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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.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

2408 results found.

  1. GRB 250106A: NOT optical observations
  2. GRB 250103B: REM optical/NIR upper limits
  3. GRB 250106A: Swift-XRT observations
  4. GRB 250106A: SVOM/VT optical candidate
  5. GRB 250106A: Swift ToO observations
  6. GRB 250106A: SVOM detection of a long burst
  7. GRB 241229A: SVOM/VT optical upperlimit
  8. GRB 250103B: LCO/1m optical afterglow candidate detection
  9. GRB 250103A: Bassano Bresciano Observatory upper limit
  10. GRB 250103A: Swift-XRT observations
  11. GRB 250101A: 1.3m DFOT optical afterglow detection
  12. GRB 241229A: 1.3m DFOT upper limit
  13. GRB 250103A: NOT spectroscopic redshift
  14. GRB 250103B:SVOM/VT optical counterpart
  15. GRB 250103A: Montarrenti Observatory optical detection
  16. GRB 250103A: NOT optical observations
  17. GRB 250103A: TSHAO optical upper limit
  18. GRB 250103A: Fermi GBM Observation
  19. GRB 250103A: SVOM/VT optical counterpart confirmation
  20. GRB 250103A: Swift ToO observations
  21. GRB 250103B: SVOM detection of a long burst
  22. GRB 250103A: Xinglong 2.16m Optical Candidate
  23. GRB 250101B: SVOM/GRM observation
  24. GRB 250103A: GOTO optical upper limit
  25. GRB 250103A: SVOM/C-GFT optical upper limit
  26. GRB 250103A: SVOM detection of a long burst (duplicate submission)
  27. GRB 250103A: SVOM detection of a long burst
  28. GRB 250101A: SVOM/C-GFT early optical observations
  29. GRB 241229B: Continued CrAO ZTSh observations
  30. GRB 241229A: EP-FXT X-ray afterglow confirmation
  31. GRB 241229B: SVOM/GRM observation
  32. GRB 241229B: SAO RAS optical upper limit
  33. GRB 241229B: CrAO ZTSh possible optical counterpart of SVOM/VT confirmation
  34. GRB 241229A: SAO RAS optical observations
  35. GRB 241229B: SVOM/VT optical candidate
  36. GRB 241229A: Swift-XRT observations
  37. GRB 241229A: EP-FXT afterglow candidates
  38. GRB 241229A: Swift ToO observations
  39. GRB 241229A: GOTO optical upper limits
  40. GRB 241229A: SVOM detection of a long burst
  41. GRB 241212A: VZLUSAT-2 detection
  42. GRB 241217A/EP241217b: continued SOAR observations
  43. GRB 241219A: SVOM/GRM observation
  44. GRB 241105A: JWST photometric observations of the host galaxy
  45. GRB 241217A / EP241217b: Non-detection in ATCA Radio Follow-up Observations
  46. GRB 241209B: host galaxy detection and GTC/OSIRIS+ spectroscopy
  47. GRB 241217A/EP241217b: SOAR afterglow detection
  48. GRB 241217A/EP241217b: tentative VLT spectroscopic redshift z=1.879
  49. GRB 241217a/EP241217B: 1.6m Mephisto optical upper limits
  50. GRB 241209B: EP-FXT afterglow detection
  51. GRB 241217A / EP241217B: GRANDMA/T1MPicduMidi optical upperlimits
  52. GRB 241217A/EP241217B: Fermi-GBM Sub-Threshold Detection
  53. GRB 241217A / EP241217b: Nanshan/HMT optical upper limit
  54. GRB 241217A: refined SVOM/MXT data analysis. Long lasting X-ray emission.
  55. GRB 241217A / EP241217b: NOT optical upper limits
  56. GRB 241217A/EP241217b: REM optical/NIR upper limits
  57. GRB 241217a: Liverpool Telescope optical follow-up
  58. GRB 241217A: GMG Optical Upper Limit
  59. GRB 241217A : SVOM/VT optical afterglow detection
  60. GRB 241217A: Swift-XRT afterglow detection
  61. GRB 241217A: LCO optical upper limit
  62. GRB 241217A: GRANDMA/TAROT optical upperlimits
  63. GRB 241217A : SVOM/ECLAIRs,GRM,MXT detection of a long burst with a bright X-ray afterglow candidate
  64. GRB 241214A: GRBAlpha detection
  65. GRB 241214A: Swift/BAT-GUANO localization skymap of a burst
  66. GRB 241212A: Swift-XRT observations
  67. GRB 241214A: SVOM/GRM observation
  68. GRB 241209B: SVOM/VT optical continuous fading
  69. GRB 241213A: SVOM/VT optical candidate
  70. GRB 241212A: Fermi GBM detection
  71. EP241208a: NOT optical upper limits
  72. GRB 241212A: Swift ToO observations
  73. EP 241208A : Detection of a long soft transient by SVOM/ECLAIRs
  74. GRB241212A: OHP/T193 optical observations
  75. GRB 241212A : SVOM/C-GFT optical upper limit at early phase
  76. GRB 241212A : SVOM/VT bright optical afterglow
  77. GRB 241212A: AstroSat CZTI detection
  78. GRB 241209B: GRANDMA/TRT upper limit
  79. GRB 241212A: SVOM detection of a bright long burst
  80. Konus-Wind detection of GRB 241209B
  81. GRB 241209B: GRBAlpha detection
  82. GRB 241206C: GRBAlpha detection
  83. GRB 241209B: Swift/BAT-GUANO localization skymap of a burst
  84. GRB 241209B: Swift-XRT afterglow detection
  85. GRB 241209B: SVOM/VT afterglow detection
  86. GRB 241209D: COLIBRÍ detection of the afterglow
  87. GRB 241209A: COLIBRÍ Optical Upper Limit
  88. GRB 241209B: BOOTES-5 optical upper limit
  89. GRB 241209B: Swift ToO observations
  90. GRB 241209B: SVOM/ECLAIRs and GRM detection of a long burst
  91. GRB 241206C: SVOM/GRM observation of a likely short burst
  92. GRB 241206B: SVOM/MXT observations: a probable flare from the QSO 1ES 1959+650
  93. GRB 241206B: GWAC-F50A optical upper limit
  94. GRB 241206B: SVOM/ECLAIRs detection of a long soft transient
  95. GRB 241204A: COLIBRÍ Optical Upper Limit
  96. GRB 241127B: detection of a long GRB by SVOM/ECLAIRs
  97. IPN triangulation of GRB 241128B
  98. SVOM/GRM observation of a short burst from soft gamma repeater Kes 73
  99. GRB 241128C: SVOM/GRM observation
  100. GRB 241128B: SVOM/GRM observation

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