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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"

21789 results found.

  1. GRB 250506A: NOT optical upper limits
  2. EP250508a: Liverpool Telescope optical upper limits
  3. EP250508a: KAIT optical upper limit
  4. GRB 250507A: KAIT optical upper limit
  5. EP250508a: refined analysis of the EP-WXT and EP-FXT observations
  6. GRB 250505B: SVOM/GRM observation of a short burst
  7. GRB 250502A: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  8. EP250508a: REM optical/NIR observations
  9. GRB 250506A: Swift-XRT afterglow detection
  10. EP250508a: COLIBRÍ Optical Limit
  11. EP250508a: Einstein Probe detection of an X-ray transient
  12. GRB 250506A: Swift/UVOT Upper Limits
  13. GRB 250506A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  14. GRB 250507A: REM optical/NIR observations
  15. GRB 250507A: SVOM/VT optical upper limit
  16. Fermi-LAT Gamma-ray Observations of IceCube-250506A
  17. GRB 250507A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  18. EP-WXT trigger 01709175213: a new X-ray outburst of LMXB MAXI J1957+032
  19. GRB 250507A: SVOM detection of a long burst
  20. GRB 250506A: Mephisto optical upper limits
  21. GRB 250502A: Bassano Bresciano Observatory upper limit
  22. GRB 250506A: Xinglong 2.16m optical upper limit
  23. GRB 250506A: SVOM improved position and MXT detection of a fading X-ray afterglow
  24. GRB 250506A: REM optical/NIR upper limits
  25. GRB 250506A: TRT optical observations
  26. GRB 250506A: SVOM/COLIBRÍ (FM-GFT) Upper Limits on the Optical Counterpart
  27. GRB 250504A: VLT/X-shooter upper limits
  28. GRB 250504A: REM optical/NIR observations
  29. GRB 250502A: REM optical/NIR observations
  30. GRB 250505A: Fermi GBM Final Real-time Localization
  31. GRB 250504A: MeerLICHT optical afterglow detection
  32. GRB 250504A: Enhanced Swift-XRT position
  33. GRB 250504A: Swift detection of a burst
  34. GRB 250502A: Swift/UVOT Follow up
  35. GRB 250502A: KAIT optical observations
  36. GRB 250502A: Montarrenti Observatory optical detection
  37. GRB 250502A: Swift-XRT afterglow detection
  38. GRB 250502A: NOT optical observations
  39. GRB 250502A: AKO Optical Afterglow Detection
  40. GRB 250502A: LCO optical counterpart detection
  41. GRB 250502A: Redshift from OSIRIS+/GTC z = 2.163
  42. GRB 250407A: VZLUSAT-2 detection
  43. Fermi-LAT Gamma-ray Observations of IceCube-250429A
  44. GRB 250502B: DDOTI Optical Observations
  45. GRB 250502A: Early optical counterpart detection by LCO.
  46. GRB 250430A: Swift/UVOT Detection
  47. GRB 250502A: TRT optical afterglow confirmation
  48. GRB 250430A: Enhanced Swift-XRT position
  49. GRB 250502A: SVOM/COLIBRÍ (FM-GFT) Detection of a Bright Optical Counterpart Candidate
  50. GRB 250502A: SVOM detection of a burst
  51. GRB 250430A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  52. GRB 250430A: KAIT optical observations
  53. GRB 250430A / EP250430a: J-band upper limits with WINTER
  54. EP250427a / GRB 250427A: OHP/T193 photometric observations: third visit
  55. GRB 250430A: DDOTI Optical Observations
  56. GRB 250430A: Leavitt Observatory optical upper limit
  57. GRB 250430A: Bassano Bresciano Observatory upper limit
  58. GRB 250430A : MITSuME Akeno optical upper limits
  59. EP250430a/GRB 250430A: Einstein Probe WXT detection of the X-ray prompt emission
  60. GRB 250430A: AKO Optical Afterglow Detection
  61. GRB 250430A: Kanata optical upper limit
  62. EP 250427A: Optical counterpart detection by LCO.
  63. GRB 250430A: Swift detection of a burst with optical counterpart
  64. EP250427a/GRB250427A: HCT optical follow-up
  65. SVOM/sb25043004: SVOM detection of a X-ray transient
  66. EP250428b: GROWTH-India telescope optical upper limit
  67. EP250428b: SAO RAS optical upper limit
  68. EP250428b: LAST optical upper limit
  69. GRB 250427A: Swift/UVOT Detection
  70. EP250428b: Einstein Probe detection of a fast X-ray transient
  71. Fermi-LAT Gamma-ray Observations of IceCube-250426A
  72. EP250427A: COLIBRÍ Continuing Optical Observations
  73. GRB250427A/EP250427a GIT optical afterglow detection:
  74. EP250427a: LT optical counterpart detection
  75. EP250427a / GRB 250427A: LCO optical counterpart detection
  76. EP250427a: REM optical/NIR afterglow detection
  77. GRB 250424A: LCO optical observation
  78. EP250427A: COLIBRÍ Optical Detection
  79. EP250427a: TRT optical counterpart detection
  80. EP250427a: Einstein Probe detection of a fast X-ray transient
  81. GRB 250424A: SVOM/GRM observation of a long burst
  82. GRB 250424A: PRIME near-infrared detection
  83. GRB 250424A: WINTER J-band detection
  84. GRB 250419A: Mondy Optical Observations
  85. GRB 250424A: Swift/UVOT Detection
  86. Konus-Wind detection of GRB 250424A
  87. GRB 250424A: Skynet Optical Observations
  88. GRB 250424A: Kilonova-Catcher optical afterglow detection
  89. GRB 250407A: GRBAlpha detection
  90. GRB 250404A / EP250404a: GRBAlpha detection
  91. GRB 250330B: GRBAlpha detection
  92. GRB 250419A: SVOM/ECLAIRs refined analysis
  93. GRB 250424A: Enhanced Swift-XRT position
  94. GRB 250424A: COLIBRÍ Detection of a Bright Optical Counterpart
  95. GRB 250424A: BlackGEM optical afterglow detection
  96. GRB 250424A: DDOTI Afterglow Detection
  97. GRB 250424A: REM optical/NIR afterglow detection
  98. GRB 250424A: Swift detection of a burst with an optical counterpart
  99. Swift GRB 250424A: Global MASTER-Net OT detection
  100. LIGO/Virgo/KAGRA S250328ae: Subaru/PFS Spectroscopic Follow up and Candidates

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