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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 071112C: optical observation
  2. GRB 071112C: emission lines and refined VLT redshift
  3. GRB 071112C MITSuME Akeno early optical observation
  4. GRB 071112C: Gemini Absorption Redshift
  5. GRB 071112B: 2nd epoch of Magellan i-band imaging
  6. GRB 071112C: SARA upper limit
  7. GRB 071112C : Second Epoch Lulin R-band observations
  8. GRB071112C MITSuME Okayama Optical Observation
  9. GRB 071112C: Swift-BAT refined analysis
  10. GRB 071112C: Swift/UVOT observations
  11. GRB 071112C: Swift XRT refined analysis
  12. GRB 071112C: Optical observations at Crni Vrh
  13. Swift UVOT upper limits of GRB071112B
  14. GRB 071112C: VLT redshift
  15. GRB 071112B: Magellan i-band imaging
  16. GRB 071112B: Gemini Optical Imaging (Correction)
  17. GRB 071112B: Gemini Optical Imaging
  18. GRB 071112B: Swift-XRT preliminary analysis
  19. GRB 071112B, Swift-BAT partial refined analysis of the SHB
  20. GRB071112C: NOT observations
  21. GRB 071112C: Palomar Pre-Imaging
  22. Swift-BAT trigger 296491 is not a GRB
  23. GRB 071112C : Lulin R-band observation
  24. GRB 071112C: RTT150 optical observations
  25. GRB 071112C: TAROT Calern observatory optical observations
  26. Swift XRT follow-up observations of GRB071028B
  27. GRB071112C Xinglong_TNT_and_EST_afterglow observations
  28. GRB 071112C: Optical and NIR afterglows observed with KANATA
  29. GRB 071112C: ROTSE-III Confirmation of Optical Counterpart
  30. GRB 071112B: ROTSE-III Rapid Optical Limits
  31. GRB 071112C: Swift detection of a burst with an optical counterpart
  32. GRB 071112B: Swift detection of a short hard burst
  33. GRB 071112: Swift detection of a possible burst
  34. GRB071109: Super-LOTIS observations
  35. VLA IInd observation of INTEGRAL burst GRB 071109
  36. Swift/UVOT initial analysis of GRB071109
  37. GRB 071109: further Swift-XRT analysis
  38. GRB 071109: TAROT Calern observatory optical observations
  39. No radio detection at Swift-XRT position
  40. GRB 071109: Swift-XRT possible X-ray counterpart
  41. VLA prompt radio detection of the INTEGRAL burst 071109
  42. GRB 071109: IBIS refined analysis
  43. GRB 071109: BOOTES-2 prompt optical observations
  44. GRB 071109: A long GRB detected by INTEGRAL
  45. GRB 071104: Swift-XRT Team Refined Analysis
  46. GRB 071104: Possible Swift UVOT Afterglow Candidate
  47. GRB 071104: Swift-XRT position
  48. GRB 071104: Gamma Ray Burst Localization by SuperAGILE
  49. GRB071010b: optical observation
  50. Swift XRT and UVOT observations of GRB071028B
  51. GRB 071101, Swift-BAT refined analysis
  52. GRB 071101: Swift-XRT Team refined analysis
  53. GRB071101: Optical and NIR upper limits by KANATA
  54. GRB0711101: Two new source from Xinglong TNT observation
  55. GRB 071101: TAROT Calern observatory optical observations
  56. GRB 071101: Swift XRT position
  57. GRB071101 LOAO B,V,R,I observation
  58. GRB 071101: BOOTES-2 prompt optical observations
  59. GRB 071101: a nearby galaxy
  60. GRB 071101: Swift detection of a burst
  61. GRB 071031, Swift-BAT refined analysis
  62. GRB 071031: Swift/UVOT detection of afterglow
  63. GRB 071031: Swift-XRT Team refined analysis
  64. GRB 071020: MITSuME Akeno optical observations
  65. GRB 071031: REM NIR and Optical observation
  66. GRB 071031, SMARTS afterglow observations
  67. GRB 071031: VLT high-resolution spectroscopy
  68. GRB071031: Rapid PROMPT Detections
  69. GRB 071031: GROND detection in all bands
  70. GRB 071031: Swift detection of a burst with an optical counterpart
  71. GRB 071028B Swift-BAT detection of a burst
  72. GRB071025: Optical+NIR observations
  73. GRB 071028: SARA observations of variable source
  74. Swift UVOT upper limits to GRB071028
  75. GRB071028: Xinglong EST V-band upper limit
  76. GRB 071028: Swift-XRT Team refined analysis
  77. GRB 071028, Swift-BAT refined analysis
  78. GRB 071028: Swift detection of a burst
  79. GRB 071025: Kuiper Telescope Optical Observations
  80. GRB 071003: Infrared Photometry with Keck Adaptive Optics
  81. GRB 071018: Revised BAT position
  82. GRB 071025A: RAPTOR Observations of Complex Early Optical Behavior
  83. GRB071021: MARGE Optical Limits
  84. GRB071020, optical upper limit
  85. GRB 071025: SARA VRI upper limits
  86. GRB 071025 Milagro GeV/TeV Observations
  87. GRB 071025: SQIID JHK photometry
  88. GRB 071025A: Complex Early-Time IR Behavior, Simultaneous with Gamma- and X-rays
  89. GRB071025: Optical Pre-imaging from Palomar
  90. Swift UVOT upper limits
  91. GRB071025: Xinglong TNT I-band upper limit
  92. GRB 071025: Swift-XRT Team refined analysis
  93. GRB 060602A: host redshift
  94. GRB 071025, Swift-BAT refined analysis
  95. GRB 071025: Early Super-LOTIS Observations
  96. GRB 071025: R/I-band update
  97. GRB071021 : CFHT Ks-band observation
  98. GRB 071025: ROTSE-III Refined Analysis
  99. GRB 071025: I-detection, R-dropout?
  100. GRB 071025: Swift XRT refined position

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