129A: ABObservatory SLOAN r’ afterglow detection
  60. GRB 250207A: REM IR afterglow detection
  61. LIGO/Virgo/KAGRA S250206dm: DDOTI Upper Limits
  62. LIGO/Virgo/KAGRA S250207bg: NED Galaxies in the Localization Volume
  63. Konus-Wind detection of GRB 250204B
  64. IceCube-250207A - IceCube observation of a high-energy neutrino candidate track-like event
  65. GRB 250207A: REM optical afterglow detection
  66. LIGO/Virgo/KAGRA S250207bg: Identification of a GW compact binary merger candidate
  67. LIGO/Virgo/KAGRA S250206dm:GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
  68. LIGO/Virgo/KAGRA S250206dm: GOTO observations of optical candidates AT 2025azn and AT 2025azm
  69. LIGO/Virgo/KAGRA S250206dm: SOAR galaxy targeted observations
  70. LIGO/Virgo/KAGRA S250206dm: Pan-STARRS observations of AT2025azm and AT2025azn
  71. LIGO/Virgo/KAGRA S250206dm: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  72. LIGO/Virgo/KAGRA S250206dm: SAGUARO Detection of Two Potential Optical Counterparts
  73. LIGO/Virgo/KAGRA S250206dm: Updated-6 NED Galaxies in the Localization Volume
  74. LIGO/Virgo/KAGRA S250206dm: Updated Sky localization and EM Bright Classification
  75. LIGO/Virgo/KAGRA S250206dm: Upper limits from Fermi-GBM Observations
  76. GRB 250207A: Fermi GBM Final Real-time Localization
  77. Fermi-LAT Gamma-ray Observations of IceCube-250203A
  78. LIGO/Virgo/KAGRA S250206dm: Coverage and upper limits from MAXI/GSC observations
  79. LIGO/Virgo/KAGRA S250206dm: Updated Sky localization and EM Bright Classification
  80. LIGO/Virgo/KAGRA S250206dm: Updated NED Galaxies in the Localization Volume
  81. LIGO/Virgo/KAGRA S250206dm: Two counterpart neutrino candidates from IceCube neutrino searches
  82. LIGO/Virgo/KAGRA S250206dm: Identification of a GW compact binary merger candidate
  83. LIGO/Virgo/KAGRA S250206dm: NED Galaxies in the Localization Volume
  84. GRB 250206A: BALROG localization (Fermi Trigger 760564296 / GRB 250206827)
  85. GRB 250206A: Fermi GBM Final Real-time Localization
  86. GRB 250205A: Fermi GBM Observation
  87. GRB 250205A: REM NIR upper limit
  88. LIGO/Virgo/KAGRA S250205ee: Updated Sky localization and Source Classification
  89. EP250205a/GRB 250205A: correction to the source localization
  90. EP250205a/GRB 250205A: Einstein Probe observation
  91. GRB 250127C: SVOM/GRM observation of a burst
  92. GRB250205A: SVOM/VT optical afterglow detection
  93. GRB 250205A: GOTO optical upper limits
  94. LIGO/Virgo/KAGRA S250205ee: Identification of a GW compact binary merger candidate
  95. GRB 250205A: SVOM detection of a burst
  96. LIGO/Virgo/KAGRA S250205bk: NED Galaxies in the Localization Volume
  97. Konus-Wind detection of GRB 250201A
  98. IPN triangulation of GRB 250201A
  99. LIGO/Virgo/KAGRA S250205bk: Updated Sky localization
  100. Konus-Wind detection of GRB 250202B

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