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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 071025A: RAPTOR Observations of Complex Early Optical Behavior
  2. GRB071021: MARGE Optical Limits
  3. GRB071020, optical upper limit
  4. GRB 071025: SARA VRI upper limits
  5. GRB 071025 Milagro GeV/TeV Observations
  6. GRB 071025: SQIID JHK photometry
  7. GRB 071025A: Complex Early-Time IR Behavior, Simultaneous with Gamma- and X-rays
  8. GRB071025: Optical Pre-imaging from Palomar
  9. Swift UVOT upper limits
  10. GRB071025: Xinglong TNT I-band upper limit
  11. GRB 071025: Swift-XRT Team refined analysis
  12. GRB 060602A: host redshift
  13. GRB 071025, Swift-BAT refined analysis
  14. GRB 071025: Early Super-LOTIS Observations
  15. GRB 071025: R/I-band update
  16. GRB071021 : CFHT Ks-band observation
  17. GRB 071025: ROTSE-III Refined Analysis
  18. GRB 071025: I-detection, R-dropout?
  19. GRB 071025: Swift XRT refined position
  20. GRB 071025a: PAIRITEL observations
  21. GRB071025: REM NIR afterglow
  22. GRB 071025: ROTSE-III Detection of Optical Counterpart
  23. GRB 071025: Swift detection of a burst
  24. GRB 071021: R-band detection and analysis
  25. GRB 071020: BTA spectroscopy
  26. GRB071021: Optical+NIR observations
  27. Possible radio detection of GRB 071021 with the VLA
  28. Optical observations of GRB 071020
  29. GRB 071021: (Relatively shallow) IR non-detections; motivation for optical spectroscopy
  30. GRB 071020: SARA observations
  31. Radio detection of GRB 071020 with the VLA
  32. GRB071010b: optical observation
  33. GRB 071021: Subaru NIR observation
  34. GRB071021: MITSuME Okayama Optical Upper Limits
  35. GRB 071021: Magellan i-band observation
  36. GRB 071021: Magellan R-band observation
  37. GRB 071021: Z-band detection
  38. GRB 071021: correction to GCNC 6968
  39. GRB 071020: Fading slowly?
  40. GRB 071010B: Fading quickly
  41. GRB 071021: optical and NIR observations
  42. GRB 071021: possible high-z burst
  43. GRB 071021, Swift-BAT refined analysis
  44. GRB071018: 2nd epoch obsevations of Xinglong TNT
  45. GRB 071021: retraction of Faulkes Telescope South candidate
  46. GRB 071021: Swift-XRT Team refined analysis
  47. GRB 071021: Xinglong TNT optical Upper Limit
  48. GRB 071021 : Lulin R-band limit
  49. Konus-Wind observation of GRB 071020
  50. GRB 071021: Faulkes Telescope South optical candidate
  51. GRB 071021: Swift detection of a burst
  52. GRB 071010B: Independent Confirmation of Break
  53. GRB071020A: Xinglong TNT Optical afterglow observations
  54. GRB 071020: Swift-XRT refined analysis
  55. GRB 071020, Swift-BAT refined analysis
  56. GRB 071020A: IR Imaging with PAIRITEL
  57. GRB 071020: VLT spectroscopy
  58. GRB 071020: ROTSE-III Analysis of Optical Counterpart
  59. GRB071020 - SDSS Pre-burst Observations
  60. GRB 071020: Swift detection of a bright burst
  61. GRB 071020A: ROTSE-III Detection of Optical Counterpart
  62. GRB 071018: Mercator Telescope optical observations
  63. Swift autonomous slewing re-enabled
  64. GRB071010b: optical observations
  65. GRB 071018: SARA observations
  66. GRB 071018: Swift-XRT observation
  67. GRB 071017 - Swift XRT observations
  68. VLA radio observation of GRB 071018
  69. GRB071018: Correction to the GCN 6936
  70. GRB071018: Correction to the GCN 6936
  71. GRB071018: Correction to the GCN 6936
  72. GRB071018: Correction to the title of the GCN 6936
  73. GRB 071018: Possible OT from Xinglong TNT observation
  74. GRB 071010B: Light Curve Break Confirmed
  75. GRB 071010A: Late-time Keck/LRIS photometry - possible host galaxy and jet break
  76. GRB 071018, Swift-BAT refined analysis
  77. GRB 071018?: Swift detection of a possible burst
  78. GRB 071010B: Suzaku WAM observation of the prompt emission
  79. GRB 071013: 3rd TLS Epoch - constraints on variability
  80. GRB 071013: TNT optical data refined analysis
  81. GRB 071010B: Keck/DEIMOS emission-line redshift
  82. GRB 071017: a SHORT GRB detected by INTEGRAL
  83. GRB 071013: TLS 2nd epoch - Kornienko candidate constant
  84. GRB071013: optical observations
  85. GRB 071010B: Optical observations of EST
  86. GRB 071010B: TLS 3rd Epoch - finally a break??
  87. GRB 071011: MITSuME Optical Observations
  88. GRB 070920A: deep optical observations at the NOT
  89. GRB 071010B: Photometry after 1.6 days
  90. GRB 071010B: Keck/LRIS Photometry
  91. GRB 071010B: TLS 2nd Epoch, refined analysis
  92. GRB 071013: TLS Upper Limit
  93. Correction to GCN circular no. # 6915 for GRB 071010B
  94. VLA detection of radio afterglow of GRB 071010B
  95. VLA non-detection of GRB 071011
  96. GRB 071013: Optical observations
  97. GRB 071013: optical observations at NOT
  98. GRB 071013, Swift-BAT refined analysis
  99. GRB071013: optical limit
  100. GRB071010B, BVRcIc field calibration

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