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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"

12316 results found.

  1. GRB 250506A: SVOM/VT optical upper limit
  2. IceCube-250506A: Upper limits from a search for additional neutrino events in IceCube
  3. GRB 250506A: Swift/UVOT Upper Limits
  4. GRB 250506A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  5. GRB 250507A: SVOM/VT optical upper limit
  6. GRB 250506A: Swift-XRT observations
  7. Fermi-LAT Gamma-ray Observations of IceCube-250506A
  8. GRB 250507A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  9. GRB 250506A: Mephisto optical upper limits
  10. GRB 250502A: Bassano Bresciano Observatory upper limit
  11. IceCube Alert 250506.59: Global MASTER-Net observations report
  12. GRB 250506A: Xinglong 2.16m optical upper limit
  13. SVOM/sb25050601: EP-FXT observations
  14. GRB 250506A: REM optical/NIR upper limits
  15. GRB 250506A: Swift XRT observations and possible counterpart detection
  16. GRB 250506A: SVOM/COLIBRÍ (FM-GFT) Upper Limits on the Optical Counterpart
  17. GRB 250504A: VLT/X-shooter upper limits
  18. Fermi GRB 250505A: Global MASTER-Net observations report
  19. GRB 250504A: SVOM/VT upper limit
  20. Fermi GRB 250504A: Global MASTER-Net observations report
  21. GRB 250504A: Swift detection of a burst
  22. Swift GRB250504.98: Global MASTER-Net observations report
  23. Fermi trigger No 767975731: Global MASTER-Net observations report
  24. Fermi-LAT Gamma-ray Observations of IceCube-250429A
  25. GRB 250430A: Swift/UVOT Detection
  26. Fermi GRB 250502B: Global MASTER-Net observations report
  27. GRB 250430A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  28. EP250428b: Pan-STARRS follow-up, upper limit on the optical counterpart, and possible host galaxy.
  29. GRB 250430A / EP250430a: J-band upper limits with WINTER
  30. EP250427a / GRB 250427A: OHP/T193 photometric observations: third visit
  31. GRB 250430A: Leavitt Observatory optical upper limit
  32. GRB 250430A: Bassano Bresciano Observatory upper limit
  33. GRB 250430A : MITSuME Akeno optical upper limits
  34. SVOM/sb25043004: EP-FXT observations
  35. IceCube-250429A: Upper limits from a search for additional neutrino events in IceCube
  36. IceCube-250426A: Upper limits from a search for additional neutrino events in IceCube
  37. GRB 250430A: Kanata optical upper limit
  38. Swift GRB250430.73: Global MASTER-Net observations report
  39. EP250428b: FTW optical and NIR observations
  40. Fermi trigger No 767623859: Global MASTER-Net observations report
  41. EP250428b: GROWTH-India telescope optical upper limit
  42. EP250428b: SVOM/VT upper limit
  43. EP250428b: SAO RAS optical upper limit
  44. EP250428b: LAST optical upper limit
  45. GRB 250427A: Swift/UVOT Detection
  46. EP250428b: Global MASTER-Net observations report
  47. Fermi-LAT Gamma-ray Observations of IceCube-250426A
  48. EP250427a: Global MASTER-Net observations report
  49. IceCube Alert 250426.74: Global MASTER-Net observations report
  50. IceCube-250416A: Upper limits from a search for additional neutrino events in IceCube
  51. IceCube-250421A: Upper limits from a search for additional neutrino events in IceCube
  52. GRB 250424A: Swift/UVOT Detection
  53. Fermi-LAT gamma-ray observations of IceCube-250421A
  54. GRB 250419a: Continued Liverpool Telescope observations
  55. GRB 250419A: Liverpool Telescope optical upper limit
  56. Swift GRB 250424A: Global MASTER-Net observations report
  57. Swift GRB 250424A: Global MASTER-Net OT detection
  58. EP250421a: Nickel optical upper limit
  59. EP250421a: Upper limits from Fermi-GBM Observations
  60. SVOM/sb25042207: XRT observations
  61. SVOM/sb25042207: BOOTES-2 early optical upper limit
  62. SVOM/sb25042207: GOTO optical upper limits
  63. GRB 250419A: Mephisto Multi-band Optical Detection
  64. EP250421a: REM optical upper limit
  65. EP250421A: COLIBRÍ Optical Upper Limit
  66. Fermi GRB 250421A: Global MASTER-Net observations report
  67. EP250421a: Global MASTER-Net observations report
  68. IceCube Alert 250421.71: Global MASTER-Net observations report
  69. IceCube-Cascade 250414A: Upper limits from a search for additional neutrino events in IceCube
  70. GRB 250419A: MASTER optical afterglow observation
  71. Fermi-LAT Gamma-ray Observations of IceCube-250416A
  72. GRB 250419A: GOTO optical counterpart detection
  73. GRB 250403A: VLT/FORS2 spectroscopic redshift z = 1.847
  74. EP250416a: GSP optical upper limit
  75. EP250416a: Global MASTER-Net observations report
  76. IceCube-250416A: Global MASTER-Net observations report
  77. SVOM/sb25041603: SVOM/COLIBRÍ (FM-GFT) Upper Limit on the Optical Counterpart
  78. EP250304a: ATCA radio observations
  79. Fermi trigger No 766148493: Global MASTER-Net observations report
  80. Fermi trigger No 766173972: Global MASTER-Net observations report
  81. Fermi GRB 250411A: Global MASTER-Net observations report
  82. GRB 250314A: e-MERLIN observations
  83. EP250227a: Further NOT optical observations
  84. EP250407a: Global MASTER-Net observations report
  85. Fermi-LAT gamma-ray observations of IceCube-250406A
  86. EP250407a: Swift-XRT observations
  87. IceCube-250406A: Upper limits from a search for additional neutrino events in IceCube
  88. GRB 250407A: Swift-XRT afterglow detection
  89. Fermi GRB 250407A: Global MASTER-Net observations report
  90. LIGO/Virgo/KAGRA S250331o: Upper limits from Swift/BAT-GUANO
  91. IceCube 250406A: DDOTI Optical Observations of the Refined Position
  92. Konus-Wind detection of GRB 250406B (short/hard)
  93. IceCube 250406.951: COLIBRÍ/DDRAGO Optical Upper Limit
  94. IceCube Alert 250406.95: Global MASTER-Net observations report
  95. Fermi trigger No 765663719: Global MASTER-Net observations report
  96. Fermi GRB 250406A: Global MASTER-Net observations report
  97. Fermi trigger No 765619921: Global MASTER-Net observations report
  98. GRB 250404A / EP250404a: RC500 INASAN-Kislovodsk optical upper limit
  99. Konus-Wind detection of GRB 250404A / EP250404a
  100. GRB 250404A / EP250404a: Mondy optical observations

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