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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 071031, SMARTS afterglow observations
  2. GRB 071031: VLT high-resolution spectroscopy
  3. GRB071031: Rapid PROMPT Detections
  4. GRB 071031: GROND detection in all bands
  5. GRB 071031: Swift detection of a burst with an optical counterpart
  6. GRB 071028B Swift-BAT detection of a burst
  7. GRB071025: Optical+NIR observations
  8. GRB 071028: SARA observations of variable source
  9. Swift UVOT upper limits to GRB071028
  10. GRB071028: Xinglong EST V-band upper limit
  11. GRB 071028: Swift-XRT Team refined analysis
  12. GRB 071028, Swift-BAT refined analysis
  13. GRB 071028: Swift detection of a burst
  14. GRB 071025: Kuiper Telescope Optical Observations
  15. GRB 071003: Infrared Photometry with Keck Adaptive Optics
  16. GRB 071018: Revised BAT position
  17. GRB 071025A: RAPTOR Observations of Complex Early Optical Behavior
  18. GRB071021: MARGE Optical Limits
  19. GRB071020, optical upper limit
  20. GRB 071025: SARA VRI upper limits
  21. GRB 071025 Milagro GeV/TeV Observations
  22. GRB 071025: SQIID JHK photometry
  23. GRB 071025A: Complex Early-Time IR Behavior, Simultaneous with Gamma- and X-rays
  24. GRB071025: Optical Pre-imaging from Palomar
  25. Swift UVOT upper limits
  26. GRB071025: Xinglong TNT I-band upper limit
  27. GRB 071025: Swift-XRT Team refined analysis
  28. GRB 060602A: host redshift
  29. GRB 071025, Swift-BAT refined analysis
  30. GRB 071025: Early Super-LOTIS Observations
  31. GRB 071025: R/I-band update
  32. GRB071021 : CFHT Ks-band observation
  33. GRB 071025: ROTSE-III Refined Analysis
  34. GRB 071025: I-detection, R-dropout?
  35. GRB 071025: Swift XRT refined position
  36. GRB 071025a: PAIRITEL observations
  37. GRB071025: REM NIR afterglow
  38. GRB 071025: ROTSE-III Detection of Optical Counterpart
  39. GRB 071025: Swift detection of a burst
  40. GRB 071021: R-band detection and analysis
  41. GRB 071020: BTA spectroscopy
  42. GRB071021: Optical+NIR observations
  43. Possible radio detection of GRB 071021 with the VLA
  44. Optical observations of GRB 071020
  45. GRB 071021: (Relatively shallow) IR non-detections; motivation for optical spectroscopy
  46. GRB 071020: SARA observations
  47. Radio detection of GRB 071020 with the VLA
  48. GRB071010b: optical observation
  49. GRB 071021: Subaru NIR observation
  50. GRB071021: MITSuME Okayama Optical Upper Limits
  51. GRB 071021: Magellan i-band observation
  52. GRB 071021: Magellan R-band observation
  53. GRB 071021: Z-band detection
  54. GRB 071021: correction to GCNC 6968
  55. GRB 071020: Fading slowly?
  56. GRB 071010B: Fading quickly
  57. GRB 071021: optical and NIR observations
  58. GRB 071021: possible high-z burst
  59. GRB 071021, Swift-BAT refined analysis
  60. GRB071018: 2nd epoch obsevations of Xinglong TNT
  61. GRB 071021: retraction of Faulkes Telescope South candidate
  62. GRB 071021: Swift-XRT Team refined analysis
  63. GRB 071021: Xinglong TNT optical Upper Limit
  64. GRB 071021 : Lulin R-band limit
  65. Konus-Wind observation of GRB 071020
  66. GRB 071021: Faulkes Telescope South optical candidate
  67. GRB 071021: Swift detection of a burst
  68. GRB 071010B: Independent Confirmation of Break
  69. GRB071020A: Xinglong TNT Optical afterglow observations
  70. GRB 071020: Swift-XRT refined analysis
  71. GRB 071020, Swift-BAT refined analysis
  72. GRB 071020A: IR Imaging with PAIRITEL
  73. GRB 071020: VLT spectroscopy
  74. GRB 071020: ROTSE-III Analysis of Optical Counterpart
  75. GRB071020 - SDSS Pre-burst Observations
  76. GRB 071020: Swift detection of a bright burst
  77. GRB 071020A: ROTSE-III Detection of Optical Counterpart
  78. GRB 071018: Mercator Telescope optical observations
  79. Swift autonomous slewing re-enabled
  80. GRB071010b: optical observations
  81. GRB 071018: SARA observations
  82. GRB 071018: Swift-XRT observation
  83. GRB 071017 - Swift XRT observations
  84. VLA radio observation of GRB 071018
  85. GRB071018: Correction to the GCN 6936
  86. GRB071018: Correction to the GCN 6936
  87. GRB071018: Correction to the GCN 6936
  88. GRB071018: Correction to the title of the GCN 6936
  89. GRB 071018: Possible OT from Xinglong TNT observation
  90. GRB 071010B: Light Curve Break Confirmed
  91. GRB 071010A: Late-time Keck/LRIS photometry - possible host galaxy and jet break
  92. GRB 071018, Swift-BAT refined analysis
  93. GRB 071018?: Swift detection of a possible burst
  94. GRB 071010B: Suzaku WAM observation of the prompt emission
  95. GRB 071013: 3rd TLS Epoch - constraints on variability
  96. GRB 071013: TNT optical data refined analysis
  97. GRB 071010B: Keck/DEIMOS emission-line redshift
  98. GRB 071017: a SHORT GRB detected by INTEGRAL
  99. GRB 071013: TLS 2nd epoch - Kornienko candidate constant
  100. GRB071013: optical observations

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