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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').
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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.

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subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

7444 results found.

  1. LIGO/Virgo/KAGRA S240421ar: Updated Sky localization
  2. LIGO/Virgo/KAGRA S240422ed: no candidate counterparts from Pan-STARRS observations of the skymap
  3. LIGO/Virgo/KAGRA S240422ed: GOTO counterpart search
  4. LIGO/Virgo/KAGRA S240423br: Retraction of GW compact binary merger candidate
  5. LIGO/Virgo/KAGRA S240422ed: no candidate counterparts from ATLAS observations
  6. LIGO/Virgo S240422ed: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  7. LIGO/Virgo/KAGRA S240422ed: GW-MMADS DECam observations
  8. LIGO/Virgo/KAGRA S240422ed: Magellan Observations
  9. LIGO/Virgo/KAGRA S240422ed: Updated NED Galaxies in the Localization Volume
  10. LIGO/Virgo/KAGRA S240422ed: AstroSat CZTI non-detection and upper limits
  11. LIGO/Virgo/KAGRA S240422ed: Upper limits from Fermi-GBM Observations
  12. LIGO/Virgo/KAGRA S240422ed: Updated Sky localization and EM Bright Classification
  13. LIGO/Virgo/KAGRA S240421ar: Upper limits from Swift/BAT-GUANO
  14. LIGO/Virgo/KAGRA S240422ed: Coverage and upper limits from MAXI/GSC observations
  15. LIGO/Virgo/KAGRA S240422ed: Identification of a GW compact binary merger candidate
  16. LIGO/Virgo/Kagra S240422ed: NED Galaxies in the Localization Volume
  17. GRB 240414A: AMI-LA radio observations
  18. EP240420a: Xinglong decaying optical counterpart
  19. GRB 240421B: Swift detection of a burst
  20. EP240420a: Nanshan optical counterpart observations
  21. EP240420a: GWAC-F50A optical upper limit
  22. LIGO/Virgo/KAGRA S240421ar: Identification of a GW unmodeled transient candidate
  23. EP240420a: NOT optical counterpart candidate and potential host
  24. GRB240418A - Candidate afterglow from NIRES
  25. IceCube-240419A - IceCube observation of a high-energy neutrino candidate track-like event
  26. IceCube-240419A - IceCube observation of a high-energy neutrino candidate track-like event
  27. LIGO/Virgo/KAGRA S240420aw: Retraction of GW compact binary merger candidate
  28. GRB 240419B: Swift detection of a burst
  29. GRB 240419A: Swift detection of a burst
  30. GRB 240418A: AKO Upper Limit
  31. GRB 240411A: GOTO early optical upper limits
  32. GRB 240418A: Swift detection of a burst
  33. LIGO/Virgo/KAGRA S240413p: X-ray upper limits from EP-WXT for the candidate AGN counterpart
  34. EP240414a: GSP detects optical candidate counterpart AT2024gsa
  35. LIGO/Virgo/KAGRA S240413p: DECam GW-MMADS candidates
  36. EP240414a: Pan-STARRS detects re-brightening of the candidate counterpart AT2024gsa
  37. LIGO/Virgo/KAGRA S240413p: historical ATLAS and ZTF observations of the candidate AGN counterpart
  38. LIGO/Virgo/KAGRA S240413p: STEP - T80S Search and Candidate Counterpart Identification
  39. EP 240416a: Xinglong and NOT decaying optical counterpart
  40. EP240416a: Kinder optical counterpart candidate
  41. GRB 240414A: GAD Observatory, La Spezia, Italy ,upper limit
  42. GRB 240415A: Earliest optical followup with the Kinder observations
  43. GRB 240415B: Swift ToO observations
  44. GRB 240415A: OHP/T193 optical observations
  45. X-ray transient EP 240414a - GTC spectroscopic observations
  46. EP 240414a: NOT optical counterpart confirmation
  47. GRB 240414A : OHP/T193 second epoch of optical follow-up and afterglow detection
  48. GRB 240414A: MarSEC Observatory, Vicenza, Italy, UPPER LIMIT
  49. EP240413A: GOTO optical upper limits
  50. EP240414a: Kinder optical counterpart candidate possibly associated with the galaxy SDSS J124601.99-094309.3
  51. LIGO/Virgo/KAGRA S240413p: Updated Sky localization
  52. LIGO/Virgo/KAGRA S240413p: Zwicky Transient Facility observations
  53. GRB 240411B: Kinder observations with Lulin observatory
  54. LIGO/Virgo/Kagra S240413p: NED Galaxies in the Localization Volume
  55. LIGO/Virgo/KAGRA S240413p: Identification of a GW compact binary merger candidate
  56. IceCube-240412A - IceCube observation of a high-energy neutrino candidate track-like event
  57. GRB 240411B: OHP/T193 optical observations
  58. GRB 240411B: Swift detection of a burst
  59. EP240408a: GROND detection of a candidate counterpart
  60. Swift Trigger 1220736: detection of 4U 1543-62.
  61. IceCube-240327B: GRANDMA/Kilonova-Catcher observations of 4FGL J0555.9+0030 and optical upper limits
  62. LXT 240402A/GRB 240402B: GECAM-C refined analysis
  63. GRB/FXT 240402B: Kinder optical counterpart candidate
  64. IceCube-240327B: GRANDMA observations of 4FGL J0555.9+0030
  65. GRB/FXT 240402B: VLT/FORS2 optical afterglow candidate
  66. IceCube-240327B: No candidates from the Zwicky Transient Facility
  67. IceCube-240327B - IceCube observation of a high-energy neutrino candidate track-like event
  68. IceCube-240327A - IceCube observation of a high-energy neutrino candidate track-like event
  69. Transient EPW20240219aa: REM optical/NIR further observations
  70. X-ray transient EP240315a: Montarrenti Observatory optical upper limit
  71. X-ray transient EP240315a: Nanshan/HMT optical upper limit
  72. Einstein Probe detected of a fast X-ray transient EP240315a
  73. IceCube-240307A - IceCube observation of a high-energy neutrino candidate track-like event
  74. GRB 231028C: Glowbug gamma-ray confirmation of a prior burst
  75. Swift detection of Swift J151857.0-572147
  76. GRB 240303A: Swift detection of a burst
  77. IceCube-240229A - IceCube observation of a high-energy neutrino candidate track-like event
  78. GRB 240225B: Swift ToO observations
  79. GRB 240225B : MITSuME Akeno optical afterglow candidate detection
  80. GRB 240225B: 3.6m DOT observation
  81. GRB 240225B: NOT optical observations
  82. GRB 240225B: Nanshan/HMT optical afterglow detection
  83. GRB 240225B: GOTO detection of a candidate optical afterglow
  84. Transient EPW20240219aa: REM optical/NIR upper limits
  85. GRB 240225B: Tiled Swift observations
  86. Transient EPW20240219aa: upper limit in gamma-ray range from SPI-ACS/INTEGRAL observations
  87. GRB 240222A: Swift detection of a burst
  88. IPN triangulation of GRB 240209A
  89. GRB 240218A: REM detection of a NIR afterglow candidate
  90. Gamma-ray flaring activity from the blazar 1ES 1959+650 observed by the Fermi-LAT
  91. GRB 240218A : r-band upper limit from Observatoire de Haute-Provence
  92. GRB 240218A: Swift detection of a burst
  93. GRB 240215A: Tiled Swift observations
  94. GRB 240209A: Fermi GBM observation
  95. GRB240209A: OHP/T193 detection of the GOTO afterglow candidate AT2024cew / GOTO24pw
  96. GRB 240209A: Wendelstein Optical Observations
  97. GRB 240214A: Tiled Swift observations
  98. GRB 240209A: NOEMA non-detection of AT2024cew / GOTO24pw counterpart candidate
  99. GRB 240209A: NOT photometry of the AT2024cew / GOTO24pw counterpart candidate
  100. GRB 240209A: GOTO optical counterpart candidate

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