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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"

32485 results found.

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

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