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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').
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"

45681 results found.

  1. EP250321a: LCO optical counterpart detection
  2. EP250321a: Swift-XRT detection of an X-ray source
  3. EP250321A: COLIBRÍ Optical Observations
  4. EP250321a: VLT/X-shooter redshift z = 4.368
  5. GRB 250320B: AstroSat CZTI detection
  6. EP250321a: REM optical/NIR afterglow detection
  7. Fermi GRB 250320B: Global MASTER-Net observations report
  8. EP250321a: BOOTES-5/JGT optical afterglow detection
  9. EP250321a: TRT optical counterpart detection
  10. EP250321a: Global MASTER-Net observations report
  11. Swift GRB 250321A: Global MASTER-Net observations report
  12. Fermi GRB 250321A: Global MASTER-Net observations report
  13. EP250321a: Einstein Probe detection of an X-ray transient
  14. GRB 250321A: GOTO optical upper limits
  15. GRB 250321A: Swift-XRT localisation
  16. GRB 250314A: Keck/NIRC2 J-band upper limit
  17. EP250226a/GRB 250226A: KAIT optical observations
  18. GRB 250321A: Fermi GBM Observation
  19. GRB 250321A: Swift detection of a burst
  20. GRB 250321A: Fermi GBM Final Real-time Localization
  21. GRB 250320B: Fermi GBM Final Real-time Localization
  22. GRB 250309B: Proof-of-concept for Joint ZTF+EP Experiment
  23. GRB 250317B: Mondy AZT-33IK Continued Optical Observations
  24. GRB 250320A: Fermi GBM Final Real-time Localization
  25. Fermi GRB 250319B: Global MASTER-Net observations report
  26. FRB 20250316A: Upper limits for gamma-ray transient from Insight-HXMT/HE observations
  27. GRB 250313A: GRBAlpha detection
  28. LIGO/Virgo/KAGRA S250206dm: LIGHETR followup observations of AT2025azn
  29. GRB 250317B: SVOM/COLIBRI (F-GFT) follow-up observations
  30. GRB 250319B: Fermi GBM Final Localization
  31. GRB 250319A: Fermi GBM Final Localization
  32. GRB 250317D: EIRSAT-1 GMOD Detection
  33. LIGO/Virgo/KAGRA S250319bu: Updated Sky localization
  34. GRB 250314A: ATCA radio upper limits
  35. EP250302a: VLA observations
  36. GRB 250317B: OHP/T193 continued follow-up
  37. LIGO/Virgo/KAGRA S250319bu: Identification of a GW compact binary merger candidate
  38. GRB 250317C: SVOM/GRM observation of a long burst
  39. GRB 250317B: Leavitt Observatory optical upper limit
  40. GRB 250309B/AT2025dws: further ATCA observations
  41. GRB 250317B: Mondy AZT-33IK Optical Observations
  42. GRB 250317C: AstroSat CZTI detection
  43. GRB 250317B: NOT optical observations suggest an optical plateau phase
  44. GRB 250317B: GTC/OSIRIS+ spectroscopic redshift z=3.44
  45. GRB 250317C: GECAM-B detection
  46. GRB 250317B: OHP/T193 optical observations
  47. Fermi trigger No 763933627: Global MASTER-Net observations report
  48. GRB250312A: Swift/UVOT Upper Limits
  49. GRB 250317B: REM optical/NIR observations
  50. GRB 250317B: Swift-XRT observations
  51. GRB 250316A: Swift/UVOT Upper Limits
  52. GRB 250314A: REM optical/NIR upper limits
  53. GRB 250316A: AbAO AS-32 Optical Upper Limit
  54. EP 250317B: Fading optical counterpart detection by LCO
  55. GRB 250316A: Swift-XRT afterglow detection
  56. GRB 250317B: LCO detection of the fading optical afterglow
  57. GRB 250317B: refined SVOM/MXT analysis
  58. GRB 250317B: SVOM/VT detection of an optical candidate from VHF data
  59. GRB 250317B: SVOM/F-GFT (COLIBRÍ) Detection of a Fading Optical Counterpart
  60. GRB 250317B: SVOM detection of a burst / correction to GRB name of GCN 39752
  61. GRB 250317B: SVOM detection of a burst
  62. GRB 250316A: Fermi GBM Observation
  63. GRB 250316A: Swift-XRT observations
  64. Fermi trigger No 763862734: Global MASTER-Net observations report
  65. GRB 250317A: Fermi GBM Final Real-time Localization
  66. Fermi GRB 250316A: Global MASTER-Net observations report
  67. GRB 250314A: SVOM/GRM analysis
  68. GRB 250316A: Swift ToO observations
  69. GRB 250316A: Swift/BAT-GUANO arcminute localization of a burst
  70. GRB 250314A: GTC z-band upper limit and updated photo-z ~ 7.27
  71. The EP-WXT trigger 01709132801 is likely a flaring star
  72. GRB 250316A: Fermi GBM Final Real-time Localization
  73. GRB 250315A/EP250315A: Fermi-GBM Sub-Threshold Detection
  74. GRB 250314A: EP-FXT afterglow detection
  75. EP250315a: refined analysis of the EP-WXT and EP-FXT observations
  76. GRB 250314A: Swift/UVOT Upper Limits
  77. GRB 250312B: GRBAlpha detection
  78. GRB 250313.89 / Fermi trigger 763594063: bright OT AT 2025ehi detection
  79. GRB 250314A: Swift XRT Detection
  80. EP250315a: optical counterpart candidate detected by Gemini North
  81. GRB 250314A: VLT/X-shooter dropout, redshift z ~ 7.3
  82. EP250315a: Einstein Probe detection of an X-ray transient
  83. GRB 250226A: Mondy AZT-33IK and Koshka Zeiss-1000 Optical Upper Limits
  84. SVOM/MXT upper limit on GRB 250314A
  85. GRB 250314A: SVOM/VT upper limit
  86. GRB 250314A: NOT near-infrared candidate counterpart
  87. GRB 250313A: Fermi GBM Detection
  88. GRB 250313A: CALET Gamma-Ray Burst Monitor detection
  89. GRB 250312B: Fermi GBM Observation
  90. GRB 250313A: Swift-XRT observations
  91. GRB250314A: SVOM/VT lack of bright optical candidate from VHF data
  92. Konus-Wind detection of GRB 250313A
  93. Konus-Wind detection of GRB 250308A
  94. GRB 250314A: SVOM detection of a burst
  95. EP250311a/GRB 250311A: Correction to EP-WXT detection time
  96. GRB 250313B: SVOM/GRM observation of a soft bright short burst
  97. GRB 250313A: SVOM/GRM observation of a bright long burst
  98. FRB 20250206A: Nondetection of Repeating Bursts from FRB 20250206A with FAST
  99. GRB 250313A: AstroSat CZTI detection of a bright long burst
  100. IceCube-250309A: MASTER detection of J140105.33-091631.6 blazar flare with Zhirkov effect

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