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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"

28058 results found.

  1. GRB 090728, RIMOTS optical upper limits
  2. GRB 090728: Swift detection of a burst
  3. GRB 090727: Swift-BAT refined analysis
  4. GRB 090727: Swift-XRT refined analysis
  5. GRB 090727: Enhanced Swift-XRT position
  6. GRB 090715B: Late-time Lick 3m observations
  7. GRB 090727: Swift detection of a burst
  8. GRB090726: Swift/UVOT observations
  9. GRB 090726, Swift-BAT refined analysis
  10. GRB 090726: Afterglow candidate photometryfrom Crni Vrh
  11. GRB 090726: D50 optical observations
  12. GRB 090711: Fermi GBM detection
  13. GRB 090726: Swift-XRT Team refined analysis
  14. GRB 090726: Enhanced Swift-XRT position
  15. GRB 090726: optical transient candidate
  16. Konus-RF and Konus-Wind observations of GRB 090718B
  17. GRB 090720B: Fermi GBM detection
  18. Swift XRT and UVOT refned analysis of GRB 090720
  19. GRB 090709A: Swift XRT Timing Analysis
  20. GRB 090715B: VLA radio detection
  21. GRB 090720 Source found in ground processing of Swift-BAT data
  22. GRB 090717B: Fermi GBM detection
  23. GRB 090717: Fermi GBM detection
  24. GRB 090719: Fermi GBM detection
  25. GRB 090718B: Fermi GBM detection
  26. GRB 090718: Fermi GBM detection
  27. GRB 090720: Fermi GBM detection
  28. GRB 090715B: further NOT optical observations
  29. GRB 090715A: Suzaku WAM observation of the prompt emission
  30. GRB 090709A - CARMA mm Observations
  31. GRB 090715B: Lick observations
  32. GRB 090715A: VLA observations
  33. GRB 090715A: Swift-BAT refined analysis
  34. GRB 090715B: Swift/UVOT followup observations
  35. GRB 090715B: Enhanced Swift-XRT position
  36. GRB 090715B: Observation of the optical afterglow
  37. GRB 090715B: Swift XRT Refined Analysis
  38. GRB 090715B: Swift-BAT refined analysis
  39. GRB 090715B: NOT optical observations
  40. GRB 090715B - Liverpool Telescope Optical Afterglow Candidate
  41. GRB 090715B: Swift detection of a burst with a possible optical counterpart
  42. GRB 090713: Fermi GBM detection
  43. GRB 090712: Swift-BAT refined analysis
  44. VLA radio observations of GRB 090709A
  45. GRB 090621B: MTM-500 optical observations
  46. GRB 090709A: deep optical observation with the 10.4m GTC
  47. GRB 090709A: Suzaku WAM observation of the prompt emission
  48. GRB 090709A: Swift UVOT upper limits
  49. GRB 090709A: WHT LIRIS observations
  50. GRB 090709B: Fermi GBM detection
  51. GRB 090709A: evidence for a very red afterglow at low z
  52. GRB 090709A: P60 Observations
  53. GRB 090709A: NOT optical observations
  54. GRB 090709A: RAPTOR Limits During Gamma-Ray Emission
  55. GRB 090709A: Swift XRT Refined Analysis
  56. GRB 090709B, Swift-BAT refined analysis
  57. GRB 090709A: Swift-BAT refined analysis
  58. GRB090709A: High Energy BAT/XRT Analysis Suggests Low to Moderate Redshift
  59. GRB 090709A: Wyoming Infrared Observatory NIR upper limits
  60. GRB 090709A, RIMOTS optical upper limits
  61. GRB 090709A: Enhanced Swift-XRT position
  62. GRB 090709A: Subaru NIR observation
  63. GRB 090709 : planned Suzaku-ToO observation
  64. GRB 090708 : Fermi GBM detection
  65. GRB 090709: Faulkes Telescope North Upper Limits
  66. GRB 090626: Suzaku WAM observation of the prompt emission
  67. GRB 090709: PAIRITEL NIR Upper Limits
  68. GRB 090704: Fermi GBM observation
  69. GRB 090709: Swift detection of a bright burst
  70. GRB 090708: Early RAPTOR Optical Limits
  71. GRB 090708, Swift-BAT refined analysis
  72. GRB 090704: a long GRB found in INTEGRAL off-line analysis
  73. GRB 090706: Fermi GBM detection
  74. Possible GRB090705: Swift-XRT observations
  75. GRB 090705: PAIRITEL NIR Observations
  76. GRB 090705: Swift detection of a possible burst
  77. XRF 090702 : RTT150 optical observations
  78. GRB 090529: CrAO optical upper limit
  79. GRB 090529: MTM-500 optical observations
  80. XRF 090702: Swift-XRT refined analysis
  81. GRB 090703: Fermi GBM detection
  82. GRB 090702: UVOT upper limits
  83. XRF 090702: VLT imaging
  84. XRF 090702: Swift-XRT afterglow position
  85. XRF 090702: a long soft GRB localized with INTEGRAL
  86. GRB 090404: Deep optical imaging and possible host association
  87. GRB 090701: Fermi GBM detection
  88. GRB 090628: Swift XRT refined analysis
  89. GRB 090630: Fermi GBM detection
  90. GRB 090628: Swift/UVOT Upper Limits
  91. GRB080628: SAO RAS optical observations
  92. GRB 090628: Swift-BAT refined analysis
  93. GRB 090628: GROND upper limits
  94. GRB 090628: Enhanced Swift-XRT position
  95. GRB 090626: IPN localization
  96. GRB 090423: Spitzer observations of the z~8.3 burst
  97. GRB 090625B: Swift/UVOT Upper Limits
  98. GRB 090625B: Swift-XRT refined analysis
  99. GRB 090626: Fermi GBM detection
  100. GRB 090625B: GROND upper limits

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Download all Circulars as a .tar.gz archive (updated once a day):
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