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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. GRB 150831A: Swift-XRT refined Analysis
  2. GRB 150831B: Swift detection of a probable burst
  3. GRB 150831A: Swift-BAT refined analysis
  4. GRB 150818A: Spectroscopic confirmation of the SN from GTC
  5. GRB 150831A: Enhanced Swift-XRT position
  6. GRB 150831A: optical upper limit ISON-SSO
  7. INTEGRAL detection of GRB 150831A
  8. GRB 150831A: Swift detection of a short burst
  9. Fermi GBM trigger 150829183 is not a GRB
  10. Fermi GBM trigger 150828520 is not a GRB
  11. Fermi GBM trigger 150827524 is not a GRB
  12. GRB 150818A: possible SN rise in light curve of Mondy observations
  13. Fermi GBM trigger 150826536 is not a GRB
  14. Konus-Wind observation of GRB 150824A
  15. IPN Triangulation of GRB 150824A
  16. GRB 150824A: Fermi GBM detection
  17. Konus-Wind observation of GRB 150821A
  18. GRB 150821A: LCOGT Siding Springs early observations
  19. Konus-Wind observation of GRB 150818A
  20. GRB 150821A: LCOGT Sutherland observations
  21. GRB 150821A, Swift-BAT refined analysis
  22. GRB 150821A: GROND afterglow observations
  23. GRB 150821A: Swift-XRT refined Analysis
  24. GRB 150819A: Mondy and TSHAO optical upper limits
  25. GRB 150821A: Swift/UVOT Detection
  26. GRB 150821A: Enhanced Swift-XRT position
  27. GRB 150821A: Fermi GBM detection
  28. GRB 150818A: continued Mondy optical observations
  29. Swift Trigger 652824 is due to noise
  30. GRB 150821A: VLT/X-shooter redshift
  31. GRB 150821A: Swift detection of a burst with an optical afterglow
  32. Swift Trigger 652824: Is most likely a noise fluctuation in the direction of M31
  33. GRB 120729A: KAIT Optical Observations
  34. KAIT Optical Upper Limits for GRB 120422A, 120724A, 120803B, 120911A, and 120923A
  35. GRB 150818A: Mondy optical observations
  36. GRB150819A: NOT imaging
  37. Konus-Wind observation of GRB 150819B
  38. GRB 150818A: Continued NOT monitoring - afterglow confirmation
  39. GRB 150819B: Fermi GBM detection
  40. GRB 150818A: 10.4m GTC spectroscopy and host galaxy
  41. IPN Triangulation of GRB 150819B (short / very intense)
  42. GRB 150818A: Mondy optical observations
  43. GRB 150818A: MITSuME Ishigakijima upper limits
  44. GRB 150819A: RATIR Optical Observations
  45. GRB 150819A: Swift-XRT refined Analysis
  46. GRB 150818A: MITSuME Akeno optical upper limits
  47. GRB 150819A: Swift-BAT refined analysis
  48. GRB 150819A: MASTER-IAC early upper limit
  49. GRB 150819A: Swift/UVOT Upper Limits
  50. GRB 150819A: Enhanced Swift-XRT position
  51. GRB 150818A: Swift-XRT update, correction to GCN 18162
  52. GRB 150819A: Prompt enhanced Swift-XRT position
  53. GRB150818A: NOT imaging
  54. GRB 150819A: Swift detection of a burst
  55. GRB 150818A: Swift-XRT refined Analysis
  56. GRB 150818A: Swift/UVOT Detection
  57. GRB 150817A: AAO optical observations
  58. GRB 150818A: Enhanced Swift-XRT position
  59. GRB 150817A: LCOGT observations
  60. GRB 150818A: Swift-BAT refined analysis
  61. GRB 150817A: Continued RATIR Optical Observations - Afterglow Confirmation
  62. GRB 150818A: Swift/UVOT candidate afterglow
  63. GRB 150818A: Planned XMM-Newton observation
  64. GRB 150817A: P60 Observations
  65. GRB 150818A: Swift detection of a burst
  66. MASTER OT inside bright ESO240-010 galaxy detection during FERMI trigger GRB150816.83 inspection
  67. GRB 150817A: Swift/UVOT Upper Limits
  68. GRB 150817A: Fermi GBM observation
  69. GRB 150817A: Swift-BAT refined analysis
  70. GRB 150817A: Swift-XRT refined Analysis
  71. GRB 150817A: Enhanced Swift-XRT position
  72. GRB 150817A: Continued RATIR Observations, Revised Candidate
  73. GRB 150817A: RATIR Optical Afterglow Candidate
  74. GRB 150817A: Swift detection of a burst
  75. Fermi GBM Trigger 150815694 is not a GRB
  76. GRB 150811A: Continued RATIR Observations
  77. GRB 150811A: Continued RATIR Observations
  78. GBM Trigger 150813665 is not a GRB
  79. Swift Trigger 652046 is a particle shower event
  80. Konus-Wind observation of GRB 150811B
  81. Swift Trigger 652046 is probably not a GRB
  82. GRB 150811A: KAIT Refined Analysis
  83. GRB 150811A: VLA Detection
  84. IPN Triangulation of GRB 150811B
  85. GRB 150811A: Continued RATIR Observations
  86. GRB 150811A: Swift/UVOT further observations
  87. GRB 150811B: Fermi GBM detection
  88. GRB 150811A: Swift-BAT refined analysis
  89. GRB 150811A: SAO RAS optical observations
  90. GRB 150811A: Swift-XRT refined Analysis
  91. GRB 150810A: Fermi GBM detection
  92. GRB 150811A: P60 Observations
  93. GRB 150811A: Enhanced Swift-XRT position
  94. GRB 150811A: LCOGT-McDonald afterglow detection
  95. GRB 150811A: Swift/UVOT Detection
  96. GRB 150811A: KAIT optical candidate
  97. GRB 150811A: RATIR Optical Afterglow Detection
  98. GRB 150811A: Swift detection of a burst
  99. Fermi GBM GRB Trigger 460608875: iPTF P48 Observations
  100. Fermi GBM trigger 150807969 is not a GRB

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