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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"

16158 results found.

  1. EP251222a: FTW optical and NIR observations
  2. GRB 251205A: Kilonova-Catcher optical afterglow detection
  3. GRB 251222A: AbAO optical observations
  4. GRB 251222A / EP251222b: Kilonova-Catcher optical afterglow detection
  5. GRB 251129A / EP251129a: VLA detection of a radio counterpart
  6. EP251222a: VLT/FORS2 spectroscopic redshift z = 0.505
  7. GRB 251222A: ZTSH BVRI optical observations
  8. GRB 251222A: SVOM/COLIBRÍ (FM-GFT) optical observations
  9. GRB 251222A: Continued 1.3m DFOT optical observation
  10. EP251220a: 3.6m DOT optical afterglow detection
  11. EP251220a: CrAO ZTSh optical observations
  12. EP251221a: Liverpool Telescope upper limits
  13. GRB 251222A / EP251222b: LCO detection of the optical counterpart
  14. EP251222a: NTT/ULTRACAM optical observations
  15. EP251222a: GOTO optical upper limit
  16. GRB 251222A / EP251222b: GOTO optical counterpart detection
  17. GRB 251222A / EP251222b: LCO optical observations
  18. GRB 251222A: 1.3m DFOT optical detection
  19. GRB251221A: 7DT optical upper limits
  20. EP251222a: GSP Optical Counterpart Detection
  21. GRB 251222A / EP251222b: VLT/X-shooter spectroscopic redshift z = 3.171
  22. GRB 251222A / EP251222b: SVOM/VT optical rebrightening
  23. EP251222b/GRB 251222A: SVOM/GRM observation
  24. GRB 251222A: PRIME near-infrared detection
  25. EP251221a: NOT optical upper limit
  26. GRB 251222A: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  27. GRB 251222A: NOT optical observations
  28. GRB 251222A: SVOM/VT optical candidate
  29. EP251220a: PRIME upper limit
  30. EP251220a: VLT/FORS2 spectroscopic redshift z = 2.375
  31. EP251220a: NOT optical observations
  32. EP251220a: FTW optical and NIR observations
  33. GRB 251221A: UAFO and Mondy optical upper limit
  34. GRB 251221A: Swift/UVOT Upper Limits
  35. GRB 251220B: SVOM/GRM observation of a short burst
  36. EP 251220a: GOTO optical counterpart detection
  37. GRB 251221A: COLIBRÍ detection of the optical counterpart
  38. EP 251220a: COLIBRÍ detection of the optical counterpart
  39. GRB 251219A: SVOM/GRM observation of a short burst
  40. IceCube-251218A: COLIBRÍ optical upper limits
  41. GRB 251214B: VIRT Optical Upper Limit
  42. GRB 251215A: Swift/UVOT Upper LImits
  43. GRB 251202A/EP251202a: Koshka optical upper limit
  44. GRB 251214B: Mondy optical upper limit
  45. GRB 251215A: COLIBRÍ optical upper limit
  46. EP251214b: KAIT optical upper limit
  47. EP251214a: Optical upper limit with Kinder observations
  48. GRB 251214B: 1.6m Mephisto observations with newly installed mosaic cameras
  49. GRB 251214B: UAFO optical upper limit
  50. GRB 251214B: VLT/X-shooter observations
  51. GRB 251202A: radio detection with the VLA
  52. GRB 251214B: AbAO optical observations
  53. GRB 251214B: LCO detection of the optical counterpart
  54. EP251214b (EP trigger 01709250023): LCO optical limits
  55. GRB 251203B: AbAO optical observations
  56. GRB 251213A: SVOM/GRM observation
  57. EP251214a: KAIT optical upper limit
  58. GRB 251214B: Swift/UVOT Detection
  59. GRB 251214B: 1.3m DFOT optical detection
  60. GRB 251214B: Xinglong-2.16m optical observation
  61. GRB 251214B : MASTER optical afterglow detection
  62. GRB 251214B: SVOM/C-GFT optical observations
  63. EP251214a: COLIBRÍ optical upper limit
  64. EP251214.305: COLIBRÍ optical upper limit
  65. GRB 251214B: Swift detection of a burst with an optical counterpart
  66. EP251212a: KAIT optical upper limit
  67. EP251212a : COLIBRÍ optical upper limit
  68. IceCube-251210A: DDOTI Optical Upper Limit
  69. GRB 251205A: 1.3m DFOT optical upper limit
  70. EP251124a: Mondy optical upper limit
  71. GRB 251129A/EP251129a: AbAO and Mondy optical observations
  72. EP251130a: Mondy and AbAO optical observations
  73. GRB 251208B: COLIBRÍ optical upper limits
  74. EP251118a / GRB 251118C: VLT/MUSE redshift confirmation
  75. GRB 251206A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  76. GRB 251208D: LAST optical upper limit
  77. GRB 251208B: GROWTH-India Telescope optical upper limits
  78. GRB 251205A: J-band detection with WINTER
  79. GRB 251208A: SVOM/GRM observation of a short burst
  80. GRB 251208C: SVOM/GRM observation of a short burst
  81. GRB 251129A: e-MERLIN C-band observations
  82. GRB 251205A: Liverpool Telescope further optical follow-up observations
  83. GRB 251208D: LCO optical upper limits
  84. GRB 251205A : MITSuME Akeno optical afterglow candidate detection
  85. GRB 251205A: FTW optical and NIR observations
  86. GRB 251205A: Liverpool Telescope further optical follow-up observations
  87. GRB 251205A: ZTF and ATLAS optical afterglow detections
  88. GRB 251205A: GROWTH-India Telescope optical observations
  89. GRB 251205A: Liverpool Telescope optical follow-up observations
  90. GRB 251203C: Swift/UVOT Upper Limit
  91. GRB 251205A: Zeiss-1000 Koshka observatory optical observations
  92. GRB 251205A: COLIBRÍ optical observations
  93. GRB 251205A: GOTO optical afterglow detection
  94. GRB 251205A: NOT optical observations
  95. GRB 251205A: GTC/OSIRIS+ redshift z = 1.100
  96. Swift GRB 251205A : MASTER OT detection with host galaxy
  97. GRB 251205A: Swift detection of a burst with an optical afterglow
  98. SVOM/sb25120502: SVOM detection of a faint X-ray transient candidate
  99. GRB 251202A / EP251202a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm and 1-m telescopes at McDonald Observatory
  100. GRB 251203C: SVOM/COLIBRÍ (FM-GFT) optical upper limit

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