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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').
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"

11751 results found.

  1. GRB 260925A: Swift-XRT refined Analysis
  2. Swift Trigger 1513439 is probably not a GRB
  3. Konus-Wind detection of GRB 260924A
  4. GRB 260924A: Optical follow-up observations with Kinder
  5. GRB 260925A: COLIBRÍ optical upper limits
  6. EP260924a: J-band upper limit with WINTER
  7. GRB 260925A: Swift detection of a burst
  8. GRB 260924A: Swift-XRT refined Analysis
  9. Konus-Wind detection of GRB 260922A
  10. Konus-Wind detection of GRB 260921A (possible merger-origin)
  11. GRB 260924A: Fermi-LAT detection of a bright burst
  12. GRB 260924A: AstroSat CZTI detection
  13. GRB 260924A: Swift detection of a burst
  14. Fermi GRB 260923A: Global MASTER-Net observations report
  15. Fermi-LAT Gamma-ray Observations of IceCube-260919A
  16. Fermi-LAT Gamma-ray Observations of IceCube-260916A
  17. EP260920a: VLT/HAWK-I near-infrared counterpart confirmation
  18. GRB 260922A: Swift-XRT refined Analysis
  19. Fermi-LAT Gamma-ray Observations of IceCube-260805A
  20. Konus-Wind detection of GRB 260810A
  21. GRB 260920A: Glowbug gamma-ray detection
  22. GRB 260922A: Swift detection of a burst
  23. GRB 260921A: AstroSat CZTI detection
  24. EP260920b: 2.2m CAHA optical afterglow detection and 10.4m GTC redshift confirmation
  25. EP Alert 260921.58: Global MASTER-Net observations report
  26. EP260920a: VLT/HAWK-I near-infrared candidate
  27. Swift GRB 260921A: Global MASTER-Net observations report
  28. GRB 260920A: AstroSat CZTI detection
  29. EP260920b: refined analysis of the EP-WXT and EP-FXT observations
  30. EP Alert 260921.01: Global MASTER-Net observations report
  31. EP260920b: Einstein Probe detection of an X-ray transient
  32. IceCube-260919A: Upper limits from a search for additional neutrino events in IceCube
  33. EP Alert 260920.66: Global MASTER-Net observations report
  34. EP-WXT detected a brightening of HMXB LS V +44 17
  35. EP260920a: NOT early time optical upper limits
  36. EP260920a: NOT optical upper limits
  37. GRB 260920A: Fermi GBM Final Real-time Localization
  38. EP260917a: Global MASTER-Net observations report
  39. EP260920a: COLIBRÍ optical upper limits
  40. IceCube Alert 260919A: Global MASTER-Net observations report
  41. EP260920a: Einstein Probe detection of an X-ray transient
  42. Konus-Wind detection of GRB 260916B (short/hard)
  43. GRB 260918A: EP-FXT follow-up observation
  44. EP Alert 260917.32: Global MASTER-Net observations report
  45. Fermi trigger No 811304653: Global MASTER-Net observations report
  46. GRB 260914A: SVOM/ECLAIRs refined analysis
  47. GRB 260916A: MAXI/GSC detection
  48. MAXI GRB260916.37: Global MASTER-Net observations report
  49. GRB 260915A: J-band upper limit by SYSU 80cm infrared telescope
  50. GRB 260915A: 10.4m GTC deep optical limits
  51. EP Alert 260914.53: Global MASTER-Net observations report
  52. SVOM GRB260914.47: Global MASTER-Net observations report
  53. GRB 260914A: SVOM detection of a burst
  54. GRB 260818A: Continued ATCA observations
  55. GRB 260909A: OHP/T193 z-band upper limit
  56. GRB 260909A: VLT optical and near-infrared upper limits
  57. EP Alert 260909.53: Global MASTER-Net observations report
  58. GRB 260909A: SVOM/GRM observation
  59. The EP-WXT trigger 01709306297 is likely the known LMXB 4U 1745-203
  60. The EP-WXT trigger 01709305715 is likely a flaring star
  61. EP260903a: EP-FXT follow-up observation
  62. GRB 260903A: SVOM/ECLAIRs refined analysis
  63. EP260903a: EP-WXT detection of a fast X-ray transient
  64. EP Alert 260903.62: Global MASTER-Net observations report
  65. SVOM GRB260903A: Global MASTER-Net observations report
  66. GRB 260903A: SVOM detection of a soft faint burst
  67. Konus-Wind detection of GRB 260829A
  68. GRB 260818A: ATCA detection of a candidate radio counterpart
  69. EP260901a: Global MASTER-Net observations report
  70. GRB 260829A: AstroSat CZTI detection
  71. EP260830a: EP-WXT detection of a fast X-ray transient
  72. Fermi-LAT Gamma-ray Observations of IceCube-260827A
  73. Fermi-LAT Gamma-ray Observations of IceCube-260825A
  74. The EP-WXT trigger 01709291839 is likely the known LMXB 4U 1745-203
  75. EP260822a: Global MASTER-Net observations report
  76. EP Alert 260820.31: Global MASTER-Net observations report
  77. IceCube Alert 260825A: Global MASTER-Net observations report
  78. GRB 260818A: further EP-FXT observations and X-ray afterglow confirmation
  79. GRB 260822A: LCO optical upper limits
  80. GRB260822B: Fermi GBM Final Localization
  81. Fermi-LAT Gamma-ray Observations of IceCube-260821A
  82. Fermi-LAT Gamma-ray Observations of IceCube-260807A
  83. IceCube-260821A: Upper limits from a search for additional neutrino events in IceCube
  84. GRB 260818B: VLA radio observations
  85. EP detected a brightening of LMXB 1ES 1735-26.9
  86. GRB260820A: Fermi GBM Final Real-Time Localization
  87. GRB 260818B: SVOM/ECLAIRs refined analysis
  88. EP260806a: SAO RAS multicolor optical observations
  89. EP260806a: SVOM/ECLAIRs detection through targeted search
  90. EP260812b: Optical upper limit with Kinder
  91. EP260812a: NOT and Liverpool Telescope upper limits:
  92. EP260812a: refined analysis of the EP-WXT and autonomous EP-FXT observation
  93. EP260812b: Einstein Probe detection of an X-ray transient
  94. EP trigger #01709278129 (EP260812b?): NOT optical counterpart
  95. GRB 260810A: AstroSat CZTI detection of a long burst
  96. EP260812a: Einstein Probe detection of an X-ray transient
  97. GRB 260809A: SAO RAS optical observations
  98. GRB 260807A: SVOM/ECLAIRs refined analysis
  99. GRB 250607A: SVOM/ECLAIRs detection through offline targeted search
  100. GRB 260808B: SVOM/ECLAIRs refined analysis

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