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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 090709A: Swift XRT Timing Analysis
  2. GRB 090715B: VLA radio detection
  3. GRB 090720 Source found in ground processing of Swift-BAT data
  4. GRB 090717B: Fermi GBM detection
  5. GRB 090717: Fermi GBM detection
  6. GRB 090719: Fermi GBM detection
  7. GRB 090718B: Fermi GBM detection
  8. GRB 090718: Fermi GBM detection
  9. GRB 090720: Fermi GBM detection
  10. GRB 090715B: further NOT optical observations
  11. GRB 090715A: Suzaku WAM observation of the prompt emission
  12. GRB 090709A - CARMA mm Observations
  13. GRB 090715B: Lick observations
  14. GRB 090715A: VLA observations
  15. Konus-Wind observations of short/hard GRB 090715A
  16. GRB 090715B: MASTER optical limit
  17. GRB 090715A: Swift-BAT refined analysis
  18. Konus-Wind and Konus-RF observations of GRB 090715B
  19. GRB 090715B: Swift/UVOT followup observations
  20. GRB 090715B: break in the optical afterglow decay
  21. GRB 090715B: Enhanced Swift-XRT position
  22. GRB 090715B: Observation of the optical afterglow
  23. GRB 090715B: Swift XRT Refined Analysis
  24. GRB090715B: WHT redshift
  25. GRB 090715B: Swift-BAT refined analysis
  26. GRB 090715B: NOT optical observations
  27. GRB 090715B - Liverpool Telescope Optical Afterglow Candidate
  28. Swift problem fixed
  29. GRB 090715B: Swift detection of a burst with a possible optical counterpart
  30. GRB 090715A: ROTSE-III Optical Limits
  31. GRB 090715: Swift detection of a short hard burst
  32. Detection of GRB 090618 by RT-2 Experiment onboard the CORONAS-PHOTON Satellite
  33. Swift satellite anomaly
  34. GRB090713 optical limit by "Pi of the Sky"
  35. GRB 090712: Fermi GBM observation
  36. GRB 090713: Fermi GBM detection
  37. GRB 090712: Swift-BAT refined analysis
  38. GRB 090712: Swift detection of a burst
  39. GRB 090709A: Xinglong TNT optical upper limit
  40. VLA radio observations of GRB 090709A
  41. GRB 090621B: MTM-500 optical observations
  42. GRB 090709A: deep optical observation with the 10.4m GTC
  43. GRB090709A : WSRT Radio observation
  44. GRB 090709A: Suzaku WAM observation of the prompt emission
  45. GRB 090709A: Swift UVOT upper limits
  46. GRB 090709A: WHT LIRIS observations
  47. GRB 090709B: Fermi GBM detection
  48. GRB 090709A: confirmation of the periodicity in the SPI-ACS data
  49. GRB 090709A: evidence for a very red afterglow at low z
  50. Konus-Wind and Konus-RF observations of GRB 090709A
  51. GRB 090709A: P60 Observations
  52. GRB 090709A: Quasiperiodic variations in the BAT light curve
  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 - PAIRITEL Discovery of a Red Afterglow
  63. GRB 090709A: Subaru NIR observation
  64. GRB 090709B: Swift detection of a burst
  65. GRB 090709 : planned Suzaku-ToO observation
  66. GRB 090708 : Fermi GBM detection
  67. GRB 090709: Faulkes Telescope North Upper Limits
  68. GRB 090626: Suzaku WAM observation of the prompt emission
  69. GRB 090709: PAIRITEL NIR Upper Limits
  70. GRB 090704: Fermi GBM observation
  71. GRB 090709: ROTSE-III Optical Limits
  72. GRB 090709: Swift detection of a bright burst
  73. GRB 090708: Early RAPTOR Optical Limits
  74. GRB 090708, Swift-BAT refined analysis
  75. GRB 090708: ROTSE-III Optical Limits
  76. GRB 090708: Swift detection of a burst
  77. GRB 090704: a long GRB found in INTEGRAL off-line analysis
  78. GRB 090706: Fermi GBM detection
  79. Swift-BAT trigger 356516 is not a GRB
  80. Possible GRB090705: Swift-XRT observations
  81. GRB 090705: PAIRITEL NIR Observations
  82. GRB 090705: Swift detection of a possible burst
  83. XRF 090702 : RTT150 optical observations
  84. GRB 090618: Mondy optical observations
  85. GRB 090529: CrAO optical upper limit
  86. GRB 090529: MTM-500 optical observations
  87. GRB 090529: Mt.Terskol optical observations
  88. XRF 090702: Swift-XRT refined analysis
  89. GRB 090703: Fermi GBM detection
  90. GRB 090702: UVOT upper limits
  91. GRB 090313: optical observations
  92. XRF 090702: VLT imaging
  93. XRF 090702: Swift-XRT afterglow position
  94. XRF 090702: a long soft GRB localized with INTEGRAL
  95. GRB 090404: Deep optical imaging and possible host association (correction)
  96. GRB 090404: Deep optical imaging and possible host association
  97. GRB 090701: Fermi GBM detection
  98. GRB 090628: Swift XRT refined analysis
  99. GRB 090630: Fermi GBM detection
  100. GRB 090618: RTT150 optical observations

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