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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"

28048 results found.

  1. Fermi trigger No 649684549: Global MASTER-Net observations report
  2. GRB 210802A: DDOTI Upper Limits
  3. GRB 210802A: BOOTES-2/TELMA optical upper limit
  4. GRB 210802A: Swift-XRT afterglow detection
  5. GRB 210802A: Fermi GBM detection
  6. GRB 210803A: BALROG localization (Fermi Trigger 649684549 / GRB 210803497)
  7. Fermi trigger No 649627691: Global MASTER-Net observations report
  8. GRB 210801A: Fermi GBM detection
  9. GRB 210731A: VLT/X-shooter redshift
  10. IceCube-210730A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  11. GRB 210731A: Swift-BAT refined analysis
  12. GRB 210801A: BALROG localization (Fermi Trigger 649519043 / GRB 210801581)
  13. GRB 210731A: Swift-XRT refined Analysis
  14. Fermi trigger No 649519043: Global MASTER-Net observations report
  15. GRB 210731A: GROND observations
  16. GRB 210731A: Fermi GBM Observation
  17. GRB 210731A: Swift/UVOT Detection of an optical afterglow
  18. GRB 210731A: MeerLICHT optical afterglow detection
  19. GRB210731A: Enhanced Swift-XRT position
  20. GRB 210731A: Swift detection of a burst
  21. Fermi-LAT Gamma-ray Observations of IceCube-210730A
  22. GRB 210730A: Campo Imperatore optical observations
  23. GRB 210730A: BOOTES-5/JGT and 2.2m CAHA telescopes optical limit
  24. GRB 210730A: TNG optical observations
  25. GRB 210730A: Fermi GBM observation
  26. GRB 210730A: AstroSat CZTI detection
  27. GRB 210730A: Swift-BAT refined analysis
  28. GRB 210730A: Swift-XRT refined Analysis
  29. GRB 210730A: Swift/UVOT Upper Limits
  30. GRB 210730A: Enhanced Swift-XRT position
  31. GRB 210730A: Swift detection of a burst near M82
  32. Fermi GBM Sub-Threshold Detection of GRB 210725B
  33. GRB 210726A: 6 GHz VLA radio upper limit
  34. IPN triangulation of GRB 210727A (short)
  35. Fermi GBM Sub-Threshold Detection of GRB 210726A
  36. GRB 210714A: Fermi GBM observation
  37. GRB 210726A: Swift-XRT refined Analysis
  38. GRB 210726A: Swift-BAT refined analysis
  39. GRB 210726A: RATIR Optical Upper Limits and Candidate Host Galaxy
  40. GRB 210727A: BALROG localization (Fermi Trigger 649072251 / GRB 210727410)
  41. GRB 210725A: AbAO optical upper limit
  42. GRB 210724A: Swift/UVOT Upper Limits
  43. GRB 210723A: Swift/UVOT Upper Limits
  44. GRB 210725A: Swift/UVOT Upper Limits
  45. GRB 210725B: Swift/UVOT Upper Limits
  46. GRB 210726A: Enhanced Swift-XRT position
  47. GRB 210726A: Swift detection of a burst
  48. GRB 210725B: Swift-XRT refined Analysis
  49. GRB 210725A: Fermi GBM detection
  50. GRB 210724A: Zeiss-1000 of Koshka observatory, optical upper limit
  51. GRB 210725A: Swift-XRT refined Analysis
  52. GRB 210725B: Swift-BAT refined analysis
  53. GRB 210724A: Swift-XRT refined Analysis
  54. GRB 210725A: Swift-BAT refined analysis
  55. GRB 210724A: Swift-BAT refined analysis
  56. GRB 210724A: Afterglow candidate from OSIRIS/GTC
  57. GRB 210725B: Enhanced Swift-XRT position
  58. GRB 210725A: MITSuME Akeno optical upper limits
  59. GRB 210725B: Swift detection of a burst
  60. GRB 210722A: continued Assy optical observations
  61. GRB 210722A: Nanshan/NEXT further optical observations
  62. GRB 210725A: Swift detection of a burst
  63. GRB 210723A: Fermi GBM Observation
  64. GRB210724A: MeerLICHT upper limits
  65. GRB 210724A: Swift detection of a burst
  66. GRB 210723A: Swift-BAT refined analysis
  67. GRB 210722A: continued Assy optical observations
  68. GRB 210723A: Swift-XRT refined Analysis
  69. GRB 210722A: D50 optical detection
  70. GRB 210722A: Fermi GBM observation
  71. GRB 210722A: Swift-BAT refined analysis
  72. GRB 210722A: Kitab optical observations, light curve
  73. GRB 210722A: Redshift from OSIRIS/GTC
  74. GRB 210723A: Swift detection of a burst
  75. GRB 210722A: RATIR Optical Observations
  76. GRB 210722A: Swift-XRT refined Analysis
  77. GRB 210722A: Swift/UVOT Detection
  78. GRB 210722A: GIT optical detection and preliminary analysis
  79. GRB 210722A: Assy optical detection
  80. GRB 210722A: Nanshan/NEXT optical afterglow observations
  81. GRB 210722A: Swift detection of a burst with a bright optical counterpart
  82. Fermi-LAT Gamma-ray Observations of IceCube-210717A
  83. GRB 210719A: GECAM detection
  84. IceCube-210717A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  85. IceCube-210717A: IceCube observation of a high-energy neutrino candidate track-like event
  86. GRB 210715B: DDOTI Upper Limits on the Afterglow
  87. GRB 210712A: Swift-BAT refined analysis
  88. GECAM detection of a short burst from SGR J1935+2154
  89. GRB 210712A: Swift-XRT refined Analysis
  90. GRB 210712A: Swift/UVOT Upper Limits
  91. GRB 210712A: Enhanced Swift-XRT position
  92. GRB 210704A: classification as long GRB and redshift estimating
  93. GRB 210704A: Lowell Discovery Telescope Optical Observations
  94. GECAM detection of a short burst from SGR J1935+2154
  95. GRB 210712A: Swift detection of a burst
  96. GRB 210709A: AstroSat CZTI detection
  97. GRB210704A: Gemini near-infrared upper limits
  98. Fermi trigger No 647624281: Global MASTER-Net observations report
  99. GECAM detection of a short burst from SGR J1935+2154
  100. GRB 210704A: OSIRIS/GTC Observations and Archival Detection of the Possible Host Galaxy

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