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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"

15679 results found.

  1. EP260512a: COLIBRÍ optical upper limits
  2. GRB 260511B: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  3. GRB 260509A: Infrared J and Hs observations with MDM/MIRAGE
  4. GRB 260510C: Infrared J and Hs detections with MDM/MIRAGE
  5. EP260507a: Infrared J and Hs upper limits with MDM/MIRAGE
  6. MASS-Cube (GRID 2.0) detection of GRB 260511A
  7. GRB 260511B: SAO RAS optical observations
  8. GRB 260511B: FRAM-ORM optical detection
  9. GRB 260511A: EP-FXT follow-up observation
  10. GRB 260511B: EP-FXT follow-up observation
  11. GRB 260511B: LCO optical counterpart detection
  12. GRB260511B: MAO/AZT-22 optical observations
  13. GRB 260511A: SVOM/VT optical observations
  14. GRB 260511B: LCO optical observations
  15. GRB 260511B: OHP/T193 spectroscopic observations
  16. GRB 260511B: GOTO optical counterpart detection
  17. GRB 260511B: Xinglong 2.16m/BEFOSC redshift confirmation
  18. GRB 260510C: SVOM/COLIBRÍ (FM-GFT) further optical observations
  19. GRB 260511B: SVOM/VT optical observations
  20. GRB 260511B: SVOM/COLIBRÍ (FM-GFT) optical observations
  21. GRB 260511B: OSIRIS+/GTC redshift z=2.006
  22. GRB 260509A: SAO RAS optical observations
  23. GRB 260511A: REM near-infrared detection
  24. GRB 260511B: GROWTH-India Telescope optical observations
  25. GRB 260511B: J-band observations by the SYSU 80 cm infrared telescope
  26. GRB 260511B: NuSTAR detection of prompt emission
  27. GRB 260511A: NuSTAR detection of prompt emission
  28. GRB 260511B: Fermi GBM Detection
  29. GRB 260511B: SVOM/VT optical observation with VHF data
  30. GRB 260511B: TRT optical observation
  31. GRB 260511B : MITSuME Akeno optical afterglow candidate detection
  32. GRB 260511A: Fermi GBM Detection
  33. GRB 260511B SVOM/C-GFT optical counterpart detection
  34. EP260509a: LCO optical upper limits
  35. GRB 260511A: UTGO H50 optical afterglow observation
  36. GRB 260510C: EP-FXT follow-up observation
  37. GRB 260510C: SVOM/VT optical counterpart confirmation
  38. GRB 260511A: SVOM/VT optical observation with VHF data
  39. GRB 260511A: KAIT optical afterglow observations
  40. GRB 260511A: LCO optical afterglow detection
  41. GRB 260511A: SVOM/COLIBRÍ (FM-GFT) optical counterpart
  42. GRB 260511A: TRT optical counterpart detection
  43. GRB 260510C: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  44. GRB 260510B: SVOM/VT optical upper limits
  45. GRB 260510C: SVOM/VT optical upper limits
  46. GRB 260510B: GOTO early upper limit
  47. GRB 260510B: LCO optical upper limits
  48. GRB 260509A: Liverpool Telescope optical observations
  49. GRB 260509A: NOT spectroscopic redshift upper limit z < 1.95
  50. GRB 260509A: LCO optical observations
  51. SVOM GRB 260509A: MASTER-OAFA optical observation
  52. GRB 260509A: KAIT optical observations
  53. GRB 260509A: SVOM/COLIBRÍ (FM-GFT) observations
  54. GRB 260509A: SVOM/VT optical candidate with VHF data
  55. GRB 260509A: LCO optical counterpart detection
  56. GRB 260509A: GOTO optical counterpart candidate
  57. EP260507a: REM optical/NIR observations
  58. EP260507a: COLIBRÍ optical observations
  59. EP260507a: SVOM/VT optical observations
  60. EP260507a: NOT optical observations
  61. EP260507a: further Liverpool Telescope observations
  62. EP260507a: Liverpool Telescope optical upper limits
  63. EP260507a: GOTO optical counterpart detection
  64. EP260507a: TRT optical counterpart detection
  65. EP260507a: Kinder optical counterpart candidate
  66. EP260507a: LCO optical counterpart
  67. EP260502a is likely a flaring star
  68. GRB 260504B: SVOM/VT optical upper limits
  69. GRB 260502A: SVOM/GRM observation of a short GRB
  70. GRB 260503A: SVOM/GRM observation of a GRB
  71. GRB 260310A / AT2026fgk: photometric monitoring and tentative maximum of a possible SN
  72. GRB 260504B: REM optical/NIR observations
  73. GRB 260504B: AST3-2 i-band upper limit
  74. SVOM GRB 260504B: MASTER-OAFA optical observations
  75. SVOM/GRM observation of a bright burst from SGR 1E1841-045
  76. GRB 260429B / EP260429a: EP-FXT follow-up observation
  77. EP260502a: BOOTES-7: early optical upper limit
  78. EP260502a: Las Cumbres upper limit
  79. GRB 260429A: SVOM/GRM observation of a short burst
  80. SN 2026kid: Optical follow-up with small-aperture telescopes in Spain and China
  81. EP260430a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  82. GRB 260429B / EP260429a: COLIBRÍ optical upper limit
  83. EP260429a: LCO optical upper limits
  84. EP260430a: LCO optical upper limits
  85. GRB 260430A / EP260430a: COLIBRÍ optical upper limit
  86. GRB 260428A: SVOM/GRM observation of a possible short burst with extended emission
  87. EP260416a: Mondy and Terskol optical upper limits
  88. GRB 260424B: COLIBRÍ optical upper limit
  89. EP260321a/SN 2026gzf: spectroscopy at Mondy observatory
  90. EP260321a: Upper limits from ATCA radio observations
  91. GRB 260421B: Kilonova-Catcher optical afterglow detection
  92. The EP-WXT trigger 01709258652: Mondy optical observations
  93. GRB 250328A: VLT host galaxy discovery and redshift z = 1.250
  94. EP260416a: Mondy optical observations
  95. GRB 260421B: 3.6m DOT optical observation
  96. EP260416a: ZTSh R band observations
  97. EP-WXT trigger 01709260362: FRAM-ORM optical observations confirm flaring star G 151-9
  98. EP250512a / GRB 250512B: VLT/X-shooter host galaxy identification and redshift z = 1.773
  99. GRB 250530A: VLT/X-shooter host galaxy redshift z = 1.486
  100. GRB 260421B: SVOM/GRM observation

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