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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"

19566 results found.

  1. GRB 260104A: Enhanced Swift-XRT position
  2. GRB 260101A: Swift/UVOT Detection
  3. GRB 260104A: Swift detection of a burst
  4. GRB 260101A: COLIBRÍ optical observations
  5. GRB 260102A: LCO optical upper limits
  6. GRB 260102A: SVOM/COLIBRÍ (FM-GFT) optical observations
  7. GRB 260102A: Swift ToO observations
  8. EP260101a: refined analysis of the EP-WXT and EP-FXT observations
  9. GRB 260102A: SVOM detection of a burst
  10. GRB 260101A: SVOM/GRM observation
  11. GRB 260101A: Enhanced Swift-XRT position
  12. EP260101a: Einstein Probe detection of an X-ray transient
  13. GRB 260101A: LCO detection of the optical counterpart
  14. GRB 260101A: Swift detection of a burst with an optical counterpart
  15. GRB 251230A: GRANDMA/TAROT Early Detection
  16. GRB 251230A/EP251230a: Optical upper limit with Kinder observations
  17. EP251229a: Optical upper limit with Kinder observations
  18. GRB 251230A: 1.3m DFOT optical upper limit
  19. GRB 251222A: Mondy Optical Observations
  20. EP251230a / GRB 251230A: refined analysis of the EP-WXT and EP-FXT observations
  21. GRB 251230A: Swift/UVOT detection
  22. GRB251230A: 7DT optical upper limits
  23. GRB 251230A: GOTO optical upper limit
  24. EP251229a: NOT optical upper limits
  25. GRB 251230A / EP251230a: SVOM/VT optical observation
  26. EP251229a: refined analysis of the EP-WXT and EP-FXT observations
  27. GRB 251230A: Enhanced Swift-XRT position
  28. GRB 251230A: Early optical counterpart detection by LCO.
  29. EP-WXT trigger 01709250662 Mephisto and 50cm telescope follow-up
  30. EP251230a / GRB 251230A: Einstein Probe detection of an X-ray transient
  31. LIGO/Virgo/KAGRA S251112cm: Candidates from the NSF-DOE Vera C. Rubin Observatory
  32. EP251229a: Einstein Probe detection of an X-ray transient
  33. GRB 251230A: Swift detection of a burst with a bright optical counterpart
  34. GRB 251222A/EP251222b: 1.6m Mephisto optical followup
  35. GRB 251129A: redshift correction and SN detection at z = 0.505 with GTC
  36. GRB 251226A: SVOM/GRM observation
  37. GRB 251222A/EP251222b: Optical detection with Kinder observations
  38. EP251222a: Optical upper limit with Kinder observations
  39. GRB 251205A: Kilonova-Catcher optical afterglow detection
  40. GRB 251222A: AbAO optical observations
  41. GRB 251222A / EP251222b: Kilonova-Catcher optical afterglow detection
  42. GRB 251129A / EP251129a: VLA detection of a radio counterpart
  43. GRB 251222A: ZTSH BVRI optical observations
  44. GRB 251222A: SVOM/COLIBRÍ (FM-GFT) optical observations
  45. GRB 251222A: Continued 1.3m DFOT optical observation
  46. EP251220a: 3.6m DOT optical afterglow detection
  47. EP251220a: CrAO ZTSh optical observations
  48. EP251221a: PRIME upper limit
  49. EP251221a: Liverpool Telescope upper limits
  50. EP251222a: refined analysis of the EP-WXT and EP-FXT observations
  51. EP251222b/GRB 251222A: refined analysis of the EP-WXT and EP-FXT observations
  52. GRB 251222A: Swift-XRT afterglow detection
  53. GRB 251222A / EP251222b: LCO detection of the optical counterpart
  54. EP251222a: NTT/ULTRACAM optical observations
  55. GRB 251222A / EP251222b: GOTO optical counterpart detection
  56. GRB 251222A / EP251222b: LCO optical observations
  57. GRB 251222A: 1.3m DFOT optical detection
  58. GRB251221A: 7DT optical upper limits
  59. EP251222b/GRB 251222A: Einstein Probe detection of an X-ray transient
  60. EP251222a: Einstein Probe detection of an X-ray transient
  61. GRB 251222A: PRIME near-infrared detection
  62. EP251221a: NOT optical upper limit
  63. GRB 251222A: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  64. IceCube-251218A: No Candidate Transients from the Zwicky Transient Facility
  65. IPN triangulation of GRB 251220B (short)
  66. GRB 251222A: Swift ToO observations
  67. GRB 251222A: SVOM/VT optical candidate
  68. GRB 251222A: SVOM detection of a long burst
  69. EP251220a: PRIME upper limit
  70. GRB 251221A: PRIME near-infrared observation
  71. GRB 251221A: UAFO and Mondy optical upper limit
  72. GRB 251221A: Swift-XRT refined Analysis
  73. EP251221a: Einstein Probe detection of a fast X-ray transient
  74. GRB 251221A: Swift/UVOT Upper Limits
  75. GRB 251221A: Enhanced Swift-XRT position
  76. GRB 251220B: SVOM/GRM observation of a short burst
  77. EP251220a: COLIBRÍ confirmation of fading and photometric redshift upper limit of z < 3.4
  78. EP 251220a: GOTO optical counterpart detection
  79. GRB 251221A: COLIBRÍ detection of the optical counterpart
  80. EP 251220a: COLIBRÍ detection of the optical counterpart
  81. GRB 251221A: Swift detection of a burst
  82. EP251220a: EP detection of a fast X-ray transient
  83. GRB 251219A: SVOM/GRM observation of a short burst
  84. GRB 251215A: Swift-XRT afterglow detection
  85. IceCube-251218A: COLIBRÍ optical upper limits
  86. GRB 251214B: VIRT Optical Upper Limit
  87. GRB 251215A: Swift/UVOT Upper LImits
  88. GRB 251202A/EP251202a: Koshka optical upper limit
  89. GRB 251214B: Mondy optical upper limit
  90. GRB 251215A: COLIBRÍ optical upper limit
  91. EP251214b: KAIT optical upper limit
  92. GRB 251215A: Swift-XRT observations
  93. EP251214a: Optical upper limit with Kinder observations
  94. GRB 251214B: 1.6m Mephisto observations with newly installed mosaic cameras
  95. GRB 251214B: UAFO optical upper limit
  96. GRB 251214B: VLT/X-shooter observations
  97. GRB 251202A: radio detection with the VLA
  98. EP251214b : Einstein Probe detection of a fast X-ray transient
  99. EP251214b : Einstein Probe detection of a fast X-ray transient
  100. GRB 251214B: AbAO optical observations

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