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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"

12089 results found.

  1. Fermi GRB 260926A: Global MASTER-Net observations report
  2. GRB 260926A: Fermi GBM Final Real-time Localization
  3. GRB 260924A: COLIBRÍ optical observations
  4. GRB 260925A: J-band upper limit by SYSU 80cm infrared telescope
  5. GRB 260925A: Swift-XRT refined Analysis
  6. Swift Trigger 1513439 is probably not a GRB
  7. Konus-Wind detection of GRB 260924A
  8. GRB 260924A: Optical follow-up observations with Kinder
  9. GRB 260925A: COLIBRÍ optical upper limits
  10. EP260924a: J-band upper limit with WINTER
  11. GRB 260925A: Swift detection of a burst
  12. GRB 260924A: Swift-XRT refined Analysis
  13. Konus-Wind detection of GRB 260922A
  14. Konus-Wind detection of GRB 260921A (possible merger-origin)
  15. GRB 260924A: Fermi-LAT detection of a bright burst
  16. GRB 260924A: AstroSat CZTI detection
  17. GRB 260924A: Swift detection of a burst
  18. Fermi GRB 260923A: Global MASTER-Net observations report
  19. Fermi-LAT Gamma-ray Observations of IceCube-260919A
  20. Fermi-LAT Gamma-ray Observations of IceCube-260916A
  21. EP260920a: VLT/HAWK-I near-infrared counterpart confirmation
  22. GRB 260922A: Swift-XRT refined Analysis
  23. Fermi-LAT Gamma-ray Observations of IceCube-260805A
  24. Konus-Wind detection of GRB 260810A
  25. GRB 260920A: Glowbug gamma-ray detection
  26. GRB 260922A: Swift detection of a burst
  27. GRB 260921A: AstroSat CZTI detection
  28. EP260920b: 2.2m CAHA optical afterglow detection and 10.4m GTC redshift confirmation
  29. EP Alert 260921.58: Global MASTER-Net observations report
  30. EP260920a: VLT/HAWK-I near-infrared candidate
  31. Swift GRB 260921A: Global MASTER-Net observations report
  32. GRB 260920A: AstroSat CZTI detection
  33. EP260920b: refined analysis of the EP-WXT and EP-FXT observations
  34. EP Alert 260921.01: Global MASTER-Net observations report
  35. EP260920b: Einstein Probe detection of an X-ray transient
  36. IceCube-260919A: Upper limits from a search for additional neutrino events in IceCube
  37. EP Alert 260920.66: Global MASTER-Net observations report
  38. EP-WXT detected a brightening of HMXB LS V +44 17
  39. EP260920a: NOT early time optical upper limits
  40. EP260920a: NOT optical upper limits
  41. GRB 260920A: Fermi GBM Final Real-time Localization
  42. EP260917a: Global MASTER-Net observations report
  43. EP260920a: COLIBRÍ optical upper limits
  44. IceCube Alert 260919A: Global MASTER-Net observations report
  45. EP260920a: Einstein Probe detection of an X-ray transient
  46. Konus-Wind detection of GRB 260916B (short/hard)
  47. GRB 260918A: EP-FXT follow-up observation
  48. EP Alert 260917.32: Global MASTER-Net observations report
  49. Fermi trigger No 811304653: Global MASTER-Net observations report
  50. GRB 260914A: SVOM/ECLAIRs refined analysis
  51. GRB 260916A: MAXI/GSC detection
  52. MAXI GRB260916.37: Global MASTER-Net observations report
  53. GRB 260915A: J-band upper limit by SYSU 80cm infrared telescope
  54. GRB 260915A: 10.4m GTC deep optical limits
  55. EP Alert 260914.53: Global MASTER-Net observations report
  56. SVOM GRB260914.47: Global MASTER-Net observations report
  57. GRB 260914A: SVOM detection of a burst
  58. GRB 260818A: Continued ATCA observations
  59. GRB 260909A: OHP/T193 z-band upper limit
  60. GRB 260909A: VLT optical and near-infrared upper limits
  61. EP Alert 260909.53: Global MASTER-Net observations report
  62. GRB 260909A: SVOM/GRM observation
  63. The EP-WXT trigger 01709306297 is likely the known LMXB 4U 1745-203
  64. The EP-WXT trigger 01709305715 is likely a flaring star
  65. EP260903a: EP-FXT follow-up observation
  66. GRB 260903A: SVOM/ECLAIRs refined analysis
  67. EP260903a: EP-WXT detection of a fast X-ray transient
  68. EP Alert 260903.62: Global MASTER-Net observations report
  69. SVOM GRB260903A: Global MASTER-Net observations report
  70. GRB 260903A: SVOM detection of a soft faint burst
  71. Konus-Wind detection of GRB 260829A
  72. GRB 260818A: ATCA detection of a candidate radio counterpart
  73. EP260901a: Global MASTER-Net observations report
  74. GRB 260829A: AstroSat CZTI detection
  75. EP260830a: EP-WXT detection of a fast X-ray transient
  76. Fermi-LAT Gamma-ray Observations of IceCube-260827A
  77. Fermi-LAT Gamma-ray Observations of IceCube-260825A
  78. The EP-WXT trigger 01709291839 is likely the known LMXB 4U 1745-203
  79. EP260822a: Global MASTER-Net observations report
  80. EP Alert 260820.31: Global MASTER-Net observations report
  81. IceCube Alert 260825A: Global MASTER-Net observations report
  82. GRB 260818A: further EP-FXT observations and X-ray afterglow confirmation
  83. GRB 260822A: LCO optical upper limits
  84. GRB260822B: Fermi GBM Final Localization
  85. Fermi-LAT Gamma-ray Observations of IceCube-260821A
  86. Fermi-LAT Gamma-ray Observations of IceCube-260807A
  87. IceCube-260821A: Upper limits from a search for additional neutrino events in IceCube
  88. GRB 260818B: VLA radio observations
  89. EP detected a brightening of LMXB 1ES 1735-26.9
  90. GRB260820A: Fermi GBM Final Real-Time Localization
  91. GRB 260818B: SVOM/ECLAIRs refined analysis
  92. EP260806a: SAO RAS multicolor optical observations
  93. EP260806a: SVOM/ECLAIRs detection through targeted search
  94. EP260812b: Optical upper limit with Kinder
  95. EP260812a: NOT and Liverpool Telescope upper limits:
  96. EP260812a: refined analysis of the EP-WXT and autonomous EP-FXT observation
  97. EP260812b: Einstein Probe detection of an X-ray transient
  98. EP trigger #01709278129 (EP260812b?): NOT optical counterpart
  99. GRB 260810A: AstroSat CZTI detection of a long burst
  100. EP260812a: Einstein Probe detection of an X-ray transient

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