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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"

32507 results found.

  1. GRB 030227: Optical limit at RIKEN
  2. GRB 030226 Optical observations
  3. IPN triangulation of GRB030306 (single small error box - REVISED)
  4. GRB030226: Optical observations at Asiago
  5. IPN triangulation of GRB030306 (two small error boxes)
  6. GRB 030226: Optical observations
  7. GRB030226: Analysis of Chandra data
  8. GRB 030227: Optical observations
  9. GRB030226, BVRc observations
  10. Chandra detection of the X-ray afterglow of GRB 030226
  11. GRB 030226, further optical/NIR imaging
  12. GRB 030226: Ic Observations
  13. GRB030227: Kiso optical upper limit
  14. GRB030227, BVRcIc field photometry
  15. GRB030226, BVRcIc field calibration
  16. GRB 030227 optical afterglow
  17. GRB 030226: Steep Decline
  18. GRB 030227: Confirmed Optical Afterglow (S1-A)
  19. GRB 030226: R band polarimetric observations
  20. GRB 030226: Optical observations
  21. GRB 030227: fading of candidate optical afterglow 'S1-A'
  22. GRB030227:Optical observations
  23. GRB 20030226: Upper limits from recent and historical observations
  24. GRB 030227, possible optical counterpart of XMM-Newton source
  25. GRB030227 - faint tentative OT candidate
  26. GRB 030226, optical observations
  27. XMM-Newton observation of GRB030227
  28. GRB 030227: Kyoto optical observation
  29. GRB 030226, optical light curve
  30. GRB 030226 spectroscopy
  31. Possible break in the GRB 030226 light curve
  32. GRB030226: optical observation
  33. GRB 030226: Confirmed decay index
  34. GRB030226: ESI spectroscopy
  35. GRB030226 (=U10893): A Long GRB Localized by the HETE WXM and SXC
  36. Two absorption systems in GRB 030226
  37. GRB 030226, optical observations
  38. GRB030226: optical observations and refined redshift
  39. GRB 030226, optical observations
  40. GRB 030226: Optical afterglow
  41. GRB 030217: Optical Observations at 4, 5, and 6 Days
  42. GRB: Non-Referencing of GCN Circulars.
  43. GRB030217: optical observations
  44. IPN triangulation of GRB030217 (small error box)
  45. GRB030115, WSRT radio observations - correction to GCN 1864
  46. GRB 030131: marginal optical detection
  47. GCN/INTEGRAL Mistake Fixed
  48. GRB 030204: Optical Observations
  49. GRB030204 field photometry
  50. GRB020819: Kiso R and I band observations
  51. GRB 030204: Correction to GCN 1856
  52. GRB030131: Candidate Optical Afterglow
  53. GRB 030115: Optical Observations
  54. GRB 030204, optical observations
  55. GRB 030131, optical observations
  56. GRB030131: Kiso optical limit for corrected position
  57. GRB030131: Optical limits for corrected position
  58. GRB 030131: afterglow candidate
  59. GRB 030115, late-time optical observations
  60. Type Ic SN2003L (SN/GRB?), optical spectrum
  61. GRB 020819: Host galaxy at Radio Position
  62. IPN triangulation of GRB030131 - CORRECTION
  63. IPN triangulation of GRB030131
  64. GRB030131: Optical limit
  65. GRB 030131 optical observations
  66. GRB030131: refined position
  67. GRB 030131 optical observations
  68. GRB030115: 1.2 mm upper limits with MAMBO @ IRAM 30m
  69. GRB030115 submm upper limit
  70. GRB 030115: Further IR observations with IRSF/SIRIUS
  71. Publicizing GRB Discoveries - A Message from NASA HQ
  72. GRB 030115, simultaneous observations by BOOTES-1
  73. GRB 030115: IR observations with IRSF/SIRIUS
  74. GRB030115: R-band counterpart of IR candidate
  75. GRB030115, afterglow candidate
  76. GRB 021211: R-band observations at late-time
  77. GRB030115: Optical Observations, Swiss Telescope at La Silla (ESO, Chile)
  78. IPN triangulation of GRB030115B (small error box)
  79. GRB 030115 : Possible IR counterpart
  80. GRB 030115: Radio Observations
  81. GRB030115 (=H2533): A Long GRB Localized by the HETE WXM and SXC
  82. Distribution of INTEGRAL SPI-ACS triggers for GRB bursts
  83. ANNOUNCEMENT ON INTEGRAL GRB ALERTS
  84. Distribution of INTEGRAL SPI-ACS triggers
  85. GRB030115: TAROT optical observations
  86. GRB 021211: VLT spectrum
  87. GRB 030115: APO Optical Observations
  88. GRB 030115, no optical candidate
  89. GRB 030115, optical observations
  90. GRB 030115, optical candidate
  91. IPN triangulation of GRB030109 (annulus)
  92. IPN triangulation of GRB030105 (large error box)
  93. IPN triangulation of GRB030102B (refined localization - portion of annulus)
  94. Coronas-F -Wind triangulation of GRB030102
  95. IPN triangulation of GRB030102 (annulus)
  96. VLT spectroscopy of the probable host of GRB 021211
  97. GRB021226
  98. GRB 021211: Probable Host and Underlying Supernova
  99. GRB 021226 registration by Helicon/Coronas-F
  100. GRB 021112: Evidence for Another Dark Optical Afterglow

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