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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"

8474 results found.

  1. LIGO/Virgo/KAGRA S240422ed: DECam GW-MMADS Candidates
  2. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-WXT for the Three Potential Electromagnetic Counterparts Reported So Far
  3. LIGO/Virgo/KAGRA S240422ed: Magellan Detection of a Potential Electromagnetic Counterpart
  4. LIGO/Virgo/KAGRA S240422ed: SAGUARO upper limits from CSS
  5. IceCube-240419A: Upper limits from a search for additional neutrino events in IceCube
  6. LIGO/Virgo/KAGRA S240421ar: Updated Sky localization
  7. LIGO/Virgo/KAGRA S240422ed: no candidate counterparts from Pan-STARRS observations of the skymap
  8. LIGO/Virgo/KAGRA S240422ed: GOTO counterpart search
  9. LIGO/Virgo/KAGRA S240423br: Retraction of GW compact binary merger candidate
  10. LIGO/Virgo/KAGRA S240422ed: no candidate counterparts from ATLAS observations
  11. LIGO/Virgo/KAGRA S240422ed: GW-MMADS DECam observations
  12. LIGO/Virgo/KAGRA S240422ed: Magellan Observations
  13. LIGO/Virgo/KAGRA S240422ed: Updated NED Galaxies in the Localization Volume
  14. LIGO/Virgo/KAGRA S240422ed: AstroSat CZTI non-detection and upper limits
  15. LIGO/Virgo/KAGRA S240422ed: Upper limits from Fermi-GBM Observations
  16. LIGO/Virgo/KAGRA S240422ed: Updated Sky localization and EM Bright Classification
  17. LIGO/Virgo/KAGRA S240421ar: Upper limits from Swift/BAT-GUANO
  18. LIGO/Virgo/KAGRA S240422ed: Coverage and upper limits from MAXI/GSC observations
  19. LIGO/Virgo/KAGRA S240422ed: Identification of a GW compact binary merger candidate
  20. LIGO/Virgo/Kagra S240422ed: NED Galaxies in the Localization Volume
  21. GRB 240414A: radio detection with the VLA
  22. GRB 240414A: AMI-LA radio observations
  23. EP240420a: Xinglong decaying optical counterpart
  24. GRB 240421B: Swift detection of a burst
  25. EP240420a: Nanshan optical counterpart observations
  26. EP240420a: GWAC-F50A optical upper limit
  27. LIGO/Virgo/KAGRA S240421ar: Identification of a GW unmodeled transient candidate
  28. EP240420a: NOT optical counterpart candidate and potential host
  29. GRB240418A - Candidate afterglow from NIRES
  30. IceCube-240419A - IceCube observation of a high-energy neutrino candidate track-like event
  31. IceCube-240419A - IceCube observation of a high-energy neutrino candidate track-like event
  32. GRB 240419B: optical afterglow from the NOT
  33. LIGO/Virgo/KAGRA S240420aw: Retraction of GW compact binary merger candidate
  34. GRB 240419B: Swift detection of a burst
  35. GRB 240419A: Swift detection of a burst
  36. GRB 240418A: AKO Upper Limit
  37. GRB 240411A: GOTO early optical upper limits
  38. GRB 240418A: Swift detection of a burst
  39. LIGO/Virgo/KAGRA S240413p: X-ray upper limits from EP-WXT for the candidate AGN counterpart
  40. EP240414a: GSP detects optical candidate counterpart AT2024gsa
  41. LIGO/Virgo/KAGRA S240413p: DECam GW-MMADS candidates
  42. IceCube-Cascade 240416A: Upper limits from a search for additional neutrino events in IceCube
  43. EP240414a: Pan-STARRS detects re-brightening of the candidate counterpart AT2024gsa
  44. LIGO/Virgo/KAGRA S240413p: historical ATLAS and ZTF observations of the candidate AGN counterpart
  45. LIGO/Virgo/KAGRA S240413p: STEP - T80S Search and Candidate Counterpart Identification
  46. EP 240416a: Xinglong and NOT decaying optical counterpart
  47. EP240416a: Kinder optical counterpart candidate
  48. GRB 240414A: GAD Observatory, La Spezia, Italy ,upper limit
  49. GRB 240415A: Earliest optical followup with the Kinder observations
  50. GRB 240415B: Swift ToO observations
  51. GRB 240415A: OHP/T193 optical observations
  52. IceCube-240412A: Upper limits from a search for additional neutrino events in IceCube
  53. X-ray transient EP 240414a - GTC spectroscopic observations
  54. EP 240414a: NOT optical counterpart confirmation
  55. GRB 240414A : OHP/T193 second epoch of optical follow-up and afterglow detection
  56. GRB 240414A: MarSEC Observatory, Vicenza, Italy, UPPER LIMIT
  57. EP240413A: GOTO optical upper limits
  58. EP240414a: Kinder optical counterpart candidate possibly associated with the galaxy SDSS J124601.99-094309.3
  59. LIGO/Virgo/KAGRA S240413p: Updated Sky localization
  60. GRB 240411B: Kinder observations with Lulin observatory
  61. LIGO/Virgo/Kagra S240413p: NED Galaxies in the Localization Volume
  62. LIGO/Virgo/KAGRA S240413p: Identification of a GW compact binary merger candidate
  63. IceCube-240412A - IceCube observation of a high-energy neutrino candidate track-like event
  64. GRB 240411B: OHP/T193 optical observations
  65. GRB 240411B: Swift detection of a burst
  66. EP240408a: GROND detection of a candidate counterpart
  67. IceCube-240327B: GRANDMA/Kilonova-Catcher observations of 4FGL J0555.9+0030 and optical upper limits
  68. GRB/FXT 240402B: Kinder optical counterpart candidate
  69. IceCube-240327B: GRANDMA observations of 4FGL J0555.9+0030
  70. GRB/FXT 240402B: VLT/FORS2 optical afterglow candidate
  71. IceCube-240327B: Upper limits from a search for additional neutrino events in IceCube
  72. IceCube-240327A: Upper limits from a search for additional neutrino events in IceCube
  73. IceCube-240327B: No candidates from the Zwicky Transient Facility
  74. IceCube-240327B - IceCube observation of a high-energy neutrino candidate track-like event
  75. IceCube-240327A - IceCube observation of a high-energy neutrino candidate track-like event
  76. Transient EPW20240219aa: REM optical/NIR further observations
  77. X-ray transient EP240315a: Montarrenti Observatory optical upper limit
  78. X-ray transient EP240315a: VLT/X-shooter spectroscopic redshift of z = 4.859
  79. X-ray transient EP240315a: Nanshan/HMT optical upper limit
  80. Einstein Probe detected of a fast X-ray transient EP240315a
  81. IceCube-240307A: Upper limits from a search for additional neutrino events in IceCube
  82. GRB 231215A: further radio observations with the VLA
  83. IceCube-240307A - IceCube observation of a high-energy neutrino candidate track-like event
  84. GRB 231028C: Glowbug gamma-ray confirmation of a prior burst
  85. Swift detection of Swift J151857.0-572147
  86. GRB 240303A: Swift detection of a burst
  87. IceCube-240229A: Upper limits from a search for additional neutrino events in IceCube
  88. IceCube-240229A - IceCube observation of a high-energy neutrino candidate track-like event
  89. GRB 240225B: Swift ToO observations
  90. GRB 240225B : MITSuME Akeno optical afterglow candidate detection
  91. GRB 240225B: 3.6m DOT observation
  92. GRB 240225B: NOT optical observations
  93. Swift-BAT triggers 1217729-1217732 are not astrophysical
  94. GRB 240225B: Nanshan/HMT optical afterglow detection
  95. GRB 240225B: GOTO detection of a candidate optical afterglow
  96. Transient EPW20240219aa: REM optical/NIR upper limits
  97. GRB 240225B: Tiled Swift observations
  98. Swift-BAT triggers 1217218-1217222 are not astrophysical
  99. Transient EPW20240219aa: upper limit in gamma-ray range from SPI-ACS/INTEGRAL observations
  100. Swift-BAT triggers 1216907-1216911 are not astrophysical

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