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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"

23413 results found.

  1. EP260126a: SVOM/VT optical upperlimit
  2. EP260128a: Einstein Probe detection of an X-ray transient
  3. GRB 260127A: COLIBRÍ optical observations
  4. EP260126a: Seimei/TriCCS optical upper limit
  5. GRB 260127A : MITSuME Akeno optical afterglow candidate detection
  6. GRB 260127A: SVOM/C-GFT optical observations
  7. GRB 260127A: Enhanced Swift-XRT position
  8. GRB 260127A: LCO optical afterglow discovery
  9. GRB 260127A: Swift detection of a burst
  10. GRB 260125A: Swift-XRT observations
  11. EP260126a: Optical upper limit with Kinder observations
  12. EP260126a: Liverpool Telescope optical upper limits
  13. EP260126a: Further NOT optical upper limits
  14. EP260126a: COLIBRÍ optical upper limits
  15. EP260126a: NOT optical observations
  16. EP260126a: Einstein Probe detection of a fast X-ray transient
  17. Konus-Wind detection of GRB 260120B
  18. GRB 260125A: GOTO candidate optical counterpart
  19. GRB 260114A: SVOM/VT optical upper limits
  20. GRB 260120A: AstroSat CZTI detection
  21. GRB 260120B: SVOM/GRM observation
  22. GRB 260122B: Swift detection of a burst
  23. EP260119a: Assy AZT-20 optical observations
  24. EP260119a: Mondy and SAO RAS optical upper limits
  25. EP260119a: Xinglong optical upper limit
  26. EP260116a: COLIBRÍ further observations
  27. GRB 251122A / EP251122a: VLT/X-shooter host redshift z = 1.765
  28. EP260105a: GTC/HiPERCAM optical observations
  29. GRB 260120B: Swift/UVOT Detection
  30. GRB 260120B: COLIBRÍ optical upper limits
  31. GRB 260120B: Enhanced Swift-XRT position
  32. GRB 260120B: SVOM/C-GFT optical counterpart detection
  33. EP260116a: COLIBRÍ observations of a tentative optical rebrightening
  34. GRB 260120B: Swift detection of a burst
  35. EP260119A: Mondy I-Band Observations
  36. GRB 260114A: Swift/UVOT Upper Limits
  37. EP260119a: Liverpool Telescope optical follow-up observations
  38. GRB 251202A: further radio observations with the VLA
  39. EP260119a: KAIT optical observations
  40. EP260119a: SVOM/VT optical observation
  41. EP260119a: NOT optical observations
  42. EP260119a: SAO RAS optical observations
  43. EP260116a: COLIBRÍ detection of a fading optical source
  44. GRB 260117A: Swift-XRT afterglow detection
  45. EP260119a: COLIBRÍ photometric redshift z ≈ 5.6
  46. EP260119a: LCO optical observations
  47. GRB 260117A: ZTSh optical upper limit
  48. EP260119a: COLIBRÍ optical counterpart candidate
  49. EP260119a: EP-WXT detection of a fast X-ray transient
  50. GRB 260117A: SVOM/COLIBRÍ (FM-GFT) optical observations
  51. Swift trigger on the HMXB 1A 1118-61
  52. GRB 260117A: SVOM/C-GFT upper limit
  53. GRB 260117A: Swift-XRT observations
  54. EP 260116a: COLIBRÍ optical upper limit
  55. Swift triggered on the HMXB 1A 1118-61
  56. FRB 20251229A: COLIBRÍ further inspection of the updated localization
  57. EP260116a: Liverpool Telescope upper limits
  58. EP260116A: 1.3m DFOT optical upper limit
  59. GRB 260114A: VLT/MUSE spectroscopic observations
  60. GRB 260111A: COLIBRÍ fading of the optical counterpart candidate
  61. EP260116a: Xinglong optical upper limit
  62. EP260116a: Einstein Probe detection of an X-ray transient
  63. GRB 260114A: VLT/HAWK-I further near-infrared upper limits
  64. GRB260114A: STEP/T80S optical limits
  65. GRB 251222A: radio detection with the VLA
  66. GRB 260114A: VLT/HAWK-I near-infrared upper limits
  67. GRB 260114A: Swift-XRT refined Analysis
  68. GRB 260114A: 6 GHz VLA observations
  69. GRB 260114A: VLT/X-shooter redshift of the putative host galaxy
  70. GRB 260114A : MITSuME Akeno optical upper limits
  71. GRB 260114A: COLIBRÍ optical upper limits
  72. GRB 260114A: TNG NIR upper limit
  73. GRB 260114A: NOT optical observations
  74. GRB 260114A: SVOM/GRM observation of a short burst
  75. GRB 260114A: Mondy optical observations
  76. GRB 260114A: GMG Optical Observation
  77. GRB 260114A: Swift detection of a short burst
  78. EP-WXT trigger 01709251266: SVOM/C-GFT confirmation of a stellar flare
  79. EP260110a: NOT and GTC Optical and Near-Infrared Observations
  80. EP260110a: TRT optical upper limits
  81. Konus-Wind detection of GRB 260101A
  82. GRB 260111A: Swift-XRT observations
  83. Swift Trigger 1439093: is probably not GRB 260113A
  84. GRB 260111A: COLIBRÍ optical afterglow candidate
  85. GRB 251230A: Mondy Optical Observations
  86. EP260110a: SVOM/VT optical upper limits
  87. Swift trigger 1436759 is not an astrophysical event
  88. EP260110a: KAIT optical upper limit
  89. EP260110a: refined analysis of the EP-WXT and EP-FXT observations
  90. EP 260110a: COLIBRÍ optical observations
  91. EP260110a: SVOM/C-GFT upper limit
  92. EP260110a: Einstein Probe detection of an X-ray transient
  93. GRB 260109C: LCO optical upper limits
  94. GRB 260109C: Kilonova-Catcher optical upper limit
  95. Swift Trigger 1434591: possible GRB 260109C
  96. GRB 260102A: Swift-XRT afterglow detection
  97. GRB 260102A: AbAO optical observations
  98. EP260105b/EP-WXT trigger 01709251028: Einstein Probe detection of an X-ray transient
  99. EP260105a: FTW optical observations
  100. EP260104a: FTW optical observations

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