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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').
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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"
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submitter:"Judith Racusin"

21769 results found.

  1. EP260530a/AT 2026nwl: COLIBRÍ optical observations
  2. GRB 260530C: SVOM/ECLAIRs detection of a burst through on-ground search
  3. GRB 260531B: GECAM-B observation
  4. GRB 260518B: SVOM/ECLAIRs detection of a soft burst possibly associated with EP 260518a and AT 2026ndp
  5. AT2026nik: EP-FXT X-ray counterpart
  6. AT 2026nuz: COLIBRÍ optical observations
  7. EP260527a/GRB 260527A: optical upper limit with Kinder observations
  8. GRB 260429B / EP260429a: COLIBRÍ optical counterpart candidate
  9. GRB 260527A/EP260527a: VLT/X-shooter tentative redshift
  10. EP260526a: SVOM/VT optical upper limits
  11. EP260527a / GRB 260527A: VLT detection of the optical and nIR counterpart
  12. EP260527a/GRB 260527A: Infrared J upper limit with MDM/MIRAGE
  13. EP260527a/GRB 260527A: EP-FXT follow-up observation
  14. Konus-Wind detection of GRB 260527A (short/hard) ~4 min before EP260527a
  15. EP260527a: SVOM/VT optical observation
  16. EP260527a: COLIBRÍ optical detection
  17. EP260527a: Einstein Probe detection of a fast X-ray transient
  18. GRB 260524A: SVOM/ECLAIRs detection of a burst through on-ground search
  19. EP260526a: LCO optical upper limits
  20. EP260526a: Einstein Probe detection of a fast X-ray transient
  21. EP260526.405: COLIBRÍ optical upper limits
  22. The EP-WXT trigger 01709266106 is not a real source
  23. EP01709266106 (EP260526a?): Liverpool Telescope upper limits
  24. EP-WXT 01709266106: NOT optical upper limits
  25. GRB 260522A: GOTO optical upper limit
  26. EP260518a: Einstein Probe detection of an sub-threshold X-ray transient with counterpart AT 2026ndp
  27. GRB 260522A: Fermi-LAT detection
  28. GRB 260519C: SVOM/GRM observation
  29. GRB 260511A: iTelescope T-75 optical detection
  30. GRB 260520B: SVOM/GRM observation
  31. Konus-Wind detection of GRB 260519C
  32. GRB 260509A: SVOM/ECLAIRs refined analysis
  33. GRB 260518A: AstroSat CZTI detection of a long burst
  34. GRB 260516D: SVOM/ECLAIRs refined analysis
  35. GRB 260515A: SVOM/ECLAIRs refined analysis
  36. GRB 260421B: radio detection with the VLA
  37. GRB 260509A: CrAO ZTSh optical upper limit
  38. GRB 260516D: GOTO optical counterpart detection
  39. GRB 260516D: LCO optical observations
  40. GRB 260515A: further Liverpool Telescope observations
  41. GRB 260516D: SVOM/COLIBRÍ (FM-GFT) optical observations
  42. GRB 260516D: GROWTH-India Telescope optical detection
  43. GRB 260516D: SVOM/VT optical bright candidate
  44. GRB 260515A: CrAO ZTSh BVRI optical observations
  45. GRB 260516D: SVOM possible detection of a burst
  46. GRB 260515A: Liverpool Telescope optical detection
  47. GRB 260515A: LCO optical counterpart detection
  48. GRB 260515A: SVOM/COLIBRÍ (FM-GFT) optical observations
  49. EP260514a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  50. EP260514a: NOT optical counterpart confirmation
  51. EP260514a: TRT optical counterpart candidate
  52. EP260514a: SVOM/VT optical candidate
  53. GRB 260515A: OHP/T193 optical observations
  54. EP260514a: COLIBRÍ optical upper limits
  55. GRB 260515A: LCO optical observations
  56. SVOM GRB 260515A: MASTER OT J151044.43+243321.7 optical counterpart detection
  57. GRB 260515A: SVOM/VT optical candidate from VHF data
  58. GRB 260515A: JinShan optical counterpart candidate
  59. GRB 260515A: SVOM detection of a burst
  60. EP260514a: GROWTH-India Telescope optical upper limit
  61. Konus-Wind detection of GRB 260512A
  62. GRB 260511B: GMG Optical Upper Limit
  63. EP260514a: Einstein Probe detection of a fast X-ray transient
  64. EP260512a: LCO optical upper limits
  65. GRB 260511B: Mephisto multi-band optical followup
  66. GRB 260512A: AstroSat CZTI detection
  67. EP260512a: EP-FXT follow-up observation
  68. EP260507a: Xinglong Schmidt optical counterpart detection
  69. GRB 260511B: further SAO RAS optical observations
  70. Konus-Wind detection of GRB 260511B
  71. EP260512a: COLIBRÍ optical upper limits
  72. EP260512a: Einstein Probe detection of an X-ray transient
  73. GRB 260511B: further J-band observations by the SYSU 80 cm infrared telescope
  74. GRB 260511B: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  75. GRB 260509A: Infrared J and Hs observations with MDM/MIRAGE
  76. GRB 260510C: Infrared J and Hs detections with MDM/MIRAGE
  77. EP260507a: Infrared J and Hs upper limits with MDM/MIRAGE
  78. Konus-Wind detection of GRB 260511A
  79. GRB 260511B: SAO RAS optical observations
  80. GRB 260511B: FRAM-ORM optical detection
  81. GRB 260511B: LCO optical counterpart detection
  82. GRB260511B: MAO/AZT-22 optical observations
  83. GRB 260511B: LCO optical observations
  84. GRB 260510C: SVOM/COLIBRÍ (FM-GFT) further optical observations
  85. GRB 260511B: SVOM/COLIBRÍ (FM-GFT) optical observations
  86. GRB 260509A: SAO RAS optical observations
  87. GRB 260511A: REM near-infrared detection
  88. GRB 260511B: GROWTH-India Telescope optical observations
  89. GRB 260511B: AstroSat CZTI detection
  90. GRB 260511B: J-band observations by the SYSU 80 cm infrared telescope
  91. GRB 260511B: SVOM/VT optical observation with VHF data
  92. GRB 260511B: TRT optical observation
  93. GRB 260510B: SVOM/ECLAIRs refined analysis
  94. GRB 260511B : MITSuME Akeno optical afterglow candidate detection
  95. GRB 260511B SVOM/C-GFT optical counterpart detection
  96. EP260509a: LCO optical upper limits
  97. GRB 260511A: UTGO H50 optical afterglow observation
  98. GRB 260510C: AstroSat CZTI detection
  99. GRB 260511B: SVOM detection of a burst
  100. EP260509a: EP-FXT non-detection and upper limit

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