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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"

32542 results found.

  1. Fermi-LAT Gamma-ray Observations of IceCube-260807A
  2. IceCube-260821A: Upper limits from a search for additional neutrino events in IceCube
  3. GRB 260818B: VLA radio observations
  4. GRB 260818B: SVOM/C-GFT optical upper limit
  5. EP260731a: SVOM/ECLAIRs detection through offline targeted search
  6. GRB 260820A: Insight-HXMT/HE detection
  7. IceCube-260821A - IceCube observation of a high-energy neutrino candidate track-like event
  8. GRB 260818B: SVOM/GRM observation
  9. GRB 260818B: Insight-HXMT detection
  10. GRB 260818B: EP-FXT follow-up observation
  11. GRB 260818A: J-band observations with WINTER
  12. GRB 260818B: SVOM/ECLAIRs refined analysis
  13. GRB 260818A: SVOM/ECLAIRs refined analysis
  14. GRB 260818B: NOT optical upper limits
  15. GRB 260810A: SVOM/GRM observation
  16. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  17. GRB260818A: EP-FXT follow-up observation
  18. GRB 260818B: LCO optical upper limits
  19. EP260806a: SAO RAS multicolor optical observations
  20. GRB 260818A: LCO optical upper limits
  21. EP260812a: AbAO optical upper limit
  22. GRB 260818A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  23. GRB 260810A: Insight-HXMT/HE detection
  24. EP260806a: SVOM/ECLAIRs detection through targeted search
  25. EP260806a: NUTTELA-TAO optical observations
  26. EP260812a: AZT-22 optical upper limit
  27. EP260812b: GTC/OSIRIS+ tentative spectroscopic redshift z = 2.034
  28. EP260806a: WFST optical observations
  29. EP260812b: Optical upper limit with Kinder
  30. GRB 260805D: SVOM/GRM detection of a possible magnetar burst
  31. GRB 260808B: Liverpool Telescope further optical observations
  32. GRB 260808B: GTC/OSIRIS+ spectroscopic redshift z = 1.295
  33. EP260812a: NOT and Liverpool Telescope upper limits:
  34. EP260812b: Liverpool Telescope observations
  35. EP260812b: GOTO detection of the optical counterpart
  36. EP260812a: refined analysis of the EP-WXT and autonomous EP-FXT observation
  37. EP260812a: SVOM/C-GFT optical upper limit
  38. EP260812b: COLIBRÍ optical observations
  39. EP260812b: SVOM/VT optical observation
  40. GRB 260808A: SVOM/GRM observation
  41. EP260812b: Einstein Probe detection of an X-ray transient
  42. Fermi GBM Sub-Threshold Detection of GRB 260809A
  43. GRB 260810A: Glowbug gamma-ray detection
  44. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical rebrightening
  45. GRB 260809A: SAO RAS optical observations
  46. GRB 260808B: SAO RAS optical observations
  47. GRB 260808B: SVOM/VT optical re-brightening at day 3
  48. GRB 260317A: SVOM/ECLAIRs detection through offline targeted search and its possible association to magnetar 1E 1841-04.5
  49. GRB 260806A: CALET Gamma-Ray Burst Monitor detection
  50. GRB 260808A: GECAM-B observation
  51. GRB 260807A: SVOM/ECLAIRs refined analysis
  52. EP260806a: MAO/AZT-22 optical observations
  53. IceCube-260807A: Upper limits from a search for additional neutrino events in IceCube
  54. GRB260808B: MAO/AZT-22 optical observations
  55. GRB 250607A: SVOM/ECLAIRs detection through offline targeted search
  56. GRB 260809A: J-band upper limit with WINTER
  57. EP260809a: VLT/X-shooter spectroscopic redshift z = 3.07
  58. GRB 260808A: CALET Gamma-Ray Burst Monitor detection
  59. GRB 260805C: CALET Gamma-Ray Burst Monitor detection
  60. GRB 260804A: CALET Gamma-Ray Burst Monitor detection
  61. GRB260809A/EPF_J234751.2+210212: EP-FXT follow-up observation
  62. GRB 260809A: SVOM/COLIBRÍ (FM-GFT) optical observation
  63. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) optical observation
  64. GRB 260809A: NOT optical observations
  65. GRB260809A: MAO/AZT-22 optical observations
  66. GRB260809A: OHP/T193 optical observations
  67. IceCube-260805A: Upper limits from a search for additional neutrino events in IceCube
  68. GRB 260809A: SVOM/VT optical counterpart
  69. EP260809a: J-band upper limit with WINTER
  70. GRB 260808B: J-band upper limit with WINTER
  71. GRB 260808B: SVOM/ECLAIRs refined analysis
  72. EP260809a:refined analysis of the EP-WXT and autonomous EP-FXT observation
  73. GRB 260808B: Liverpool Telescope optical observations
  74. GRB 260808B: NOT optical observations
  75. GRB 260808B: LCO optical observations
  76. GRB 260808A: NuSTAR detection of prompt emission
  77. EP260809a: COLIBRÍ optical observations
  78. EP260809a: LCO optical observation
  79. GRB260808B: OHP/T193 optical observations
  80. GRB 260808B / EPF_J230056.0+082842: EP-FXT follow-up observation
  81. GRB 260808B: SVOM/VT optical afterglow confirmation
  82. GRB 260808B: SVOM/VT optical candidate from VHF data ( localization correction for GCN 45317 )
  83. GRB 260808B: SVOM/VT optical candidate from VHF data
  84. Fermi GRB 260808A: Global MASTER-Net observations report
  85. EP260806a: ZTF serendipitous detection of ZTF26abmjjnm / AT 2026yeh
  86. IceCube-260805A: One candidate from the Zwicky Transient Facility
  87. GRB 260807A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  88. IceCube-260807A - IceCube observation of a high-energy neutrino candidate track-like event
  89. EP260806a: COLIBRÍ optical observations
  90. EP260806a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  91. EP260806a: SVOM/VT optical observation
  92. EP260806a: Liverpool Telescope observations of the counterpart show a blue colour
  93. EP260806a: OSIRIS+/GTC redshift z=0.089
  94. EP260731a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  95. EP260806a: LCO likely optical counterpart
  96. GRB 260715A: cubesat Avion detection
  97. GRB 260709A: cubesat Avion detection
  98. GRB 260708A: cubesat Avion detection
  99. SN 2026stf / GRB 260708A: ATLAS forced photometry
  100. IceCube-260805A - IceCube observation of a high-energy neutrino candidate track-like event

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