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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 070621: VLT optical observations
  2. GRB 070621: Swift/UVOT Upper Limits
  3. Keck Laser Guide Star Adaptive Optics Imaging of GRB 070621
  4. GRB 070621: Swift-BAT refined analysis
  5. WHT observations of GRB070621
  6. GRB070621: Swift XRT refined analysis
  7. GRB 070621: Gemini South optical imaging
  8. GRB 070621: UVOT-enhanced XRT position
  9. Observations of GRB070612A at Calar Alto
  10. GRB 070621: NOT observations
  11. GRB070621: OPTIMA-Burst optical upper limit
  12. GRB 070621: TAROT Calern observatory optical observations
  13. GRB 070621: Watcher Observations
  14. GRB 070621: ROTSE-III Prompt Optical Limits
  15. GRB 070621: Swift detection of a burst
  16. GMRT upper limit of GRB 070610/SWIFT J195509.6+261406 in 610 MHz
  17. GRB 070612A: TNG optical observations
  18. Swift/UVOT detection of GRB070616 optical afterglow.
  19. GRB070612A: Gemini Spectroscopic Redshift
  20. GRB 070612A: NOT observations
  21. GRB070616: Optical Observation by MITSuME Akeno
  22. GRB 070612B: Optical Observation by MITSuME Akeno
  23. GRB070616: Optical Observation by MITSuME Okayama
  24. GRB 070616, Swift-BAT further refined analysis
  25. GRB 070616: Swift XRT refined circular
  26. GRB 070612A: Possible WSRT Radio Detection
  27. GRB 070616: BTA astrometry and finding chart
  28. GRB 070616: BTA optical observations
  29. Swift/UVOT observations of GRB070616
  30. GRB 070616: TLS observation
  31. Swift XRT observations of the INTEGRAL burst GRB070615: Possible
  32. GRB 070616, Swift-BAT partial refined analysis
  33. GRB 070616: Swift detection of a burst
  34. GRB 070612B: optical observations
  35. UVOT Observations of INTEGRAL burst GRB070615
  36. VLA upper limit on GRB 070610
  37. GRB 070615
  38. GRB 070615: A long GRB detected by INTEGRAL
  39. SWIFT J195509.6+261406 (GRB 070610): further observations
  40. GRB 070612A: Super-LOTIS observations
  41. GRB 070612A: Rapid Decay
  42. GRB 070612A: Suzaku/WAM observation of the prompt emission
  43. SWIFT J195509.6+261406 / GRB 070610: OPTIMA-Burst observations
  44. GRB070612A: MITSuME Okayama Observation
  45. GRB 070612A: continued SARA observations
  46. GRB 070612A: spectral lag
  47. GRB 070611: Watcher Observations
  48. Swift Trigger 282176 is Cygnus X-1
  49. GRB 070612A: MDM Observations
  50. GRB 070612A: P60 Confirmation of Afterglow and An Underlying, Nearby
  51. GRB 070612B: SARA upper limit
  52. GRB 070612B, Swift-BAT refined analysis
  53. GRB 070612A, Swift-BAT refined analysis
  54. GRB 070612B: Swift-XRT refined analysis
  55. SWIFT J195509.6+261406 / GRB 070610: SWIFT continued observations
  56. GRB 070612B: Swift/UVOT upper limits
  57. GRB 070612B: FRAM limit
  58. GRB070612B: P60 Observations
  59. GRB 070612B: KAIT limits
  60. GRB 070612A: SARA detection of possible OT
  61. GRB 070612B: Swift XRT position from downlink data
  62. GRB 070610: TAROT Calern observatory optical observations
  63. GRB 070610: MITSuME OAO optical upper limit
  64. GRB 070612B: Swift detection of a burst
  65. GRB070612 - SDSS Pre-Burst Observations
  66. GRB 070612: Swift detection of a burst
  67. GRB 070610: OPTIMA-Burst detection of continued strong flaring activity
  68. GRB 070610: SARA upper limit
  69. GRB 070610: Swift-XRT refined analysis
  70. GRB 070610: TLS RRM sees flaring behaviour - Galactic transient?
  71. GRB 070611: Swift/UVOT Observations
  72. GRB 070611: Swift-XRT refined analysis
  73. GRB 070611, Swift-BAT refined analysis
  74. GRB 070610: Optical observations from OSN
  75. GRB 070610: Watcher Observations
  76. GRB 070611: VLT redshift
  77. GRB 060121 : pseudo-z = 1.9 ('intermediate-duration' burst)
  78. GRB 070611: ROTSE-III Detection of Late Rising Optical Counterpart
  79. GRB 070611; Swift-XRT position
  80. GRB 070611: ROTSE-III Optical Limits
  81. GRB 070611: Swift detection of a burst
  82. GRB 070610: Swift-UVOT Upper Limits
  83. GRB 070610: OPTIMA-Burst high-time-resolution optical observations
  84. GRB 070610, Swift-BAT refined analysis
  85. GRB 070610; Swift-XRT position
  86. GRB 070610: Swift detection of a burst
  87. GRB 070412: TAROT Calern observatory optical observations
  88. GRB 070411: TAROT Calern observatory optical observations
  89. GRB 070419A, deep LBT photometry and possible supernova detection
  90. GRB070520B: optical observations
  91. GRB070520: optical observation
  92. GRB070518: optical observation
  93. GRB070521: optical observation
  94. Swift/UVOT refined analysis of GRB070531
  95. GRB 070531: NOT nIR observations
  96. GRB 070531: Swift-BAT refined analysis
  97. GRB 070531: I-band observations from IAC80
  98. GRB 070531: Swift-XRT position
  99. GRB 070531: Liverpool Telescope Optical Observations
  100. GRB 070531: Swift detection of a burst

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