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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"

23410 results found.

  1. EP260105a: SVOM/VT optical upperlimit
  2. FRB 20251229A: A potentially hyperactive repeating fast radio burst source
  3. EP260105a: refined analysis of the EP-WXT and EP-FXT observations
  4. EP260105a: LCO Optical Upper limit
  5. EP260104a: Einstein Probe detection of a fast X-ray transient
  6. GRB 260101A: COLIBRÍ optical upper limits
  7. EP260105a: Einstein Probe detection of an X-ray transient
  8. GRB 260104A: COLIBRÍ optical upper limits
  9. GRB 251230A/EP-WXT trigger 01709250693: Mephisto optical upper limits
  10. GRB 260104A: Swift-XRT refined Analysis
  11. GRB 260104A: Enhanced Swift-XRT position
  12. GRB 260101A: Swift/UVOT Detection
  13. GRB 260104A: Swift detection of a burst
  14. GRB 260101A: COLIBRÍ optical observations
  15. GRB 260102A: LCO optical upper limits
  16. GRB 260102A: Swift-XRT observations
  17. GRB 260102A: SVOM/COLIBRÍ (FM-GFT) optical observations
  18. EP260101a: refined analysis of the EP-WXT and EP-FXT observations
  19. GRB 260102A: SVOM detection of a burst
  20. GRB 260101A: SVOM/GRM observation
  21. GRB 260101A: Swift-XRT refined Analysis
  22. GRB 260101A: Enhanced Swift-XRT position
  23. EP260101a: Einstein Probe detection of an X-ray transient
  24. GRB 260101A: LCO detection of the optical counterpart
  25. GRB 260101A: Swift detection of a burst with an optical counterpart
  26. GRB 251230A: GRANDMA/TAROT Early Detection
  27. GRB 251230A/EP251230a: Optical upper limit with Kinder observations
  28. EP251229a: Optical upper limit with Kinder observations
  29. GRB 251230A: 1.3m DFOT optical upper limit
  30. GRB 251230A: Swift-XRT refined Analysis
  31. GRB 251222A: Mondy Optical Observations
  32. EP251230a / GRB 251230A: refined analysis of the EP-WXT and EP-FXT observations
  33. GRB 251230A: Swift/UVOT detection
  34. GRB251230A: 7DT optical upper limits
  35. GRB 251230A: GOTO optical upper limit
  36. EP251229a: NOT optical upper limits
  37. GRB 251230A / EP251230a: SVOM/VT optical observation
  38. EP251229a: refined analysis of the EP-WXT and EP-FXT observations
  39. GRB 251230A: Enhanced Swift-XRT position
  40. GRB 251230A: Early optical counterpart detection by LCO.
  41. EP-WXT trigger 01709250662 Mephisto and 50cm telescope follow-up
  42. EP251230a / GRB 251230A: Einstein Probe detection of an X-ray transient
  43. LIGO/Virgo/KAGRA S251112cm: Candidates from the NSF-DOE Vera C. Rubin Observatory
  44. EP251229a: Einstein Probe detection of an X-ray transient
  45. GRB 251230A: Swift detection of a burst with a bright optical counterpart
  46. GRB 251226A: Glowbug gamma-ray detection
  47. GRB 251222A/EP251222b: 1.6m Mephisto optical followup
  48. GRB 251226A: SVOM/GRM observation
  49. GRB 251222A/EP251222b: Optical detection with Kinder observations
  50. EP251222a: Optical upper limit with Kinder observations
  51. GRB 251205A: Kilonova-Catcher optical afterglow detection
  52. GRB 251222A: AbAO optical observations
  53. GRB 251222A / EP251222b: Kilonova-Catcher optical afterglow detection
  54. GRB 251129A / EP251129a: VLA detection of a radio counterpart
  55. GRB 251222A: ZTSH BVRI optical observations
  56. GRB 251222A: SVOM/COLIBRÍ (FM-GFT) optical observations
  57. GRB 251222A: Continued 1.3m DFOT optical observation
  58. EP251220a: 3.6m DOT optical afterglow detection
  59. EP251220a: CrAO ZTSh optical observations
  60. EP251221a: PRIME upper limit
  61. EP251221a: Liverpool Telescope upper limits
  62. EP251222a: refined analysis of the EP-WXT and EP-FXT observations
  63. EP251222b/GRB 251222A: refined analysis of the EP-WXT and EP-FXT observations
  64. GRB 251222A: Swift-XRT afterglow detection
  65. GRB 251222A / EP251222b: LCO detection of the optical counterpart
  66. EP251222a: NTT/ULTRACAM optical observations
  67. GRB 251222A / EP251222b: GOTO optical counterpart detection
  68. GRB 251222A / EP251222b: LCO optical observations
  69. GRB 251222A: 1.3m DFOT optical detection
  70. GRB251221A: 7DT optical upper limits
  71. EP251222b/GRB 251222A: Einstein Probe detection of an X-ray transient
  72. EP251222a: Einstein Probe detection of an X-ray transient
  73. GRB 251222A: PRIME near-infrared detection
  74. EP251221a: NOT optical upper limit
  75. GRB 251222A: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  76. GRB 251222A: NOT optical observations
  77. IceCube-251218A: No Candidate Transients from the Zwicky Transient Facility
  78. IPN triangulation of GRB 251220B (short)
  79. GRB 251222A: SVOM/VT optical candidate
  80. GRB 251222A: SVOM detection of a long burst
  81. EP251220a: PRIME upper limit
  82. GRB 251221A: PRIME near-infrared observation
  83. GRB 251221A: UAFO and Mondy optical upper limit
  84. GRB 251221A: Swift-XRT refined Analysis
  85. EP251221a: Einstein Probe detection of a fast X-ray transient
  86. GRB 251221A: Swift/UVOT Upper Limits
  87. GRB 251221A: Enhanced Swift-XRT position
  88. GRB 251220B: SVOM/GRM observation of a short burst
  89. EP251220a: COLIBRÍ confirmation of fading and photometric redshift upper limit of z < 3.4
  90. EP 251220a: GOTO optical counterpart detection
  91. GRB 251221A: COLIBRÍ detection of the optical counterpart
  92. EP 251220a: COLIBRÍ detection of the optical counterpart
  93. GRB 251221A: Swift detection of a burst
  94. EP251220a: EP detection of a fast X-ray transient
  95. GRB 251219A: SVOM/GRM observation of a short burst
  96. GRB 251215A: Swift-XRT afterglow detection
  97. IceCube-251218A: COLIBRÍ optical upper limits
  98. GRB 251214B: VIRT Optical Upper Limit
  99. GRB 251215A: Swift/UVOT Upper LImits
  100. GRB 251202A/EP251202a: Koshka optical upper limit

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