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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

32685 results found.

  1. EP260429a: LCO optical upper limits
  2. EP260430a: LCO optical upper limits
  3. GRB 260430A / EP260430a: COLIBRÍ optical upper limit
  4. Fermi GRB 260429A: Global MASTER-Net observations report
  5. EP260430a: Global MASTER-Net observations report
  6. GRB 260428A: SVOM/GRM observation of a possible short burst with extended emission
  7. GRB 260428A: GECAM-B detection of a possible long duration Type I burst
  8. IceCube-260425A: Upper limits from a search for additional neutrino events in IceCube
  9. GRB 260428A: AstroSat CZTI detection
  10. Fermi GRB 260428A: Global MASTER-Net observations report
  11. EP260416a: Mondy and Terskol optical upper limits
  12. GRB 260424B: Glowbug gamma-ray detection of a short burst
  13. GRB 260424B: COLIBRÍ optical upper limit
  14. Konus-Wind detection of GRB 260424B
  15. Fermi-LAT Gamma-ray Observations of IceCube-260425A
  16. EP260321a/SN 2026gzf: spectroscopy at Mondy observatory
  17. IPN triangulation of GRB 260424B (short)
  18. IceCube-260425A - IceCube observation of a high-energy neutrino candidate track-like event
  19. GRB 260305A: likely detection by Fermi-LAT and the LAT gamma-ray position
  20. GRB 260401A: cubesat Avion detection
  21. EP260321a: Upper limits from ATCA radio observations
  22. GRB 260421B: Kilonova-Catcher optical afterglow detection
  23. GRB 260421B: Insight-HXMT/HE detection
  24. The EP-WXT trigger 01709258652: Mondy optical observations
  25. GRB 250328A: VLT host galaxy discovery and redshift z = 1.250
  26. EP260416a: Mondy optical observations
  27. GRB 260421B: SVOM/ECLAIRs refined analysis
  28. GRB 260421B: 3.6m DOT optical observation
  29. EP260416a: ZTSh R band observations
  30. EP-WXT trigger 01709260362: FRAM-ORM optical observations confirm flaring star G 151-9
  31. EP250512a / GRB 250512B: VLT/X-shooter host galaxy identification and redshift z = 1.773
  32. GRB 250530A: VLT/X-shooter host galaxy redshift z = 1.486
  33. GRB 260419A: AstroSat CZTI detection
  34. GRB 260421B: SVOM/GRM observation
  35. GRB260421B: J band upper limit by SYSU 80cm infrared telescope
  36. GRB 260421B: EP-FXT follow-up observation
  37. GOTO26djh/AT2026jpw: ATCA radio detection
  38. GRB 260421B: J-band upper limit with WINTER
  39. GRB 260421B: LCO optical counterpart detection
  40. GRB 260421B: Fermi GBM Observation
  41. GRB 260421A: AstroSat CZTI detection
  42. GOTO26djh/AT2026jpw: radio detection at 15GHz
  43. GRB 260412A: SVOM/ECLAIRs refined analysis
  44. GRB 260421B: SVOM/VT optical observations
  45. EP260416a: J band upper limit by SYSU 80cm infrared telescope
  46. GRB 260310A: Late-time Chandra X-ray Detection
  47. GRB 260418A: Insight-HXMT/HE detection
  48. EP260416a: 1.3m DFOT optical observation
  49. GRB 260415A: CALET Gamma-Ray Burst Monitor detection
  50. GRB 260415B: CALET Gamma-Ray Burst Monitor detection
  51. Fermi GRB 260421C: Global MASTER-Net observations report
  52. GRB 260421B: VLT/X-shooter spectroscopic redshift z = 2.115
  53. Fermi GRB 260421B: Global MASTER-Net observations report
  54. GRB 260421B: BOOTES-7 early optical afterglow detection
  55. GRB 260421B: LCO optical afterglow confirmation
  56. GRB 260421B: SVOM/COLIBRÍ (FM-GFT) optical detection of a candidate counterpart
  57. GRB 260421B: TRT optical counterpart detection
  58. GRB 260421B: SVOM detection of a long burst
  59. Fermi GRB 260421A: Global MASTER-Net observations report
  60. EP260321a: VLA radio follow-up
  61. GRB 260412A: LCOGT Optical Upper Limits
  62. EP260416a: Optical follow-up observations with Kinder
  63. GOTO26djh/AT2026jpw: CrAO and Mondy optical observations of the transient
  64. EP-WXT trigger 01709260303: KAIT optical observations
  65. EP260416a: 1.5m OSN and 2.2m CAHA optical monitoring
  66. GRB 260417A: SVOM/GRM observation
  67. EP260321A/AT2026gzf: Optical observation from 1.3m DFOT
  68. EP260417a: GROWTH-India Telescope optical upper limit
  69. Fermi GRB 260417B: Global MASTER-Net observations report
  70. EP260417b: GROWTH-India Telescope optical upper limit
  71. EP260416a: Ondrejov D50 optical detection
  72. EP260416a: VLT/FORS2 spectroscopic redshift confirmation
  73. EP260417a: Global MASTER-Net observations report
  74. EP260417a/GRB 260417A: refined analysis of the EP-WXT and follow-up EP-FXT observations
  75. EP260416a: NOT tentative spectroscopic redshift of z =1.909
  76. EP260416a: GMG Optical Observation
  77. Fermi GRB 260417A: Global MASTER-Net observations report
  78. Konus-Wind detection of GRB 260411B
  79. GRB 260417A: AstroSat CZTI detection
  80. IPN triangulation of GRB 260411B
  81. EP260416a: LCO observations confirm end of flaring phase
  82. EP260324a / AT2026hir: Further multiband optical follow-up with the PKU 60cm Telescope
  83. EP260417a: TRT optical counterpart detection
  84. EP260416a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  85. EP-WXT trigger 01709259586: KAIT optical observations
  86. EP260416a: KAIT optical upper limit
  87. GRB 260414A: Insight-HXMT/HE detection
  88. EP260416a: COLIBRÍ confirmation of the optical rebrightening
  89. EP260416a: WFST optical observations and rebrightening
  90. GOTO26djh/AT2026jpw: ZTSh R,I bands observations of the transient
  91. EP260416a: SVOM/VT optical observation
  92. GOTO26djh/AT2026jpw: SVOM/VT optical observation
  93. GRB 260415B: Glowbug gamma-ray detection
  94. GRB 260411B: Glowbug gamma-ray detection
  95. GRB 260415A: Insight-HXMT/HE detection
  96. EP260416a: COLIBRÍ optical counterpart candidate
  97. COLIBRI optical observations of the transient GOTO26djh/AT2026jpw
  98. EP260416a: Global MASTER-Net observations report
  99. GOTO26djh/AT2026jpw : MASTER OT observation
  100. GOTO26djh/AT2026jpw: EP-FXT X-ray counterpart detection

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