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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. 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"

19859 results found.

  1. AT2026nik: EP-FXT X-ray counterpart
  2. AT 2026nuz: COLIBRÍ optical observations
  3. EP260527a/GRB 260527A: optical upper limit with Kinder observations
  4. GRB 260429B / EP260429a: COLIBRÍ optical counterpart candidate
  5. GRB 260527A/EP260527a: VLT/X-shooter tentative redshift
  6. EP250526a: SVOM/VT optical upper limits
  7. EP260527a / GRB 260527A: VLT detection of the optical and nIR counterpart
  8. EP260527a/GRB 260527A: Infrared J upper limit with MDM/MIRAGE
  9. GRB 260527A: CALET Gamma-Ray Burst Monitor detection
  10. EP260527a/GRB 260527A: EP-FXT follow-up observation
  11. Konus-Wind detection of GRB 260527A (short/hard) ~4 min before EP260527a
  12. EP260527a: SVOM/VT optical observation
  13. EP260527a: COLIBRÍ optical detection
  14. EP260527a: Einstein Probe detection of a fast X-ray transient
  15. GRB 260524A: SVOM/ECLAIRs detection of a burst through on-ground search
  16. EP260526a: LCO optical upper limits
  17. EP260526a: Einstein Probe detection of a fast X-ray transient
  18. EP260526.405: COLIBRÍ optical upper limits
  19. The EP-WXT trigger 01709266106 is not a real source
  20. EP01709266106 (EP260526a?): Liverpool Telescope upper limits
  21. EP-WXT 01709266106: NOT optical upper limits
  22. Fermi GRB 260525A: Global MASTER-Net observations report
  23. GRB 260523B: AstroSat CZTI detection
  24. EP260518a: Einstein Probe detection of an sub-threshold X-ray transient with counterpart AT 2026ndp
  25. GRB 260511A: iTelescope T-75 optical detection
  26. GRB 260520B: SVOM/GRM observation
  27. GRB 260509A: SVOM/ECLAIRs refined analysis
  28. GRB 260516D: SVOM/ECLAIRs refined analysis
  29. GRB 260515A: SVOM/ECLAIRs refined analysis
  30. GRB 260421B: radio detection with the VLA
  31. GRID detection of GRB 260511A
  32. GRB 260509A: CrAO ZTSh optical upper limit
  33. GRB 260516D: GOTO optical counterpart detection
  34. GRB 260516D: LCO optical observations
  35. GRB 260515A: further Liverpool Telescope observations
  36. GRB 260516D: SVOM/COLIBRÍ (FM-GFT) optical observations
  37. GRB 260516D: GROWTH-India Telescope optical detection
  38. GRB 260516D: SVOM/VT optical bright candidate
  39. GRB 260515A: CrAO ZTSh BVRI optical observations
  40. GRB 260515A: LCO optical counterpart detection
  41. GRB 260515A: SVOM/COLIBRÍ (FM-GFT) optical observations
  42. EP260514a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  43. EP260514a: NOT optical counterpart confirmation
  44. EP260514a: TRT optical counterpart candidate
  45. EP260514a: SVOM/VT optical candidate
  46. GRB 260515A: OHP/T193 optical observations
  47. EP260514a: COLIBRÍ optical upper limits
  48. GRID detection of GRB 260507A
  49. GRB 260515A: LCO optical observations
  50. SVOM GRB 260515A: MASTER OT J151044.43+243321.7 optical counterpart detection
  51. GRB 260515A: SVOM/VT optical candidate from VHF data
  52. GRB 260515A: JinShan optical counterpart candidate
  53. GRB 260515A: SVOM detection of a burst
  54. EP260514a: GROWTH-India Telescope optical upper limit
  55. GRB 260511B: GMG Optical Upper Limit
  56. EP260514a: Einstein Probe detection of a fast X-ray transient
  57. EP260512a: LCO optical upper limits
  58. GRB 260511B: Mephisto multi-band optical followup
  59. EP260512a: EP-FXT follow-up observation
  60. EP260507a: Xinglong Schmidt optical counterpart detection
  61. GRB 260511B: further SAO RAS optical observations
  62. EP260512a: COLIBRÍ optical upper limits
  63. EP260512a: Einstein Probe detection of an X-ray transient
  64. GRB 260511B: further J-band observations by the SYSU 80 cm infrared telescope
  65. GRB 260511B: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  66. GRB 260509A: Infrared J and Hs observations with MDM/MIRAGE
  67. GRB 260510C: Infrared J and Hs detections with MDM/MIRAGE
  68. EP260507a: Infrared J and Hs upper limits with MDM/MIRAGE
  69. MASS-Cube (GRID 2.0) detection of GRB 260511A
  70. MASS-Cube (GRID 2.0) detection of GRB 260507A
  71. GRB 260511B: SAO RAS optical observations
  72. GRB 260511B: FRAM-ORM optical detection
  73. GRB 260511B: LCO optical counterpart detection
  74. GRB260511B: MAO/AZT-22 optical observations
  75. GRB 260511B: LCO optical observations
  76. GRB 260511B: OHP/T193 spectroscopic observations
  77. GRB 260510C: SVOM/COLIBRÍ (FM-GFT) further optical observations
  78. GRB 260511B: SVOM/COLIBRÍ (FM-GFT) optical observations
  79. GRB 260509A: SAO RAS optical observations
  80. GRB 260511A: REM near-infrared detection
  81. GRB 260511B: GROWTH-India Telescope optical observations
  82. GRB 260511B: AstroSat CZTI detection
  83. GRB 260511B: J-band observations by the SYSU 80 cm infrared telescope
  84. GRB 260511B: SVOM/VT optical observation with VHF data
  85. GRB 260511B: TRT optical observation
  86. GRB 260510B: SVOM/ECLAIRs refined analysis
  87. GRB 260511B : MITSuME Akeno optical afterglow candidate detection
  88. GRB 260511B SVOM/C-GFT optical counterpart detection
  89. EP260509a: LCO optical upper limits
  90. GRB 260511A: UTGO H50 optical afterglow observation
  91. GRB 260511B: SVOM detection of a burst
  92. EP260509a: EP-FXT non-detection and upper limit
  93. GRB 260511A: SVOM/VT optical observation with VHF data
  94. GRB 260511A: KAIT optical afterglow observations
  95. GRB 260511A: LCO optical afterglow detection
  96. GRB 260511A: SVOM/COLIBRÍ (FM-GFT) optical counterpart
  97. GRB 260511A: TRT optical counterpart detection
  98. GRB 260511A: SVOM detection of a bright burst
  99. GRB 260510C: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  100. GRB 260510B: GOTO early upper limit

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