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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"

32569 results found.

  1. IceCube-260425A - IceCube observation of a high-energy neutrino candidate track-like event
  2. GRB 260305A: likely detection by Fermi-LAT and the LAT gamma-ray position
  3. GRB 260401A: cubesat Avion detection
  4. EP260321a: Upper limits from ATCA radio observations
  5. GRB 260421B: Kilonova-Catcher optical afterglow detection
  6. GRB 260421B: Insight-HXMT/HE detection
  7. The EP-WXT trigger 01709258652: Mondy optical observations
  8. GRB 250328A: VLT host galaxy discovery and redshift z = 1.250
  9. EP260416a: Mondy optical observations
  10. GRB 260421B: SVOM/ECLAIRs refined analysis
  11. GRB 260421B: 3.6m DOT optical observation
  12. EP260416a: ZTSh R band observations
  13. EP-WXT trigger 01709260362: FRAM-ORM optical observations confirm flaring star G 151-9
  14. EP250512a / GRB 250512B: VLT/X-shooter host galaxy identification and redshift z = 1.773
  15. GRB 250530A: VLT/X-shooter host galaxy redshift z = 1.486
  16. GRB 260419A: AstroSat CZTI detection
  17. GRB 260421B: SVOM/GRM observation
  18. GRB260421B: J band upper limit by SYSU 80cm infrared telescope
  19. GRB 260421B: EP-FXT follow-up observation
  20. GOTO26djh/AT2026jpw: ATCA radio detection
  21. GRB 260421B: J-band upper limit with WINTER
  22. GRB 260421B: LCO optical counterpart detection
  23. GRB 260421B: Fermi GBM Observation
  24. GRB 260421A: AstroSat CZTI detection
  25. GOTO26djh/AT2026jpw: radio detection at 15GHz
  26. GRB 260412A: SVOM/ECLAIRs refined analysis
  27. GRB 260421B: SVOM/VT optical observations
  28. EP260416a: J band upper limit by SYSU 80cm infrared telescope
  29. GRB 260310A: Late-time Chandra X-ray Detection
  30. GRB 260418A: Insight-HXMT/HE detection
  31. EP260416a: 1.3m DFOT optical observation
  32. GRB 260415A: CALET Gamma-Ray Burst Monitor detection
  33. GRB 260415B: CALET Gamma-Ray Burst Monitor detection
  34. Fermi GRB 260421C: Global MASTER-Net observations report
  35. GRB 260421B: VLT/X-shooter spectroscopic redshift z = 2.115
  36. Fermi GRB 260421B: Global MASTER-Net observations report
  37. GRB 260421B: BOOTES-7 early optical afterglow detection
  38. GRB 260421B: LCO optical afterglow confirmation
  39. GRB 260421B: SVOM/COLIBRÍ (FM-GFT) optical detection of a candidate counterpart
  40. GRB 260421B: TRT optical counterpart detection
  41. GRB 260421B: SVOM detection of a long burst
  42. Fermi GRB 260421A: Global MASTER-Net observations report
  43. EP260321a: VLA radio follow-up
  44. GRB 260412A: LCOGT Optical Upper Limits
  45. EP260416a: Optical follow-up observations with Kinder
  46. GOTO26djh/AT2026jpw: CrAO and Mondy optical observations of the transient
  47. EP-WXT trigger 01709260303: KAIT optical observations
  48. EP260416a: 1.5m OSN and 2.2m CAHA optical monitoring
  49. GRB 260417A: SVOM/GRM observation
  50. EP260321A/AT2026gzf: Optical observation from 1.3m DFOT
  51. EP260417a: GROWTH-India Telescope optical upper limit
  52. Fermi GRB 260417B: Global MASTER-Net observations report
  53. EP260417b: GROWTH-India Telescope optical upper limit
  54. EP260416a: Ondrejov D50 optical detection
  55. EP260416a: VLT/FORS2 spectroscopic redshift confirmation
  56. EP260417a: Global MASTER-Net observations report
  57. EP260417a/GRB 260417A: refined analysis of the EP-WXT and follow-up EP-FXT observations
  58. EP260416a: NOT tentative spectroscopic redshift of z =1.909
  59. EP260416a: GMG Optical Observation
  60. Fermi GRB 260417A: Global MASTER-Net observations report
  61. Konus-Wind detection of GRB 260411B
  62. GRB 260417A: AstroSat CZTI detection
  63. IPN triangulation of GRB 260411B
  64. EP260416a: LCO observations confirm end of flaring phase
  65. EP260324a / AT2026hir: Further multiband optical follow-up with the PKU 60cm Telescope
  66. EP260417a: TRT optical counterpart detection
  67. EP260416a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  68. EP-WXT trigger 01709259586: KAIT optical observations
  69. EP260416a: KAIT optical upper limit
  70. GRB 260414A: Insight-HXMT/HE detection
  71. EP260416a: COLIBRÍ confirmation of the optical rebrightening
  72. EP260416a: WFST optical observations and rebrightening
  73. GOTO26djh/AT2026jpw: ZTSh R,I bands observations of the transient
  74. EP260416a: SVOM/VT optical observation
  75. GOTO26djh/AT2026jpw: SVOM/VT optical observation
  76. GRB 260415B: Glowbug gamma-ray detection
  77. GRB 260411B: Glowbug gamma-ray detection
  78. GRB 260415A: Insight-HXMT/HE detection
  79. EP260416a: COLIBRÍ optical counterpart candidate
  80. COLIBRI optical observations of the transient GOTO26djh/AT2026jpw
  81. EP260416a: Global MASTER-Net observations report
  82. GOTO26djh/AT2026jpw : MASTER OT observation
  83. GOTO26djh/AT2026jpw: EP-FXT X-ray counterpart detection
  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. GRB 260414A: Glowbug gamma-ray detection
  88. EP260409a: Early NIR limits from MIRAGE on the MDM 1.3m telescope
  89. EP260321a: CMO SAI J,K observations
  90. GRB 260412A: Insight-HXMT/HE detection
  91. Fermi GRB 260413A: Global MASTER-Net observations report
  92. GRB 260410A: Glowbug gamma-ray detection of a short burst
  93. GRB 260410B: Insight-HXMT/HE detection
  94. GRB 260410A: Insight-HXMT/HE detection
  95. Konus-Wind detection of GRB 260410A (short/hard)
  96. GRB 260411B: GECAM-B observation of a long burst
  97. EP260321a: SVOM/VT optical observations and color changes around peak
  98. GRB 260410A: CALET Gamma-Ray Burst Monitor detection
  99. GRB 260412A: GECAM-B observation of a long burst
  100. Fermi GRB 260412A: Global MASTER-Net observations report

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