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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. X-ray transient in NGC 2770: Optical observations with Astrotel-Caucasus
  2. Optical Spectroscopy of the Transient in NGC 2770
  3. Swift UVOT Observations of the X-ray transient in NGC 2770
  4. Early OT detection of XRF in NGC 2770 in Asiago frames
  5. Bright X-ray transient / possible XRF in NGC 2770: TNG R imaging
  6. Possible XRF in NGC 2770 - NOT observations of the optical counterpart
  7. Bright X-ray Transient (a XRF? ) in NGC 2770 - A SN optical counterpart?
  8. Bright X-ray Transient in NGC 2770 - A low-luminosity XRF?
  9. GRB 071227: Suzaku WAM observation of the prompt emission
  10. GRB 071227: optical afterglow
  11. Further Swift-BAT analysis of GRB 071227
  12. Konus-Wind observation of GRB 071227
  13. GRB 071227: Magellan redshift confirmation
  14. GRB 071227: Swift-XRT refined analysis
  15. GRB 071227: VLT probable redshift of the candidate host galaxy
  16. GRB 071227: Magellan observations
  17. GRB071227: Swift/UVOT refined analysis
  18. GRB 071227: REM NIR and Optical observations
  19. Swift-BAT refined analysis of short GRB 071227
  20. GRB 071227: Swift detection of a burst
  21. GRB071020: optical observations
  22. GRB 070429B: Possible UVOT Detection of an Optical Afterglow
  23. Swift-BAT trigger 298308 is not a GRB
  24. GRB 071208?: Swift detection of a possible burst
  25. IBAS Alert #4772 in not a GRB
  26. GRB 071125: Suzaku WAM observation of the prompt emission
  27. GRB 070429B: Probable host galaxy and redshift
  28. GRB 071129, Swift-BAT refined analysis
  29. GRB 071129: Swift detection of a burst
  30. Konus-Wind and Konus-A observations of GRB 071125
  31. IPN triangulation of very bright GRB 071125
  32. GRB 071112C: Optical/NIR observations
  33. Disregard the "GRB 071126" position
  34. GRB 071126: Enhanced Swift-XRT position
  35. VLA radio detection of GRB 071122
  36. GRB071122: Swift/UVOT Observations
  37. GRB071104: NIR Afterglow Candidate at TNG
  38. GRB 071122: MASTER optical observation
  39. GRB 071122, Swift-BAT refined analysis
  40. GRB 071122 Swift XRT position update sent in error.
  41. GRB 071122 Swift-XRT refined analysis
  42. GRB 071122: Corrected P60 Coordinates
  43. GRB071122: Gemini Absorption redshift
  44. GRB 071122: P60 Optical Afterglow Candidate
  45. GRB 071122: ROTSE-III Optical Limits
  46. GRB 071122: Swift detection of a burst
  47. GRB 071118: P60 Observations
  48. GRB071118 MITSuME OAO optical observation
  49. GRB 071118: Observations from OSN
  50. GRB 071117: VLT observations and probable redshift
  51. Swift/UVOT observations of GRB071118
  52. GRB 071117: Swift-XRT revised position
  53. Konus-Wind and Konus-A observations of GRB 071117
  54. Swift XRT follow-up observations of GRB071008
  55. Swift/UVOT upper limits for GRB 071117
  56. GRB071118: Swift XRT refined analysis
  57. GRB 071117: Gemini Optical Afterglow Discovery
  58. GRB 071118, Swift-BAT refined analysis
  59. GRB 071117: TAROT La Silla observatory optical observations
  60. GRB 071112B: Gemini Image Differencing
  61. GRB 071118: Swift detection of a burst
  62. GRB 071117: Gemini Observations
  63. GRB 071117: Las Campanas optical observations
  64. GRB 071117: Swift-XRT refined analysis
  65. GRB 071117, Swift-BAT refined analysis
  66. VLT FORS2 observations of short hard GRB071112B
  67. GRB 071117: Swift/XRT position
  68. GRB 071117: Initial Swift/UVOT observations
  69. GRB 071117: Swift detection of a bright burst
  70. Swift detection of MXB 0656-072
  71. VLA radio upper limit on GRB 071112C
  72. ATCA radio observations of short hard burst GRB 071112B
  73. GRB 071112C: Optical and NIR data observed with KANATA
  74. Correction to the Swift-BAT Transient Identification (trigger=296683)
  75. GRB 071112C: WSRT Radio Observations
  76. GRB071112C: Errata of MITSuME Ic band photometry
  77. GRB 071112C: optical observation
  78. GRB 071112C: optical observation
  79. GRB 071112C: emission lines and refined VLT redshift
  80. GRB 071112C MITSuME Akeno early optical observation
  81. GRB 071112C: Gemini Absorption Redshift
  82. GRB 071112B: 2nd epoch of Magellan i-band imaging
  83. GRB 071112C: SARA upper limit
  84. GRB 071112C : Second Epoch Lulin R-band observations
  85. GRB071112C MITSuME Okayama Optical Observation
  86. GRB 071112C: Swift-BAT refined analysis
  87. GRB 071112C: Swift/UVOT observations
  88. GRB 071112C: Swift XRT refined analysis
  89. GRB 071112C: Optical observations at Crni Vrh
  90. Swift UVOT upper limits of GRB071112B
  91. GRB 071112C: VLT redshift
  92. GRB 071112B: Magellan i-band imaging
  93. GRB 071112B: Gemini Optical Imaging (Correction)
  94. GRB 071112B: Gemini Optical Imaging
  95. GRB 071112B: Swift-XRT preliminary analysis
  96. GRB 071112B, Swift-BAT partial refined analysis of the SHB
  97. GRB071112C: NOT observations
  98. GRB 071112C: Palomar Pre-Imaging
  99. Swift-BAT trigger 296491 is not a GRB
  100. GRB 071112C : Lulin R-band observation

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