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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"

22089 results found.

  1. GRB 250706A: GROWTH-India Telescope optical upper limit
  2. GRB 250706B: SVOM detection of a long burst
  3. GRB 250706A: Swift detection of a burst
  4. GRB 250704B: Swift-XRT refined Analysis
  5. GRBs 250702B,C,D,E / EP250702a: J band upper limit by SYSU 80cm infrared telescope
  6. EP250702a/GRB250702 B,E,D: MeerKAT radio counterpart
  7. EP250702a/GRB 250702B,C,D,E: Archival radio observations from ASKAP VAST
  8. GRB 250704B: Swift/UVOT Upper Limits
  9. GRB 250704A: Swift/UVOT Detection
  10. LIGO/Virgo/KAGRA S250705cb: Identification of a GW compact binary merger candidate
  11. Radio observation of GRBs 250702B,C,E / EP250702a with the Allen Telescope Array
  12. IPN triangulation of GRB 250703A
  13. GRB 250702F: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  14. EP250704a / GRB 250704B: NOT observations of the optical afterglow
  15. EP250704a/GRB 250704B VLT/HAWK-I NIR afterglow detection
  16. GRB 250702F: Kilonova-Catcher optical afterglow detection
  17. GRB 250702F: Monte Agliale Observatory optical observations
  18. GRB250702F: afterglow detected by joint EP-ZTF shadowing program
  19. EP250704a / GRB 250704B: JinShan optical observations
  20. EP250704a / GRB 250704B: SAO RAS optical observations
  21. EP250704a / GRB 250704B : GROWTH-India Telescope optical observations
  22. LIGO/Virgo/KAGRA S250704ab: NED Galaxies in the 3-Initial Localization Volume
  23. EP250704a / GRB 250704B: Pan-STARRS iz-band imaging and photometry
  24. EP250704a: refined analysis of the EP-WXT and FXT follow-up observations
  25. LIGO/Virgo/KAGRA S250704ab: Upper limits from Fermi-GBM Observations
  26. GRB 250704A: VLT/X-shooter afterglow discovery and spectroscopic redshift z = 1.091
  27. GRBs 250702B/C/D/E / EP250702a: Swift/UVOT Upper Limits
  28. EP250704a / GRB250704B: Swift-XRT counterpart detection
  29. GRB 250704A: Swift-XRT afterglow detection
  30. GRB 250702B / EP2050702a: FTW optical and NIR observations
  31. Konus-Wind detection of GRB 250702F
  32. EP250704a / GRB 250704B - REM observations
  33. GRB 250702F: GROWTH-India Telescope optical observations
  34. EP250704a / GRB 250704B: VLT/FORS2 optical afterglow detection
  35. GRB 250704A: REM retraction of optical afterglow detection and updated limit
  36. EP250702a: WFST optical observations
  37. EP250704a: COLIBRÍ optical counterpart candidate
  38. EP250704a: Einstein Probe detection of an X-ray transient
  39. GRB 250704A: REM detection of the optical afterglow
  40. LIGO/Virgo/KAGRA S250704ab: Identification of a GW compact binary merger candidate
  41. GRB 250704A: SVOM detection of a burst
  42. GRB 250702F: Swift/UVOT Detection
  43. GRBs 250702B,C,D,E / EP250702a: 2.2m CAHA optical upper limit
  44. GRB 250702F: Leavitt Observatory optical observations
  45. GRB 250702F: AKO Optical Afterglow Detection
  46. GRBs 250702B,C,D,E / EP250702a: VLT/HAWK-I NIR candidate
  47. GRBs 250702B,C,D,E / EP250702a: SVOM/GRM observation
  48. GRB 250702F: Skynet Optical Observations
  49. GRB 250424A: VIRT Optical Upper Limit
  50. GRBs 250702B/C/D/E / EP250702a: Swift XRT localization
  51. GRB 250702B,C,D,E/EP250702a: COLIBRÍ optical upper limit
  52. GRB 250702F: TRT Optical Observation
  53. GRB 250703A: DDOTI Optical Upper Limit
  54. GRB 250702F: REM optical afterglow detection
  55. GRB 250702F: DDOTI Optical Observation
  56. GRB 250703A: Fermi GBM Final Real-time Localization
  57. EP250702a/GRB 250702B,C,D,E: GOTO optical upper limits
  58. GRB 250702F: COLIBRÍ Observations of the Afterglow
  59. EP250702a : an X-ray transient detected by Einstein Probe likely associated with GRB 250702B,C,D,E
  60. GRB 250702D, C, E: Swift/BAT-GUANO localization skymap of a burst or galactic transient
  61. GRB 250702F: Enhanced Swift-XRT position
  62. GRB 250702F: NOT observations of the optical afterglow
  63. GRB 250702F: Swift detection of a burst with an optical counterpart
  64. IPN triangulation of GRB 250627A (short)
  65. LIGO/Virgo/KAGRA S250702n: Identification of a GW compact binary merger candidate
  66. LIGO/Virgo/KAGRA S250701bq: Identification of a GW compact binary merger candidate
  67. LIGO/Virgo/KAGRA S250701bp: Identification of a GW compact binary merger candidate
  68. GRB 250628B: Swift-XRT observations
  69. GRB 250628B: SVOM/VT optical upper limit
  70. GRB 250628B: EP-FXT counterpart detection
  71. LIGO/Virgo/KAGRA S250629bs: Identification of a GW compact binary merger candidate
  72. LIGO/Virgo/KAGRA S250629ae: Identification of a GW compact binary merger candidate
  73. GRB 250628A: REM optical/NIR upper limits
  74. LIGO/Virgo/KAGRA S250628am: Identification of a GW compact binary merger candidate
  75. GRB 250628A: VLT/X-shooter upper limits
  76. GRB 250628A: Swift/UVOT Upper Limits
  77. GRB 250628A: Swift-XRT refined Analysis
  78. GRB 250628A: Enhanced Swift-XRT position
  79. GRB 250628A: Swift detection of a burst
  80. GRB 250625A: Leavitt Observatory afterglow detection
  81. GRB 250625A: AbAO and INASAN Kislovodsk Optical Observations
  82. GRB 250625A: SVOM/C-GFT upper limit in early phase
  83. GRB 250625A: Swift/UVOT Upper Limits
  84. GRB 250625A: ABObservatory afterglow detection
  85. GRB 250625A: OHP/T193 optical detection
  86. GRB 250625A: COLIBRÍ optical observations
  87. GRB 250625A: JinShan optical observations
  88. GRB250625A: Fermi GBM Observation
  89. GRB 250625A: NOT z-band upper limit
  90. GRB 250625A: SAO RAS possible optical afterglow
  91. GRB 250625A: Enhanced Swift-XRT position
  92. GRB 250625A: Swift detection of a burst
  93. GRB 250617B: Mondy and SAO RAS optical observations on 2025-06-23, 2025-06-24
  94. GRB 241018A: Maidanak optical observations
  95. GRB 250620C: AstroSat CZTI detection
  96. IPN triangulation of GRB 250620С (long/bright)
  97. GRB 250621B: SVOM/GRM detection of a possible magnetar X-ray burst
  98. GRB 250620C: SVOM/GRM observation
  99. GRB 250620A: SVOM/GRM observation of a short burst
  100. GRB 250617B: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.

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