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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"

32546 results found.

  1. GRB 260421B: Fermi GBM Observation
  2. GRB 260421A: AstroSat CZTI detection
  3. GOTO26djh/AT2026jpw: radio detection at 15GHz
  4. GRB 260412A: SVOM/ECLAIRs refined analysis
  5. GRB 260421B: SVOM/VT optical observations
  6. EP260416a: J band upper limit by SYSU 80cm infrared telescope
  7. GRB 260310A: Late-time Chandra X-ray Detection
  8. GRB 260418A: Insight-HXMT/HE detection
  9. EP260416a: 1.3m DFOT optical observation
  10. GRB 260415A: CALET Gamma-Ray Burst Monitor detection
  11. GRB 260415B: CALET Gamma-Ray Burst Monitor detection
  12. Fermi GRB 260421C: Global MASTER-Net observations report
  13. GRB 260421B: VLT/X-shooter spectroscopic redshift z = 2.115
  14. Fermi GRB 260421B: Global MASTER-Net observations report
  15. GRB 260421B: BOOTES-7 early optical afterglow detection
  16. GRB 260421B: LCO optical afterglow confirmation
  17. GRB 260421B: SVOM/COLIBRÍ (FM-GFT) optical detection of a candidate counterpart
  18. GRB 260421B: TRT optical counterpart detection
  19. GRB 260421B: SVOM detection of a long burst
  20. Fermi GRB 260421A: Global MASTER-Net observations report
  21. EP260321a: VLA radio follow-up
  22. GRB 260412A: LCOGT Optical Upper Limits
  23. EP260416a: Optical follow-up observations with Kinder
  24. GOTO26djh/AT2026jpw: CrAO and Mondy optical observations of the transient
  25. EP-WXT trigger 01709260303: KAIT optical observations
  26. EP260416a: 1.5m OSN and 2.2m CAHA optical monitoring
  27. GRB 260417A: SVOM/GRM observation
  28. EP260321A/AT2026gzf: Optical observation from 1.3m DFOT
  29. EP260417a: GROWTH-India Telescope optical upper limit
  30. Fermi GRB 260417B: Global MASTER-Net observations report
  31. EP260417b: GROWTH-India Telescope optical upper limit
  32. EP260416a: Ondrejov D50 optical detection
  33. EP260416a: VLT/FORS2 spectroscopic redshift confirmation
  34. EP260417a: Global MASTER-Net observations report
  35. EP260417a/GRB 260417A: refined analysis of the EP-WXT and follow-up EP-FXT observations
  36. EP260416a: NOT tentative spectroscopic redshift of z =1.909
  37. EP260416a: GMG Optical Observation
  38. Fermi GRB 260417A: Global MASTER-Net observations report
  39. Konus-Wind detection of GRB 260411B
  40. GRB 260417A: AstroSat CZTI detection
  41. IPN triangulation of GRB 260411B
  42. EP260416a: LCO observations confirm end of flaring phase
  43. EP260324a / AT2026hir: Further multiband optical follow-up with the PKU 60cm Telescope
  44. EP260417a: TRT optical counterpart detection
  45. EP260416a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  46. EP-WXT trigger 01709259586: KAIT optical observations
  47. EP260416a: KAIT optical upper limit
  48. GRB 260414A: Insight-HXMT/HE detection
  49. EP260416a: COLIBRÍ confirmation of the optical rebrightening
  50. EP260416a: WFST optical observations and rebrightening
  51. GOTO26djh/AT2026jpw: ZTSh R,I bands observations of the transient
  52. EP260416a: SVOM/VT optical observation
  53. GOTO26djh/AT2026jpw: SVOM/VT optical observation
  54. GRB 260415B: Glowbug gamma-ray detection
  55. GRB 260411B: Glowbug gamma-ray detection
  56. GRB 260415A: Insight-HXMT/HE detection
  57. EP260416a: COLIBRÍ optical counterpart candidate
  58. COLIBRI optical observations of the transient GOTO26djh/AT2026jpw
  59. EP260416a: Global MASTER-Net observations report
  60. GOTO26djh/AT2026jpw : MASTER OT observation
  61. GOTO26djh/AT2026jpw: EP-FXT X-ray counterpart detection
  62. GOTO26djh/AT2026jpw transient: SAO RAS optical observations
  63. NOT r-band observations of the transient GOTO26djh/AT2026jpw
  64. GRB 260415B: NuSTAR detection of long prompt emission
  65. GRB 260414A: Glowbug gamma-ray detection
  66. EP260409a: Early NIR limits from MIRAGE on the MDM 1.3m telescope
  67. EP260321a: CMO SAI J,K observations
  68. GRB 260412A: Insight-HXMT/HE detection
  69. Fermi GRB 260413A: Global MASTER-Net observations report
  70. GRB 260410A: Glowbug gamma-ray detection of a short burst
  71. GRB 260410B: Insight-HXMT/HE detection
  72. GRB 260410A: Insight-HXMT/HE detection
  73. Konus-Wind detection of GRB 260410A (short/hard)
  74. GRB 260411B: GECAM-B observation of a long burst
  75. EP260321a: SVOM/VT optical observations and color changes around peak
  76. GRB 260410A: CALET Gamma-Ray Burst Monitor detection
  77. GRB 260412A: GECAM-B observation of a long burst
  78. Fermi GRB 260412A: Global MASTER-Net observations report
  79. GRB 260412A: Fermi GBM Observation
  80. GRB 260310A / AT2026fgk: NuSTAR detection of the rebrightening
  81. GRB 260411B: Fermi-LAT detection
  82. GRB 260412A: SVOM detection of a long burst
  83. GRB 260411B: COLIBRÍ optical observations
  84. GRB 260410B: Fermi GBM Observation
  85. GRB 260411B: Ondrejov D50 optical afterglow detection
  86. GRB260411B: 3.6m DOT optical observation
  87. GRB 260411A: SVOM/GRM observation
  88. GRB 260411B: SVOM/GRM observation of a long burst
  89. GRB 260409A: Insight-HXMT/HE detection
  90. GRB 260411B: Fermi GBM Detection
  91. GRB 260411B: GOTO optical counterpart candidate
  92. EP260409a: Gemini/FLAMINGOS2 J-band counterpart
  93. GRB 260410A: COLIBRÍ optical upper limit
  94. EP-WXT01709259790: Optical Upper limits with kinder observations
  95. GRB 260410A: Fermi GBM Observation
  96. GRB 260410B: SVOM/GRM detection of a short faint burst
  97. GRB 260410A: Fermi-LAT detection
  98. EP260409a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  99. EP260321a: Chandra X-ray Non-detection
  100. GRB 260310A/AT2026fgk: Kilonova-Catcher SN peak identification

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