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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. VLA upper limit on GRB 070610
  2. GRB 070615
  3. GRB 070615: A long GRB detected by INTEGRAL
  4. SWIFT J195509.6+261406 (GRB 070610): further observations
  5. GRB 070612A: Super-LOTIS observations
  6. GRB 070612A: Rapid Decay
  7. GRB 070612A: Suzaku/WAM observation of the prompt emission
  8. SWIFT J195509.6+261406 / GRB 070610: OPTIMA-Burst observations
  9. GRB070612A: MITSuME Okayama Observation
  10. GRB 070612A: continued SARA observations
  11. GRB 070612A: spectral lag
  12. GRB 070611: Watcher Observations
  13. Swift Trigger 282176 is Cygnus X-1
  14. GRB 070612A: MDM Observations
  15. GRB 070612A: P60 Confirmation of Afterglow and An Underlying, Nearby
  16. GRB 070612B: SARA upper limit
  17. GRB 070612B, Swift-BAT refined analysis
  18. GRB 070612A, Swift-BAT refined analysis
  19. GRB 070612B: Swift-XRT refined analysis
  20. SWIFT J195509.6+261406 / GRB 070610: SWIFT continued observations
  21. GRB 070612B: Swift/UVOT upper limits
  22. GRB 070612B: FRAM limit
  23. GRB070612B: P60 Observations
  24. GRB 070612B: KAIT limits
  25. GRB 070612A: SARA detection of possible OT
  26. GRB 070612B: Swift XRT position from downlink data
  27. GRB 070610: TAROT Calern observatory optical observations
  28. GRB 070610: MITSuME OAO optical upper limit
  29. GRB 070612B: Swift detection of a burst
  30. GRB070612 - SDSS Pre-Burst Observations
  31. GRB 070612: Swift detection of a burst
  32. GRB 070610: OPTIMA-Burst detection of continued strong flaring activity
  33. GRB 070610: SARA upper limit
  34. GRB 070610: Swift-XRT refined analysis
  35. GRB 070610: TLS RRM sees flaring behaviour - Galactic transient?
  36. GRB 070611: Swift/UVOT Observations
  37. GRB 070611: Swift-XRT refined analysis
  38. GRB 070611, Swift-BAT refined analysis
  39. GRB 070610: Optical observations from OSN
  40. GRB 070610: Watcher Observations
  41. GRB 070611: VLT redshift
  42. GRB 060121 : pseudo-z = 1.9 ('intermediate-duration' burst)
  43. GRB 070611: ROTSE-III Detection of Late Rising Optical Counterpart
  44. GRB 070611; Swift-XRT position
  45. GRB 070611: ROTSE-III Optical Limits
  46. GRB 070611: Swift detection of a burst
  47. GRB 070610: Swift-UVOT Upper Limits
  48. GRB 070610: OPTIMA-Burst high-time-resolution optical observations
  49. GRB 070610, Swift-BAT refined analysis
  50. GRB 070610; Swift-XRT position
  51. GRB 070610: Swift detection of a burst
  52. GRB 070412: TAROT Calern observatory optical observations
  53. GRB 070411: TAROT Calern observatory optical observations
  54. GRB 070419A, deep LBT photometry and possible supernova detection
  55. GRB070520B: optical observations
  56. GRB070520: optical observation
  57. GRB070518: optical observation
  58. GRB070521: optical observation
  59. Swift/UVOT refined analysis of GRB070531
  60. GRB 070531: NOT nIR observations
  61. GRB 070531: Swift-BAT refined analysis
  62. GRB 070531: I-band observations from IAC80
  63. GRB 070531: Swift-XRT position
  64. GRB 070531: Liverpool Telescope Optical Observations
  65. GRB 070531: Swift detection of a burst
  66. GRB 070529: SARA upper limit
  67. Swift/UVOT refined analysis of GRB070529
  68. GRB 070529: MARGE Observations
  69. GRB 070529: Optical aterglow from MIRO
  70. GRB 070529: Gemini Redshift
  71. GRB 070529: Swift-XRT refined analysis
  72. GRB 070529, Swift-BAT refined analysis
  73. GRB 070529: Xinglong TNT Optical Upper Limit
  74. GRB 070529: Swift detection of a burst with an optical aterglow
  75. GRB 070412: Deep Keck imaging
  76. Swift Triggers 280447, 280450 and 280451 are invalid
  77. Swift trigger 280447 is probably a Galactic transient
  78. GRB 070518, deep LBT photometry
  79. GRB 070518: MARGE Observations
  80. GRB 070521: pseudo-z ~ 2.28 from prompt emission spectrum
  81. Konus-Wind observation of GRB 070521
  82. GRB 070518: optical observation
  83. GRB070521: Second Epoch Gemini Imaging
  84. GRB070521: NIR observations
  85. GRB070520B: NIR observations
  86. GRB 070521: Swift/UVOT Upper Limits
  87. GRB 070521, optical observation
  88. GRB 070521: Swift-XRT refined analysis
  89. GRB 070521: Keck imaging
  90. GRB070521: Gemini Observations
  91. GROND upper limits of GRB 070521
  92. GRB 070521 Milagro GeV/TeV Observations
  93. GRB 070520B: SARA upper limit
  94. GRB 070520A: SARA upper limit
  95. GRB 070521: SARA upper limit
  96. GRB 070521: Subaru observations and possible host detection
  97. GRB070518: Optical/NIR observation
  98. GRB 070520B: Swift/UVOT Upper Limits
  99. GRB 070520A: Subaru Observations
  100. GRB 070521, Swift-BAT refined analysis

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