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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"

20955 results found.

  1. Fermi GRB 260514A: Global MASTER-Net observations report
  2. EP260512a: EP-FXT follow-up observation
  3. EP260507a: Xinglong Schmidt optical counterpart detection
  4. EP260512a: Global MASTER-Net observations report
  5. Fermi GRB 260513A: Global MASTER-Net observations report
  6. Fermi GRB 260512A: Global MASTER-Net observations report
  7. GRB 260511B: further SAO RAS optical observations
  8. GRB 260509A: SVOM/VT optical observations
  9. GRB 260511B: further J-band observations by the SYSU 80 cm infrared telescope
  10. GRB 260511B: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  11. GRB 260509A: Infrared J and Hs observations with MDM/MIRAGE
  12. GRB 260510C: Infrared J and Hs detections with MDM/MIRAGE
  13. EP260507a: Infrared J and Hs upper limits with MDM/MIRAGE
  14. GRB 260511B: SAO RAS optical observations
  15. GRB 260511B: FRAM-ORM optical detection
  16. GRB 260511B: LCO optical counterpart detection
  17. GRB260511B: MAO/AZT-22 optical observations
  18. GRB 260511A: SVOM/VT optical observations
  19. GRB 260511B: LCO optical observations
  20. GRB 260511B: OHP/T193 spectroscopic observations
  21. GRB 260511B: GOTO optical counterpart detection
  22. GRB 260510C: SVOM/COLIBRÍ (FM-GFT) further optical observations
  23. GRB 260511B: SVOM/VT optical observations
  24. GRB 260511B: SVOM/COLIBRÍ (FM-GFT) optical observations
  25. GRB 260509A: SAO RAS optical observations
  26. GRB 260511A: REM near-infrared detection
  27. GRB 260511B: GROWTH-India Telescope optical observations
  28. GRB 260511B: J-band observations by the SYSU 80 cm infrared telescope
  29. GRB 260510B: SVOM/ECLAIRs refined analysis
  30. GRB 260511B SVOM/C-GFT optical counterpart detection
  31. GRB 260511A: UTGO H50 optical afterglow observation
  32. GRB 260510C: SVOM/VT optical counterpart confirmation
  33. EP260509a: EP-FXT non-detection and upper limit
  34. GRB 260511A: SVOM/VT optical observation with VHF data
  35. Fermi GRB 260511A: Global MASTER-Net observations report
  36. GRB 260511A: KAIT optical afterglow observations
  37. GRB 260510B: SVOM/VT optical upper limits
  38. GRB 260510C: SVOM/VT optical upper limits
  39. EP260509a: Global MASTER-Net observations report
  40. GRB 260510B: GOTO early upper limit
  41. GRB 260509A: Liverpool Telescope optical observations
  42. GRB 260509A: LCO optical observations
  43. SVOM GRB 260509A: MASTER-OAFA optical observation
  44. Fermi GRB 260510A: Global MASTER-Net observations report
  45. GRB 260509A: KAIT optical observations
  46. GRB 260509A: SVOM/COLIBRÍ (FM-GFT) observations
  47. GRB 260509A: SVOM/VT optical candidate with VHF data
  48. GRB 260509A: GOTO optical counterpart candidate
  49. EP260507a: REM optical/NIR observations
  50. EP260507a: refined analysis of the EP-WXT and EP-FXT observations
  51. EP260507a: COLIBRÍ optical observations
  52. EP260507a: SVOM/VT optical observations
  53. EP260507a: NOT optical observations
  54. EP260507a: further Liverpool Telescope observations
  55. EP260507a: Liverpool Telescope optical upper limits
  56. EP260507a: GOTO optical counterpart detection
  57. EP260507a: Kinder optical counterpart candidate
  58. GRB 260504B: SVOM/ECLAIRs refined analysis
  59. EP260502a is likely a flaring star
  60. Fermi GRB 260506A: Global MASTER-Net observations report
  61. IceCube Alert 260505A: Global MASTER-Net observations report
  62. GRB 260504B: SVOM/VT optical upper limits
  63. GRB 260421B: radio observation with the VLA
  64. Fermi-LAT Gamma-ray Observations of IceCube-260504A
  65. GRB 260310A / AT2026fgk: photometric monitoring and tentative maximum of a possible SN
  66. GRB 260504B: REM optical/NIR observations
  67. GRB 260504B: AST3-2 i-band upper limit
  68. SVOM GRB 260504B: MASTER-OAFA optical observations
  69. Fermi GRB 260504A: Global MASTER-Net observations report
  70. GRB 260429B / EP260429a: EP-FXT follow-up observation
  71. EP260502a: BOOTES-7 observations of a fading catalogued source close to the X-ray position
  72. SN 2026kid: Optical follow-up with small-aperture telescopes in Spain and China
  73. EP260429a: Global MASTER-Net observations report
  74. EP260430a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  75. Fermi GRB 260429A: Global MASTER-Net observations report
  76. EP260430a: Global MASTER-Net observations report
  77. Fermi GRB 260428A: Global MASTER-Net observations report
  78. GRB 260424B: COLIBRÍ optical upper limit
  79. Fermi-LAT Gamma-ray Observations of IceCube-260425A
  80. IceCube Alert 260425A: Global MASTER-Net observations report
  81. Fermi trigger No 798737427: Global MASTER-Net observations report
  82. EP260321a: Upper limits from ATCA radio observations
  83. GRB 260421B: Kilonova-Catcher optical afterglow detection
  84. The EP-WXT trigger 01709258652: Mondy optical observations
  85. GRB 250328A: VLT host galaxy discovery and redshift z = 1.250
  86. EP260416a: Mondy optical observations
  87. GRB 260421B: SVOM/ECLAIRs refined analysis
  88. GRB 260421B: 3.6m DOT optical observation
  89. EP260416a: ZTSh R band observations
  90. EP-WXT trigger 01709260362: FRAM-ORM optical observations confirm flaring star G 151-9
  91. GRB260421B: J band upper limit by SYSU 80cm infrared telescope
  92. GOTO26djh/AT2026jpw: ATCA radio detection
  93. GRB 260421B: J-band upper limit with WINTER
  94. GRB 260421B: LCO optical counterpart detection
  95. GOTO26djh/AT2026jpw: radio detection at 15GHz
  96. GRB 260412A: SVOM/ECLAIRs refined analysis
  97. GRB 260421B: SVOM/VT optical observations
  98. EP260416a: J band upper limit by SYSU 80cm infrared telescope
  99. GRB 260310A: Late-time Chandra X-ray Detection
  100. EP260416a: 1.3m DFOT optical observation

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