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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"

42583 results found.

  1. GRB 000620, optical observations
  2. GRB000418, HST/STIS Observations
  3. GRB990123: Late-time HST/STIS observations of the host
  4. GRB 990506, HST/STIS Observations of the Host Galaxy
  5. GRB000623
  6. GRB 000620: J-band observations
  7. GRB000620, optical observations
  8. GRB000615: H-band observations
  9. GRB990308, HST/STIS observations of the host galaxy
  10. GRB000620 Optical observations
  11. IPN annulus for GRB000620
  12. GRB000620: BeppoSAX WFC and GRBM detection
  13. GRB000615, Radio observations
  14. GRB000607, optical observations
  15. GRB 000615: NIR further observations
  16. BeppoSAX ALERT: GRB000620
  17. GRB000620: BeppoSAX Alert
  18. GRB990123, HST/STIS observations of the host galaxy
  19. GRB000616 optical observations
  20. GRB 000615, near-infrared observations
  21. GRB 990123: Late-time HST/STIS 50CCD observations of the host
  22. GRB 000615: NIR observations
  23. GRB000615: BeppoSAX NFI follow-up preliminary analysis
  24. GRB980425, HST/STIS observations of the host galaxy
  25. GRB000615: BeppoSAX GRB Alert
  26. The Hosts of GRB 980703 and GRB 971214
  27. GRB 000301C: Further Late-Time HST/STIS observations
  28. GRB000528: follow-up X-ray measurements and update of IPN annulus
  29. Optical Follow-up of GRB000529 Error Box
  30. GRB980519, HST/STIS observations of the host galaxy
  31. GRB000607, Radio Observations
  32. BeppoSAX X-ray transient/possible GRB000608
  33. GRB000604 optical non-detection
  34. GRB000604 - Optical observations
  35. GRB000607, A SHORT, HARD BURST
  36. GRB000604, optical observations
  37. GRB000528, optical observations at ESO
  38. GRB 000604 optical observations
  39. GRB 000418: Detection of the Host Galaxy
  40. GRB000604, optical observations, comparison with DPOSS
  41. GRB000604 [IPN Position]
  42. GRB000528, Radio Observations
  43. X-ray Afterglow of GRB 000529
  44. GRB000529: BeppoSAX NFI follow-up preliminary analysis
  45. GRB000528: BeppoSAX NFI follow-up preliminary analysis
  46. GRB000529: Optical Observations
  47. IPN localization and time history of GRB000528
  48. New IPN localization of GRB000529
  49. GRB000519: Optical observations
  50. GRB000529: BeppoSAX WFC position
  51. GRB000528: BeppoSAX GRBM observations
  52. GRB 000528 Optical Observations
  53. GRB000519, BVRI field photometry
  54. IPN triangulation of GRB000519
  55. IPN triangulation of GRB000516
  56. Re: GRB000508B : Optical observations
  57. GRB 000418, Optical observation
  58. GRB000508B, BVR field photometry
  59. Possible GRB-related phenomenon
  60. RXTE/ASM and IPN localization of GRB 000508B
  61. GRB000424, UBVRI field photometry
  62. GRB 000424 Optical Observations
  63. GRB000418, UBVRI field photometry update
  64. The redshift of GRB 000418
  65. GRB000424, optical observations
  66. GRB 000429, optical observation
  67. GRB 000429, UBVRI field photometry
  68. IPN localization of GRB000429
  69. GRB 000418, UBVRI field photometry
  70. GRB000418, Radio detection
  71. GRB000418, K'-band photometry
  72. GRB 000418, optical observation
  73. GRB000424 Optical Observations
  74. GRB 000418, Optical Observation
  75. GRB000424, optical observations
  76. GRB 000424, Optical Observations
  77. GRB 000418, Optical Observation
  78. GRB000418, near-infrared observations
  79. BeppoSAX GRB000424
  80. Correction to IPN error box for GRB000419
  81. IPN error box for GRB000418
  82. GRB000419 [IPN Position]
  83. BATSE observations of FXT/GRB 000416 = 1SAXJ1715.0-7134
  84. GRB000416 BRJK observations
  85. 1SAXJ1715.0-7134 refined position
  86. RE: Budget cuts in BeppoSAX operations: impact on GRB observation
  87. X-ray burst or X-ray rich GRB 000416 observed by BeppoSAX
  88. Budget cuts in BeppoSAX operations: impact on GRB observations
  89. GRB 000408, optical observations
  90. Refined IPN error box for GRB000408
  91. GRB 991208, UBVRI field photometry
  92. GRB000301c results
  93. GRB 000301C: Late-Time HST/STIS CCD Imaging of the field
  94. GRB000408 [IPN Position]
  95. GRB000326 Optical Observations
  96. GRB000301C - Addendum to GCN 623
  97. GRB000301C - R magnitude lower limit
  98. GRB000326, Further VLA observations
  99. GRB 000323, optical observations
  100. GRB 000326: Optical Observations

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