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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 150818A: TSHAO and SAO RAS optical observations
  2. GRB 150902A: Swift-XRT afterglow detection
  3. ANTARES neutrino detection: ANU 2.3m and Kepler K2 Observations of the Swift x-ray source
  4. ANTARES neutrino detection: CAHA photometry & spectroscopy of the Swift source
  5. ANTARES neutrino Alert150901.32 alert and Swift XRT counterpart: MASTER optical observations and new possible candidate
  6. ANTARES neutrino detection and Swift/XRT counterpart: GMG observation
  7. GRB 150902A: Swift/UVOT Upper Limits
  8. GRB 150902A: Swift-XRT observations
  9. ANTARES neutrino detection: Optical/NIR spectroscopy of the Swift/XRT counterpart candidate from NOT
  10. GRB 150831A: 9.8 GHz VLA upper limits
  11. GRB 150902A: MASTER-SAAO optical observations
  12. Konus-Wind observation of GRB 150902A
  13. GRB 150901A, Swift-BAT refined analysis
  14. ANTARES neutrino detection and possible Swift X-ray counterpart
  15. GRB 150902A: Swift ToO observations
  16. GRB 150902A: Fermi GBM detection
  17. GRB 150902A: Fermi-LAT detection
  18. GRB 150831B: Swift/UVOT Upper Limits
  19. Konus-Wind observation of GRB 150831A
  20. GRB 150901A: Swift detection of a burst
  21. GRB 150821A: Flattening in the UVOT light curve
  22. GRB 150831B: Swift-BAT refined analysis
  23. GRB 150831B: Swift-XRT refined Analysis
  24. GRB 150831B: MASTER-IAC early optical observations
  25. GRB 150831B: Fermi GBM detection
  26. GRB 150831A: GROND Upper Limits
  27. GRB 150831A: Swift/UVOT Upper Limits
  28. GRB 150831B: Swift-XRT observations
  29. GRB 150831A: Swift-XRT refined Analysis
  30. GRB 150831B: Swift detection of a probable burst
  31. GRB 150831A: Swift-BAT refined analysis
  32. GRB 150818A: Spectroscopic confirmation of the SN from GTC
  33. GRB 150831A: Enhanced Swift-XRT position
  34. GRB 150831A: optical upper limit ISON-SSO
  35. INTEGRAL detection of GRB 150831A
  36. GRB 150831A: Swift detection of a short burst
  37. Fermi GBM trigger 150829183 is not a GRB
  38. Fermi GBM trigger 150828520 is not a GRB
  39. Fermi GBM trigger 150827524 is not a GRB
  40. GRB 150818A: possible SN rise in light curve of Mondy observations
  41. Fermi GBM trigger 150826536 is not a GRB
  42. Konus-Wind observation of GRB 150824A
  43. IPN Triangulation of GRB 150824A
  44. GRB 150824A: Fermi GBM detection
  45. Konus-Wind observation of GRB 150821A
  46. GRB 150821A: LCOGT Siding Springs early observations
  47. Konus-Wind observation of GRB 150818A
  48. GRB 150821A: LCOGT Sutherland observations
  49. GRB 150821A, Swift-BAT refined analysis
  50. GRB 150821A: GROND afterglow observations
  51. GRB 150821A: Swift-XRT refined Analysis
  52. GRB 150819A: Mondy and TSHAO optical upper limits
  53. GRB 150821A: Swift/UVOT Detection
  54. GRB 150821A: Enhanced Swift-XRT position
  55. GRB 150821A: Fermi GBM detection
  56. GRB 150818A: continued Mondy optical observations
  57. Swift Trigger 652824 is due to noise
  58. GRB 150821A: VLT/X-shooter redshift
  59. GRB 150821A: Swift detection of a burst with an optical afterglow
  60. Swift Trigger 652824: Is most likely a noise fluctuation in the direction of M31
  61. GRB 120729A: KAIT Optical Observations
  62. KAIT Optical Upper Limits for GRB 120422A, 120724A, 120803B, 120911A, and 120923A
  63. GRB 150818A: Mondy optical observations
  64. GRB150819A: NOT imaging
  65. Konus-Wind observation of GRB 150819B
  66. GRB 150818A: Continued NOT monitoring - afterglow confirmation
  67. GRB 150819B: Fermi GBM detection
  68. GRB 150818A: 10.4m GTC spectroscopy and host galaxy
  69. IPN Triangulation of GRB 150819B (short / very intense)
  70. GRB 150818A: Mondy optical observations
  71. GRB 150818A: MITSuME Ishigakijima upper limits
  72. GRB 150819A: RATIR Optical Observations
  73. GRB 150819A: Swift-XRT refined Analysis
  74. GRB 150818A: MITSuME Akeno optical upper limits
  75. GRB 150819A: Swift-BAT refined analysis
  76. GRB 150819A: MASTER-IAC early upper limit
  77. GRB 150819A: Swift/UVOT Upper Limits
  78. GRB 150819A: Enhanced Swift-XRT position
  79. GRB 150818A: Swift-XRT update, correction to GCN 18162
  80. GRB 150819A: Prompt enhanced Swift-XRT position
  81. GRB150818A: NOT imaging
  82. GRB 150819A: Swift detection of a burst
  83. GRB 150818A: Swift-XRT refined Analysis
  84. GRB 150818A: Swift/UVOT Detection
  85. GRB 150817A: AAO optical observations
  86. GRB 150818A: Enhanced Swift-XRT position
  87. GRB 150817A: LCOGT observations
  88. GRB 150818A: Swift-BAT refined analysis
  89. GRB 150817A: Continued RATIR Optical Observations - Afterglow Confirmation
  90. GRB 150818A: Swift/UVOT candidate afterglow
  91. GRB 150818A: Planned XMM-Newton observation
  92. GRB 150817A: P60 Observations
  93. GRB 150818A: Swift detection of a burst
  94. MASTER OT inside bright ESO240-010 galaxy detection during FERMI trigger GRB150816.83 inspection
  95. GRB 150817A: Swift/UVOT Upper Limits
  96. GRB 150817A: Fermi GBM observation
  97. GRB 150817A: Swift-BAT refined analysis
  98. GRB 150817A: Swift-XRT refined Analysis
  99. GRB 150817A: Enhanced Swift-XRT position
  100. GRB 150817A: Continued RATIR Observations, Revised Candidate

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