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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').
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"

23413 results found.

  1. GRB 250704B / EP250704a: Mondy and AbAO optical observations
  2. GRB 250702F: radio detection with the VLA
  3. GRB 250706B/C: Fermi-LAT detection
  4. GRB 250704A: SVOM/COLIBRÍ (FM-GFT) optical observations
  5. EP250702a/GRB250702 B,D,E: GRANDMA Upper Limit
  6. GRB 250706B: Swift/UVOT Detection
  7. EP250702a/ GRB 250702B: NuSTAR X-ray Observations
  8. GRB 250704A: Swift/BAT-GUANO localization skymap of a burst
  9. GRB 250702F: GRANDMA observations
  10. GRB 250706B: refined SVOM/MXT data analysis
  11. GRB 250706A: Swift/UVOT Upper Limits
  12. GRB 250706B: REM optical observations
  13. GRB 250706A: REM optical/NIR observations
  14. EP250706a/GRB 250706A: EP-WXT detection of a fast X-ray transient
  15. IceCube-250416A: DDOTI Optical Upper Limit
  16. IceCube-250706A: COLIBRÍ optical upper limits
  17. GRB 250706A: JinShan optical upper limits
  18. GRB 250706A: SAO RAS optical observations
  19. EP250704A: NOWT Detection
  20. GRB 250706A: SVOM/C-GFT upper limit in eary phase
  21. GRB 250706B: iTelescope optical observations
  22. EP250704a / GRB 250704B: end of optical plateau phase and rapid fading of the counterpart
  23. GRB 250706B: SVOM/VT optical observation
  24. GRB 250706B: TRT bright optical counterpart detection
  25. GRB 250706A: GROWTH-India Telescope optical upper limit
  26. GRB 250706B: SVOM detection of a long burst
  27. GRB 250706A: Swift detection of a burst
  28. GRB 250704B: Swift-XRT refined Analysis
  29. GRBs 250702B,C,D,E / EP250702a: J band upper limit by SYSU 80cm infrared telescope
  30. EP250702a/GRB250702 B,E,D: MeerKAT radio counterpart
  31. EP250702a/GRB 250702B,C,D,E: Archival radio observations from ASKAP VAST
  32. GRB 250704B: Swift/UVOT Upper Limits
  33. GRB 250704A: Swift/UVOT Detection
  34. LIGO/Virgo/KAGRA S250705cb: Identification of a GW compact binary merger candidate
  35. Radio observation of GRBs 250702B,C,E / EP250702a with the Allen Telescope Array
  36. IPN triangulation of GRB 250703A
  37. GRB 250702F: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  38. EP250704a / GRB 250704B: NOT observations of the optical afterglow
  39. EP250704a/GRB 250704B VLT/HAWK-I NIR afterglow detection
  40. GRB 250702F: Kilonova-Catcher optical afterglow detection
  41. GRB 250702F: Monte Agliale Observatory optical observations
  42. GRB250702F: afterglow detected by joint EP-ZTF shadowing program
  43. EP250704a / GRB 250704B: JinShan optical observations
  44. EP250704a / GRB 250704B: SAO RAS optical observations
  45. EP250704a / GRB 250704B : GROWTH-India Telescope optical observations
  46. LIGO/Virgo/KAGRA S250704ab: NED Galaxies in the 3-Initial Localization Volume
  47. EP250704a / GRB 250704B: Pan-STARRS iz-band imaging and photometry
  48. EP250704a: refined analysis of the EP-WXT and FXT follow-up observations
  49. LIGO/Virgo/KAGRA S250704ab: Upper limits from Fermi-GBM Observations
  50. GRB 250704A: VLT/X-shooter afterglow discovery and spectroscopic redshift z = 1.091
  51. GRBs 250702B/C/D/E / EP250702a: Swift/UVOT Upper Limits
  52. EP250704a / GRB250704B: Swift-XRT counterpart detection
  53. GRB 250704A: Swift-XRT afterglow detection
  54. GRB 250702B / EP2050702a: FTW optical and NIR observations
  55. Konus-Wind detection of GRB 250702F
  56. EP250704a / GRB 250704B - REM observations
  57. GRB 250702F: GROWTH-India Telescope optical observations
  58. EP250704a / GRB 250704B: VLT/FORS2 optical afterglow detection
  59. GRB 250704A: REM retraction of optical afterglow detection and updated limit
  60. EP250702a: WFST optical observations
  61. EP250704a: COLIBRÍ optical counterpart candidate
  62. EP250704a: Einstein Probe detection of an X-ray transient
  63. GRB 250704A: REM detection of the optical afterglow
  64. LIGO/Virgo/KAGRA S250704ab: Identification of a GW compact binary merger candidate
  65. GRB 250704A: SVOM detection of a burst
  66. GRB 250702F: Swift/UVOT Detection
  67. GRBs 250702B,C,D,E / EP250702a: 2.2m CAHA optical upper limit
  68. GRB 250702F: Leavitt Observatory optical observations
  69. GRB 250702F: AKO Optical Afterglow Detection
  70. GRBs 250702B,C,D,E / EP250702a: VLT/HAWK-I NIR candidate
  71. GRBs 250702B,C,D,E / EP250702a: SVOM/GRM observation
  72. GRB 250702F: Skynet Optical Observations
  73. GRB 250424A: VIRT Optical Upper Limit
  74. GRBs 250702B/C/D/E / EP250702a: Swift XRT localization
  75. GRB 250702B,C,D,E/EP250702a: COLIBRÍ optical upper limit
  76. GRB 250702F: TRT Optical Observation
  77. GRB 250703A: DDOTI Optical Upper Limit
  78. GRB 250702F: REM optical afterglow detection
  79. GRB 250702F: DDOTI Optical Observation
  80. GRB 250703A: Fermi GBM Final Real-time Localization
  81. EP250702a/GRB 250702B,C,D,E: GOTO optical upper limits
  82. GRB 250702F: COLIBRÍ Observations of the Afterglow
  83. EP250702a : an X-ray transient detected by Einstein Probe likely associated with GRB 250702B,C,D,E
  84. GRB 250702D, C, E: Swift/BAT-GUANO localization skymap of a burst or galactic transient
  85. GRB 250702F: Enhanced Swift-XRT position
  86. GRB 250702F: NOT observations of the optical afterglow
  87. GRB 250702F: Swift detection of a burst with an optical counterpart
  88. IPN triangulation of GRB 250627A (short)
  89. LIGO/Virgo/KAGRA S250702n: Identification of a GW compact binary merger candidate
  90. LIGO/Virgo/KAGRA S250701bq: Identification of a GW compact binary merger candidate
  91. LIGO/Virgo/KAGRA S250701bp: Identification of a GW compact binary merger candidate
  92. GRB 250628B: Swift-XRT observations
  93. GRB 250628B: SVOM/VT optical upper limit
  94. GRB 250628B: EP-FXT counterpart detection
  95. LIGO/Virgo/KAGRA S250629bs: Identification of a GW compact binary merger candidate
  96. LIGO/Virgo/KAGRA S250629ae: Identification of a GW compact binary merger candidate
  97. GRB 250628A: REM optical/NIR upper limits
  98. LIGO/Virgo/KAGRA S250628am: Identification of a GW compact binary merger candidate
  99. GRB 250628A: VLT/X-shooter upper limits
  100. GRB 250628A: Swift/UVOT Upper Limits

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