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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"

32685 results found.

  1. GRB 250322A: AstroSat CZTI detection of a short burst
  2. GRB250322A: STEP/T80S optical limits
  3. GRB 250322A: Gemini-South optical observations
  4. GRB 250322A: VLT optical observations
  5. GRB 250322A: VLT near-infrared observations
  6. FRB 250316A: DDOTI Continued Optical Observations
  7. GRB 250322A: NOT optical upper limits
  8. GRB 250321B: SVOM/COLIBRÍ (F-GFT) follow-up observations
  9. FRB 20250316A: Kinder optical upper limits of the Einstein Probe candidate X-ray source EP J120944.2+585060
  10. GRB 250322A: MASTER optical observation
  11. EP250321a: Liverpool Telescope optical follow-up
  12. EP250321a: Mondy AZT-33IK Optical Observations
  13. EP250321a: refined analysis of the EP-WXT and EP-FXT observations
  14. EP250321a: KAIT optical observations
  15. EP250321A: COLIBRÍ Continuing Optical Observations
  16. GRB 250225B: GECAM-A detection
  17. GRB 250312A: GECAM-A detection
  18. GRB 250321B: Swift ToO observations
  19. EP250321a: WFST optical observations
  20. GRB 250320B: NuSTAR detection of the prompt emission from two broad bursts and preliminary analysis
  21. GRB 250320A: NuSTAR Detection of the Prompt Emission and Preliminary Results
  22. GRB 250320B: Fermi GBM Observation
  23. EP250321a: Xinglong 216 decaying optical observations
  24. GRB 250321A: Swift-BAT refined analysis
  25. GRB 250320B: Fermi-LAT detection
  26. EP250321a: SVOM/VT optical observation
  27. EP 250321A: Optical counterpart detection by LCO.
  28. EP250321a: Kinder optical follow-up observations
  29. GRB 250321A: Swift/UVOT Upper Limits
  30. GRB 250320B: SVOM/GRM observation of a long burst
  31. EP250321a: LCO optical counterpart detection
  32. EP250321a: Swift-XRT detection of an X-ray source
  33. EP250321A: COLIBRÍ Optical Observations
  34. EP250321a: VLT/X-shooter redshift z = 4.368
  35. GRB 250320B: AstroSat CZTI detection
  36. EP250321a: REM optical/NIR afterglow detection
  37. Fermi GRB 250320B: Global MASTER-Net observations report
  38. EP250321a: TRT optical counterpart detection
  39. EP250321a: Global MASTER-Net observations report
  40. Swift GRB 250321A: Global MASTER-Net observations report
  41. Fermi GRB 250321A: Global MASTER-Net observations report
  42. GRB 250321A: GOTO optical upper limits
  43. GRB 250321A: Swift-XRT localisation
  44. GRB 250314A: Keck/NIRC2 J-band upper limit
  45. EP250226a/GRB 250226A: KAIT optical observations
  46. GRB 250321A: Fermi GBM Observation
  47. GRB 250309B: Proof-of-concept for Joint ZTF+EP Experiment
  48. GRB 250317B: Mondy AZT-33IK Continued Optical Observations
  49. Fermi GRB 250319B: Global MASTER-Net observations report
  50. GRB 250313A: GRBAlpha detection
  51. LIGO/Virgo/KAGRA S250206dm: LIGHETR followup observations of AT2025azn
  52. GRB 250317B: SVOM/COLIBRI (F-GFT) follow-up observations
  53. LIGO/Virgo/KAGRA S250319bu: Updated Sky localization
  54. GRB 250314A: ATCA radio upper limits
  55. EP250302a: VLA observations
  56. GRB 250317B: OHP/T193 continued follow-up
  57. LIGO/Virgo/KAGRA S250319bu: Identification of a GW compact binary merger candidate
  58. GRB 250317C: SVOM/GRM observation of a long burst
  59. GRB 250317B: Leavitt Observatory optical upper limit
  60. GRB 250309B/AT2025dws: further ATCA observations
  61. GRB 250317B: Mondy AZT-33IK Optical Observations
  62. GRB 250317C: AstroSat CZTI detection
  63. GRB 250317B: NOT optical observations suggest an optical plateau phase
  64. GRB 250317B: GTC/OSIRIS+ spectroscopic redshift z=3.44
  65. GRB 250317B: OHP/T193 optical observations
  66. GRB250312A: Swift/UVOT Upper Limits
  67. GRB 250317B: REM optical/NIR observations
  68. GRB 250317B: Swift-XRT observations
  69. GRB 250316A: Swift/UVOT Upper Limits
  70. GRB 250314A: REM optical/NIR upper limits
  71. GRB 250316A: AbAO AS-32 Optical Upper Limit
  72. EP 250317B: Fading optical counterpart detection by LCO
  73. GRB 250317B: LCO detection of the fading optical afterglow
  74. GRB 250317B: refined SVOM/MXT analysis
  75. GRB 250317B: SVOM/VT detection of an optical candidate from VHF data
  76. GRB 250317B: SVOM/F-GFT (COLIBRÍ) Detection of a Fading Optical Counterpart
  77. GRB 250317B: SVOM detection of a burst / correction to GRB name of GCN 39752
  78. GRB 250316A: Fermi GBM Observation
  79. GRB 250316A: Swift-XRT observations
  80. Fermi GRB 250316A: Global MASTER-Net observations report
  81. GRB 250314A: SVOM/GRM analysis
  82. GRB 250316A: Swift ToO observations
  83. GRB 250316A: Swift/BAT-GUANO arcminute localization of a burst
  84. GRB 250314A: GTC z-band upper limit and updated photo-z ~ 7.27
  85. GRB 250315A/EP250315A: Fermi-GBM Sub-Threshold Detection
  86. GRB 250314A: EP-FXT afterglow detection
  87. EP250315a: refined analysis of the EP-WXT and EP-FXT observations
  88. GRB 250314A: Swift/UVOT Upper Limits
  89. GRB 250312B: GRBAlpha detection
  90. GRB 250314A: Swift XRT Detection
  91. EP250315a: optical counterpart candidate detected by Gemini North
  92. GRB 250314A: VLT/X-shooter dropout, redshift z ~ 7.3
  93. GRB 250226A: Mondy AZT-33IK and Koshka Zeiss-1000 Optical Upper Limits
  94. SVOM/MXT upper limit on GRB 250314A
  95. GRB 250314A: SVOM/VT upper limit
  96. GRB 250314A: NOT near-infrared candidate counterpart
  97. GRB 250313A: Fermi GBM Detection
  98. GRB 250313A: CALET Gamma-Ray Burst Monitor detection
  99. GRB 250312B: Fermi GBM Observation
  100. GRB250314A: SVOM/VT lack of bright optical candidate from VHF data

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