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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"

41974 results found.

  1. Fermi GRB 250702B: Global MASTER-Net observations report
  2. GRB 250702D, C, E: Swift/BAT-GUANO localization skymap of a burst or galactic transient
  3. GRB 250702F: Enhanced Swift-XRT position
  4. GRB 250702F: GTC/OSIRIS+ spectroscopic redshift z = 1.520
  5. GRB 250702F: NOT observations of the optical afterglow
  6. GRB 250702F: MASTER optical afterglow observation
  7. Fermi GRB 250702F: Global MASTER-Net observations report
  8. Fermi GRB 250702C: Global MASTER-Net observations report
  9. GRB 250702F: GOTO optical counterpart detection
  10. GRB 250702F: Ondrejov D50 optical afterglow detection
  11. GRB 250702F: Swift detection of a burst with an optical counterpart
  12. Swift GRB 250702F: Global MASTER-Net observations report
  13. GRB 250702F: Fermi GBM Final Real-time Localization
  14. Fermi GBM Triggers 250702B, C, D and E are likely from the same source
  15. GRB 250702E: Fermi GBM Final Real-time Localization
  16. Konus-Wind detection of GRB 250627A
  17. GRB 250702A: Fermi GBM Detection
  18. GRB 250702D: Fermi GBM Final Localization Correction
  19. GRB 250702C: Fermi GBM Final Real-time Localization
  20. LIGO/Virgo/KAGRA S250702n: Identification of a GW compact binary merger candidate
  21. GRB 250702B: Fermi GBM Final Real-time Localization
  22. GRB 250702A: BALROG localization (Fermi Trigger 773142852 / GRB 250702413)
  23. GRB 250702A: Fermi GBM Final Real-time Localization
  24. LIGO/Virgo/KAGRA S250701bq: Identification of a GW compact binary merger candidate
  25. LIGO/Virgo/KAGRA S250701bp: Identification of a GW compact binary merger candidate
  26. GRB 250628B: Swift-XRT observations
  27. GRB 250628B: SVOM/VT optical upper limit
  28. GRB 250628B: EP-FXT counterpart detection
  29. GRB 250627A: Insight-HXMT detection
  30. GRB 250627A: SVOM/GRM detection of a short burst
  31. LIGO/Virgo/KAGRA S250629bs: Identification of a GW compact binary merger candidate
  32. LIGO/Virgo/KAGRA S250629ae: Identification of a GW compact binary merger candidate
  33. GRB 250628A: REM optical/NIR upper limits
  34. GRB 250628C: Fermi GBM Final Real-time Localization
  35. LIGO/Virgo/KAGRA S250628am: Identification of a GW compact binary merger candidate
  36. GRB 250628B: SVOM detection of a long burst
  37. GRB 250625A: VLT/X-shooter spectroscopic observations at the afterglow position
  38. GRB 250628A: VLT/X-shooter upper limits
  39. GRB 250628A: Swift/UVOT Upper Limits
  40. GRB 250628A: Swift-XRT refined Analysis
  41. Fermi GRB 250626A: Global MASTER-Net observations report
  42. Swift GRB 250628A: Global MASTER-Net observations report
  43. GRB 250628A: Enhanced Swift-XRT position
  44. GRB 250628A: Swift detection of a burst
  45. GRB 250625A: Swift-BAT refined analysis
  46. GRB 250625A: Leavitt Observatory afterglow detection
  47. GRB 250625A: AbAO and INASAN Kislovodsk Optical Observations
  48. The EP-WXT trigger 01709179435 is likely a new outburst of the CV SS Cyg
  49. GRB 250625A: GTC/OSIRIS+ spectroscopic observations of the potential host galaxy
  50. GRB 250626A: Fermi GBM Final Real-time Localization
  51. GRB 250625A: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
  52. GRB 250625A: SVOM/C-GFT upper limit in early phase
  53. GRB 250625A: GECAM-B detection
  54. GRB 250625A: Swift/UVOT Upper Limits
  55. GRB 250625A: ABObservatory afterglow detection
  56. GRB 250625A: OHP/T193 optical detection
  57. GRB 250625A: COLIBRÍ optical observations
  58. GRB 250625A: Fermi-LAT detection
  59. GRB 250625A: Swift-XRT refined Analysis
  60. GRB 250625A: JinShan optical observations
  61. GRB250625A: Fermi GBM Observation
  62. Swift GRB 250625A: Global MASTER-Net observations report
  63. GRB 250625A: NOT z-band upper limit
  64. GRB 250625A: SVOM/VT optical confirmation
  65. GRB 250620B: Fermi GBM Observation
  66. GRB 250625A: SAO RAS possible optical afterglow
  67. GRB 250625A: Enhanced Swift-XRT position
  68. Fermi GRB 250625A: Global MASTER-Net observations report
  69. GRB 250625A: Swift detection of a burst
  70. GRB 250625A: Fermi GBM Final Real-time Localization
  71. GRB 250617B: Mondy and SAO RAS optical observations on 2025-06-23, 2025-06-24
  72. GRB 250620A: AstroSat CZTI detection
  73. The EP-WXT trigger 01709179396 is likely a flaring star CSTAR 38580
  74. GRB 241018A: Maidanak optical observations
  75. GRB 250620C: AstroSat CZTI detection
  76. Fermi GRB 250624A: Global MASTER-Net observations report
  77. GRB 250624A: Fermi GBM Final Real-time Localization
  78. sb25061207/GRB 250612D - SVOM/ECLAIRs refined analysis
  79. Fermi GRB 250623A: Global MASTER-Net observations report
  80. GRB 250623A: Fermi GBM Final Real-time Localization
  81. GRB 250617B: Swift-BAT refined analysis
  82. Fermi trigger No 772190032: Global MASTER-Net observations report
  83. Konus-Wind detection of GRB 250620C
  84. IPN triangulation of GRB 250620C (long/bright)
  85. GRB 250621B: SVOM/GRM detection of a possible magnetar X-ray burst
  86. GRB 250620C: SVOM/GRM observation
  87. GRB 250620A: SVOM/GRM observation of a short burst
  88. GRB250620A: Fermi GBM Observation
  89. GRB 250617B: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  90. Fermi GRB 250621A: Global MASTER-Net observations report
  91. GRB 250619B: Fermi GBM Observation
  92. GRB 250621A: Fermi GBM Final Real-time Localization
  93. GRB 250620B: Swift/BAT-GUANO localization skymap of a burst
  94. GRB250620C: Fermi GBM Observation
  95. GRB 250506A - SVOM/ECLAIRs Refined analysis
  96. The EP-WXT trigger 01709179071 is likely a flaring star
  97. GRB 250620A: Swift/BAT-GUANO subthreshold detection of a possibly short burst
  98. GRB 250619B: Swift/BAT-GUANO localization skymap of a burst
  99. GRB 250620C: Fermi GBM Final Real-time Localization
  100. Fermi trigger No 772128434: Global MASTER-Net observations report

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