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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').
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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"

2212 results found.

  1. IceCube Alert 260930A: Global MASTER-Net observations report
  2. The EP-WXT trigger 01709320790 is likely a flaring star
  3. EP260927a: SVOM/ECLAIRs Upper Limit
  4. GRB 260926C: AstroSat CZTI detection
  5. GRB 260926C: GECAM-B observation
  6. GRB 260926A: GECAM-B observation
  7. EP260927a: Global MASTER-Net observations report
  8. EP260927a: Einstein Probe detection of a fast X-ray transient
  9. GRB 260926B: Glowbug gamma-ray detection of a likely short burst
  10. GRB 260926A: Glowbug gamma-ray detection
  11. GRB 260924A: VLA detection
  12. GRB 260924A: AbAO optical observations
  13. Fermi GRB 260928A: Global MASTER-Net observations report
  14. GRB 260928A: Fermi GBM Final Real-time Localization
  15. EP260924a: Global MASTER-Net observations report
  16. GRB 260924A: Upper limits from a neutrino search with IceCube
  17. Fermi GRB 260926C: Global MASTER-Net observations report
  18. GRB 260926C: Fermi GBM Final Real-time Localization
  19. GRB260914A: MAO/AZT-22 optical observations
  20. GRB 260926B: Fermi GBM Final Real-time Localization
  21. Fermi GRB 260926A: Global MASTER-Net observations report
  22. GRB 260924A: Near-infrared detection with MDM/MIRAGE
  23. GRB 260926A: Fermi GBM Final Real-time Localization
  24. The EP-WXT trigger 01709320726 is likely a flaring star
  25. GRB 260924A: COLIBRÍ optical observations
  26. GRB 260924A: Second-epoch J-band upper limit from the SYSU 80 cm infrared telescope
  27. EP260924a: J-band upper limit by SYSU 80cm infrared telescope
  28. GRB 260925A: J-band upper limit by SYSU 80cm infrared telescope
  29. EP260924a: EP-FXT follow-up observation
  30. GRB 260923A: Glowbug gamma-ray detection
  31. GRB 260924A: Optical follow-up observations with Kinder
  32. GRB 260922A: Glowbug gamma-ray detection
  33. GRB 260925A: COLIBRÍ optical upper limits
  34. GRB 260924A: Ondrejov D50 optical afterglow detection
  35. EP260924a: J-band upper limit with WINTER
  36. GRB 260924A: SVOM/GRM observation
  37. GRB 260924A: 2.2m CAHA spectroscopic redshift z = 3.51
  38. GRB 260923A: Insight-HXMT/HE detection
  39. EP260924a: EP-WXT detection of an X-ray transient
  40. GRB 260924A: J-band observations by the SYSU 80 cm infrared telescope
  41. GRB 260924A: GROWTH-India Telescope optical observations
  42. GRB 260924A: NuSTAR detection of prompt emission
  43. GRB 260922A: NuSTAR detection of prompt emission
  44. GRB 260921A: NuSTAR detection of prompt emission
  45. GRB 260921A: SVOM/GRM observation
  46. GRB 260922A: COLIBRÍ Confirmation of the Optical Counterpart
  47. GRB 260924A: Fermi GRB Observation
  48. GRB 260924A: Fermi-LAT detection of a bright burst
  49. GRB 260924A: AstroSat CZTI detection
  50. GRB 260920A: SVOM/GRM observation
  51. GRB 260924A: NOT optical counterpart confirmation
  52. GRB 260922A: CALET Gamma-Ray Burst Monitor detection
  53. The EP-WXT trigger 01709319842 is likely a flaring star
  54. GRB 260924A: Fermi GBM Final Real-time Localization
  55. Fermi GRB 260923A: Global MASTER-Net observations report
  56. GRB 260923A: Fermi GBM Final Real-time Localization
  57. EP260806a: e-MERLIN detection at 5 GHz
  58. GRB 260922A: Ondrejov D50 optical limit
  59. Fermi-LAT Gamma-ray Observations of IceCube-260919A
  60. Fermi-LAT Gamma-ray Observations of IceCube-260916A
  61. ATCA observations of GRB 260909A
  62. EP260920a: VLT/HAWK-I near-infrared counterpart confirmation
  63. GRB 260922A: J-band upper limit with WINTER
  64. GRB 260922A: COLIBRÍ optical upper limits
  65. Fermi-LAT Gamma-ray Observations of IceCube-260805A
  66. GRB 260920A: Glowbug gamma-ray detection
  67. GRB 260918A: SVOM/ECLAIRs refined analysis
  68. GRB 260922A: SVOM/C-GFT optical upper limit
  69. GRB 260917C: AstroSat CZTI detection
  70. GRB 260920B/EP260920b: GECAM-B detection of a burst
  71. GRB 260921A: AstroSat CZTI detection
  72. GRB 260921B: Fermi GBM Final Localization
  73. GRB 260921A: Fermi GBM Observation
  74. EP260920b: 2.2m CAHA optical afterglow detection and 10.4m GTC redshift confirmation
  75. EP Alert 260921.58: Global MASTER-Net observations report
  76. GRB 260917B:: SVOM/ECLAIRs refined analysis
  77. The EP-WXT trigger 01709319528 is likely a flaring star
  78. EP260920a: VLT/HAWK-I near-infrared candidate
  79. Swift GRB 260921A: Global MASTER-Net observations report
  80. EP260920b: VLT/X-shooter spectroscopic redshift z = 3.582
  81. GRB 260921A: Fermi GBM Final Real-time Localization
  82. EP260920b: LCO observations
  83. GRB 260920A: AstroSat CZTI detection
  84. EP260920b: SVOM/VT optical observation
  85. EP260920b: refined analysis of the EP-WXT and EP-FXT observations
  86. EP260920b: COLIBRÍ optical observations
  87. The EP-WXT trigger 01709318601 is likely a flaring star
  88. EP Alert 260921.01: Global MASTER-Net observations report
  89. EP260920b: Global MASTER-Net observations report
  90. EP260920b: Einstein Probe detection of an X-ray transient
  91. IceCube-260919A: Upper limits from a search for additional neutrino events in IceCube
  92. EP Alert 260920.66: Global MASTER-Net observations report
  93. EP-WXT detected a brightening of HMXB LS V +44 17
  94. EP260920a: NOT early time optical upper limits
  95. EP260920a: NOT optical upper limits
  96. GRB 260920A: Fermi GBM Final Real-time Localization
  97. EP260920a: SVOM/VT optical upper limits
  98. EP260917a: Global MASTER-Net observations report
  99. EP260920a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  100. EP260920a: COLIBRÍ optical upper limits

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