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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"

11678 results found.

  1. The EP-WXT trigger 01709291839 is likely the known LMXB 4U 1745-203
  2. EP260822a: Global MASTER-Net observations report
  3. EP Alert 260820.31: Global MASTER-Net observations report
  4. IceCube Alert 260825A: Global MASTER-Net observations report
  5. GRB 260818A: further EP-FXT observations and X-ray afterglow confirmation
  6. GRB 260822A: LCO optical upper limits
  7. GRB260822B: Fermi GBM Final Localization
  8. Fermi-LAT Gamma-ray Observations of IceCube-260821A
  9. Fermi-LAT Gamma-ray Observations of IceCube-260807A
  10. IceCube-260821A: Upper limits from a search for additional neutrino events in IceCube
  11. GRB 260818B: VLA radio observations
  12. EP detected a brightening of LMXB 1ES 1735-26.9
  13. GRB260820A: Fermi GBM Final Real-Time Localization
  14. GRB 260818B: SVOM/ECLAIRs refined analysis
  15. EP260806a: SAO RAS multicolor optical observations
  16. EP260806a: SVOM/ECLAIRs detection through targeted search
  17. EP260812b: Optical upper limit with Kinder
  18. EP260812a: NOT and Liverpool Telescope upper limits:
  19. EP260812a: refined analysis of the EP-WXT and autonomous EP-FXT observation
  20. EP260812b: Einstein Probe detection of an X-ray transient
  21. EP trigger #01709278129 (EP260812b?): NOT optical counterpart
  22. GRB 260810A: AstroSat CZTI detection of a long burst
  23. EP260812a: Einstein Probe detection of an X-ray transient
  24. GRB 260809A: SAO RAS optical observations
  25. GRB 260807A: SVOM/ECLAIRs refined analysis
  26. GRB 250607A: SVOM/ECLAIRs detection through offline targeted search
  27. GRB 260808B: SVOM/ECLAIRs refined analysis
  28. EP260809a:refined analysis of the EP-WXT and autonomous EP-FXT observation
  29. GRB 260808B: LCO optical observations
  30. GRB 260808A: NuSTAR detection of prompt emission
  31. EP260809a: COLIBRÍ optical observations
  32. EP260809a: Einstein Probe detection of an X-ray transient
  33. GRB 260808B: SVOM/VT optical candidate from VHF data ( localization correction for GCN 45317 )
  34. GRB 260808B: SVOM/VT optical candidate from VHF data
  35. GRB 260808B: SVOM detection of a faint burst
  36. GRB 260807A: SVOM possible detection of a faint burst
  37. EP260806a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  38. EP260731a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  39. EP260806a: Einstein Probe detection of an X-ray transient
  40. SN 2026stf / GRB 260708A: ATLAS forced photometry
  41. Fermi GRB 260802B: Global MASTER-Net observations report
  42. GRB 260802A/EP J223759.5+531421: SVOM detection of a possible magnetar burst
  43. GRB 260731A: AstroSat CZTI detection of a long burst
  44. Fermi-LAT Gamma-ray Observations of IceCube-260722A
  45. GRB 260730B: AstroSat CZTI detection
  46. EP260731a: Einstein Probe detection of an X-ray transient
  47. EP260729a: Einstein Probe detection of an X-ray transient
  48. EP260727a: SAO RAS optical observations
  49. EP260728a: Einstein Probe detection of a fast X-ray transient
  50. EP260727a:refined analysis of the EP-WXT and EP-FXT observation
  51. Konus-Wind detection of GRB 260727A
  52. EP260727a: Einstein Probe detection of an X-ray transient
  53. GRB 260727A: AstroSat CZTI detection
  54. EP260723a: further EP-FXT follow-up observation
  55. EP260725a: EP-WXT detection of an X-ray transient
  56. EP260723a: EP-WXT detection of a fast X-ray transient
  57. Konus-Wind detection of GRB 260721A
  58. Konus-Wind detection of GRB 260714B
  59. GRB 260705A: Retraction of optical counterpart
  60. Fermi trigger No 806104130: Global MASTER-Net observations report
  61. Fermi GRB 260718A: Global MASTER-Net observations report
  62. GRB 260718A: SVOM detection of a burst
  63. sb26071506: SVOM detection of a X-ray transient
  64. GRB 260710A: AstroSat CZTI detection
  65. GRB 260709A: AstroSat CZTI detection
  66. GRB 260714B: AstroSat CZTI detection
  67. GRB 260714B: Fermi-LAT detection
  68. IceCube-260712A: LAST optical follow-up observations of the IceCube neutrino candidate
  69. EP260713a: Einstein Probe detection of an X-ray transient
  70. Fermi-LAT Gamma-ray Observations of IceCube-260712A
  71. Fermi-LAT Gamma-ray Observations of IceCube-260708A
  72. Fermi-LAT Gamma-ray Observations of IceCube-260704A
  73. EP-WXT trigger 0170924151 : RAPAS optical counterpart candidate detection
  74. GRB 260705C: AstroSat CZTI detection
  75. GRB 260706A : GRANDMA Upper limits
  76. IceCube-260708A: One candidate from the Zwicky Transient Facility
  77. GRB260708B: MAXI/GSC detection
  78. GRB 260708A: Fermi-LAT detection
  79. EP260707a: LCOGT Optical Upper Limit
  80. EP260707a: Einstein Probe detection of an X-ray transient
  81. GRB 260704A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  82. The EP-WXT trigger 01709274141 is likely a flaring star
  83. IPN triangulation of GRB 260627A
  84. GRB 260706A: SVOM detection of a burst
  85. GRB 260629A: AstroSat CZTI detection
  86. GRB 260704A: SVOM detection of a possible GRB
  87. EP260703a: EP-WXT detection of a fast X-ray transient
  88. EP260628b: EP-WXT detection of an X-ray transient and EP-FXT follow-up observation
  89. Fermi GRB 260703A: Global MASTER-Net observations report
  90. GRB 260610B / AT2026owq: SAO RAS, CrAO and INASAN further optical observations and light curve
  91. Fermi trigger No 804552016: Global MASTER-Net observations report
  92. Fermi-LAT Gamma-ray Observations of IceCube-260622A
  93. EP260628a: EP-WXT detection of a fast X-ray transient
  94. Konus-Wind detection of GRB 260623B / EP260623a
  95. EP260623a: FTW optical and NIR observations
  96. Konus-Wind detection of GRB 260618B
  97. EP260623a:refined analysis of the EP-WXT and EP-FXT observation
  98. EP260623a: Optical follow-up observations with Kinder
  99. EP260623a: FRAM-ORM detection of the optical afterglow rise, peak and decay
  100. EP260623a: Einstein Probe detection of an X-ray transient

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