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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.

"N/A_MC170630_R1" does not adhere to advanced search syntax. Please refer to the documentation and try again.
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"

10919 results found.

  1. GRB 260401A: cubesat Avion detection
  2. The EP-WXT trigger 01709258652: Mondy optical observations
  3. GRB 250328A: VLT host galaxy discovery and redshift z = 1.250
  4. EP260416a: Mondy optical observations
  5. EP260416a: ZTSh R band observations
  6. EP250512a / GRB 250512B: VLT/X-shooter host galaxy identification and redshift z = 1.773
  7. GRB 250530A: VLT/X-shooter host galaxy redshift z = 1.486
  8. GRB 260421B: SVOM/VT optical observations
  9. GRB 260415A: CALET Gamma-Ray Burst Monitor detection
  10. GRB 260415B: CALET Gamma-Ray Burst Monitor detection
  11. GRB 260421B: VLT/X-shooter spectroscopic redshift z = 2.115
  12. EP260416a: Optical follow-up observations with Kinder
  13. GOTO26djh/AT2026jpw: CrAO and Mondy optical observations of the transient
  14. EP260416a: VLT/FORS2 spectroscopic redshift confirmation
  15. GOTO26djh/AT2026jpw: ZTSh R,I bands observations of the transient
  16. EP260416a: SVOM/VT optical observation
  17. GOTO26djh/AT2026jpw: SVOM/VT optical observation
  18. GOTO26djh/AT2026jpw transient: SAO RAS optical observations
  19. NOT r-band observations of the transient GOTO26djh/AT2026jpw
  20. EP260321a: CMO SAI J,K observations
  21. EP260321a: SVOM/VT optical observations and color changes around peak
  22. GRB 260410A: CALET Gamma-Ray Burst Monitor detection
  23. The EP-WXT trigger 01709260010 is likely a flaring star
  24. GRB 260411B: Fermi-LAT detection
  25. EP-WXT01709259790: Optical Upper limits with kinder observations
  26. EP260409a: SVOM/VT optical upper limits
  27. GRB 260407A: CALET Gamma-Ray Burst Monitor detection
  28. EP260321a: VLA radio detection
  29. EP260405a: GMOS-N optical upper limits
  30. EP260405a: SVOM/VT optical upper limits
  31. GRB 260330B: SVOM/VT further optical observation
  32. EP260403a: LCO optical observations of the counterpart
  33. GRB 260330B: SVOM/VT optical candidate
  34. GRB 260402A / EP260402a: SVOM/VT optical upper limits
  35. GRB 260401A: CALET Gamma-Ray Burst Monitor detection
  36. GRB 260401A: MAXI/GSC detection
  37. EP260329b: Mondy and Assy-Turgen optical upper limits
  38. GRB 260330B: SVOM/VT optical upper limits
  39. EP260329b: Optical follow-up with Kinder observations
  40. EP260329a: Optical upper limit with Kinder observations
  41. EP260327a: SVOM/VT optical upper limits
  42. EP260327a: Gemini-North optical upper limits
  43. GRB 260310A: OSIRIS+/GTC spectroscopic detection of the associated BL-Ic, SN 2026fgk
  44. GRB 260310A / AT2026fgk: Late-time infrared detection with MIRAGE on the MDM 1.3m telescope
  45. EP260321a: VLT/FORS2 spectroscopy confirmation of an associated type Ic-BL supernova SN 2026gzf
  46. GRB 260310A: LBT optical observations
  47. EP260321A: Mondy optical observations
  48. GRB 260316B: CALET Gamma-Ray Burst Monitor detection
  49. EP260321a / AT2026gzf: VLT/X-shooter detection of supernova-like spectral features at z = 0.0344
  50. EP260321a: Continued brightening from Kinder follow-up of the emerging supernova candidate
  51. EP260321a: VLT imaging and spectroscopy show the variable source to be at z = 0.0343
  52. EP260321a: further Kinder optical observations
  53. GRB 260321A: SVOM/VT optical upper limits
  54. EP260321a: SVOM/VT optical upper limit
  55. GRB 260310A: continued optical observation at Mondy
  56. EP260321a: Kinder observations detect a blue variable star and set limits on a source from the z =0.034 galaxy within the error circle
  57. GRB 260310A: no evidence of re-brightening up to 9.6 days in optical observation at Mondy
  58. GRB 260310A/AT2026fgk: LBT near-infrared observations
  59. GRB 260310A / AT 2026fgk: radio detection with the VLA
  60. GRB 260310A / AT2026fgk: SVOM/VT optical observations
  61. IceCube-260315A/AT2026fpm: EP-FXT follow-up observation
  62. EP260316a / GRB 260316A: SVOM/VT optical upper limits
  63. EP260316a: optical upper limit with Kinder observations
  64. EP260314a: optical upper limit with Kinder observations
  65. EP260314a: SVOM/VT optical candidate
  66. GRB 260310A / AT2026fgk: SAO RAS optical observations
  67. GRB 260310A / AT2026fgk: Multiband optical follow-up with Kinder observations
  68. GRB 260310A: NOT optical polarimetry
  69. GRB 260310A/AT 2026fgk: Bok spectroscopic observation
  70. GRB 260310A / AT2026fgk: OSIRIS+/GTC spectroscopy confirms redshift z = 0.153
  71. GRB 260307A: CALET Gamma-Ray Burst Monitor detection
  72. GRB 260312A: Swift detection of a burst
  73. GRB 260131A/B: radio detection with the VLA
  74. EP260306a: Mondy optical upper limit
  75. GRB 260208A: radio detection with the VLA
  76. GRB 260307B: SVOM/VT upper limit with X band data analysis
  77. GRB 260307B: SVOM/VT optical candidate
  78. EP260302a: SVOM/VT optical observation
  79. EP260306a: Gemini-North redshift z = 4.773
  80. EP260306a: SVOM/VT optical observation
  81. EP260302a: Gemini-South redshift z = 1.535
  82. GRB 260211A: SVOM/VT optical rebrightening at 20 days after the burst, SN candidate
  83. GRB 260303A: SVOM/VT optical observations
  84. GRB 260303A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  85. EP260227a: Mondy optical observations
  86. EP260227a: SVOM/VT optical observation
  87. GRB 260228A: SVOM/VT optical upper limits
  88. EP260227A: 3.6m DOT optical afterglow detection
  89. EP260227a: likely GTC/OSIRIS+ redshift z = 2.714
  90. EP260227a: Liverpool Telescope observations
  91. GRB 260225A: SVOM/VT optical continued observations and upper limit
  92. EP/WXT trigger 01709258681 (EP260227a?): LCO candidate afterglow
  93. GRB 260223A: 7DT detection and Medium-band SED of Afterglow
  94. EP260214a: VLT/FORS2 optical observations
  95. GRB 260226A: CALET Gamma-Ray Burst Monitor detection
  96. EP260214a: VLA 6 GHz detection
  97. GRB 260225A: SVOM/VT optical observation
  98. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) Detection of an Optical Counterpart Candidate
  99. GRB 260225A: SVOM/VT optical upper limits
  100. EP260126a: VLA 6 GHz detection

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