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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"

20355 results found.

  1. GRB 251222A: Mondy Optical Observations
  2. EP251230a / GRB 251230A: refined analysis of the EP-WXT and EP-FXT observations
  3. GRB 251230A: Swift/UVOT detection
  4. GRB251230A: 7DT optical upper limits
  5. GRB 251230A / EP251230a: NOT observations and spectroscopic redshift upper limit z < 2.2
  6. GRB 251230A: GOTO optical upper limit
  7. EP251229a: NOT optical upper limits
  8. GRB 251230A / EP251230a: SVOM/VT optical observation
  9. EP251229a: refined analysis of the EP-WXT and EP-FXT observations
  10. GRB 251230A: Enhanced Swift-XRT position
  11. GRB 251230A: Early optical counterpart detection by LCO.
  12. EP-WXT trigger 01709250662 Mephisto and 50cm telescope follow-up
  13. EP251230a / GRB 251230A: Einstein Probe detection of an X-ray transient
  14. LIGO/Virgo/KAGRA S251112cm: Candidates from the NSF-DOE Vera C. Rubin Observatory
  15. EP251229a: Einstein Probe detection of an X-ray transient
  16. GRB 251230A: Swift detection of a burst with a bright optical counterpart
  17. GRB 251222A/EP251222b: 1.6m Mephisto optical followup
  18. GRB 251226A: SVOM/GRM observation
  19. IceCube-251225A: Upper limits from a search for additional neutrino events in IceCube
  20. GRB 251222A/EP251222b: Optical detection with Kinder observations
  21. EP251222a: Optical upper limit with Kinder observations
  22. GRB 251205A: Kilonova-Catcher optical afterglow detection
  23. GRB 251222A: AbAO optical observations
  24. GRB 251222A / EP251222b: Kilonova-Catcher optical afterglow detection
  25. GRB 251129A / EP251129a: VLA detection of a radio counterpart
  26. GRB 251222A: ZTSH BVRI optical observations
  27. GRB 251222A: SVOM/COLIBRÍ (FM-GFT) optical observations
  28. GRB 251222A: Continued 1.3m DFOT optical observation
  29. EP251220a: 3.6m DOT optical afterglow detection
  30. EP251220a: CrAO ZTSh optical observations
  31. EP251221a: PRIME upper limit
  32. EP251221a: Liverpool Telescope upper limits
  33. EP251222a: refined analysis of the EP-WXT and EP-FXT observations
  34. EP251222b/GRB 251222A: refined analysis of the EP-WXT and EP-FXT observations
  35. GRB 251222A: Swift-XRT afterglow detection
  36. GRB 251222A / EP251222b: LCO detection of the optical counterpart
  37. EP251222a: NTT/ULTRACAM optical observations
  38. GRB 251222A / EP251222b: GOTO optical counterpart detection
  39. GRB 251222A / EP251222b: LCO optical observations
  40. GRB 251222A: 1.3m DFOT optical detection
  41. GRB251221A: 7DT optical upper limits
  42. EP251222b/GRB 251222A: Einstein Probe detection of an X-ray transient
  43. EP251222a: Einstein Probe detection of an X-ray transient
  44. GRB 251222A: PRIME near-infrared detection
  45. EP251221a: NOT optical upper limit
  46. GRB 251222A: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  47. IceCube-251218A: No Candidate Transients from the Zwicky Transient Facility
  48. IPN triangulation of GRB 251220B (short)
  49. GRB 251222A: SVOM/VT optical candidate
  50. GRB 251222A: SVOM detection of a long burst
  51. EP251220a: PRIME upper limit
  52. EP251220a: VLT/FORS2 spectroscopic redshift z = 2.375
  53. GRB 251221A: PRIME near-infrared observation
  54. GRB 251221A: UAFO and Mondy optical upper limit
  55. EP251221a: Einstein Probe detection of a fast X-ray transient
  56. GRB 251221A: Swift/UVOT Upper Limits
  57. GRB 251221A: Enhanced Swift-XRT position
  58. GRB 251220B: SVOM/GRM observation of a short burst
  59. EP251220a: COLIBRÍ confirmation of fading and photometric redshift upper limit of z < 3.4
  60. EP 251220a: GOTO optical counterpart detection
  61. GRB 251221A: COLIBRÍ detection of the optical counterpart
  62. EP 251220a: COLIBRÍ detection of the optical counterpart
  63. GRB 251221A: Swift detection of a burst
  64. EP251220a: EP detection of a fast X-ray transient
  65. GRB 251219A: SVOM/GRM observation of a short burst
  66. Fermi-LAT Gamma-ray Observations of IceCube-251218A
  67. GRB 251215A: Swift-XRT afterglow detection
  68. IceCube-251218A: Upper limits from a search for additional neutrino events in IceCube
  69. IceCube-251218A: COLIBRÍ optical upper limits
  70. GRB 251214B: VIRT Optical Upper Limit
  71. GRB 251215A: Swift/UVOT Upper LImits
  72. GRB 251202A/EP251202a: Koshka optical upper limit
  73. GRB 251214B: Mondy optical upper limit
  74. GRB 251215A: COLIBRÍ optical upper limit
  75. EP251214b: KAIT optical upper limit
  76. EP251214a: Optical upper limit with Kinder observations
  77. GRB 251214B: 1.6m Mephisto observations with newly installed mosaic cameras
  78. GRB 251214B: UAFO optical upper limit
  79. GRB 251214B: VLT/X-shooter observations
  80. GRB 251213A: GRID-10B observation
  81. GRB 251202A: radio detection with the VLA
  82. EP251214b : Einstein Probe detection of a fast X-ray transient
  83. EP251214b : Einstein Probe detection of a fast X-ray transient
  84. GRB 251214B: AbAO optical observations
  85. GRB 251214B: LCO detection of the optical counterpart
  86. EP251214b (EP trigger 01709250023): LCO optical limits
  87. GRID detection of GRB 251213A
  88. GRB 251203B: AbAO optical observations
  89. GRB 251213A: SVOM/GRM observation
  90. EP251214a: KAIT optical upper limit
  91. GRB 251213A: AstroSat CZTI detection
  92. GRB 251214B: Swift/UVOT Detection
  93. GRB 251214B: COLIBRÍ observations of the afterglow
  94. EP251214a: EP-FXT non-detection and upper limit
  95. GRB 251214B: 1.3m DFOT optical detection
  96. GRB 251214B: Enhanced Swift-XRT position
  97. GRB 251214B: Xinglong-2.16m optical observation
  98. GRB 251214B : MASTER optical afterglow detection
  99. GRB 251214B: SVOM/C-GFT optical observations
  100. EP251214a: COLIBRÍ optical upper limit

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