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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"

8480 results found.

  1. GRB 240225B: GOTO detection of a candidate optical afterglow
  2. Transient EPW20240219aa: REM optical/NIR upper limits
  3. GRB 240225B: Tiled Swift observations
  4. Swift-BAT triggers 1217218-1217222 are not astrophysical
  5. Transient EPW20240219aa: upper limit in gamma-ray range from SPI-ACS/INTEGRAL observations
  6. Swift-BAT triggers 1216907-1216911 are not astrophysical
  7. Fermi GBM Sub-Threshold Detection of EPW20240219aa as a likely GRB
  8. GRB 240222A: Swift detection of a burst
  9. Swift-BAT triggers 1216743-1216748 are not astrophysical
  10. IPN triangulation of GRB 240209A
  11. GRB 240218A: REM detection of a NIR afterglow candidate
  12. Gamma-ray flaring activity from the blazar 1ES 1959+650 observed by the Fermi-LAT
  13. GRB 240218A : r-band upper limit from Observatoire de Haute-Provence
  14. GRB 240218A: Swift detection of a burst
  15. GRB 240215A: Tiled Swift observations
  16. GRB 240209A: Fermi GBM observation
  17. GRB240209A: OHP/T193 detection of the GOTO afterglow candidate AT2024cew / GOTO24pw
  18. GRB 240209A: Wendelstein Optical Observations
  19. GRB 240214A: Tiled Swift observations
  20. GRB 240214A/1H 0451-560: MAXI/GSC detection
  21. GRB 240209A: NOEMA non-detection of AT2024cew / GOTO24pw counterpart candidate
  22. GRB 240209A: NOT photometry of the AT2024cew / GOTO24pw counterpart candidate
  23. GRB 240209A: GOTO optical counterpart candidate
  24. GRB240204A: Swift/UVOT Upper Limits
  25. GRB 240205B: ATCA detection of radio counterpart
  26. IceCube-240204A: Upper limits from a search for additional neutrino events in IceCube
  27. GRB 240204A: Mondy optical afterglow candidate
  28. IceCube-240204A - IceCube observation of a high-energy neutrino candidate track-like event
  29. Swift-BAT triggers 1212787, 1212789 are not astrophysical.
  30. GRB 240128A: Tiled Swift observations
  31. GRB 240122A: ATCA detection of radio counterpart
  32. IceCube-240123A: Upper limits from a search for additional neutrino events in IceCube
  33. Swift Trigger 1211211 and 1211212 are not astrophysical
  34. GRB240122A: PRIME near infrared detection
  35. Swift trigger 1210856 is not astrophysical
  36. GRB 240123A : MITSuME Akeno optical afterglow candidate detection
  37. Fermi/GBM trigger 727752941: BALROG analysis retraction
  38. GRB 240122A: Swift/UVOT Upper Limits
  39. Fermi GBM Sub-Threshold Detection of GRB 240123A
  40. IceCube-240123A - IceCube observation of a high-energy neutrino candidate track-like event
  41. GRB 240123A: Swift detection of a burst with a possible optical counterpart
  42. GRB 240122A: VLT/X-shooter redshift confirmation
  43. GRB 240122A: LT non-detection of GOTO candidate counterpart confirms fading
  44. GRB 240122A: GOTO optical counterpart candidate
  45. GRB 240122A: Tiled Swift observations
  46. IceCube-240105A: Detection of NIR flare of PKS 0446+11 with WINTER
  47. GRB 240118A: Swift ToO observations
  48. GRB 240118A: AbAO optical upper limit
  49. Swift Trigger 1209406 is not an astrophysical event
  50. LIGO/Virgo/KAGRA S240109a: Upper limits from Swift/BAT-GUANO
  51. IceCube-240105A: ZTF optical observation of blazar PKS 0446+11
  52. GRB 240112C: Swift detection of a burst with an optical counterpart
  53. IceCube-240105A: Upper limits from a search for additional neutrino events in IceCube
  54. LIGO/Virgo/KAGRA S240109a: Updated Sky localization
  55. GRB 231215A: radio detection with the VLA
  56. GRB 230818A: further radio observations with the VLA
  57. GRB 230812B: further radio observations with the VLA
  58. LIGO/Virgo/KAGRA S240109a: Identification of a GW compact binary merger candidate
  59. LIGO/Virgo/KAGRA S240104bl: Upper limits from Swift/BAT-GUANO
  60. Update of IceCube-240105A - Corrected errors
  61. LIGO/Virgo/KAGRA S240107b: Updated Sky localization and Source Classification
  62. LIGO/Virgo/KAGRA S240107b: Identification of a GW compact binary merger candidate
  63. GRB 240101A: 1.3m DFOT optical observations
  64. IceCube-240105A - IceCube observation of a high-energy neutrino candidate track-like event
  65. LIGO/Virgo/KAGRA S240104bl: Updated Sky localization
  66. LIGO/Virgo/KAGRA S240104bl: Identification of a GW compact binary merger candidate
  67. GRB 231220A: Swift-UVOT upper limit
  68. GRB 240101B: MarSEC Observatory, Vicenza, Italy, UPPER LIMIT
  69. IceCube-Cascade 231230A: Upper limits from a search for additional neutrino events in IceCube
  70. GRB 240101B: KAIT Optical Upper Limit
  71. GRB 240101A: KAIT Optical Upper Limit
  72. GRB 240101B: Swift detection of a burst
  73. LIGO/Virgo/KAGRA S231231ag: Updated Sky localization and Source Classification
  74. LIGO/Virgo/KAGRA S231231ag: Identification of a GW compact binary merger candidate
  75. GRB 231230A: Swift detection of a burst
  76. LIGO/Virgo/KAGRA S231224e: Upper limits from Swift/BAT-GUANO
  77. LIGO/Virgo/KAGRA S231226av: Updated Sky localization
  78. LIGO/Virgo/KAGRA S231226av: Identification of a GW compact binary merger candidate
  79. LIGO/Virgo/KAGRA S231224e: Updated Sky localization and Source Classification
  80. LIGO/Virgo/KAGRA S231224e: Identification of a GW compact binary merger candidate
  81. LIGO/Virgo/KAGRA S231223j: Updated Sky localization
  82. LIGO/Virgo/KAGRA S231223j: Identification of a GW compact binary merger candidate
  83. GRB 231222A: Tiled Swift observations
  84. GRB 231220A: Swift-XRT follow-up observations
  85. GRB 231220A: Swift ToO observations
  86. GRB 231216A: GAD Observatory, La Spezia, Italy upper limit
  87. GRB 231216A: optical upper limits from the INAF Asiago Observatory
  88. GRB 231215A: AMI-LA radio detection
  89. GRB 231216A: Swift detection of a burst
  90. GRB 231215A: GAD Observatory, La Spezia, Italy upper limit;
  91. GRB 231215A : OHP/T193 optical afterglow detection
  92. LIGO/Virgo/KAGRA S231215i: 3 counterpart neutrino candidate events from an IceCube neutrino search
  93. GRB 231215A : MITSuME Akeno optical afterglow candidate detection
  94. GRB 231214A: Swift detection of a burst
  95. IceCube-231211A: Upper limits from a search for additional neutrino events in IceCube
  96. LIGO/Virgo/KAGRA S231213ap: Updated Sky localization
  97. LIGO/Virgo/KAGRA S231213ap: Identification of a GW compact binary merger candidate
  98. IceCube-231211A - IceCube observation of a high-energy neutrino candidate track-like event
  99. LIGO/Virgo/KAGRA S231206cc: Upper limits from Swift/BAT-GUANO
  100. LIGO/Virgo/KAGRA S231206ca: Upper limits from Swift/BAT-GUANO

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