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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"

24356 results found.

  1. GRB030329:optical observations by MASTER
  2. GRB030329 (=H2652): A Long, Extremely Bright GRB Localized by the HETE WXM and SXC
  3. GRB 030328: Optical observations
  4. GRB030328: optical spectroscopy at TNG
  5. GRB030328 (=H2650): A Long, Bright GRB Localized by the HETE WXM and SXC
  6. GRB030324, optical observations
  7. GRB030324, optical observations
  8. GRB 030324: TAROT optical observations
  9. GRB030323: V, R, I photometry
  10. GRB030323 (=H2640): A Faint, Long GRB Localized by the HETE WXM and SXC
  11. GRB030324 (=H2641): A Long GRB Localized in Real Time by the HETE WXM
  12. GRB030324 (=H2641): A Long GRB Localized in Real Time by the HETE WXM
  13. VLT/FORS2 spectra of GRB 030323
  14. IPN triangulation of GRB030320
  15. Possible GRB 030320 localized by INTEGRAL
  16. GRB030226, addendum to GCN 1892
  17. IPN upper limit to a GRB associated with SN2003L
  18. GRB030226: Optical observations at Asiago
  19. IPN triangulation of GRB030306 (two small error boxes)
  20. IPN triangulation of GRB030306 (intense; annulus only so far)
  21. GRB 030226: Optical observations
  22. GRB030226: Analysis of Chandra data
  23. GRB 030227: Optical observations
  24. GRB030226, BVRc observations
  25. Chandra detection of the X-ray afterglow of GRB 030226
  26. GRB 030226, further optical/NIR imaging
  27. GRB 030226: Ic Observations
  28. GRB030227: Kiso optical upper limit
  29. GRB 030227 optical afterglow
  30. 030302: NOT A GRB
  31. 030228: NOT A GRB
  32. GRB 030226: Steep Decline
  33. GRB 030227: Confirmed Optical Afterglow (S1-A)
  34. GRB 030226: Optical observations
  35. GRB030227:Optical observations
  36. GRB 030227, possible optical counterpart of XMM-Newton source
  37. GRB030227: Kiso optical observations
  38. GRB 030226, optical light curve
  39. GRB030227: refined INTEGRAL position
  40. GRB030227 localized by INTEGRAL
  41. Possible break in the GRB 030226 light curve
  42. GRB 030226 : Predicted light curve
  43. GRB030226 (=U10893): A Long GRB Localized by the HETE WXM and SXC
  44. GRB 030226 simultaneous optical observations
  45. Two absorption systems in GRB 030226
  46. GRB 030226 Optical Spectra and R,I,z' Imaging
  47. GRB: Non-Referencing of GCN Circulars.
  48. GRB 030131: marginal optical detection
  49. GRB 030204: Optical Observations
  50. GRB030131: Candidate Optical Afterglow
  51. GRB 030204, optical observations
  52. GRB 030131, optical observations
  53. GRB030131: Kiso optical limit for corrected position
  54. GRB030131: Optical limits for corrected position
  55. GRB 030115, late-time optical observations
  56. GRB030131: corrected INTEGRAL position
  57. GRB030131: Kiso Observations
  58. GRB 020819: Host galaxy at Radio Position
  59. IPN triangulation of GRB030131
  60. GRB030131: Optical limit
  61. GRB030131: refined position
  62. A long GRB detected by INTEGRAL
  63. IPN triangulation of GRB030119 (two large error boxes)
  64. IPN triangulation of GRB030117 (two large error boxes)
  65. Publicizing GRB Discoveries - A Message from NASA HQ
  66. GRB 030115, simultaneous observations by BOOTES-1
  67. GRB030115: R-band counterpart of IR candidate
  68. GRB 021211: R-band observations at late-time
  69. GRB030115: Optical Observations, Swiss Telescope at La Silla (ESO, Chile)
  70. GRB030115 (=H2533): A Long GRB Localized by the HETE WXM and SXC
  71. ANNOUNCEMENT ON INTEGRAL GRB ALERTS
  72. GRB 021211: VLT spectrum
  73. Information about where HETE will be pointing
  74. IPN triangulation of GRB030105 (large error box)
  75. IPN triangulation of GRB030102B (refined localization - portion of annulus)
  76. VLT spectroscopy of the probable host of GRB 021211
  77. IPN triangulation of GRB030101 (two large error boxes)
  78. GRB021219, optical observations
  79. GRB021219, optical observation by MASTER
  80. XRF 020903 : HST observations
  81. GRB 021211: CTIO observations
  82. GRB021211: Measurement of Early Time Afterglow
  83. VLT spectrum of GRB 021211
  84. IPN triangulation of GRB021211B (two large error boxes)
  85. GRB 021211: early break in light curve
  86. GRB021204: Kiso Observations
  87. GRB 021211, R- and I-band observations
  88. GRB021211, OT at 108 s
  89. GRB021211 (HETE2493), OT at 143 sec
  90. GRB021211 (=H2493): A Bright, Long GRB Localized by HETE-2 in Near-Real Time
  91. GRB 021204: Optical Observations at RIKEN
  92. IPN detection of renewed activity from SGR1806-20
  93. GRB 021201: BOOTES simultaneous optical observations
  94. Radio Catalog of GRB Afterglows
  95. GRB021004, late time optical observations
  96. GRB021004 Chandra Observation
  97. IPN triangulation of GRB021119 (large error box)
  98. IPN BURST POSITION
  99. IPN triangulation of GRB021125 (INTEGRAL BURST)
  100. IPN confirmation of the reactivation of SGR1900+14

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