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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"

32759 results found.

  1. EP 250321A: Optical counterpart detection by LCO.
  2. EP250321a: Kinder optical follow-up observations
  3. GRB 250321A: Swift/UVOT Upper Limits
  4. GRB 250320B: SVOM/GRM observation of a long burst
  5. EP250321a: LCO optical counterpart detection
  6. EP250321a: Swift-XRT detection of an X-ray source
  7. EP250321A: COLIBRÍ Optical Observations
  8. EP250321a: VLT/X-shooter redshift z = 4.368
  9. GRB 250320B: AstroSat CZTI detection
  10. EP250321a: REM optical/NIR afterglow detection
  11. Fermi GRB 250320B: Global MASTER-Net observations report
  12. EP250321a: TRT optical counterpart detection
  13. EP250321a: Global MASTER-Net observations report
  14. Swift GRB 250321A: Global MASTER-Net observations report
  15. Fermi GRB 250321A: Global MASTER-Net observations report
  16. GRB 250321A: GOTO optical upper limits
  17. GRB 250321A: Swift-XRT localisation
  18. GRB 250314A: Keck/NIRC2 J-band upper limit
  19. EP250226a/GRB 250226A: KAIT optical observations
  20. GRB 250321A: Fermi GBM Observation
  21. GRB 250309B: Proof-of-concept for Joint ZTF+EP Experiment
  22. GRB 250317B: Mondy AZT-33IK Continued Optical Observations
  23. Fermi GRB 250319B: Global MASTER-Net observations report
  24. GRB 250313A: GRBAlpha detection
  25. LIGO/Virgo/KAGRA S250206dm: LIGHETR followup observations of AT2025azn
  26. GRB 250317B: SVOM/COLIBRI (F-GFT) follow-up observations
  27. LIGO/Virgo/KAGRA S250319bu: Updated Sky localization
  28. GRB 250314A: ATCA radio upper limits
  29. EP250302a: VLA observations
  30. GRB 250317B: OHP/T193 continued follow-up
  31. LIGO/Virgo/KAGRA S250319bu: Identification of a GW compact binary merger candidate
  32. GRB 250317C: SVOM/GRM observation of a long burst
  33. GRB 250317B: Leavitt Observatory optical upper limit
  34. GRB 250309B/AT2025dws: further ATCA observations
  35. GRB 250317B: Mondy AZT-33IK Optical Observations
  36. GRB 250317C: AstroSat CZTI detection
  37. GRB 250317B: NOT optical observations suggest an optical plateau phase
  38. GRB 250317B: GTC/OSIRIS+ spectroscopic redshift z=3.44
  39. GRB 250317B: OHP/T193 optical observations
  40. GRB250312A: Swift/UVOT Upper Limits
  41. GRB 250317B: REM optical/NIR observations
  42. GRB 250317B: Swift-XRT observations
  43. GRB 250316A: Swift/UVOT Upper Limits
  44. GRB 250314A: REM optical/NIR upper limits
  45. GRB 250316A: AbAO AS-32 Optical Upper Limit
  46. EP 250317B: Fading optical counterpart detection by LCO
  47. GRB 250317B: LCO detection of the fading optical afterglow
  48. GRB 250317B: refined SVOM/MXT analysis
  49. GRB 250317B: SVOM/VT detection of an optical candidate from VHF data
  50. GRB 250317B: SVOM/F-GFT (COLIBRÍ) Detection of a Fading Optical Counterpart
  51. GRB 250317B: SVOM detection of a burst / correction to GRB name of GCN 39752
  52. GRB 250316A: Fermi GBM Observation
  53. GRB 250316A: Swift-XRT observations
  54. Fermi GRB 250316A: Global MASTER-Net observations report
  55. GRB 250314A: SVOM/GRM analysis
  56. GRB 250316A: Swift ToO observations
  57. GRB 250316A: Swift/BAT-GUANO arcminute localization of a burst
  58. GRB 250314A: GTC z-band upper limit and updated photo-z ~ 7.27
  59. GRB 250315A/EP250315A: Fermi-GBM Sub-Threshold Detection
  60. GRB 250314A: EP-FXT afterglow detection
  61. EP250315a: refined analysis of the EP-WXT and EP-FXT observations
  62. GRB 250314A: Swift/UVOT Upper Limits
  63. GRB 250312B: GRBAlpha detection
  64. GRB 250314A: Swift XRT Detection
  65. EP250315a: optical counterpart candidate detected by Gemini North
  66. GRB 250314A: VLT/X-shooter dropout, redshift z ~ 7.3
  67. GRB 250226A: Mondy AZT-33IK and Koshka Zeiss-1000 Optical Upper Limits
  68. SVOM/MXT upper limit on GRB 250314A
  69. GRB 250314A: SVOM/VT upper limit
  70. GRB 250314A: NOT near-infrared candidate counterpart
  71. GRB 250313A: Fermi GBM Detection
  72. GRB 250313A: CALET Gamma-Ray Burst Monitor detection
  73. GRB 250312B: Fermi GBM Observation
  74. GRB250314A: SVOM/VT lack of bright optical candidate from VHF data
  75. Konus-Wind detection of GRB 250313A
  76. Konus-Wind detection of GRB 250308A
  77. EP250311a/GRB 250311A: Correction to EP-WXT detection time
  78. GRB 250313A: SVOM/GRM observation of a bright long burst
  79. FRB 20250206A: Nondetection of Repeating Bursts from FRB 20250206A with FAST
  80. GRB 250313A: AstroSat CZTI detection of a bright long burst
  81. IceCube-250309A: MASTER detection of J140105.33-091631.6 blazar flare with Zhirkov effect
  82. GRB 250313A: Fermi-LAT detection
  83. GRB 250313A: Swift ToO observations
  84. EP250304a: Pan-STARRS r and i-band imaging and photometry
  85. GRB 250312B: Swift/BAT-GUANO localization skymap of a burst
  86. EP trigger ID 01709061302: Lick/Kast spectroscopy with the 3 m Shane telescope
  87. Fermi GRB 250313A: Global MASTER-Net observations report
  88. GRB 250309B: PRIME near-infrared upper limits in 2nd epoch
  89. EP250304a: SVOM/VT optical observation
  90. EP250311a/GRB 250311A: EP-FXT follow-up observation
  91. ATCA detection of the radio counterpart of GRB 250309B-AT2025dws
  92. EP250302a: Chandra X-ray Detection
  93. Fermi GRB 250312B: Global MASTER-Net observations report
  94. GRB 250226B: Fermi GBM Observation
  95. Swift GRB 250312A: Global MASTER-Net observations report
  96. GRB 250302A: Fermi GBM Observation
  97. GRB 250309B/AT2025dws: Daochen/RC-10 optical counterpart observation
  98. GRB 241213A: VIRT Optical Upper Limit
  99. GRB 241228A: VIRT Optical Upper Limit
  100. GRB 250311A/EP250311a: Optical upper limits with Kinder observations

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