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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"

28109 results found.

  1. EP260430a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  2. GRB 260424B: AstroSat CZTI detection
  3. GRB 260429B / EP260429a: COLIBRÍ optical upper limit
  4. EP260429a: LCO optical upper limits
  5. EP260430a: LCO optical upper limits
  6. GRB 260430A / EP260430a: COLIBRÍ optical upper limit
  7. GRB 260429A: Fermi GBM Detection
  8. Fermi GRB 260429A: Global MASTER-Net observations report
  9. EP260430a: Global MASTER-Net observations report
  10. EP260430a: Einstein Probe detection of an X-ray transient
  11. EP260429a: EP-WXT detection of a fast X-ray transient
  12. GRB 260428A: SVOM/GRM observation of a possible short burst with extended emission
  13. IceCube-260425A: Upper limits from a search for additional neutrino events in IceCube
  14. Fermi GRB 260428A: Global MASTER-Net observations report
  15. EP260416a: Mondy and Terskol optical upper limits
  16. GRB 260424B: Glowbug gamma-ray detection of a short burst
  17. GRB 260424B: COLIBRÍ optical upper limit
  18. Fermi-LAT Gamma-ray Observations of IceCube-260425A
  19. GRB 260305A: likely detection by Fermi-LAT and the LAT gamma-ray position
  20. IceCube Alert 260425A: Global MASTER-Net observations report
  21. Fermi trigger No 798737427: Global MASTER-Net observations report
  22. GRB 260401A: cubesat Avion detection
  23. EP260321a: Upper limits from ATCA radio observations
  24. GRB 260421B: Kilonova-Catcher optical afterglow detection
  25. The EP-WXT trigger 01709258652: Mondy optical observations
  26. EP260416a: Mondy optical observations
  27. GRB 260421B: 3.6m DOT optical observation
  28. EP260416a: ZTSh R band observations
  29. IceCube-Cascade 260418A: Upper limits from a search for additional neutrino events in IceCube
  30. GRB 260421B: SVOM/GRM observation
  31. GRB260421B: J band upper limit by SYSU 80cm infrared telescope
  32. GRB 260421B: EP-FXT follow-up observation
  33. GOTO26djh/AT2026jpw: ATCA radio detection
  34. GRB 260421B: J-band upper limit with WINTER
  35. GRB 260421B: LCO optical counterpart detection
  36. GRB 260421B: Fermi GBM Observation
  37. GOTO26djh/AT2026jpw: radio detection at 15GHz
  38. GRB 260421B: SVOM/VT optical observations
  39. EP260416a: J band upper limit by SYSU 80cm infrared telescope
  40. GRB 260310A: Late-time Chandra X-ray Detection
  41. EP260416a: 1.3m DFOT optical observation
  42. Fermi GRB 260421C: Global MASTER-Net observations report
  43. GRB 260421B: VLT/X-shooter spectroscopic redshift z = 2.115
  44. Fermi GRB 260421B: Global MASTER-Net observations report
  45. GRB 260421B: LCO optical afterglow confirmation
  46. GRB 260421B: SVOM/COLIBRÍ (FM-GFT) optical detection of a candidate counterpart
  47. GRB 260421B: TRT optical counterpart detection
  48. GRB 260421B: SVOM detection of a long burst
  49. GRB 260421B: BALROG localization (Fermi Trigger 798437606 / GRB 260421176)
  50. Fermi GRB 260421A: Global MASTER-Net observations report
  51. EP260321a: VLA radio follow-up
  52. GRB 260412A: LCOGT Optical Upper Limits
  53. EP260416a: Optical follow-up observations with Kinder
  54. GOTO26djh/AT2026jpw: CrAO and Mondy optical observations of the transient
  55. GRB 260417A: SVOM/GRM observation
  56. EP260321A/AT2026gzf: Optical observation from 1.3m DFOT
  57. Fermi trigger No 798275385: Global MASTER-Net observations report
  58. EP260417a: GROWTH-India Telescope optical upper limit
  59. Fermi GRB 260417B: Global MASTER-Net observations report
  60. EP260417b: GROWTH-India Telescope optical upper limit
  61. EP260416a: Ondrejov D50 optical detection
  62. EP260417a: Global MASTER-Net observations report
  63. EP260417a/GRB 260417A: refined analysis of the EP-WXT and follow-up EP-FXT observations
  64. EP260416a: GMG Optical Observation
  65. Fermi GRB 260417A: Global MASTER-Net observations report
  66. EP260416a: LCO observations confirm end of flaring phase
  67. EP260324a / AT2026hir: Further multiband optical follow-up with the PKU 60cm Telescope
  68. EP260417a: TRT optical counterpart detection
  69. EP260417a: Einstein Probe detection of an X-ray transient
  70. EP260416a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  71. EP260417b: Einstein Probe detection of a fast X-ray transient
  72. EP260416a: KAIT optical upper limit
  73. EP260416a: COLIBRÍ confirmation of the optical rebrightening
  74. EP260416a: WFST optical observations and rebrightening
  75. GOTO26djh/AT2026jpw: ZTSh R,I bands observations of the transient
  76. GOTO26djh/AT2026jpw: SVOM/VT optical observation
  77. GRB 260415B: Glowbug gamma-ray detection
  78. GRB 260411B: Glowbug gamma-ray detection
  79. EP260416a: COLIBRÍ optical counterpart candidate
  80. COLIBRI optical observations of the transient GOTO26djh/AT2026jpw
  81. EP260416a: Global MASTER-Net observations report
  82. EP260416a: Einstein Probe detection of an X-ray transient
  83. GOTO26djh/AT2026jpw : MASTER OT observation
  84. GOTO26djh/AT2026jpw transient: SAO RAS optical observations
  85. NOT r-band observations of the transient GOTO26djh/AT2026jpw
  86. GRB 260415B: NuSTAR detection of long prompt emission
  87. GOTO discovery of fast-fading transient GOTO26djh/AT2026jpw, a candidate orphan afterglow
  88. Fermi trigger No 797912738: Global MASTER-Net observations report
  89. GRB 260414A: Glowbug gamma-ray detection
  90. EP260409a: Early NIR limits from MIRAGE on the MDM 1.3m telescope
  91. EP260321a: CMO SAI J,K observations
  92. Fermi GRB 260413A: Global MASTER-Net observations report
  93. GRB 260410A: Glowbug gamma-ray detection of a short burst
  94. Fermi GRB 260412A: Global MASTER-Net observations report
  95. GRB 260412A: Fermi GBM Observation
  96. GRB 260411B: Fermi-LAT detection
  97. GRB 260411B: COLIBRÍ optical observations
  98. GRB 260410B: Fermi GBM Observation
  99. GRB260411B: 3.6m DOT optical observation
  100. GRB 260411A: SVOM/GRM observation

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