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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"

28055 results found.

  1. GRB 030226 simultaneous optical observations
  2. GRB 030226, optical observations
  3. GRB030226: Optical decay index
  4. GRB 030226 Optical Spectra and R,I,z' Imaging
  5. GRB: Non-Referencing of GCN Circulars.
  6. IPN triangulation of GRB030217 (small error box)
  7. GRB 030131: marginal optical detection
  8. GRB 030204: Optical Observations
  9. GRB030204 field photometry
  10. GRB020819: Kiso R and I band observations
  11. GRB030131: Candidate Optical Afterglow
  12. IPN triangulation of GRB030204 (small error box)
  13. GRB 030131, optical observations
  14. GRB 030131: afterglow candidate
  15. GRB 030115, late-time optical observations
  16. GRB030131: corrected INTEGRAL position
  17. GRB 020819: Host galaxy at Radio Position
  18. IPN triangulation of GRB030131
  19. GRB 030131 optical observations
  20. GRB 030131 optical observations
  21. A long GRB detected by INTEGRAL
  22. GRB030115: 1.2 mm upper limits with MAMBO @ IRAM 30m
  23. GRB 030115, simultaneous observations by BOOTES-1
  24. GRB 030115: IR observations with IRSF/SIRIUS
  25. IPN triangulation of GRB030115C (large error box)
  26. GRB030115, afterglow candidate
  27. GRB 021211: R-band observations at late-time
  28. GRB030115: Optical Observations, Swiss Telescope at La Silla (ESO, Chile)
  29. GRB 030115 : Possible IR counterpart
  30. GRB030115 (=H2533): A Long GRB Localized by the HETE WXM and SXC
  31. Distribution of INTEGRAL SPI-ACS triggers for GRB bursts
  32. GRB 030115: APO Optical Observations
  33. Information about where HETE will be pointing
  34. VLT spectroscopy of the probable host of GRB 021211
  35. IPN triangulation of GRB030101 (two large error boxes)
  36. GRB 021211: Probable Host and Underlying Supernova
  37. GRB 021112: Evidence for Another Dark Optical Afterglow
  38. GRB 021219: OSN optical observations
  39. GRB021219, optical observations
  40. GRB021219, optical observation by MASTER
  41. VLT spectra of GRB 021211 revisited
  42. GRB021219: a long GRB localized by INTEGRAL
  43. GRB021211: APO optical observations
  44. XRF 020903 : HST observations
  45. GRB 021201: Optical Observations
  46. GRB 021211: CTIO observations
  47. GRB021211, BVRI field photometry
  48. GRB021211: Optical observations in CrAO
  49. GRB 021211, optical observations
  50. GRB021211: Kiso Observations
  51. GRB 021201, optical observations
  52. GRB021211: Optical observations
  53. GRB 021201 (short/hard), NOT observations
  54. SUB-MM SEARCH FOR GRB 021211
  55. Chandra observation of the IPN error box of GRB021201 (short/hard)
  56. GRB 021211, R- and I-band observations
  57. GRB021211 - Upper limits from recent and historical observations
  58. GRB021211 (=H2493): A Bright, Long GRB Localized by HETE-2 in Near-Real Time
  59. IPN triangulation of GRB021206 (small error box)
  60. IPN triangulation of GRB021205 (large error box)
  61. GRB021201, BVRcIc field photometry
  62. GRB 021201: BOOTES simultaneous optical observations
  63. IPN triangulation of GRB021201 (short/hard burst, small error box)
  64. GRB021004, late time optical observations
  65. GRB021004 Chandra Observation
  66. IPN detection of continued SGR1900+14 activity
  67. Improved IPN error box for GRB021125
  68. IPN BURST POSITION
  69. IPN triangulation of GRB021125 (INTEGRAL BURST)
  70. GRB021125 : A long GRB localized by INTEGRAL
  71. IPN confirmation of the reactivation of SGR1900+14
  72. GRB021113, SPI ACS observation
  73. GRB 021112: Afterglow or Variable Star?
  74. GRB021113: optical observations at Bisei
  75. GRB 021113: Evidence for a Dark Optical Afterglow
  76. GRB021112, BVRI field photometry
  77. GRB 021112: Variable Source in R-band search
  78. GRB021112: Optical Observations
  79. IPN triangulation of GRB021113 (=H2449; annulus)
  80. GRB 021113: Optical observations
  81. GRB 021112: RAPTOR Observations
  82. GRB021113 (=H2449): A Long GRB Localized by HETE
  83. GRB021112 (=H2448): A Long GRB Localized by HETE
  84. GRB 021016: Optical Observations
  85. GRB021104(=H2434): A Long, X-Ray-Rich GRB Localized by HETE
  86. IPN triangulation of bursts from SGR1900+14, November 1-2, 2002
  87. SGR1900+14 activity, November 2-4, 2002
  88. GRB021104: optical observations
  89. Detection of activity from SGR 1900+14 with the RXTE/PCA
  90. IPN triangulation of GRB021027 (single large error box)
  91. IPN triangulation of GRB021027 (two large error boxes)
  92. GRB 021023: Curious K-band Source(s) Just Outside of IPN Localization
  93. GRB 021004: optical observations
  94. IPN triangulation of GRB021023 (small error boc)
  95. GRB 020813; likely host galaxy.
  96. IPN triangulation of GRB021020 (smaller error box)
  97. IPN triangulation of GRB021020
  98. GRB 021008, optical observations
  99. IPN triangulation of GRB021016 (small error box)
  100. IPN triangulation of GRB021014 (large error box)

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