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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"

21577 results found.

  1. GRB 221009A: Lowell Discovery Telescope Afterglow Detection
  2. GRB221009A: LCOGT Continued Observations - Optical Upper Limits
  3. GRB 221009A/Swift J1913.1+1946: low-frequency ASKAP observations
  4. Fermi trigger No 687345829: Global MASTER-Net observations report
  5. Fermi trigger No 687344475: Global MASTER-Net observations report
  6. Fermi trigger No 687340841: Global MASTER-Net observations report
  7. Fermi trigger No 687337536: Global MASTER-Net observations report
  8. GRB 221006A: Swift-XRT afterglow detection
  9. GRB 221009A: Sayan observatory 1.6-m telescope observations
  10. Fermi trigger No 687281393: Global MASTER-Net observations report
  11. Integral GRB221013.04: Global MASTER-Net observations report
  12. Integral GRB221013.00: Global MASTER-Net observations report
  13. Integral GRB221012.99: Global MASTER-Net observations report
  14. Integral GRB221012.94: Global MASTER-Net observations report
  15. Integral GRB221012.91: Global MASTER-Net observations report
  16. Integral GRB221012.88: Global MASTER-Net observations report
  17. Integral GRB221012.87: Global MASTER-Net observations report
  18. Integral GRB221012.77: Global MASTER-Net observations report
  19. Integral GRB221012.74: Global MASTER-Net observations report
  20. Integral GRB221012.72: Global MASTER-Net observations report
  21. Integral GRB221012.71: Global MASTER-Net observations report
  22. Integral GRB221012.68: Global MASTER-Net observations report
  23. Integral GRB221012.68: Global MASTER-Net observations report
  24. Integral GRB221012.98: Global MASTER-Net observations report
  25. Afterglow limits of GRB 221006A from OHP
  26. Fermi-GBM Observations of High Bursting Activity from SGR J1935+2154
  27. GRB 221009A/Swift J1913.1+1946: SMA observations
  28. INTEGRAL shows increasing activity in SGR J1935+2154
  29. GRB 221009A: COATLI Continued Monitoring of the Afterglow
  30. Integral GRB221012.63: Global MASTER-Net observations report
  31. Integral GRB221012.61: Global MASTER-Net observations report
  32. Integral GRB221012.60: Global MASTER-Net observations report
  33. Integral GRB221012.53: Global MASTER-Net observations report
  34. GRB 221009A/Swift J1913.1+1946: eMERLIN observations
  35. Fermi trigger No 687205006: Global MASTER-Net observations report
  36. INTEGRAL detection of a burst from SGR J1935+2154
  37. GRB 221009A: NuSTAR Detection
  38. GRB 221009A: NICER follow-up observations
  39. GRB 221009A: LCOGT Optical Afterglow Detection
  40. GRB221009A: INTEGRAL detection of Hard X-ray emission up to 38 hours after trigger
  41. GRB 221009A: planned observation with the Imaging X-ray Polarimetry Explorer (IXPE)
  42. Fermi trigger No 687190301: Global MASTER-Net observations report
  43. GRB 221009A: Sintez-Newton/CrAO optical observations
  44. GRB 221009A: Upper limits from HAWC 8 hours after trigger
  45. GRB 221006A: Swift ToO observations
  46. GRB 221009A: BlackGEM optical observations
  47. GRB 221009A: NOEMA mm detection
  48. GRB 221006A: CALET Gamma-Ray Burst Monitor detection
  49. Integral GRB221010.89: Global MASTER-Net observations report
  50. Fermi trigger No 687077239: Global MASTER-Net observations report
  51. GRB 221009A: Continued Swift/XRT observations
  52. GRB 221009A/Swift J1913.1+1946: Assy optical afterglow observation
  53. GRB 221009A/Swift J1913.1+1946: Lick/Nickel telescope optical observations
  54. GRB 221009A: Lulin SLT-40cm optical observations
  55. GRB 221009A (Swift J1913.1+1946): Burke-Gaffney Observatory optical observations
  56. GRB221009A/Swift J1913.1+1946: SRG/ART-XC observation
  57. GRB221009A/Swift J1913.1+1946: INTEGRAL SPI/ACS observations
  58. GRB 221009A: Fermi-LAT refined analysis
  59. GRB 221009: Swift/UVOT Detection
  60. GRB221009A/Swift J1913.1+1946: ATA follow-up observations
  61. GRB 221009A or Swift J1913.1+1946: PRIME near-infrared detection
  62. GRB 221009A/Swift J1913.1+1946: AMI-LA observations
  63. GRB 221009A: REM optical and NIR detection of the afterglow
  64. Swift J1913.1+1946: Early Optical Photometry
  65. GRB 221009A: Redshift from X-shooter/VLT
  66. GRB 221009A: Nanshan/NEXT photometry and Xinglong-2.16m spectroscopy
  67. GRB 221009A (Swift J1913.1+1946): MeerLICHT observations
  68. GRB 221009A (Swift J1913.1+1946): Mondy optical observations
  69. GRB 221009A BOOTES-2/TELMA and OSN optical detections
  70. Swift J1913.1+1946: Optical photometry
  71. Fermi trigger No 687014224: Global MASTER-Net observations report
  72. Swift J1913.1+1946: Liverpool Telescope imaging and spectroscopy
  73. GRB 221008A: Swift-XRT observations
  74. GRB 221008A: Tiled Swift observations
  75. GRB 220915A: Detection by GRBAlpha
  76. GRB 221006A: Swift-XRT observations
  77. GRB 221006A: Tiled Swift observations
  78. Fermi trigger No 686588176: Global MASTER-Net observations report
  79. GRB220927A: Detection by GRBAlpha
  80. GRB 220921A: ATCA detection of radio counterpart
  81. Fermi trigger No 686403226: Global MASTER-Net observations report
  82. Fermi trigger No 686350260: Global MASTER-Net observations report
  83. Konus-Wind detection of GRB 220930A
  84. GRB 220930A: Swift/UVOT Upper Limits
  85. Swift GRB 220930A: Global MASTER-Net observations report
  86. Fermi-LAT gamma-ray observations of IceCube-220928A
  87. Konus-Wind detection of GRB 220927A
  88. Fermi GRB 220927A: Global MASTER-Net observations report
  89. GRB 220921A: LCOGT Optical Observations
  90. GRB 220611A: Host galaxy redshift from VLT/X-shooter
  91. Integral GRB220926.44: Global MASTER-Net observations report
  92. Swift GRB220926.34: Global MASTER-Net observations report
  93. Swift GRB 220926A: Global MASTER-Net observations report
  94. Fermi GRB 220925A: Global MASTER-Net observations report
  95. GRB 220924A: Swift/BAT-GUANO detection outside the coded FOV
  96. GRB 220921A: further MeerLICHT observations
  97. Fermi trigger No 685748699: Global MASTER-Net observations report
  98. Swift GRB220923.47: Global MASTER-Net observations report
  99. GRB 220921A: ALMA detection
  100. GRB 220921A: DDOTI Detection of the Afterglow

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