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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"

5819 results found.

  1. LIGO/Virgo/KAGRA S251112cm: J-GEM follow-up observations
  2. SVOM GRB251116C: Global MASTER-Net observations report
  3. Fermi GRB 251115A: Global MASTER-Net observations report
  4. LIGO/Virgo/KAGRA S251112cm: NED Galaxies in the 4-Update Localization Volume
  5. GRB 251112A: Swift-BAT refined analysis
  6. LIGO/Virgo/KAGRA S251112cm: Swift XRT observations, 20 X-ray sources
  7. LIGO/Virgo/KAGRA S251112cm: Candidates from the Zwicky Transient Facility
  8. Fermi Gamma-ray Burst Monitor trigger 784717756/251113381 is not a GRB
  9. GRB 251112A: Swift-XRT refined Analysis
  10. LIGO/Virgo/KAGRA S251112cm: Detection of two young transients by BlackGEM/MeerLICHT: AT2025adgp and AT2025adgq
  11. LIGO/Virgo/KAGRA S251112cm: Coverage and upper limits from MAXI/GSC observations
  12. LIGO/Virgo/KAGRA S251112cm: Initial GOTO-South observations
  13. LIGO/Virgo/KAGRA S251112cm: NED Galaxies in the 3-Initial Localization Volume
  14. LIGO/Virgo/KAGRA S251112cm: Identification of a GW compact binary merger candidate
  15. GRB 251111A: Swift-XRT observations
  16. GRB 251013C: Chandra X-ray observations and jet break detection
  17. GRB 251111A: SVOM/COLIBRÍ (FM-GFT) optical counterpart detection
  18. SVOM GRB251108.54: Global MASTER-Net observations report
  19. SVOM GRB251106.83: Global MASTER-Net observations report
  20. GRB 250920C: TERI Gamma-ray detection
  21. Fermi GRB 251103A: Global MASTER-Net observations report
  22. GRB 251103B: GROWTH-India Telescope optical upper limits
  23. GRB 251103B: Swift detection of a burst
  24. GRB 251103A: BOOTES-2/TELMA optical afterglow
  25. GRB 251103A: NOT optical afterglow candidate
  26. Fermi GRB 251102A: Global MASTER-Net observations report
  27. GRB 250926B: VZLUSAT-2 detection
  28. GRB 250926A: VZLUSAT-2 detection
  29. GRB 250925A: VZLUSAT-2 detection
  30. GRB 251028A: MAXI/GSC detection
  31. Fermi-LAT Gamma-ray Observations of IceCube-251025A
  32. EP251027.145: COLIBRÍ optical upper limits
  33. GRB 251017A: Mondy AZT-33IK and Koshka Zeiss-1000 optical observations
  34. GRB 251017A: INASAN-Kislovodsk optical observations
  35. GRB 251026B: Tentative GOTO optical counterpart candidate
  36. GRB 251025B: MAO/AZT-22 optical observations
  37. Fermi GRB 251025C: Global MASTER-Net observations report
  38. GRB 251026A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  39. GRB 251025A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  40. EP251023b: Global MASTER-Net observations report
  41. EP251023a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm telescope at Teide Observatory
  42. IPN triangulation of GRB 251016B
  43. EP251023a: COLIBRÍ optical observations
  44. EP251021b/GRB 251021A: SVOM/VT optical candidate
  45. GRB 251023B / MAXI J0451+122: MAXI/GSC detection
  46. Fermi GRB 251023A: Global MASTER-Net observations report
  47. EP251023a: Einstein Probe detection of an X-ray transient
  48. LIGO/Virgo/KAGRA S251021u: Identification of a GW compact binary merger candidate
  49. Fermi-LAT gamma-ray observations of IceCube-251018A
  50. GRB 251013C: Leavitt Observatory optical photometry
  51. GRB 251017A: COLIBRÍ Early Afterglow Detection
  52. GRB 251017A: Swift detection of a burst with an optical counterpart
  53. sb25101602: Swift-XRT counterpart detection
  54. GRB 251011B: SVOM/VT optical upper limit
  55. LIGO/Virgo/KAGRA S251014cn: NED Galaxies in the 3-Initial Localization Volume
  56. GRB 251014A: DDOTI Upper Limit
  57. Fermi GRB 251013C: Global MASTER-Net observations report
  58. GRB 251011B inspection: MASTER orphan GRB detection
  59. GRB 251011B : MASTER optical observations
  60. GRB 251011B: Swift detection of a burst
  61. GRB 251009B (short): Glowbug gamma-ray detection
  62. GRB 251009A: Fermi GBM Final Localization
  63. GRB 250916A: TERI Gamma-ray detection
  64. GRB 250919A: TERI gamma-ray detection
  65. EP251006a: Global MASTER-Net observations report
  66. EP250911a: Koshka Zeiss-1000 Optical Upper Limit
  67. GRB 250902A: MSU cubesats detection
  68. Fermi GBM Sub-Threshold Detection of GRB 250910A
  69. GRB 251003A: Swift detection of a burst
  70. Fermi GRB 251002A: Global MASTER-Net observations report
  71. GRB 250930A: SVOM/GRM observation
  72. GRB 251001B: Swift detection of a burst
  73. LIGO/Virgo/KAGRA S250830bp: SOAR spectroscopy of two DESGW candidates
  74. LIGO/Virgo/KAGRA S250818k: further MeerKAT monitoring
  75. GRB 250925A: MAO/AZT-22 optical observations
  76. Fermi GRB 250929A: Global MASTER-Net observations report
  77. GRB 250925A: Mondy I-band optical observations
  78. GRB 250916A: SVOM/VT optical observation
  79. LIGO/Virgo/KAGRA S250929c: Identification of a GW compact binary merger candidate
  80. Fermi-LAT Gamma-ray Observations of IceCube-250926A
  81. GRB 250924A: SVOM/GRM observation
  82. LIGO/Virgo/KAGRA S250927cy: Identification of a GW compact binary merger candidate
  83. LIGO/Virgo/KAGRA S250927ck: Identification of a GW compact binary merger candidate
  84. IceCube-250926A: Upper limits from a search for additional neutrino events in IceCube
  85. GRB 250926A: Insight-HXMT detection
  86. Fermi trigger No 780609036: Global MASTER-Net observations report
  87. IceCube Alert 250926.52: Global MASTER-Net observations report
  88. GRB 250920C: ULL-ASTRO-MASTER early detection of the optical afterglow with LCO 40-cm telescope at Siding Spring Observatory
  89. GRB 250926A: AstroSat CZTI detection
  90. GRB 250925A: Mondy and AbAO optical observations
  91. GRB 250925A: COLIBRÍ photometric redshift
  92. IceCube-250926A - IceCube observation of a high-energy neutrino candidate track-like event
  93. GRB 250925A: SVOM/GWAC-F60A upper limit
  94. GRB 250925A/EP250925a: EP-WXT detection
  95. GRB 250926A: DDOTI Optical Observations and Spatial Coincidence with the Orion Nebula
  96. GRB 250925A : MITSuME Akeno optical upper limits
  97. GRB 250925A: JinShan optical observations
  98. GRB 250925A: COLIBRÍ optical photometry of the afterglow
  99. Fermi GRB 250926A: Global MASTER-Net observations report
  100. GRB250925A: Liverpool Telescope optical observations

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