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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"

7293 results found.

  1. LIGO/Virgo/KAGRA S240830gn: Identification of a GW compact binary merger candidate
  2. GRB 240828B: SVOM/C-GFT optical upper limit
  3. GRB 240828B: KAIT optical upper limit
  4. GRB 240828A: KAIT Optical Afterglow Candidate
  5. GRB 240828A: Tiled Swift observations
  6. GRB 240825A: Upper limits from a neutrino search with IceCube
  7. GRB 240828B: Swift ToO observations
  8. GRB 240821A: PRIME near-infrared observations
  9. SVOM GRB 240821A: optical afterglow discovery
  10. GRB 240821A: the second and third EP-FXT follow-up observations and afterglow candidates
  11. LIGO/Virgo/KAGRA S240825ar: Updated Sky localization
  12. LIGO/Virgo/KAGRA S240825ar: Updated Sky localization
  13. GRB 240824B: KAIT optical upper limit
  14. GRB 240824B: NOT optical upper limit
  15. GRB 240825A: Skynet Optical Afterglow observations
  16. GRB 240825A: Swift detection of a burst with a bright optical counterpart
  17. GRB 240824A: SVOM/C-GFT optical upper limit
  18. LIGO/Virgo/KAGRA S240825ar: Identification of a GW compact binary merger candidate
  19. GRB 240824B: Swift ToO observations
  20. GRB240824A: GRANDMA/TAROT-TCA Upper Limit
  21. GRB 240824A: Swift detection of a burst
  22. SGR 1E 1841-045 / Kes 73: Montarrenti Observatory optical upper limits
  23. EP240820a: PRIME J-band Observations
  24. GRB 240821A: GMG Optical Upper Limit
  25. GRB 240821A: Swift ToO observations
  26. GRB 240821A: EP-FXT follow-up observation and afterglow candidates
  27. GRB 240819A: JinShan optical upper limits on one Swift/XRT source
  28. GRB 240819A: KAIT optical upper limit
  29. EP240816a: PRIME upper limits
  30. GRB 240819A: Swift ToO observations
  31. EP240816b: KAIT optical upper limit
  32. LIGO/Virgo/KAGRA S240813d: Updated Sky localization
  33. LIGO/Virgo/KAGRA S240813d: Identification of a GW compact binary merger candidate
  34. LIGO/Virgo/KAGRA S240813c: Updated Sky localization
  35. LIGO/Virgo/KAGRA S240813c: Identification of a GW compact binary merger candidate
  36. GRB 240811A: Swift detection of a burst
  37. LIGO/Virgo/KAGRA S240807h: Updated Sky localization and EM Bright Classification
  38. GRB 240809A: Swift detection of a burst with a bright optical counterpart
  39. IceCube-240808A - IceCube observation of a high-energy neutrino candidate track-like event
  40. S240807h: Identification of a GW compact binary merger candidate
  41. The EP-WXT trigger 01709018832 on August 7th is likely a flaring star
  42. GRB 240626B: VZLUSAT-2 detection
  43. EP240806a: GSP optical counterpart detection
  44. GRB 240805B: Optical detection with 1.6m Mephisto
  45. GRB 240805B: BTA optical afterglow candidate
  46. EP240804a: GSP detects optical candidate counterpart
  47. GRB 240805B: Swift detection of a burst
  48. EP240804a: NOT optical counterpart detection
  49. EP240802a: Montarrenti Observatory optical upper limit
  50. EP240801a: GSP follow-up observations of the candidate counterpart
  51. EP240801a: Kinder follow-up observations of the candidate counterpart
  52. EP240708a: Kinder follow-up observations of the candidate counterpart (duplicate submission of GCN 37002)
  53. GRB 240730A: KAIT Optical Upper Limit
  54. GRB 240730A: Swift detection of a burst
  55. LIGO/Virgo/KAGRA S240615dg: GRAWITA wide-field optical observations
  56. GRB 240727A: observations of optical counterpart.
  57. GRB 240727B: Swift ToO observations
  58. GRB 240727A: KAIT Optical Afterglow Candidate
  59. IceCube-240725A - IceCube observation of a high-energy neutrino candidate track-like event
  60. Swift Trigger 1244778 is not a GRB
  61. LIGO/Virgo/KAGRA S240716b: Upper limits from Swift/BAT-GUANO
  62. LIGO/Virgo/KAGRA S240703ad: Upper limits from Swift/BAT-GUANO
  63. IceCube-240721A - IceCube observation of a high-energy neutrino candidate track-like event
  64. LIGO/Virgo/KAGRA S240716b: Updated Sky localization
  65. GRB 240715A: TRT optical upper limit on one Swift/XRT candidate
  66. LIGO/Virgo/KAGRA S240716b: Identification of a GW compact binary merger candidate
  67. GRB 240715A: Swift ToO observations
  68. GRB 240713A: optical upper limits from the INAF Asiago Observatory
  69. The EP-WXT source triggered on July 14th is likely a flaring star
  70. GRB 240713A: Tiled Swift observations
  71. GRB 240712A: Swift detection of a burst
  72. LIGO/Virgo/KAGRA S240711cm: Coverage and upper limits from MAXI/GSC observations
  73. LIGO/Virgo/KAGRA S240627by: Updated Sky localization and EM Bright Classification
  74. EP240708a: KAIT optical upper limit
  75. LIGO/Virgo/KAGRA S240705at: Updated Sky localization
  76. LIGO/Virgo/KAGRA S240705at: Identification of a GW compact binary merger candidate
  77. EP240703a: KAIT optical upper limit
  78. EP240703a: BTA observations
  79. EP240703a: Liverpool Telescope optical follow-up observations
  80. EP240703a/GRB 240703A: TRT optical candidate likely not real
  81. EP240703a: Kinder optical follow-up observations
  82. LIGO/Virgo/KAGRA S240703ad: Updated Sky localization
  83. LIGO/Virgo/KAGRA S240703ad: Identification of a GW compact binary merger candidate
  84. EP240703a/GRB 240703A: TRT and JinShan decaying optical afterglow candidate
  85. LIGO/Virgo/KAGRA S240422ed: Updated significance estimate
  86. LIGO/Virgo/KAGRA S240627by: Upper limits from Swift/BAT-GUANO
  87. LIGO/Virgo/KAGRA S240630t: Updated Sky localization
  88. LIGO/Virgo/KAGRA S240629by: Updated Sky localization
  89. LIGO/Virgo/KAGRA S240630t: Identification of a GW compact binary merger candidate
  90. LIGO/Virgo/KAGRA S240629by: Upper limits from Fermi-GBM Observations
  91. LIGO/Virgo/KAGRA S240629by: Coverage and upper limits from MAXI/GSC observations
  92. LIGO/Virgo/KAGRA S240629by: Identification of a GW compact binary merger candidate
  93. EP240626a: Montarrenti Observatory optical upper limit
  94. EP240626a: KAIT optical upper limit
  95. LIGO/Virgo/KAGRA S240627by: Identification of a GW compact binary merger candidate
  96. EP240625a: NOT optical counterpart candidate
  97. LIGO/Virgo/KAGRA S240622h: Upper limits from Swift/BAT-GUANO
  98. LIGO/Virgo/KAGRA S240621dy: Upper limits from Swift/BAT-GUANO
  99. LIGO/Virgo/KAGRA S240618ah: Upper limits from Swift/BAT-GUANO
  100. LIGO/Virgo/KAGRA S240624cd: Retraction of GW unmodeled transient candidate

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