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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"
  1. IPN localization of bright GRB 110518A
  2. Radio observations of GRB 110428A with the EVLA
  3. GRB 110519A, Swift-BAT refined analysis
  4. GRB 110519A: Swift detection of a burst
  5. GRB 110503A optical observation
  6. GRB 110426A: Fermi GBM detection
  7. GRB 110428A: Fermi-GBM observation
  8. GRB 110503A: TAROT Calern observatory optical observations
  9. GRB 110503A: Jet Break seen from TLS
  10. GRB 110503A optical observations
  11. Konus-Wind observation of GRB 110503A
  12. GRB 110422A: MASTER first 30 min OT light curve
  13. GRB 110422A: Herschel FIR observation preliminary report
  14. GRB 110503A: optical observation in CrAO
  15. GRB 110503A: R-band Detection
  16. GRB 110503A: Centimeter observation from EVLA
  17. GRB 110503A: Millimeter observation from SMA
  18. GRB 110503A: SARA-N Observations and Photometric Calibration
  19. GRB 110503A: Swift/UVOT Observations
  20. GRB 110503A: Swift-XRT refined Analysis
  21. GRB 110503A: PAIRITEL NIR Detection
  22. GRB 110503A: redshift confirmation from TNG
  23. GRB 110503A - TLS Afterglow Observations
  24. GRB 110503A: Swift-BAT refined analysis
  25. GRB 110503A: NOT afterglow photometry
  26. GRB 110503A: Redshift from 10.4m GTC
  27. GRB 110503A: Enhanced Swift-XRT position
  28. GRB 110503A: Swift detection of a burst with a bright optical counterpart
  29. GRB 110426A: Swift/XRT non-detection
  30. GRB 110428A : X-ray afterglow confirmation
  31. GRB 110428A: Suzaku WAM observation of the prompt emission
  32. Fermi-GBM data processing and delivery
  33. GRB 110422A: optical observations in CrAO
  34. GRB 110422A: Update of Herschel FIR observation schedule
  35. GRB 110428A : Swift-XRT observations
  36. Konus-Wind observation of GRB 110428A
  37. GRB 110428A: Fermi-LAT Detection
  38. GRB 110426A: MASTER synchronous with MAXI/GSC observations
  39. GRB 110426A: MAXI/GSC detection of a GRB
  40. GRB 110422A: optical observations in CrAO, second epoch
  41. GRB 110422A: Redshift confirmation from GTC
  42. GRB 110422A: tentative redshift from TNG
  43. GRB 110422A: Suzaku WAM observation of the prompt emission
  44. GRB 110422A: Herschel observation scheduled
  45. GRB110422A: NOT optical follow-ups
  46. GRB 110422A: optical observations in CrAO
  47. GRB110422A: MITSuME Ishigakijima Optical Observation
  48. Konus-Wind observation of GRB 110422A
  49. GRB 110422A: Further NOT observation
  50. GRB 110422A: Swift/UVOT Detection of optical afterglow
  51. GRB 110422A: Swift-XRT refined Analysis
  52. GRB 110422A: CQUEAN griz Observation
  53. GRB 110422A: THO optical observations
  54. GRB 110422A: Enhanced Swift-XRT position
  55. GRB 110422A: correction to the GCN circ. 11958
  56. GRB 110422A: TNG optical observations
  57. GRB 110422A: SAO RAS optical observations
  58. GRB 110422A: NOT optical observation
  59. GRB 110422A: MASTER earlier OT polarization observations
  60. GRB 110422A: Swift-BAT refined analysis
  61. GRB 110422A: Mondy optical observations
  62. GRB 110422A: Swift detection of a burst
  63. GRB 110328A/Swift J164449.3+573451: Maidanak Optical Observation
  64. GRB 110420B: Swift/UVOT Upper Limits
  65. GRB110420A: GROND detection of the Optical/NIR Afterglow Candidate
  66. GRB 110420B: Swift-XRT afterglow candidate retraction
  67. GRB 110420B: Fermi GBM observation
  68. Konus-Wind observation of GRB 110420A
  69. GRB 110420B: Spectral lag indicates short hard burst
  70. GRB 110420B, GROND observations
  71. GRB 110420A Swift/UVOT Observations
  72. GRB 110420B: Swift-XRT afterglow candidate
  73. GRB 110420B: Swift-BAT refined analysis
  74. GRB 110420A: Swift-BAT refined analysis
  75. GRB 110420B: Swift detection of a short hard burst
  76. GRB 110420A: Swift-XRT refined Analysis
  77. GRB 110420A: Enhanced Swift-XRT position
  78. GRB 110420A: Swift detection of a burst with optical counterpart
  79. GRB110414A: MITSuME Ishigakijima Optical upper limits
  80. GRB 110414A: GROND upper limits
  81. GRB110414A: MITSuME Okayama Optical upper limits
  82. GRB 110414A: Swift-BAT Refined Analysis
  83. GRB 110414A: Swift/UVOT Upper limits
  84. GRB 110414A: Swift-XRT refined Analysis
  85. GRB 110414A: Enhanced Swift-XRT position
  86. GRB 110328A / Swift J164449.3+573451: WISE quiescent source upper limit
  87. GRB 110414A : Faulkes Telescope North observations
  88. GRB 110414A: Swift detection of a burst
  89. GRB 110411A: PAIRITEL NIR Upper Limits
  90. GRB 110412A: Swift-BAT refined analysis
  91. GRB 110411A: optical limits from OSN
  92. GRB 110411A: Swift-XRT refined Analysis
  93. GRB 110412A: Fermi GBM observation
  94. GRB 110411A: Swift/UVOT Upper Limits
  95. GRB 110411A: MASTER prompt and follow-up optical limits
  96. GRB 110411A : Xinglong TNT OT candidate
  97. GRB 110412A: Swift detection of a burst
  98. GRB 110411A, Swift-BAT refined analysis
  99. GRB 110411A: Enhanced Swift-XRT position
  100. GRB 110411A: MASTER optical observations

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