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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.

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

16161 results found.

  1. GRB 240414A : MITSuME Akeno optical upper limits
  2. GRB 240414A : OHP/T193 redshift determination
  3. GRB 240414A : OHP/T193 optical counterpart detection
  4. EP240408a: GSP optical upper limit
  5. GRB 240411B: CrAO/ZTSh optical observations
  6. GRB 240411B: Kinder observations with Lulin observatory
  7. GRB 240411B: 1.3m DFOT Optical observations
  8. GRB 240411B: OHP/T193 optical observations
  9. GRB 240411B: LCO optical afterglow detection
  10. EP240408A: MASTER optical observations
  11. EP240408a: GROND detection of a candidate counterpart
  12. EP240408a: BOOTES-6/DPRT optical upper limit
  13. X-ray transient EP240315a: second epoch e-MERLIN radio observations
  14. IceCube-240327B: GRANDMA/Kilonova-Catcher observations of 4FGL J0555.9+0030 and optical upper limits
  15. X-ray transient LXT 240402A: WFST optical upper limits​
  16. GRB/FXT 240402B: Kinder optical counterpart candidate
  17. IceCube-240327B: GRANDMA observations of 4FGL J0555.9+0030
  18. GRB/FXT 240402B: VLT/FORS2 optical afterglow candidate
  19. X-ray transient LXT240402A: AST3-3 optical upper limits
  20. LXT 240402A: MASTER optical observations with AGN in error-box
  21. GRB 240402B: GWAC-F50A optical upper limit
  22. X-ray transient EP240331a: Kinder optical upper limits
  23. X-ray transient EP240331A: GRANDMA-Kilonova catcher optical upper limit
  24. EP240331A: MASTER optical observations
  25. Transient EP240315a: J-band observations of AT2024eju with WIRC
  26. X-ray transient EP20240331a: MeerLICHT optical upper limits
  27. X-ray transient EP240315a: continued ATCA monitoring
  28. X-ray transient EP240315a: e-MERLIN radio observations
  29. X-ray transient EP240315a: Ondrejov D50 optical limit
  30. Transient EPW20240219aa: REM optical/NIR further observations
  31. X-ray transient EP240315a: ATCA detection of radio counterpart
  32. X-ray transient EP240315a: GTC/HiPERCAM photometry
  33. X-ray transient EP240315a: MeerKAT radio detection
  34. X-ray transient EP240315a: GTC/OSIRIS spectroscopic redshift confirmation
  35. X-ray transient EP240315a: PRIME near infrared detection
  36. X-ray transient EP240315a: 3.6 m TNG NIR detection
  37. X-ray transient EP240315a/AT2024eju: TShAO (Zeiss-1000) observatory optical upper limit
  38. X-ray transient EP240315a: EP-FXT detection of the X-ray afterglow
  39. X-ray transient EP240315a: Kitab observatory optical upper limitns
  40. X-ray transient EP240315a: Montarrenti Observatory optical upper limit
  41. X-ray transient EP240315a: orphan FXT?
  42. X-ray transient EP240315a: Kinder follow-up observations for AT 2024eju with Lulin observatory
  43. X-ray transient EP240315a: GROND J-band detection
  44. X-ray transient EP240315a: VLT/X-shooter spectroscopic redshift of z = 4.859
  45. X-ray transient EP240315a: Nanshan/HMT optical upper limit
  46. AT2024eju: followup observations with Liverpool Telescope suggest a fading transient
  47. X-ray transient EP240315a: ATLAS detection of a possible optical counterpart AT2024eju
  48. Einstein Probe detected of a fast X-ray transient EP240315a
  49. GRB240204A: VIRT optical upper limit
  50. Transient EPW20240219aa: Optical observations with LDT
  51. GRB 240225B: Swift-XRT afterglow detection
  52. GRB 240225B: further SAO RAS optical observations
  53. GRB 240225B: VLT/X-shooter redshift
  54. GRB 240225B : MITSuME Akeno optical afterglow candidate detection
  55. GRB 240225B: 3.6m DOT observation
  56. GRB 240225B: SAO RAS optical observations
  57. GRB 240225B: Mondy afterglow observations
  58. GRB 240225B: Liverpool Telescope afterglow observations
  59. Swift J1727.8-1613 (GRB 230824A): Madrona Peak Observatory - optical follow-up
  60. GRB 240225B: Liverpool Telescope optical afterglow observations
  61. GRB 240225B: NOT optical observations
  62. GRB 240225B: Nanshan/HMT optical afterglow detection
  63. GRB 240225B: Swift-XRT observations
  64. GRB 240225B: GOTO detection of a candidate optical afterglow
  65. Transient EPW20240219aa: REM optical/NIR upper limits
  66. Transient EPW20240219aa: Xinglong-2.16m optical upper limit
  67. Transient EPW20240219aa: GECKO: LOAO Optical Upper Limits
  68. Transient EPW20240219aa: 7DT Optical Upper Limits
  69. Transient EPW20240219aa: Mondy optical observations
  70. Transient EPW20240219aa: Liverpool Telescope non-detection and limiting magnitude
  71. GRB 240222A: Swift/UVOT Upper Limits
  72. GRB 240222A: REM optical and NIR early-time observations
  73. GRB 240218A: MeerLICHT upper limits
  74. IPN triangulation of GRB 240209A
  75. GRB 240218A: REM detection of a NIR afterglow candidate
  76. GRB 240209A: Classification of AT2024cew/GOTO24pw as Type Ia-pec supernova
  77. GRB 240209A: Fermi GBM observation
  78. GRB240209A: OHP/T193 detection of the GOTO afterglow candidate AT2024cew / GOTO24pw
  79. GRB 240209A: Wendelstein Optical Observations
  80. GRB 240209A: NOEMA non-detection of AT2024cew / GOTO24pw counterpart candidate
  81. GRB 240209A: NOT photometry of the AT2024cew / GOTO24pw counterpart candidate
  82. GRB 240209A: GOTO optical counterpart candidate
  83. GRB 240205B: PRIME near infrared detection
  84. GRB240204A: Swift/UVOT Upper Limits
  85. GRB 240205B: VLT/X-shooter redshift
  86. GRB 240205B: BOOTES-6 optical afterglow follow-up
  87. GRB 240205B: REM detection of the optical/NIR afterglow
  88. GRB 240204A: Mondy optical afterglow observations
  89. GRB 240204A : OHP/T193/T120 optical afterglow fading detection
  90. GRB 240205B: Skynet Optical Afterglow Observations
  91. GRB 240205B: BOOTES-7 optical afterglow follow-up
  92. GRB 240204a: Liverpool Telescope optical afterglow detection
  93. GRB 240204A: Osservatorio Astronomico Nastro Verde upper limit
  94. GRB 240204A: optical afterglow detection with LCOGT 1m telescopes at Sutherland and Teide Observatories
  95. GRB 240204A: Montarrenti Observatory optical observations
  96. GRB 240204A: Mondy optical afterglow candidate
  97. GRB240122A: PRIME near infrared detection
  98. GRB 240123A: further SAO RAS optical observations
  99. GRB 240123A: Mondy continued optical observations and the PL decay index
  100. GRB 240123A: SAO RAS optical observations

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