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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 prompt radio detection of the INTEGRAL burst 071109
  2. GRB 071109: IBIS refined analysis
  3. GRB 071109: BOOTES-2 prompt optical observations
  4. GRB 071109: A long GRB detected by INTEGRAL
  5. GRB 071104: Swift-XRT Team Refined Analysis
  6. GRB 071104: Possible Swift UVOT Afterglow Candidate
  7. GRB 071104: Swift-XRT position
  8. GRB 071104: Gamma Ray Burst Localization by SuperAGILE
  9. GRB071010b: optical observation
  10. Swift XRT and UVOT observations of GRB071028B
  11. GRB 071101, Swift-BAT refined analysis
  12. GRB 071101: Swift-XRT Team refined analysis
  13. GRB071101: Optical and NIR upper limits by KANATA
  14. GRB0711101: Two new source from Xinglong TNT observation
  15. GRB 071101: TAROT Calern observatory optical observations
  16. GRB 071101: Swift XRT position
  17. GRB071101 LOAO B,V,R,I observation
  18. GRB 071101: BOOTES-2 prompt optical observations
  19. GRB 071101: a nearby galaxy
  20. GRB 071101: Swift detection of a burst
  21. GRB 071031, Swift-BAT refined analysis
  22. GRB 071031: Swift/UVOT detection of afterglow
  23. GRB 071031: Swift-XRT Team refined analysis
  24. GRB 071020: MITSuME Akeno optical observations
  25. GRB 071031: REM NIR and Optical observation
  26. GRB 071031, SMARTS afterglow observations
  27. GRB 071031: VLT high-resolution spectroscopy
  28. GRB071031: Rapid PROMPT Detections
  29. GRB 071031: GROND detection in all bands
  30. GRB 071031: Swift detection of a burst with an optical counterpart
  31. GRB 071028B Swift-BAT detection of a burst
  32. GRB071025: Optical+NIR observations
  33. GRB 071028: SARA observations of variable source
  34. Swift UVOT upper limits to GRB071028
  35. GRB071028: Xinglong EST V-band upper limit
  36. GRB 071028: Swift-XRT Team refined analysis
  37. GRB 071028, Swift-BAT refined analysis
  38. GRB 071028: Swift detection of a burst
  39. GRB 071025: Kuiper Telescope Optical Observations
  40. GRB 071003: Infrared Photometry with Keck Adaptive Optics
  41. GRB 071018: Revised BAT position
  42. GRB 071025A: RAPTOR Observations of Complex Early Optical Behavior
  43. GRB071021: MARGE Optical Limits
  44. GRB071020, optical upper limit
  45. GRB 071025: SARA VRI upper limits
  46. GRB 071025 Milagro GeV/TeV Observations
  47. GRB 071025: SQIID JHK photometry
  48. GRB 071025A: Complex Early-Time IR Behavior, Simultaneous with Gamma- and X-rays
  49. GRB071025: Optical Pre-imaging from Palomar
  50. Swift UVOT upper limits
  51. GRB071025: Xinglong TNT I-band upper limit
  52. GRB 071025: Swift-XRT Team refined analysis
  53. GRB 060602A: host redshift
  54. GRB 071025, Swift-BAT refined analysis
  55. GRB 071025: Early Super-LOTIS Observations
  56. GRB 071025: R/I-band update
  57. GRB071021 : CFHT Ks-band observation
  58. GRB 071025: ROTSE-III Refined Analysis
  59. GRB 071025: I-detection, R-dropout?
  60. GRB 071025: Swift XRT refined position
  61. GRB 071025a: PAIRITEL observations
  62. GRB071025: REM NIR afterglow
  63. GRB 071025: ROTSE-III Detection of Optical Counterpart
  64. GRB 071025: Swift detection of a burst
  65. GRB 071021: R-band detection and analysis
  66. GRB 071020: BTA spectroscopy
  67. GRB071021: Optical+NIR observations
  68. Possible radio detection of GRB 071021 with the VLA
  69. Optical observations of GRB 071020
  70. GRB 071021: (Relatively shallow) IR non-detections; motivation for optical spectroscopy
  71. GRB 071020: SARA observations
  72. Radio detection of GRB 071020 with the VLA
  73. GRB071010b: optical observation
  74. GRB 071021: Subaru NIR observation
  75. GRB071021: MITSuME Okayama Optical Upper Limits
  76. GRB 071021: Magellan i-band observation
  77. GRB 071021: Magellan R-band observation
  78. GRB 071021: Z-band detection
  79. GRB 071021: correction to GCNC 6968
  80. GRB 071020: Fading slowly?
  81. GRB 071010B: Fading quickly
  82. GRB 071021: optical and NIR observations
  83. GRB 071021: possible high-z burst
  84. GRB 071021, Swift-BAT refined analysis
  85. GRB071018: 2nd epoch obsevations of Xinglong TNT
  86. GRB 071021: retraction of Faulkes Telescope South candidate
  87. GRB 071021: Swift-XRT Team refined analysis
  88. GRB 071021: Xinglong TNT optical Upper Limit
  89. GRB 071021 : Lulin R-band limit
  90. Konus-Wind observation of GRB 071020
  91. GRB 071021: Faulkes Telescope South optical candidate
  92. GRB 071021: Swift detection of a burst
  93. GRB 071010B: Independent Confirmation of Break
  94. GRB071020A: Xinglong TNT Optical afterglow observations
  95. GRB 071020: Swift-XRT refined analysis
  96. GRB 071020, Swift-BAT refined analysis
  97. GRB 071020A: IR Imaging with PAIRITEL
  98. GRB 071020: VLT spectroscopy
  99. GRB 071020: ROTSE-III Analysis of Optical Counterpart
  100. GRB071020 - SDSS Pre-burst Observations

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