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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"

28045 results found.

  1. NuSTAR Transient 260828: LCO Optical Upper Limits
  2. EP260901a: EP-WXT detection of a fast X-ray transient
  3. GRB 260830A: NuSTAR detection of prompt emission
  4. GRB 260831B: LCO optical upper limits
  5. EP260830a: Global MASTER-Net observations report
  6. EP260830a: EP-WXT detection of a fast X-ray transient
  7. GRB 260827A: SVOM/GRM observation
  8. NuSTAR 260828: a 1100s hard X-ray transient
  9. GRB 260831B: SVOM detection of a possible burst
  10. GRB 260827A: Glowbug gamma-ray detection
  11. Fermi-LAT Gamma-ray Observations of IceCube-260827A
  12. Fermi-LAT Gamma-ray Observations of IceCube-260825A
  13. GRB 260825A: SVOM/GRM observation of a long burst
  14. GRB 260829A: Fermi GBM Detection
  15. GRB 260825A: AstroSat CZTI detection
  16. GRB 260829A: BALROG localization (Fermi Trigger 809676494 / GRB 260829256)
  17. IceCube-260827A: Upper limits from a search for additional neutrino events in IceCube
  18. IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube
  19. IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube
  20. GRB 260818B: Further EP-FXT observation
  21. GRB 260818B: VLT optical and nIR observations
  22. GRB 260818B: TNG NIR observations
  23. MAXI GRB260827.40: Global MASTER-Net observations report
  24. GRB 260818B: 6 GHz VLA observations
  25. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  26. GRB 260808B: SAO RAS observations of the optical rebrightening
  27. EP260822a: Global MASTER-Net observations report
  28. EP Alert 260820.31: Global MASTER-Net observations report
  29. GRB 260807A: EP-FXT follow-up observations
  30. IceCube Alert 260825A: Global MASTER-Net observations report
  31. IceCube-Cascade 260824A: Upper limits from a search for additional neutrino events in IceCube
  32. GRB 260822A: PRIME near-infrared upper limits from multiple epochs
  33. GRB 260822A: the candidate optical afterglow is an unrelated type-Ia SN
  34. GRB 260818A: further EP-FXT observations and X-ray afterglow confirmation
  35. EP260822a: EP-FXT non-detection and upper limit
  36. GRB 260822A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  37. EP260822a: Einstein Probe detection of a fast X-ray transient
  38. GRB 260822A: LCO optical upper limits
  39. GRB 260822A: GROWTH-India Telescope Upper Limits
  40. Fermi-LAT Gamma-ray Observations of IceCube-260821A
  41. Fermi-LAT Gamma-ray Observations of IceCube-260807A
  42. IceCube-260821A: Upper limits from a search for additional neutrino events in IceCube
  43. GRB 260818B: VLA radio observations
  44. GRB 260818B: SVOM/C-GFT optical upper limit
  45. EP260731a: SVOM/ECLAIRs detection through offline targeted search
  46. IceCube Alert 260821A: Global MASTER-Net observations report
  47. GRB 260820A: Insight-HXMT/HE detection
  48. EP detected a brightening of LMXB 1ES 1735-26.9
  49. GRB 260818A: J-band observations with WINTER
  50. GRB 260818A: SVOM/ECLAIRs refined analysis
  51. GRB 260818B: NOT optical upper limits
  52. GRB 260810A: SVOM/GRM observation
  53. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  54. GRB 260818B: LCO optical upper limits
  55. GRB 260818B: SVOM detection of a short burst
  56. EP260806a: SAO RAS multicolor optical observations
  57. GRB 260818A: LCO optical upper limits
  58. EP260812a: AbAO optical upper limit
  59. GRB 260818A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  60. GRB 260810A: Insight-HXMT/HE detection
  61. GRB 260818A: SVOM possible detection of a long and faint GRB
  62. EP260806a: NUTTELA-TAO optical observations
  63. The EP-WXT trigger 01709281429 is likely a flaring star
  64. EP260812a: AZT-22 optical upper limit
  65. EP260806a: WFST optical observations
  66. EP260812b: Optical upper limit with Kinder
  67. GRB 260805D: SVOM/GRM detection of a possible magnetar burst
  68. GRB 260808B: Liverpool Telescope further optical observations
  69. GRB 260813A: BALROG localization (Fermi Trigger 808341387 / GRB 260813803)
  70. EP260812a: NOT and Liverpool Telescope upper limits:
  71. EP260812b: Liverpool Telescope observations
  72. EP260812b: GOTO detection of the optical counterpart
  73. EP260812a: refined analysis of the EP-WXT and autonomous EP-FXT observation
  74. EP260812a: SVOM/C-GFT optical upper limit
  75. EP260812b: COLIBRÍ optical observations
  76. EP260812b: SVOM/VT optical observation
  77. GRB 260808A: SVOM/GRM observation
  78. EP260812b: Einstein Probe detection of an X-ray transient
  79. EP trigger #01709278129 (EP260812b?): NOT optical counterpart
  80. Fermi GBM Sub-Threshold Detection of GRB 260809A
  81. GRB 260810A: Glowbug gamma-ray detection
  82. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical rebrightening
  83. GRB 260810A: AstroSat CZTI detection of a long burst
  84. EP260812a: Einstein Probe detection of an X-ray transient
  85. GRB 260809A: SAO RAS optical observations
  86. GRB 260808B: SAO RAS optical observations
  87. GRB 260317A: SVOM/ECLAIRs detection through offline targeted search and its possible association to magnetar 1E 1841-04.5
  88. EP260806a: MAO/AZT-22 optical observations
  89. IceCube-260807A: Upper limits from a search for additional neutrino events in IceCube
  90. GRB260808B: MAO/AZT-22 optical observations
  91. GRB 250607A: SVOM/ECLAIRs detection through offline targeted search
  92. GRB 260809A: J-band upper limit with WINTER
  93. GRB 260806A: Glowbug gamma-ray detection
  94. GRB260809A/EPF_J234751.2+210212: EP-FXT follow-up observation
  95. GRB 260809A: SVOM/COLIBRÍ (FM-GFT) optical observation
  96. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) optical observation
  97. GRB 260809A: NOT optical observations
  98. GRB260809A: MAO/AZT-22 optical observations
  99. GRB260809A: OHP/T193 optical observations
  100. IceCube-260805A: Upper limits from a search for additional neutrino events in IceCube

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