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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"

8474 results found.

  1. Fermi GBM Sub-Threshold Detection of EPW20240219aa as a likely GRB
  2. GRB 240222A: Swift detection of a burst
  3. Swift-BAT triggers 1216743-1216748 are not astrophysical
  4. IPN triangulation of GRB 240209A
  5. GRB 240218A: REM detection of a NIR afterglow candidate
  6. Gamma-ray flaring activity from the blazar 1ES 1959+650 observed by the Fermi-LAT
  7. GRB 240218A : r-band upper limit from Observatoire de Haute-Provence
  8. GRB 240218A: Swift detection of a burst
  9. GRB 240215A: Tiled Swift observations
  10. GRB 240209A: Fermi GBM observation
  11. GRB240209A: OHP/T193 detection of the GOTO afterglow candidate AT2024cew / GOTO24pw
  12. GRB 240209A: Wendelstein Optical Observations
  13. GRB 240214A: Tiled Swift observations
  14. GRB 240214A/1H 0451-560: MAXI/GSC detection
  15. GRB 240209A: NOEMA non-detection of AT2024cew / GOTO24pw counterpart candidate
  16. GRB 240209A: NOT photometry of the AT2024cew / GOTO24pw counterpart candidate
  17. GRB 240209A: GOTO optical counterpart candidate
  18. GRB240204A: Swift/UVOT Upper Limits
  19. GRB 240205B: ATCA detection of radio counterpart
  20. IceCube-240204A: Upper limits from a search for additional neutrino events in IceCube
  21. GRB 240204A: Mondy optical afterglow candidate
  22. IceCube-240204A - IceCube observation of a high-energy neutrino candidate track-like event
  23. Swift-BAT triggers 1212787, 1212789 are not astrophysical.
  24. GRB 240128A: Tiled Swift observations
  25. GRB 240122A: ATCA detection of radio counterpart
  26. IceCube-240123A: Upper limits from a search for additional neutrino events in IceCube
  27. Swift Trigger 1211211 and 1211212 are not astrophysical
  28. GRB240122A: PRIME near infrared detection
  29. Swift trigger 1210856 is not astrophysical
  30. GRB 240123A : MITSuME Akeno optical afterglow candidate detection
  31. Fermi/GBM trigger 727752941: BALROG analysis retraction
  32. GRB 240122A: Swift/UVOT Upper Limits
  33. Fermi GBM Sub-Threshold Detection of GRB 240123A
  34. IceCube-240123A - IceCube observation of a high-energy neutrino candidate track-like event
  35. GRB 240123A: Swift detection of a burst with a possible optical counterpart
  36. GRB 240122A: VLT/X-shooter redshift confirmation
  37. GRB 240122A: LT non-detection of GOTO candidate counterpart confirms fading
  38. GRB 240122A: GOTO optical counterpart candidate
  39. GRB 240122A: Tiled Swift observations
  40. IceCube-240105A: Detection of NIR flare of PKS 0446+11 with WINTER
  41. GRB 240118A: Swift ToO observations
  42. GRB 240118A: AbAO optical upper limit
  43. Swift Trigger 1209406 is not an astrophysical event
  44. LIGO/Virgo/KAGRA S240109a: Upper limits from Swift/BAT-GUANO
  45. IceCube-240105A: ZTF optical observation of blazar PKS 0446+11
  46. GRB 240112C: Swift detection of a burst with an optical counterpart
  47. IceCube-240105A: Upper limits from a search for additional neutrino events in IceCube
  48. LIGO/Virgo/KAGRA S240109a: Updated Sky localization
  49. GRB 231215A: radio detection with the VLA
  50. GRB 230818A: further radio observations with the VLA
  51. GRB 230812B: further radio observations with the VLA
  52. LIGO/Virgo/KAGRA S240109a: Identification of a GW compact binary merger candidate
  53. LIGO/Virgo/KAGRA S240104bl: Upper limits from Swift/BAT-GUANO
  54. Update of IceCube-240105A - Corrected errors
  55. LIGO/Virgo/KAGRA S240107b: Updated Sky localization and Source Classification
  56. LIGO/Virgo/KAGRA S240107b: Identification of a GW compact binary merger candidate
  57. GRB 240101A: 1.3m DFOT optical observations
  58. IceCube-240105A - IceCube observation of a high-energy neutrino candidate track-like event
  59. LIGO/Virgo/KAGRA S240104bl: Updated Sky localization
  60. LIGO/Virgo/KAGRA S240104bl: Identification of a GW compact binary merger candidate
  61. GRB 231220A: Swift-UVOT upper limit
  62. GRB 240101B: MarSEC Observatory, Vicenza, Italy, UPPER LIMIT
  63. IceCube-Cascade 231230A: Upper limits from a search for additional neutrino events in IceCube
  64. GRB 240101B: KAIT Optical Upper Limit
  65. GRB 240101A: KAIT Optical Upper Limit
  66. GRB 240101B: Swift detection of a burst
  67. LIGO/Virgo/KAGRA S231231ag: Updated Sky localization and Source Classification
  68. LIGO/Virgo/KAGRA S231231ag: Identification of a GW compact binary merger candidate
  69. GRB 231230A: Swift detection of a burst
  70. LIGO/Virgo/KAGRA S231224e: Upper limits from Swift/BAT-GUANO
  71. LIGO/Virgo/KAGRA S231226av: Updated Sky localization
  72. LIGO/Virgo/KAGRA S231226av: Identification of a GW compact binary merger candidate
  73. LIGO/Virgo/KAGRA S231224e: Updated Sky localization and Source Classification
  74. LIGO/Virgo/KAGRA S231224e: Identification of a GW compact binary merger candidate
  75. LIGO/Virgo/KAGRA S231223j: Updated Sky localization
  76. LIGO/Virgo/KAGRA S231223j: Identification of a GW compact binary merger candidate
  77. GRB 231222A: Tiled Swift observations
  78. GRB 231220A: Swift-XRT follow-up observations
  79. GRB 231220A: Swift ToO observations
  80. GRB 231216A: GAD Observatory, La Spezia, Italy upper limit
  81. GRB 231216A: optical upper limits from the INAF Asiago Observatory
  82. GRB 231215A: AMI-LA radio detection
  83. GRB 231216A: Swift detection of a burst
  84. GRB 231215A: GAD Observatory, La Spezia, Italy upper limit;
  85. GRB 231215A : OHP/T193 optical afterglow detection
  86. LIGO/Virgo/KAGRA S231215i: 3 counterpart neutrino candidate events from an IceCube neutrino search
  87. GRB 231215A : MITSuME Akeno optical afterglow candidate detection
  88. GRB 231214A: Swift detection of a burst
  89. IceCube-231211A: Upper limits from a search for additional neutrino events in IceCube
  90. LIGO/Virgo/KAGRA S231213ap: Updated Sky localization
  91. LIGO/Virgo/KAGRA S231213ap: Identification of a GW compact binary merger candidate
  92. IceCube-231211A - IceCube observation of a high-energy neutrino candidate track-like event
  93. LIGO/Virgo/KAGRA S231206cc: Upper limits from Swift/BAT-GUANO
  94. LIGO/Virgo/KAGRA S231206ca: Upper limits from Swift/BAT-GUANO
  95. IceCube-231202A: No candidates from the Zwicky Transient Facility
  96. LIGO/Virgo/KAGRA S231206ca: Updated Sky localization
  97. LIGO/Virgo/KAGRA S231206cc: Updated Sky localization and Source Classification
  98. LIGO/Virgo/KAGRA S231206cc: Identification of a GW compact binary merger candidate
  99. LIGO/Virgo/KAGRA S231206ca: Identification of a GW compact binary merger candidate
  100. LIGO/Virgo/KAGRA S231205c: One counterpart neutrino candidate event from an IceCube neutrino search

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