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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"

28094 results found.

  1. GRB 221022A: Swift-XRT observations
  2. GRB 221024A: Swift-XRT refined Analysis
  3. GRB 221023A: Fermi GBM Observation
  4. GRB 221025A: Fermi-LAT detection
  5. IPN triangulation of GRB 221022B (long)
  6. GRB 221024A: GIT confirmation of the optical afterglow
  7. GRB 221024A: Enhanced Swift-XRT position
  8. GRB 221024A: D50 candidate afterglow
  9. GRB 221022A: Fermi GBM detection
  10. GRB 221023A: Fermi-LAT detection
  11. GRB 221022B: Fermi GBM detection
  12. GRB 221021A: Fermi GBM observation
  13. GRB 221024A: Swift detection of a burst
  14. GRB 221023A: Fermi GBM Final Localization
  15. GRB 221022A: Swift/BAT-GUANO detection
  16. GRB 221022B: Swift/BAT-GUANO detection outside the coded FOV
  17. GRB 221009A: Analysis of the initial episode using data of GBM/Fermi and SPI-ACS/INTEGRAL
  18. GRB 221021A: Swift/BAT-GUANO detection outside the coded FOV
  19. SGR 1935+21542: VZLUSAT-2 and GRBAlpha joint detection
  20. GRB221009A: LBT optical imaging
  21. GRB 221009A: Peak luminosity of the supernova vs. synchrotron afterglow
  22. GRB 221017A: Swift-XRT observations
  23. GRB 221009A: TNG NIR detection
  24. GRB 221009A: BOAO NIR detections
  25. GRB 221009A X-ray light-curve and the indication of TeV light-curve
  26. GRB 221013B: Swift/BAT-GUANO detection
  27. SGR 1935+2154: Bursting activity detected by VZLUSAT-2
  28. GRB 221009A: GRANDMA observations
  29. The probability of observing GRB 221009A at z = 0.151
  30. GRB 221009A: Medicina Radio Telescope observations
  31. AGILE detection of short X-ray flaring activity contemporary to SGR J1935+2154 reported bursts
  32. GRB 221009A: Second epoch of NuSTAR data
  33. GRB 221016A: Swift-BAT refined analysis
  34. GRB 221016A: Swift/UVOT Detection
  35. GRB 221016A: Swift-XRT refined Analysis
  36. GRB 221016A: Fermi GBM observation
  37. GRB 221009A: A type I BdHN of exceptional energetics
  38. MAXI GRB221017.24: Global MASTER-Net observations report
  39. GRB 221016A: z-band upper limit, possible afterglow brightening
  40. GRB 221017A: MAXI/GSC detection
  41. GRB 221016A: Enhanced Swift-XRT position
  42. GRB 221016A: LCOGT Optical Afterglow Detection
  43. GRB 221016A: Swift detection of a burst
  44. GRB 221009A: Faulkes Telescope North continued optical afterglow follow-up
  45. Konus-Wind observation of the recent SGR 1935+2154 activity
  46. GRB 221009A: VLT spectroscopic detection of the host galaxy
  47. GRB 221009A: Armchair Energetics
  48. GRB 221009A: ALMA and ACA detections
  49. GRB 221009A: Large Binocular Telescope Observatory optical afterglow detection
  50. MAXI/GSC refined analysis of the bright X-ray afterglow of GRB 221009A/Swift J1913.1+1946
  51. GRB 221009A: continued REM optical/NIR observations and evidence for an achromatic steepening in the afterglow light curve
  52. GRB 221009A: OHP optical observations
  53. MAXI GRB 221006A: Redshifts of the possible host galaxies
  54. GRB221009A: LCOGT Continued Observations - Optical Upper Limits
  55. GRB 221009A/Swift J1913.1+1946: low-frequency ASKAP observations
  56. GRB 221006A: Swift-XRT afterglow detection
  57. GRB 221009A: MITSuME Okayama optical observation
  58. GRB 221009A: Sayan observatory 1.6-m telescope observations
  59. GRB 221009A: GMG observation
  60. Afterglow limits of GRB 221006A from OHP
  61. GRB221009A: optical afterglow measurements from Konkoly Observatory
  62. GRB 221009A/Swift J1913.1+1946: SMA observations
  63. INTEGRAL shows increasing activity in SGR J1935+2154
  64. GRB 221009A: COATLI Continued Monitoring of the Afterglow
  65. INTEGRAL detection of a burst from SGR J1935+2154
  66. GRB 221009A: NICER follow-up observations
  67. GRB 221009A: LCOGT Optical Afterglow Detection
  68. GRB 221009A: COATLI Detection of the Afterglow
  69. GRB 221009A (Swift J1913.1+1946): Swift-BAT refined analysis
  70. GRB 221009A: Upper limits from HAWC 8 hours after trigger
  71. Swift/XRT discovery of multiple dust-scattering X-ray rings around GRB 221009A
  72. GRB 221009A: BlackGEM optical observations
  73. GRB 221009A/Swift J1913.1+1946: Lick/Nickel telescope optical observations
  74. Konus-Wind detection of GRB 221009A
  75. GRB 221009A: Lulin SLT-40cm optical observations
  76. GRB 221009A: Upper limits from a neutrino search with IceCube
  77. GRB 221009A (Swift J1913.1+1946): Burke-Gaffney Observatory optical observations
  78. GRB221009A/Swift J1913.1+1946: SRG/ART-XC observation
  79. GRB 221009A / Swift J1913.1+1946: GIT detection of the optical afterglow
  80. GRB221009A/Swift J1913.1+1946: Solar Orbiter STIX measurements
  81. GRB221009A/Swift J1913.1+1946: INTEGRAL SPI/ACS observations
  82. ​GRB 221009A: Multi-color detection of the optical
  83. GRB 221009A: Fermi-LAT refined analysis
  84. GRB 221009: Swift/UVOT Detection
  85. GRB221009A/Swift J1913.1+1946: ATA follow-up observations
  86. GRB 221009A or Swift J1913.1+1946: PRIME near-infrared detection
  87. GRB 221009A/Swift J1913.1+1946: AMI-LA observations
  88. GRB 221009A: REM optical and NIR detection of the afterglow
  89. GRB 221009A: Swift-XRT refined Analysis
  90. GRB 221009A: Nanshan/NEXT photometry and Xinglong-2.16m spectroscopy
  91. GRB 221009A (Swift J1913.1+1946): MeerLICHT observations
  92. Swift J1913.1+1946 : Pre-discovery limits from ZTF
  93. Swift J1913.1+1946: Optical photometry
  94. Fermi trigger No 687014224: Global MASTER-Net observations report
  95. GRB 221009A or Swift J1913.1+1946: Fermi-LAT detection
  96. GRB 221009A: Fermi GBM detection of an extraordinarily bright GRB
  97. Swift GRB221009.59: Global MASTER-Net OT detection
  98. GRB 221008A: Swift-XRT observations
  99. Swift J1913.1+1946 a new bright hard X-ray and optical transient
  100. GRB 221008A: MAXI/GSC detection

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