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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.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

38598 results found.

  1. GOTO26djh/AT2026jpw: ATCA radio detection
  2. GRB 260421B: LCO optical counterpart detection
  3. GRB 260421B: Fermi GBM Observation
  4. Fermi Gamma-ray Burst Monitor trigger 798482368/260421694 is not a GRB
  5. GRB 260421A: AstroSat CZTI detection
  6. GRB 260412A: SVOM/ECLAIRs refined analysis
  7. GRB 260421B: SVOM/VT optical observations
  8. EP260416a: J band upper limit by SYSU 80cm infrared telescope
  9. GRB 260310A: Late-time Chandra X-ray Detection
  10. GRB 260418A: Insight-HXMT/HE detection
  11. EP260416a: 1.3m DFOT optical observation
  12. GRB 260415A: CALET Gamma-Ray Burst Monitor detection
  13. GRB 260415B: CALET Gamma-Ray Burst Monitor detection
  14. GRB 260421C: Fermi GBM Final Real-time Localization
  15. GRB 260421B: VLT/X-shooter spectroscopic redshift z = 2.115
  16. GRB 260421B: BOOTES-7 early optical afterglow detection
  17. GRB 260421B: LCO optical afterglow confirmation
  18. GRB 260421B: SVOM/COLIBRÍ (FM-GFT) optical detection of a candidate counterpart
  19. GRB 260421B: TRT optical counterpart detection
  20. GRB 260421B: SVOM detection of a long burst
  21. GRB 260421B: BALROG localization (Fermi Trigger 798437606 / GRB 260421176)
  22. GRB 260421B: Fermi GBM Final Real-time Localization
  23. GRB 260421A: Fermi GBM Final Real-time Localization
  24. GRB 260412A: LCOGT Optical Upper Limits
  25. The EP-WXT trigger 01709260314 is likely a flaring star
  26. EP260416a: Optical follow-up observations with Kinder
  27. GOTO26djh/AT2026jpw: CrAO and Mondy optical observations of the transient
  28. EP-WXT trigger 01709260303: KAIT optical observations
  29. EP260416a: 1.5m OSN and 2.2m CAHA optical monitoring
  30. The EP-WXT trigger 01709260303 is likely a flaring star
  31. GRB 260417A: SVOM/GRM observation
  32. EP260321A/AT2026gzf: Optical observation from 1.3m DFOT
  33. GRB 260419B: Fermi GBM Final Real-time Localization
  34. GRB 260419A: Fermi GBM Final Real-time Localization
  35. EP260417a: GROWTH-India Telescope optical upper limit
  36. EP260417b: GROWTH-India Telescope optical upper limit
  37. EP260416a: Ondrejov D50 optical detection
  38. GRB 260418B: Fermi GBM Final Real-time Localization
  39. EP260416a: VLT/FORS2 spectroscopic redshift confirmation
  40. EP260417a/GRB 260417A: refined analysis of the EP-WXT and follow-up EP-FXT observations
  41. EP260416a: NOT tentative spectroscopic redshift of z =1.909
  42. GRB 260418A: Fermi GBM Final Real-time Localization
  43. EP260416a: GMG Optical Observation
  44. Konus-Wind detection of GRB 260411B
  45. GRB 260417B: Fermi GBM Final Real-time Localization
  46. GRB 260417A: AstroSat CZTI detection
  47. IPN triangulation of GRB 260411B
  48. EP260416a: LCO observations confirm end of flaring phase
  49. EP260324a / AT2026hir: Further multiband optical follow-up with the PKU 60cm Telescope
  50. EP260417a: Einstein Probe detection of an X-ray transient
  51. EP260416a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  52. EP260417b: Einstein Probe detection of a fast X-ray transient
  53. EP-WXT trigger 01709259586: KAIT optical observations
  54. EP260416a: KAIT optical upper limit
  55. GRB 260414A: Insight-HXMT/HE detection
  56. EP260416a: COLIBRÍ confirmation of the optical rebrightening
  57. EP260416a: WFST optical observations and rebrightening
  58. GRB 260417A: Fermi GBM Final Real-time Localization
  59. GOTO26djh/AT2026jpw: ZTSh R,I bands observations of the transient
  60. EP260416a: SVOM/VT optical observation
  61. GOTO26djh/AT2026jpw: SVOM/VT optical observation
  62. GRB 260415B: Glowbug gamma-ray detection
  63. GRB 260411B: Glowbug gamma-ray detection
  64. GRB 260415A: Insight-HXMT/HE detection
  65. EP260416a: COLIBRÍ optical counterpart candidate
  66. COLIBRI optical observations of the transient GOTO26djh/AT2026jpw
  67. EP260416a: Einstein Probe detection of an X-ray transient
  68. GOTO26djh/AT2026jpw : MASTER OT observation
  69. GOTO26djh/AT2026jpw: EP-FXT X-ray counterpart detection
  70. GOTO26djh/AT2026jpw transient: SAO RAS optical observations
  71. NOT r-band observations of the transient GOTO26djh/AT2026jpw
  72. GRB 260415B: NuSTAR detection of long prompt emission
  73. GOTO discovery of fast-fading transient GOTO26djh/AT2026jpw, a candidate orphan afterglow
  74. GRB 260415B: Fermi GBM Final Localization
  75. GRB 260415A: Fermi GBM Final Real-time Localization
  76. GRB 260414A: Glowbug gamma-ray detection
  77. EP260409a: Early NIR limits from MIRAGE on the MDM 1.3m telescope
  78. EP260321a: CMO SAI J,K observations
  79. GRB 260412A: Insight-HXMT/HE detection
  80. GRB 260414A: Fermi GBM Final Real-time Localization
  81. The EP-WXT trigger 01709260122 is likely a flaring star
  82. GRB 260410A: Glowbug gamma-ray detection of a short burst
  83. GRB 260413A: Fermi GBM Final Real-time Localization
  84. GRB 260410B: Insight-HXMT/HE detection
  85. GRB 260410A: Insight-HXMT/HE detection
  86. Konus-Wind detection of GRB 260410A (short/hard)
  87. GRB 260411B: GECAM-B observation of a long burst
  88. EP260321a: SVOM/VT optical observations and color changes around peak
  89. GRB 260410A: CALET Gamma-Ray Burst Monitor detection
  90. The EP-WXT trigger 01709260010 is likely a flaring star
  91. GRB 260412A: GECAM-B observation of a long burst
  92. GRB 260412A: Fermi GBM Observation
  93. GRB 260411B: Fermi-LAT detection
  94. GRB 260412A: SVOM detection of a long burst
  95. GRB 260412A: Fermi GBM Final Real-time Localization
  96. GRB 260411B: COLIBRÍ optical observations
  97. GRB 260410B: Fermi GBM Observation
  98. GRB260411B: 3.6m DOT optical observation
  99. GRB 260411A: SVOM/GRM observation
  100. GRB 260407B: SVOM/GRM detection of a possible magnetar X-ray burst

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