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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"

42556 results found.

  1. The EP-WXT trigger 01709320726 is likely a flaring star
  2. GRB 260924A: COLIBRÍ optical observations
  3. GRB 260924A: Second-epoch J-band upper limit from the SYSU 80 cm infrared telescope
  4. EP260924a: J-band upper limit by SYSU 80cm infrared telescope
  5. GRB 260925A: J-band upper limit by SYSU 80cm infrared telescope
  6. GRB 260925A: Swift-XRT refined Analysis
  7. EP260924a: EP-FXT follow-up observation
  8. Swift Trigger 1513439 is probably not a GRB
  9. Konus-Wind detection of GRB 260924A
  10. GRB 260924A: Extreme Isotropic-equivalent Gamma-ray Energy and encouragement for multiwavelength follow-up observations
  11. GRB 260923A: Glowbug gamma-ray detection
  12. GRB 260924A: Optical follow-up observations with Kinder
  13. GRB 260922A: Glowbug gamma-ray detection
  14. GRB 260925A: Enhanced Swift-XRT position
  15. GRB 260925A: FRAM-Auger optical limit
  16. GRB 260924A: Ondrejov D50 optical afterglow detection
  17. EP260924a: J-band upper limit with WINTER
  18. GRB 260924A: SVOM/GRM observation
  19. GRB 260924A: 2.2m CAHA spectroscopic redshift z = 3.51
  20. GRB 260925A: Swift detection of a burst
  21. GRB 260923A: Insight-HXMT/HE detection
  22. EP260924a: EP-WXT detection of an X-ray transient
  23. GRB 260924A: Swift/UVOT Detection
  24. GRB 260924A: GROWTH-India Telescope optical observations
  25. GRB 260924A: Swift-BAT refined analysis
  26. GRB 260924A: NuSTAR detection of prompt emission
  27. GRB 260924A: Swift/UVOT Upper Limits
  28. GRB 260924A: Swift-XRT refined Analysis
  29. Konus-Wind detection of GRB 260922A
  30. GRB 260922A: NuSTAR detection of prompt emission
  31. GRB 260921A: NuSTAR detection of prompt emission
  32. GRB 260921A: SVOM/GRM observation
  33. GRB 260922A: COLIBRÍ Confirmation of the Optical Counterpart
  34. GRB 260924A: Fermi GRB Observation
  35. Konus-Wind detection of GRB 260921A (possible merger-origin)
  36. GRB 260924A: Fermi-LAT detection of a bright burst
  37. GRB 260924A: AstroSat CZTI detection
  38. GRB 260920A: SVOM/GRM observation
  39. GRB 260924A: NOT optical counterpart confirmation
  40. GRB 260924A: detection of a bright optical afterglow by the 1.5m OSN telescope
  41. GRB 260922A: CALET Gamma-Ray Burst Monitor detection
  42. GRB 260924A: Enhanced Swift-XRT position
  43. The EP-WXT trigger 01709319842 is likely a flaring star
  44. GRB 260924A: Swift detection of a burst
  45. GRB 260924A: Fermi GBM Final Real-time Localization
  46. Fermi GRB 260923A: Global MASTER-Net observations report
  47. GRB 260923A: Fermi GBM Final Real-time Localization
  48. Trigger_21914: Swift ToO observations
  49. EP260806a: e-MERLIN detection at 5 GHz
  50. GRB 260922A: Ondrejov D50 optical limit
  51. Fermi-LAT Gamma-ray Observations of IceCube-260919A
  52. Fermi-LAT Gamma-ray Observations of IceCube-260916A
  53. ATCA observations of GRB 260909A
  54. GRB 260922A: Swift-BAT refined analysis
  55. EP260920a: VLT/HAWK-I near-infrared counterpart confirmation
  56. GRB 260922A: J-band upper limit with WINTER
  57. GRB 260922A: Swift-XRT refined Analysis
  58. GRB 260922A: Enhanced Swift-XRT position
  59. Fermi-LAT Gamma-ray Observations of IceCube-260805A
  60. Konus-Wind detection of GRB 260810A
  61. GRB 260920A: Glowbug gamma-ray detection
  62. GRB 260918A: SVOM/ECLAIRs refined analysis
  63. GRB 260922A: SVOM/C-GFT optical upper limit
  64. GRB 260922A: Swift detection of a burst
  65. GRB 260917C: AstroSat CZTI detection
  66. GRB 260920B/EP260920b: GECAM-B detection of a burst
  67. GRB 260921A: AstroSat CZTI detection
  68. GRB 260921A: Swift-BAT refined analysis
  69. GRB 260921B: Fermi GBM Final Localization
  70. GRB 260921A: Fermi GBM Observation
  71. EP260920b: 2.2m CAHA optical afterglow detection and 10.4m GTC redshift confirmation
  72. EP Alert 260921.58: Global MASTER-Net observations report
  73. GRB 260917B:: SVOM/ECLAIRs refined analysis
  74. The EP-WXT trigger 01709319528 is likely a flaring star
  75. EP260920a: VLT/HAWK-I near-infrared candidate
  76. Swift GRB 260921A: MASTER OT J094129.58+025052.5 possible optical counterpart detection with host galaxy (z=1.3)
  77. Swift GRB 260921A: Global MASTER-Net observations report
  78. GRB 260921A: Swift detection of a burst
  79. EP260920b: VLT/X-shooter spectroscopic redshift z = 3.582
  80. GRB 260921A: Fermi GBM Final Real-time Localization
  81. EP260920b: LCO observations
  82. GRB 260920A: AstroSat CZTI detection
  83. EP260920b: SVOM/VT optical observation
  84. EP260920b: refined analysis of the EP-WXT and EP-FXT observations
  85. EP260920b: COLIBRÍ optical observations
  86. EP260920b: LCO optical counterpart detection
  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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