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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"

8294 results found.

  1. IceCube-240307A: Upper limits from a search for additional neutrino events in IceCube
  2. GRB 231215A: further radio observations with the VLA
  3. IceCube-240307A - IceCube observation of a high-energy neutrino candidate track-like event
  4. GRB 231028C: Glowbug gamma-ray confirmation of a prior burst
  5. Swift detection of Swift J151857.0-572147
  6. GRB 240303A: Swift detection of a burst
  7. IceCube-240229A: Upper limits from a search for additional neutrino events in IceCube
  8. IceCube-240229A - IceCube observation of a high-energy neutrino candidate track-like event
  9. GRB 240225B: Swift ToO observations
  10. GRB 240225B : MITSuME Akeno optical afterglow candidate detection
  11. GRB 240225B: 3.6m DOT observation
  12. GRB 240225B: NOT optical observations
  13. Swift-BAT triggers 1217729-1217732 are not astrophysical
  14. GRB 240225B: Nanshan/HMT optical afterglow detection
  15. GRB 240225B: GOTO detection of a candidate optical afterglow
  16. Transient EPW20240219aa: REM optical/NIR upper limits
  17. GRB 240225B: Tiled Swift observations
  18. Swift-BAT triggers 1217218-1217222 are not astrophysical
  19. Transient EPW20240219aa: upper limit in gamma-ray range from SPI-ACS/INTEGRAL observations
  20. Swift-BAT triggers 1216907-1216911 are not astrophysical
  21. Fermi GBM Sub-Threshold Detection of EPW20240219aa as a likely GRB
  22. GRB 240222A: Swift detection of a burst
  23. Swift-BAT triggers 1216743-1216748 are not astrophysical
  24. IPN triangulation of GRB 240209A
  25. GRB 240218A: REM detection of a NIR afterglow candidate
  26. Gamma-ray flaring activity from the blazar 1ES 1959+650 observed by the Fermi-LAT
  27. GRB 240218A : r-band upper limit from Observatoire de Haute-Provence
  28. GRB 240218A: Swift detection of a burst
  29. GRB 240215A: Tiled Swift observations
  30. GRB 240209A: Fermi GBM observation
  31. GRB240209A: OHP/T193 detection of the GOTO afterglow candidate AT2024cew / GOTO24pw
  32. GRB 240209A: Wendelstein Optical Observations
  33. GRB 240214A: Tiled Swift observations
  34. GRB 240214A/1H 0451-560: MAXI/GSC detection
  35. GRB 240209A: NOEMA non-detection of AT2024cew / GOTO24pw counterpart candidate
  36. GRB 240209A: NOT photometry of the AT2024cew / GOTO24pw counterpart candidate
  37. GRB 240209A: GOTO optical counterpart candidate
  38. GRB240204A: Swift/UVOT Upper Limits
  39. GRB 240205B: ATCA detection of radio counterpart
  40. IceCube-240204A: Upper limits from a search for additional neutrino events in IceCube
  41. GRB 240204A: Mondy optical afterglow candidate
  42. IceCube-240204A - IceCube observation of a high-energy neutrino candidate track-like event
  43. Swift-BAT triggers 1212787, 1212789 are not astrophysical.
  44. GRB 240128A: Tiled Swift observations
  45. GRB 240122A: ATCA detection of radio counterpart
  46. IceCube-240123A: Upper limits from a search for additional neutrino events in IceCube
  47. Swift Trigger 1211211 and 1211212 are not astrophysical
  48. GRB240122A: PRIME near infrared detection
  49. Swift trigger 1210856 is not astrophysical
  50. GRB 240123A : MITSuME Akeno optical afterglow candidate detection
  51. Fermi/GBM trigger 727752941: BALROG analysis retraction
  52. GRB 240122A: Swift/UVOT Upper Limits
  53. Fermi GBM Sub-Threshold Detection of GRB 240123A
  54. IceCube-240123A - IceCube observation of a high-energy neutrino candidate track-like event
  55. GRB 240123A: Swift detection of a burst with a possible optical counterpart
  56. GRB 240122A: VLT/X-shooter redshift confirmation
  57. GRB 240122A: LT non-detection of GOTO candidate counterpart confirms fading
  58. GRB 240122A: GOTO optical counterpart candidate
  59. GRB 240122A: Tiled Swift observations
  60. IceCube-240105A: Detection of NIR flare of PKS 0446+11 with WINTER
  61. GRB 240118A: Swift ToO observations
  62. GRB 240118A: AbAO optical upper limit
  63. Swift Trigger 1209406 is not an astrophysical event
  64. LIGO/Virgo/KAGRA S240109a: Upper limits from Swift/BAT-GUANO
  65. IceCube-240105A: ZTF optical observation of blazar PKS 0446+11
  66. GRB 240112C: Swift detection of a burst with an optical counterpart
  67. IceCube-240105A: Upper limits from a search for additional neutrino events in IceCube
  68. LIGO/Virgo/KAGRA S240109a: Updated Sky localization
  69. GRB 231215A: radio detection with the VLA
  70. GRB 230818A: further radio observations with the VLA
  71. GRB 230812B: further radio observations with the VLA
  72. LIGO/Virgo/KAGRA S240109a: Identification of a GW compact binary merger candidate
  73. LIGO/Virgo/KAGRA S240104bl: Upper limits from Swift/BAT-GUANO
  74. Update of IceCube-240105A - Corrected errors
  75. LIGO/Virgo/KAGRA S240107b: Updated Sky localization and Source Classification
  76. LIGO/Virgo/KAGRA S240107b: Identification of a GW compact binary merger candidate
  77. GRB 240101A: 1.3m DFOT optical observations
  78. IceCube-240105A - IceCube observation of a high-energy neutrino candidate track-like event
  79. LIGO/Virgo/KAGRA S240104bl: Updated Sky localization
  80. LIGO/Virgo/KAGRA S240104bl: Identification of a GW compact binary merger candidate
  81. GRB 231220A: Swift-UVOT upper limit
  82. GRB 240101B: MarSEC Observatory, Vicenza, Italy, UPPER LIMIT
  83. IceCube-Cascade 231230A: Upper limits from a search for additional neutrino events in IceCube
  84. GRB 240101B: KAIT Optical Upper Limit
  85. GRB 240101A: KAIT Optical Upper Limit
  86. GRB 240101B: Swift detection of a burst
  87. LIGO/Virgo/KAGRA S231231ag: Updated Sky localization and Source Classification
  88. LIGO/Virgo/KAGRA S231231ag: Identification of a GW compact binary merger candidate
  89. GRB 231230A: Swift detection of a burst
  90. LIGO/Virgo/KAGRA S231224e: Upper limits from Swift/BAT-GUANO
  91. LIGO/Virgo/KAGRA S231226av: Updated Sky localization
  92. LIGO/Virgo/KAGRA S231226av: Identification of a GW compact binary merger candidate
  93. LIGO/Virgo/KAGRA S231224e: Updated Sky localization and Source Classification
  94. LIGO/Virgo/KAGRA S231224e: Identification of a GW compact binary merger candidate
  95. LIGO/Virgo/KAGRA S231223j: Updated Sky localization
  96. LIGO/Virgo/KAGRA S231223j: Identification of a GW compact binary merger candidate
  97. GRB 231222A: Tiled Swift observations
  98. GRB 231220A: Swift-XRT follow-up observations
  99. GRB 231220A: Swift ToO observations
  100. GRB 231216A: GAD Observatory, La Spezia, Italy upper limit

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