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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"

38354 results found.

  1. GRB 260924A: VLA detection
  2. GRB 260924A: Swift/UVOT UV grism spectrum results
  3. GRB 260924A: AbAO optical observations
  4. GRB 260928A: Fermi GBM Final Real-time Localization
  5. Swift Trigger 1513439: consistent with noise and not astrophysical
  6. GRB 260924A: Upper limits from a neutrino search with IceCube
  7. GRB 260926C: Fermi GBM Final Real-time Localization
  8. GRB260914A: MAO/AZT-22 optical observations
  9. GRB 260926B: Fermi GBM Final Real-time Localization
  10. GRB 260924A: Near-infrared detection with MDM/MIRAGE
  11. GRB 260926A: Fermi GBM Final Real-time Localization
  12. The EP-WXT trigger 01709320726 is likely a flaring star
  13. GRB 260924A: COLIBRÍ optical observations
  14. GRB 260924A: Second-epoch J-band upper limit from the SYSU 80 cm infrared telescope
  15. EP260924a: J-band upper limit by SYSU 80cm infrared telescope
  16. GRB 260925A: J-band upper limit by SYSU 80cm infrared telescope
  17. GRB 260925A: Swift-XRT refined Analysis
  18. EP260924a: EP-FXT follow-up observation
  19. Swift Trigger 1513439 is probably not a GRB
  20. GRB 260925A: Swift/UVOT Upper Limits
  21. Konus-Wind detection of GRB 260924A
  22. GRB 260923A: Glowbug gamma-ray detection
  23. GRB 260924A: Optical follow-up observations with Kinder
  24. GRB 260922A: Glowbug gamma-ray detection
  25. GRB 260925A: Enhanced Swift-XRT position
  26. GRB 260925A: COLIBRÍ optical upper limits
  27. GRB 260924A: Ondrejov D50 optical afterglow detection
  28. EP260924a: J-band upper limit with WINTER
  29. GRB 260924A: SVOM/GRM observation
  30. GRB 260924A: 2.2m CAHA spectroscopic redshift z = 3.51
  31. GRB 260925A: Swift detection of a burst
  32. GRB 260923A: Insight-HXMT/HE detection
  33. EP260924a: EP-WXT detection of an X-ray transient
  34. GRB 260924A: J-band observations by the SYSU 80 cm infrared telescope
  35. GRB 260924A: Swift/UVOT Detection
  36. GRB 260924A: GROWTH-India Telescope optical observations
  37. GRB 260924A: NuSTAR detection of prompt emission
  38. GRB 260924A: Swift-XRT refined Analysis
  39. Konus-Wind detection of GRB 260922A
  40. GRB 260922A: NuSTAR detection of prompt emission
  41. GRB 260921A: NuSTAR detection of prompt emission
  42. Konus-Wind detection of GRB 260921A (correction to GCN 45722)
  43. GRB 260921A: SVOM/GRM observation
  44. GRB 260922A: COLIBRÍ Confirmation of the Optical Counterpart
  45. GRB 260924A: Fermi GRB Observation
  46. Konus-Wind detection of GRB 260921A (possible merger-origin)
  47. GRB 260924A: Fermi-LAT detection of a bright burst
  48. GRB 260924A: AstroSat CZTI detection
  49. GRB 260920A: SVOM/GRM observation
  50. GRB 260924A: NOT optical counterpart confirmation
  51. GRB 260924A: detection of a bright optical afterglow by the 1.5m OSN telescope
  52. GRB 260922A: CALET Gamma-Ray Burst Monitor detection
  53. GRB 260924A: Enhanced Swift-XRT position
  54. The EP-WXT trigger 01709319842 is likely a flaring star
  55. GRB 260924A: Swift detection of a burst
  56. GRB 260924A: Fermi GBM Final Real-time Localization
  57. GRB 260923A: Fermi GBM Final Real-time Localization
  58. Trigger_21914: Swift ToO observations
  59. EP260806a: e-MERLIN detection at 5 GHz
  60. Fermi-LAT Gamma-ray Observations of IceCube-260919A
  61. Fermi-LAT Gamma-ray Observations of IceCube-260916A
  62. ATCA observations of GRB 260909A
  63. EP260920a: VLT/HAWK-I near-infrared counterpart confirmation
  64. GRB 260922A: J-band upper limit with WINTER
  65. GRB 260922A: Swift/UVOT Upper Limits
  66. GRB 260922A: COLIBRÍ Optical Counterpart Candidate (correction to GCN 45698)
  67. GRB 260922A: COLIBRÍ optical upper limits
  68. GRB 260922A: Swift-XRT refined Analysis
  69. GRB 260922A: Enhanced Swift-XRT position
  70. Fermi-LAT Gamma-ray Observations of IceCube-260805A
  71. Konus-Wind detection of GRB 260810A
  72. GRB 260920A: Glowbug gamma-ray detection
  73. GRB 260918A: SVOM/ECLAIRs refined analysis
  74. GRB 260922A: SVOM/C-GFT optical upper limit
  75. GRB 260922A: Swift detection of a burst
  76. GRB 260917C: AstroSat CZTI detection
  77. GRB 260920B/EP260920b: GECAM-B detection of a burst
  78. GRB 260921A: AstroSat CZTI detection
  79. GRB 260921B: Fermi GBM Final Localization
  80. GRB 260921A: Fermi GBM Observation
  81. EP260920b: 2.2m CAHA optical afterglow detection and 10.4m GTC redshift confirmation
  82. GRB 260917B:: SVOM/ECLAIRs refined analysis
  83. The EP-WXT trigger 01709319528 is likely a flaring star
  84. EP260920a: VLT/HAWK-I near-infrared candidate
  85. GRB 260921A: Swift detection of a burst
  86. EP260920b: VLT/X-shooter spectroscopic redshift z = 3.582
  87. GRB 260921A: Fermi GBM Final Real-time Localization
  88. EP260920b: LCO observations
  89. GRB 260920A: AstroSat CZTI detection
  90. EP260920b: SVOM/VT optical observation
  91. EP260920b: refined analysis of the EP-WXT and EP-FXT observations
  92. EP260920b: COLIBRÍ optical observations
  93. The EP-WXT trigger 01709318601 is likely a flaring star
  94. EP260920b: Einstein Probe detection of an X-ray transient
  95. IceCube-260919A: Upper limits from a search for additional neutrino events in IceCube
  96. EP-WXT detected a brightening of HMXB LS V +44 17
  97. EP260920a: NOT early time optical upper limits
  98. EP260920a: NOT optical upper limits
  99. GRB 260920A: Fermi GBM Final Real-time Localization
  100. EP260920a: SVOM/VT optical upper limits

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