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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"

42254 results found.

  1. GRB 030226: Optical observations
  2. GRB 030227: fading of candidate optical afterglow 'S1-A'
  3. GRB030227:Optical observations
  4. GRB 20030226: Upper limits from recent and historical observations
  5. GRB 030227, possible optical counterpart of XMM-Newton source
  6. GRB030227 - faint tentative OT candidate
  7. GRB 030226, optical observations
  8. XMM-Newton observation of GRB030227
  9. GRB030227: Kiso optical observations
  10. GRB 030227: Kyoto optical observation
  11. GRB 030226, optical light curve
  12. GRB 030226 spectroscopy
  13. GRB030227: refined INTEGRAL position
  14. GRB030227 localized by INTEGRAL
  15. Possible break in the GRB 030226 light curve
  16. GRB 030226 : Predicted light curve
  17. GRB030226: optical observation
  18. GRB 030226: Confirmed decay index
  19. GRB030226: ESI spectroscopy
  20. GRB030226 (=U10893): A Long GRB Localized by the HETE WXM and SXC
  21. GRB 030226 simultaneous optical observations
  22. Two absorption systems in GRB 030226
  23. GRB 030226, optical observations
  24. GRB030226: optical observations and refined redshift
  25. GRB030226: Optical decay index
  26. GRB 030226 Optical Spectra and R,I,z' Imaging
  27. GRB 030226, optical observations
  28. GRB 030226: Optical afterglow
  29. GRB030226: Candidate optical afterglow
  30. GRB 030217: Optical Observations at 4, 5, and 6 Days
  31. GRB: Non-Referencing of GCN Circulars.
  32. GRB030217: optical observations
  33. IPN triangulation of GRB030217 (small error box)
  34. IPN triangulation of GRB030215A and GRB030215B (annuli)
  35. GRB030115, WSRT radio observations - correction to GCN 1864
  36. GRB 030131: marginal optical detection
  37. GRB030115, WSRT radio observations
  38. IPN triangulation of GRB030206 (annulus)
  39. GRB 030204: Optical Observations
  40. GRB030204 field photometry
  41. GRB020819: Kiso R and I band observations
  42. GRB030131: Candidate Optical Afterglow
  43. GRB 030115: Optical Observations
  44. GRB 030204, optical observations
  45. IPN triangulation of GRB030202 (annulus)
  46. GRB 030131, optical observations
  47. GRB030131: Kiso optical limit for corrected position
  48. GRB030131: Optical limits for corrected position
  49. GRB 030131: afterglow candidate
  50. GRB 030115, late-time optical observations
  51. GRB030131: corrected INTEGRAL position
  52. Type Ic SN2003L (SN/GRB?), optical spectrum
  53. GRB030131: Kiso Observations
  54. GRB 020819: Host galaxy at Radio Position
  55. IPN triangulation of GRB030131 - CORRECTION
  56. GRB 020819: afterglow candidate
  57. IPN triangulation of GRB030131
  58. GRB030131: Optical limit
  59. GRB 030131 optical observations
  60. GRB030131: refined position
  61. GRB 030131 optical observations
  62. A long GRB detected by INTEGRAL
  63. GRB030115: 1.2 mm upper limits with MAMBO @ IRAM 30m
  64. Type Ic SN2003L (SN/GRB?) Radio Observations
  65. GRB030115 submm upper limit
  66. GRB 030115: Further IR observations with IRSF/SIRIUS
  67. Publicizing GRB Discoveries - A Message from NASA HQ
  68. GRB 030115: Radio detection of IR candidate
  69. GRB 030115, simultaneous observations by BOOTES-1
  70. GRB 030115: IR observations with IRSF/SIRIUS
  71. GRB030115: R-band counterpart of IR candidate
  72. GRB030115, afterglow candidate
  73. GRB 021211: R-band observations at late-time
  74. GRB030115: Optical Observations, Swiss Telescope at La Silla (ESO, Chile)
  75. IPN triangulation of GRB030115B (small error box)
  76. GRB 030115 : Possible IR counterpart
  77. GRB 030115: Radio Observations
  78. GRB030115 (=H2533): A Long GRB Localized by the HETE WXM and SXC
  79. Distribution of INTEGRAL SPI-ACS triggers for GRB bursts
  80. Distribution of INTEGRAL SPI-ACS triggers
  81. GRB030115: R-band observations at Asiago
  82. GRB030115: TAROT optical observations
  83. GRB 021211: VLT spectrum
  84. GRB 030115: APO Optical Observations
  85. GRB 030115, no optical candidate
  86. GRB 030115, optical observations
  87. GRB 030115, optical candidate
  88. Information about where HETE will be pointing
  89. IPN triangulation of GRB030109 (annulus)
  90. IPN triangulation of GRB030105 (large error box)
  91. Coronas-F -Wind triangulation of GRB030102
  92. VLT spectroscopy of the probable host of GRB 021211
  93. GRB 021211: Probable Host and Underlying Supernova
  94. Probable GRB in INTEGRAL SPI-ACS
  95. IPN triangulation of GRB021223 (two large error boxes)
  96. GRB021211, radio observations
  97. GRB 021112: Evidence for Another Dark Optical Afterglow
  98. GRB 021219: OSN optical observations
  99. GRB021219, optical observations
  100. IPN triangulation of GRB021219

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