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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"

15985 results found.

  1. GRB 251230A/EP#01709250693 (likely EP251230a): FTW optical and NIR observations
  2. The EP-WXT trigger 01709250693/GRB 251230A: Las Cumbres detection of the optical counterpart
  3. GRB 251230A: Swift detection of a burst with a bright optical counterpart
  4. GRB 251222A/EP251222b: 1.6m Mephisto optical followup
  5. GRB 251129A: redshift correction and SN detection at z = 0.505 with GTC
  6. GRB 251226A: SVOM/GRM observation
  7. GRB 251222A: NUTTelA-TAO Early Measurements
  8. GRB 251222A/EP251222b: Optical detection with Kinder observations
  9. EP251222a: Optical upper limit with Kinder observations
  10. GRB 251222A/EP251222b: FTW optical and NIR observations
  11. EP251222a: FTW optical and NIR observations
  12. GRB 251205A: Kilonova-Catcher optical afterglow detection
  13. GRB 251222A: AbAO optical observations
  14. GRB 251222A / EP251222b: Kilonova-Catcher optical afterglow detection
  15. GRB 251129A / EP251129a: VLA detection of a radio counterpart
  16. EP251222a: VLT/FORS2 spectroscopic redshift z = 0.505
  17. GRB 251222A: ZTSH BVRI optical observations
  18. GRB 251222A: SVOM/COLIBRÍ (FM-GFT) optical observations
  19. GRB 251222A: Continued 1.3m DFOT optical observation
  20. EP251220a: 3.6m DOT optical afterglow detection
  21. EP251220a: CrAO ZTSh optical observations
  22. EP251221a: Liverpool Telescope upper limits
  23. GRB 251222A / EP251222b: LCO detection of the optical counterpart
  24. EP251222a: NTT/ULTRACAM optical observations
  25. EP251222a: GOTO optical upper limit
  26. GRB 251222A / EP251222b: GOTO optical counterpart detection
  27. GRB 251222A / EP251222b: LCO optical observations
  28. GRB 251222A: 1.3m DFOT optical detection
  29. GRB251221A: 7DT optical upper limits
  30. EP251222a: GSP Optical Counterpart Detection
  31. GRB 251222A / EP251222b: VLT/X-shooter spectroscopic redshift z = 3.171
  32. GRB 251222A / EP251222b: SVOM/VT optical rebrightening
  33. EP251222b/GRB 251222A: SVOM/GRM observation
  34. GRB 251222A: PRIME near-infrared detection
  35. EP251221a: NOT optical upper limit
  36. GRB 251222A: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  37. GRB 251222A: NOT optical observations
  38. GRB 251222A: SVOM/VT optical candidate
  39. EP251220a: PRIME upper limit
  40. EP251220a: VLT/FORS2 spectroscopic redshift z = 2.375
  41. EP251220a: NOT optical observations
  42. EP251220a: FTW optical and NIR observations
  43. GRB 251221A: UAFO and Mondy optical upper limit
  44. GRB 251221A: Swift/UVOT Upper Limits
  45. GRB 251220B: SVOM/GRM observation of a short burst
  46. EP 251220a: GOTO optical counterpart detection
  47. GRB 251221A: COLIBRÍ detection of the optical counterpart
  48. EP 251220a: COLIBRÍ detection of the optical counterpart
  49. GRB 251219A: SVOM/GRM observation of a short burst
  50. IceCube-251218A: COLIBRÍ optical upper limits
  51. GRB 251214B: VIRT Optical Upper Limit
  52. GRB 251215A: Swift/UVOT Upper LImits
  53. GRB 251202A/EP251202a: Koshka optical upper limit
  54. GRB 251214B: Mondy optical upper limit
  55. GRB 251215A: COLIBRÍ optical upper limit
  56. EP251214b: KAIT optical upper limit
  57. EP251214a: Optical upper limit with Kinder observations
  58. GRB 251214B: 1.6m Mephisto observations with newly installed mosaic cameras
  59. GRB 251214B: UAFO optical upper limit
  60. GRB 251214B: VLT/X-shooter observations
  61. GRB 251202A: radio detection with the VLA
  62. GRB 251214B: AbAO optical observations
  63. GRB 251214B: LCO detection of the optical counterpart
  64. EP251214b (EP trigger 01709250023): LCO optical limits
  65. GRB 251203B: AbAO optical observations
  66. GRB 251213A: SVOM/GRM observation
  67. EP251214a: KAIT optical upper limit
  68. GRB 251214B: Swift/UVOT Detection
  69. GRB 251214B: 1.3m DFOT optical detection
  70. GRB 251214B: Xinglong-2.16m optical observation
  71. GRB 251214B : MASTER optical afterglow detection
  72. GRB 251214B: SVOM/C-GFT optical observations
  73. EP251214a: COLIBRÍ optical upper limit
  74. EP251214.305: COLIBRÍ optical upper limit
  75. GRB 251214B: Swift detection of a burst with an optical counterpart
  76. EP251212a: KAIT optical upper limit
  77. EP251212a : COLIBRÍ optical upper limit
  78. IceCube-251210A: DDOTI Optical Upper Limit
  79. GRB 251205A: 1.3m DFOT optical upper limit
  80. EP251124a: Mondy optical upper limit
  81. GRB 251129A/EP251129a: AbAO and Mondy optical observations
  82. EP251130a: Mondy and AbAO optical observations
  83. GRB 251208B: COLIBRÍ optical upper limits
  84. EP251118a / GRB 251118C: VLT/MUSE redshift confirmation
  85. GRB 251206A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  86. GRB 251208D: LAST optical upper limit
  87. GRB 251208B: GROWTH-India Telescope optical upper limits
  88. GRB 251205A: J-band detection with WINTER
  89. GRB 251208A: SVOM/GRM observation of a short burst
  90. GRB 251208C: SVOM/GRM observation of a short burst
  91. GRB 251205A: Liverpool Telescope further optical follow-up observations
  92. GRB 251208D: LCO optical upper limits
  93. GRB 251205A : MITSuME Akeno optical afterglow candidate detection
  94. GRB 251205A: FTW optical and NIR observations
  95. GRB 251205A: Liverpool Telescope further optical follow-up observations
  96. GRB 251205A: ZTF and ATLAS optical afterglow detections
  97. GRB 251205A: GROWTH-India Telescope optical observations
  98. GRB 251205A: Liverpool Telescope optical follow-up observations
  99. GRB 251203C: Swift/UVOT Upper Limit
  100. GRB 251205A: Zeiss-1000 Koshka observatory optical observations

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