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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

18513 results found.

  1. EP250508a: KAIT optical upper limit
  2. GRB 250507A: KAIT optical upper limit
  3. EP250508a: refined analysis of the EP-WXT and EP-FXT observations
  4. GRB 250505B: SVOM/GRM observation of a short burst
  5. GRB 250502A: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  6. EP250508a: REM optical/NIR observations
  7. GRB 250506A: Swift-XRT afterglow detection
  8. EP250508a: COLIBRÍ Optical Limit
  9. EP250508a: Einstein Probe detection of an X-ray transient
  10. GRB 250506A: Swift/UVOT Upper Limits
  11. GRB 250507A: follow-up observation with EP-FXT
  12. GRB 250506A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  13. GRB 250507A: REM optical/NIR observations
  14. GRB 250507A: SVOM/VT optical upper limit
  15. GRB 250507A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  16. EP-WXT trigger 01709175213: a new X-ray outburst of LMXB MAXI J1957+032
  17. GRB 250507A: SVOM detection of a long burst
  18. GRB 250506A: Mephisto optical upper limits
  19. GRB 250502A: Bassano Bresciano Observatory upper limit
  20. GRB 250506A: Xinglong 2.16m optical upper limit
  21. SVOM/sb25050601: EP-FXT observations
  22. GRB 250506A: REM optical/NIR upper limits
  23. GRB 250506A: TRT optical observations
  24. GRB 250506A: SVOM/COLIBRÍ (FM-GFT) Upper Limits on the Optical Counterpart
  25. GRB 250504A: VLT/X-shooter upper limits
  26. GRB 250504A: REM optical/NIR observations
  27. GRB 250502A: REM optical/NIR observations
  28. GRB 250504A: MeerLICHT optical afterglow detection
  29. GRB 250504A: Enhanced Swift-XRT position
  30. GRB 250504A: Swift detection of a burst
  31. Swift GRB250504.98: Global MASTER-Net observations report
  32. GRB 250502A: Swift/UVOT Follow up
  33. GRB 250502A: KAIT optical observations
  34. GRB 250502A: Montarrenti Observatory optical detection
  35. GRB 250502A: Swift-XRT afterglow detection
  36. GRB 250502A: NOT optical observations
  37. GRB 250502B: AstroSat CZTI detection
  38. GRB 250502A: AKO Optical Afterglow Detection
  39. GRB 250502A: LCO optical counterpart detection
  40. GRB 250502A: Redshift from OSIRIS+/GTC z = 2.163
  41. GRB 250407A: VZLUSAT-2 detection
  42. GRB 250502B: DDOTI Optical Observations
  43. GRB 250502A: Early optical counterpart detection by LCO.
  44. GRB 250430A: Swift/UVOT Detection
  45. GRB 250502A: TRT optical afterglow confirmation
  46. GRB 250430A: Enhanced Swift-XRT position
  47. GRB 250502A: SVOM/COLIBRÍ (FM-GFT) Detection of a Bright Optical Counterpart Candidate
  48. GRB 250502A: SVOM detection of a burst
  49. GRB 250430A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  50. GRB 250430A: KAIT optical observations
  51. GRB 250430A / EP250430a: J-band upper limits with WINTER
  52. GRB 250430A: DDOTI Optical Observations
  53. GRB 250430A: Leavitt Observatory optical upper limit
  54. GRB 250430A: Bassano Bresciano Observatory upper limit
  55. GRB 250430A : MITSuME Akeno optical upper limits
  56. SVOM/sb25043004: EP-FXT observations
  57. EP250430a/GRB 250430A: Einstein Probe WXT detection of the X-ray prompt emission
  58. GRB 250430A: AKO Optical Afterglow Detection
  59. GRB 250430A: Kanata optical upper limit
  60. EP 250427A: Optical counterpart detection by LCO.
  61. GRB 250430A: Swift detection of a burst with optical counterpart
  62. EP250427a/GRB250427A: HCT optical follow-up
  63. SVOM/sb25043004: SVOM detection of a X-ray transient
  64. EP250428b: refined analysis of the EP-FXT follow-up observation
  65. EP250428b: GROWTH-India telescope optical upper limit
  66. EP250428b: SAO RAS optical upper limit
  67. EP250428b: LAST optical upper limit
  68. GRB 250427A: Swift/UVOT Detection
  69. EP250428b: Einstein Probe detection of a fast X-ray transient
  70. EP250427a: EP-FXT follow-up observations
  71. EP250427A: COLIBRÍ Continuing Optical Observations
  72. GRB250427A/EP250427a GIT optical afterglow detection:
  73. EP250427a: LT optical counterpart detection
  74. EP250427a / GRB 250427A: LCO optical counterpart detection
  75. EP250427a: REM optical/NIR afterglow detection
  76. GRB 250424A: LCO optical observation
  77. EP250427A: COLIBRÍ Optical Detection
  78. EP250427a: TRT optical counterpart detection
  79. EP250427a: Einstein Probe detection of a fast X-ray transient
  80. GRB 250424A: SVOM/GRM observation of a long burst
  81. GRB 250424A: PRIME near-infrared detection
  82. GRB 250424A: WINTER J-band detection
  83. GRB 250419A: Mondy Optical Observations
  84. GRB 250424A: Swift/UVOT Detection
  85. GRB 250424A: Skynet Optical Observations
  86. GRB 250424A: Kilonova-Catcher optical afterglow detection
  87. GRB 250424A: Enhanced Swift-XRT position
  88. GRB 250424A: COLIBRÍ Detection of a Bright Optical Counterpart
  89. GRB 250424A: BlackGEM optical afterglow detection
  90. GRB 250424A: DDOTI Afterglow Detection
  91. GRB 250424A: REM optical/NIR afterglow detection
  92. GRB 250424A: Swift detection of a burst with an optical counterpart
  93. LIGO/Virgo/KAGRA S250328ae: Subaru/PFS Spectroscopic Follow up and Candidates
  94. EP250421a: Nickel optical upper limit
  95. IceCube-250421A: DDOTI Detection of the LAST Candidate
  96. GRB 250419A: Mephisto Multi-band Optical Detection
  97. GRB 250419A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  98. IC-250421A: LAST optical observations of the IceCube neutrino candidate
  99. EP250421a: NOT optical observations
  100. GRB 250419A: Optical Observations via Virtual Telescope Project

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