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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"

7296 results found.

  1. EP240413A: GOTO optical upper limits
  2. EP240414a: Kinder optical counterpart candidate possibly associated with the galaxy SDSS J124601.99-094309.3
  3. LIGO/Virgo/KAGRA S240413p: Updated Sky localization
  4. LIGO/Virgo/KAGRA S240413p: Zwicky Transient Facility observations
  5. GRB 240411B: Kinder observations with Lulin observatory
  6. LIGO/Virgo/Kagra S240413p: NED Galaxies in the Localization Volume
  7. LIGO/Virgo/KAGRA S240413p: Identification of a GW compact binary merger candidate
  8. IceCube-240412A - IceCube observation of a high-energy neutrino candidate track-like event
  9. GRB 240411B: OHP/T193 optical observations
  10. GRB 240411B: Swift detection of a burst
  11. EP240408a: GROND detection of a candidate counterpart
  12. Swift Trigger 1220736: detection of 4U 1543-62.
  13. IceCube-240327B: GRANDMA/Kilonova-Catcher observations of 4FGL J0555.9+0030 and optical upper limits
  14. LXT 240402A/GRB 240402B: GECAM-C refined analysis
  15. GRB/FXT 240402B: Kinder optical counterpart candidate
  16. IceCube-240327B: GRANDMA observations of 4FGL J0555.9+0030
  17. GRB/FXT 240402B: VLT/FORS2 optical afterglow candidate
  18. IceCube-240327B: No candidates from the Zwicky Transient Facility
  19. IceCube-240327B - IceCube observation of a high-energy neutrino candidate track-like event
  20. IceCube-240327A - IceCube observation of a high-energy neutrino candidate track-like event
  21. Transient EPW20240219aa: REM optical/NIR further observations
  22. X-ray transient EP240315a: Montarrenti Observatory optical upper limit
  23. X-ray transient EP240315a: Nanshan/HMT optical upper limit
  24. Einstein Probe detected of a fast X-ray transient EP240315a
  25. IceCube-240307A - IceCube observation of a high-energy neutrino candidate track-like event
  26. GRB 231028C: Glowbug gamma-ray confirmation of a prior burst
  27. Swift detection of Swift J151857.0-572147
  28. GRB 240303A: Swift detection of a burst
  29. IceCube-240229A - IceCube observation of a high-energy neutrino candidate track-like event
  30. GRB 240225B: Swift ToO observations
  31. GRB 240225B : MITSuME Akeno optical afterglow candidate detection
  32. GRB 240225B: 3.6m DOT observation
  33. GRB 240225B: NOT optical observations
  34. GRB 240225B: Nanshan/HMT optical afterglow detection
  35. GRB 240225B: GOTO detection of a candidate optical afterglow
  36. Transient EPW20240219aa: REM optical/NIR upper limits
  37. GRB 240225B: Tiled Swift observations
  38. Transient EPW20240219aa: upper limit in gamma-ray range from SPI-ACS/INTEGRAL observations
  39. GRB 240222A: Swift detection of a burst
  40. IPN triangulation of GRB 240209A
  41. GRB 240218A: REM detection of a NIR afterglow candidate
  42. Gamma-ray flaring activity from the blazar 1ES 1959+650 observed by the Fermi-LAT
  43. GRB 240218A : r-band upper limit from Observatoire de Haute-Provence
  44. GRB 240218A: Swift detection of a burst
  45. GRB 240215A: Tiled Swift observations
  46. GRB 240209A: Fermi GBM observation
  47. GRB240209A: OHP/T193 detection of the GOTO afterglow candidate AT2024cew / GOTO24pw
  48. GRB 240209A: Wendelstein Optical Observations
  49. GRB 240214A: Tiled Swift observations
  50. GRB 240209A: NOEMA non-detection of AT2024cew / GOTO24pw counterpart candidate
  51. GRB 240209A: NOT photometry of the AT2024cew / GOTO24pw counterpart candidate
  52. GRB 240209A: GOTO optical counterpart candidate
  53. GRB240204A: Swift/UVOT Upper Limits
  54. GRB 240205B: ATCA detection of radio counterpart
  55. GRB 240204A: Mondy optical afterglow candidate
  56. IceCube-240204A - IceCube observation of a high-energy neutrino candidate track-like event
  57. GRB 240128A: Tiled Swift observations
  58. GRB 240122A: ATCA detection of radio counterpart
  59. GRB240122A: PRIME near infrared detection
  60. GRB 240123A : MITSuME Akeno optical afterglow candidate detection
  61. GRB 240122A: Swift/UVOT Upper Limits
  62. IceCube-240123A - IceCube observation of a high-energy neutrino candidate track-like event
  63. GRB 240123A: Swift detection of a burst with a possible optical counterpart
  64. GRB 240122A: VLT/X-shooter redshift confirmation
  65. GRB 240122A: LT non-detection of GOTO candidate counterpart confirms fading
  66. GRB 240122A: GOTO optical counterpart candidate
  67. GRB 240122A: Tiled Swift observations
  68. IceCube-240105A: Detection of NIR flare of PKS 0446+11 with WINTER
  69. GRB 240118A: Swift ToO observations
  70. GRB 240118A: AbAO optical upper limit
  71. LIGO/Virgo/KAGRA S240109a: Upper limits from Swift/BAT-GUANO
  72. IceCube-240105A: ZTF optical observation of blazar PKS 0446+11
  73. GRB 240112C: Swift detection of a burst with an optical counterpart
  74. LIGO/Virgo/KAGRA S240109a: Updated Sky localization
  75. LIGO/Virgo/KAGRA S240109a: Identification of a GW compact binary merger candidate
  76. LIGO/Virgo/KAGRA S240104bl: Upper limits from Swift/BAT-GUANO
  77. Update of IceCube-240105A - Corrected errors
  78. LIGO/Virgo/KAGRA S240107b: Updated Sky localization and Source Classification
  79. LIGO/Virgo/KAGRA S240107b: Identification of a GW compact binary merger candidate
  80. GRB 240101A: 1.3m DFOT optical observations
  81. IceCube-240105A - IceCube observation of a high-energy neutrino candidate track-like event
  82. LIGO/Virgo/KAGRA S240104bl: Updated Sky localization
  83. LIGO/Virgo/KAGRA S240104bl: Identification of a GW compact binary merger candidate
  84. GRB 231220A: Swift-UVOT upper limit
  85. GRB 240101B: MarSEC Observatory, Vicenza, Italy, UPPER LIMIT
  86. GRB 240101B: KAIT Optical Upper Limit
  87. GRB 240101A: KAIT Optical Upper Limit
  88. GRB 240101B: Swift detection of a burst
  89. LIGO/Virgo/KAGRA S231231ag: Updated Sky localization and Source Classification
  90. LIGO/Virgo/KAGRA S231231ag: Identification of a GW compact binary merger candidate
  91. GRB 231230A: Swift detection of a burst
  92. LIGO/Virgo/KAGRA S231224e: Upper limits from Swift/BAT-GUANO
  93. LIGO/Virgo/KAGRA S231226av: Updated Sky localization
  94. LIGO/Virgo/KAGRA S231226av: Identification of a GW compact binary merger candidate
  95. LIGO/Virgo/KAGRA S231224e: Updated Sky localization and Source Classification
  96. LIGO/Virgo/KAGRA S231224e: Identification of a GW compact binary merger candidate
  97. LIGO/Virgo/KAGRA S231223j: Updated Sky localization
  98. LIGO/Virgo/KAGRA S231223j: Identification of a GW compact binary merger candidate
  99. GRB 231222A: Tiled Swift observations
  100. GRB 231220A: Swift-XRT follow-up observations

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