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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. GRB000419 [IPN Position]
  2. GRB000416 Optical Observations
  3. BATSE observations of FXT/GRB 000416 = 1SAXJ1715.0-7134
  4. GRB000416 BRJK observations
  5. 1SAXJ1715.0-7134 refined position
  6. RE: Budget cuts in BeppoSAX operations: impact on GRB observation
  7. X-ray burst or X-ray rich GRB 000416 observed by BeppoSAX
  8. Budget cuts in BeppoSAX operations: impact on GRB observations
  9. GRB 000408, optical observations
  10. Refined IPN error box for GRB000408
  11. GRB 991208, UBVRI field photometry
  12. GRB000301c results
  13. GRB000408: Optical CCD Observations from MIRO
  14. GRB000408, lotis optical observations
  15. GRB 000301C: Late-Time HST/STIS CCD Imaging of the field
  16. GRB000408 [IPN Position]
  17. GRB000326 Optical Observations
  18. GRB000301C - Addendum to GCN 623
  19. GRB000301C - R magnitude lower limit
  20. GRB000326, Further VLA observations
  21. GRB 000323, optical observations
  22. GRB 000326: Optical Observations
  23. GRB000326, Radio observations
  24. GRB000326 [IPN Position]
  25. GRB 000307 optical observations
  26. GRB000323 [IPN Position]
  27. Single error box for GRB000315
  28. GRB000315 [IPN Positions]
  29. GRB000313, Radio observations
  30. GRB 000313 - optical transient in the BATSE error box
  31. GRB000301C - B and R photometry
  32. GRB000301C - R photometry
  33. GRB 000307, Optical Observations
  34. GRB 000307, BVRI Field Photometry
  35. GRB 000301C: Optical Spectrum and Redshift
  36. GRB 000301C: Optical Spectrum and Redshift
  37. GRB 000301C: A Precise Redshift Determination
  38. GRB 000301C, Optical Observation
  39. GRB 000301C: HST/STIS-PRISM NUV-MAMA spectroscopy
  40. GRB 000301C: HST/STIS CCD Imaging of the field
  41. IPN error box for GRB000307
  42. GRB 000301c: K' observations
  43. GRB000301C, optical R-band observations
  44. GRB000301c - R photometry and nearby faint source confirmation
  45. GRB 000301C, Optical Observation
  46. GRB 000301c: K' observations
  47. GRB 000301C Optical Observations
  48. GRB 000301C: K' Observations
  49. GRB000301C OT candidate optical observations
  50. GRB000301C - Host galaxy not detected in R (?)
  51. Optical observations of GRB000301c
  52. GRB000301C, Radio observations
  53. GRB000301C, Radio observations
  54. GRB000301C optical observations
  55. GRB000301C, near-infrared observations (JHK' imaging)
  56. GRB 000301c near-IR observations
  57. GRB 000301C, Optical Color
  58. GRB000301C, Optical Spectroscopy
  59. GRB 000301C, UBVRI field photometry
  60. GRB 000301C, Optical Observation
  61. GRB000301C, optical observations
  62. GRB000301C 250 GHz detection
  63. GRB 000301C R-band observation
  64. GRB 000301C, Optical Observation
  65. GRB000301C, near-infrared observations (JHK' photometry)
  66. GRB 000301C: OT confirmed
  67. GRB000301c optical observations
  68. GRB 000301A, Radio Observations
  69. GRB000301C, optical observations
  70. GRB000301c, near-infrared observations
  71. GRB000301C
  72. GRB 000301C : Optical Candidate
  73. Radio observations of the error box of GRB000301A
  74. GRB000301C: RXTE/ASM and IPN localizations
  75. GRB000301A [IPN Position]
  76. GRB000226 [IPN Position]
  77. HST Observations of GRB 990712
  78. GRB 000214 near-IR observations
  79. GRB 000115 Optical observations
  80. GRB 000214, Radio Observations
  81. GRB 000214 ``Valentine's Day Burst'': BeppoSAX NFI Observation
  82. GRB000210, Radio Observations
  83. Correction to GCN 557 (GRB000214: BeppoSAX GRBM and WFC Detection)
  84. GRB 000115, BVRI field photometry
  85. GRB000214: BeppoSAX GRBM and WFC Detection
  86. IPN annulus for GRB000214
  87. BATSE GRB trigger criterion changed
  88. Optical observations of GRB000210
  89. GRB000210 X-ray afterglow
  90. GRB000214: X-ray afterglow candidate
  91. GRB000214 refined BeppoSAX-WFC position
  92. BeppoSAX GRB000214 ("S. Valentine's day GRB")
  93. GRB 000210: BATSE Observations
  94. Correction to Chandra Position of GRB000210 afterglow
  95. Optical observations of the Chandra X-ray source for GRB000210
  96. GRB000210, Radio Observations
  97. Optical candidate for GRB000210
  98. Chandra Observations of GRB000210 X-ray Afterglow
  99. IPN triangulation of GRB000210
  100. GRB000210: possible afterglow detection with BeppoSAX NFI

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