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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"

7445 results found.

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

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