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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"

38348 results found.

  1. GRB 260926C: Fermi GBM Final Real-time Localization
  2. GRB260914A: MAO/AZT-22 optical observations
  3. GRB 260926B: Fermi GBM Final Real-time Localization
  4. GRB 260924A: Near-infrared detection with MDM/MIRAGE
  5. GRB 260926A: Fermi GBM Final Real-time Localization
  6. The EP-WXT trigger 01709320726 is likely a flaring star
  7. GRB 260924A: COLIBRÍ optical observations
  8. GRB 260924A: Second-epoch J-band upper limit from the SYSU 80 cm infrared telescope
  9. EP260924a: J-band upper limit by SYSU 80cm infrared telescope
  10. GRB 260925A: J-band upper limit by SYSU 80cm infrared telescope
  11. GRB 260925A: Swift-XRT refined Analysis
  12. EP260924a: EP-FXT follow-up observation
  13. Swift Trigger 1513439 is probably not a GRB
  14. GRB 260925A: Swift/UVOT Upper Limits
  15. Konus-Wind detection of GRB 260924A
  16. GRB 260923A: Glowbug gamma-ray detection
  17. GRB 260924A: Optical follow-up observations with Kinder
  18. GRB 260922A: Glowbug gamma-ray detection
  19. GRB 260925A: Enhanced Swift-XRT position
  20. GRB 260925A: COLIBRÍ optical upper limits
  21. GRB 260924A: Ondrejov D50 optical afterglow detection
  22. EP260924a: J-band upper limit with WINTER
  23. GRB 260924A: SVOM/GRM observation
  24. GRB 260924A: 2.2m CAHA spectroscopic redshift z = 3.51
  25. GRB 260925A: Swift detection of a burst
  26. GRB 260923A: Insight-HXMT/HE detection
  27. EP260924a: EP-WXT detection of an X-ray transient
  28. GRB 260924A: J-band observations by the SYSU 80 cm infrared telescope
  29. GRB 260924A: Swift/UVOT Detection
  30. GRB 260924A: GROWTH-India Telescope optical observations
  31. GRB 260924A: NuSTAR detection of prompt emission
  32. GRB 260924A: Swift-XRT refined Analysis
  33. Konus-Wind detection of GRB 260922A
  34. GRB 260922A: NuSTAR detection of prompt emission
  35. GRB 260921A: NuSTAR detection of prompt emission
  36. Konus-Wind detection of GRB 260921A (correction to GCN 45722)
  37. GRB 260921A: SVOM/GRM observation
  38. GRB 260922A: COLIBRÍ Confirmation of the Optical Counterpart
  39. GRB 260924A: Fermi GRB Observation
  40. Konus-Wind detection of GRB 260921A (possible merger-origin)
  41. GRB 260924A: Fermi-LAT detection of a bright burst
  42. GRB 260924A: AstroSat CZTI detection
  43. GRB 260920A: SVOM/GRM observation
  44. GRB 260924A: NOT optical counterpart confirmation
  45. GRB 260924A: detection of a bright optical afterglow by the 1.5m OSN telescope
  46. GRB 260922A: CALET Gamma-Ray Burst Monitor detection
  47. GRB 260924A: Enhanced Swift-XRT position
  48. The EP-WXT trigger 01709319842 is likely a flaring star
  49. GRB 260924A: Swift detection of a burst
  50. GRB 260924A: Fermi GBM Final Real-time Localization
  51. GRB 260923A: Fermi GBM Final Real-time Localization
  52. Trigger_21914: Swift ToO observations
  53. EP260806a: e-MERLIN detection at 5 GHz
  54. Fermi-LAT Gamma-ray Observations of IceCube-260919A
  55. Fermi-LAT Gamma-ray Observations of IceCube-260916A
  56. ATCA observations of GRB 260909A
  57. EP260920a: VLT/HAWK-I near-infrared counterpart confirmation
  58. GRB 260922A: J-band upper limit with WINTER
  59. GRB 260922A: Swift/UVOT Upper Limits
  60. GRB 260922A: COLIBRÍ Optical Counterpart Candidate (correction to GCN 45698)
  61. GRB 260922A: COLIBRÍ optical upper limits
  62. GRB 260922A: Swift-XRT refined Analysis
  63. GRB 260922A: Enhanced Swift-XRT position
  64. Fermi-LAT Gamma-ray Observations of IceCube-260805A
  65. Konus-Wind detection of GRB 260810A
  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 260922A: Swift detection of a burst
  70. GRB 260917C: AstroSat CZTI detection
  71. GRB 260920B/EP260920b: GECAM-B detection of a burst
  72. GRB 260921A: AstroSat CZTI detection
  73. GRB 260921B: Fermi GBM Final Localization
  74. GRB 260921A: Fermi GBM Observation
  75. EP260920b: 2.2m CAHA optical afterglow detection and 10.4m GTC redshift confirmation
  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. GRB 260921A: Swift detection of a burst
  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. EP260920b: Einstein Probe detection of an X-ray transient
  89. IceCube-260919A: Upper limits from a search for additional neutrino events in IceCube
  90. EP-WXT detected a brightening of HMXB LS V +44 17
  91. EP260920a: NOT early time optical upper limits
  92. EP260920a: NOT optical upper limits
  93. GRB 260920A: Fermi GBM Final Real-time Localization
  94. EP260920a: SVOM/VT optical upper limits
  95. EP260920a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  96. EP260920a: COLIBRÍ optical upper limits
  97. EP260920a: Update of the LCO optical counterpart candidate
  98. EP260917b: EP-FXT non-detection and upper limit
  99. EP260920a: Einstein Probe detection of an X-ray transient
  100. GRB 260915A: VLT optical and near-infrared upper limits

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