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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"

15503 results found.

  1. GRB 260515A: JinShan optical counterpart candidate
  2. EP260514a: GROWTH-India Telescope optical upper limit
  3. GRB 260511B: NOT optical observations
  4. GRB 260511B: GMG Optical Upper Limit
  5. EP260512a: LCO optical upper limits
  6. GRB 260511B: Mephisto multi-band optical followup
  7. EP260507a: Xinglong Schmidt optical counterpart detection
  8. GRB 260511B: further SAO RAS optical observations
  9. GRB 260509A: SVOM/VT optical observations
  10. EP260512a: COLIBRÍ optical upper limits
  11. GRB 260511B: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  12. GRB 260509A: Infrared J and Hs observations with MDM/MIRAGE
  13. GRB 260510C: Infrared J and Hs detections with MDM/MIRAGE
  14. EP260507a: Infrared J and Hs upper limits with MDM/MIRAGE
  15. MASS-Cube (GRID 2.0) detection of GRB 260511A
  16. GRB 260511B: SAO RAS optical observations
  17. GRB 260511B: FRAM-ORM optical detection
  18. GRB 260511A: EP-FXT follow-up observation
  19. GRB 260511B: EP-FXT follow-up observation
  20. GRB 260511B: LCO optical counterpart detection
  21. GRB260511B: MAO/AZT-22 optical observations
  22. GRB 260511A: SVOM/VT optical observations
  23. GRB 260511B: LCO optical observations
  24. GRB 260511B: OHP/T193 spectroscopic observations
  25. GRB 260511B: GOTO optical counterpart detection
  26. GRB 260511B: Xinglong 2.16m/BEFOSC redshift confirmation
  27. GRB 260510C: SVOM/COLIBRÍ (FM-GFT) further optical observations
  28. GRB 260511B: SVOM/VT optical observations
  29. GRB 260511B: SVOM/COLIBRÍ (FM-GFT) optical observations
  30. GRB 260511B: OSIRIS+/GTC redshift z=2.006
  31. GRB 260509A: SAO RAS optical observations
  32. GRB 260511A: REM near-infrared detection
  33. GRB 260511B: GROWTH-India Telescope optical observations
  34. GRB 260511B: J-band observations by the SYSU 80 cm infrared telescope
  35. GRB 260511B: NuSTAR detection of prompt emission
  36. GRB 260511A: NuSTAR detection of prompt emission
  37. GRB 260511B: Fermi GBM Detection
  38. GRB 260511B: SVOM/VT optical observation with VHF data
  39. GRB 260511B: TRT optical observation
  40. GRB 260511B : MITSuME Akeno optical afterglow candidate detection
  41. GRB 260511A: Fermi GBM Detection
  42. GRB 260511B SVOM/C-GFT optical counterpart detection
  43. EP260509a: LCO optical upper limits
  44. GRB 260511A: UTGO H50 optical afterglow observation
  45. GRB 260510C: EP-FXT follow-up observation
  46. GRB 260510C: SVOM/VT optical counterpart confirmation
  47. GRB 260511A: SVOM/VT optical observation with VHF data
  48. GRB 260511A: KAIT optical afterglow observations
  49. GRB 260511A: LCO optical afterglow detection
  50. GRB 260511A: SVOM/COLIBRÍ (FM-GFT) optical counterpart
  51. GRB 260511A: TRT optical counterpart detection
  52. GRB 260510C: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  53. GRB 260510B: SVOM/VT optical upper limits
  54. GRB 260510C: SVOM/VT optical upper limits
  55. GRB 260510B: GOTO early upper limit
  56. GRB 260510B: LCO optical upper limits
  57. GRB 260509A: Liverpool Telescope optical observations
  58. GRB 260509A: NOT spectroscopic redshift upper limit z < 1.95
  59. GRB 260509A: LCO optical observations
  60. SVOM GRB 260509A: MASTER-OAFA optical observation
  61. GRB 260509A: KAIT optical observations
  62. GRB 260509A: SVOM/COLIBRÍ (FM-GFT) observations
  63. GRB 260509A: SVOM/VT optical candidate with VHF data
  64. GRB 260509A: LCO optical counterpart detection
  65. GRB 260509A: GOTO optical counterpart candidate
  66. EP260507a: REM optical/NIR observations
  67. EP260507a: COLIBRÍ optical observations
  68. EP260507a: SVOM/VT optical observations
  69. EP260507a: NOT optical observations
  70. EP260507a: further Liverpool Telescope observations
  71. EP260507a: Liverpool Telescope optical upper limits
  72. EP260507a: GOTO optical counterpart detection
  73. EP260507a: TRT optical counterpart detection
  74. EP260507a: Kinder optical counterpart candidate
  75. EP260507a: LCO optical counterpart
  76. EP260502a is likely a flaring star
  77. GRB 260504B: SVOM/VT optical upper limits
  78. GRB 260502A: SVOM/GRM observation of a short GRB
  79. GRB 260503A: SVOM/GRM observation of a GRB
  80. GRB 260310A / AT2026fgk: photometric monitoring and tentative maximum of a possible SN
  81. GRB 260504B: REM optical/NIR observations
  82. GRB 260504B: AST3-2 i-band upper limit
  83. SVOM GRB 260504B: MASTER-OAFA optical observations
  84. SVOM/GRM observation of a bright burst from SGR 1E1841-045
  85. GRB 260429B / EP260429a: EP-FXT follow-up observation
  86. EP260502a: BOOTES-7: early optical upper limit
  87. EP260502a: Las Cumbres upper limit
  88. GRB 260429A: SVOM/GRM observation of a short burst
  89. SN 2026kid: Optical follow-up with small-aperture telescopes in Spain and China
  90. EP260430a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  91. GRB 260429B / EP260429a: COLIBRÍ optical upper limit
  92. EP260429a: LCO optical upper limits
  93. EP260430a: LCO optical upper limits
  94. GRB 260430A / EP260430a: COLIBRÍ optical upper limit
  95. GRB 260428A: SVOM/GRM observation of a possible short burst with extended emission
  96. EP260416a: Mondy and Terskol optical upper limits
  97. GRB 260424B: COLIBRÍ optical upper limit
  98. EP260321a/SN 2026gzf: spectroscopy at Mondy observatory
  99. EP260321a: Upper limits from ATCA radio observations
  100. GRB 260421B: Kilonova-Catcher optical afterglow detection

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