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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"

28054 results found.

  1. GRB 030226, optical observations
  2. GRB030226: Optical decay index
  3. GRB 030226 Optical Spectra and R,I,z' Imaging
  4. GRB: Non-Referencing of GCN Circulars.
  5. IPN triangulation of GRB030217 (small error box)
  6. GRB 030131: marginal optical detection
  7. GRB 030204: Optical Observations
  8. GRB030204 field photometry
  9. GRB020819: Kiso R and I band observations
  10. GRB030131: Candidate Optical Afterglow
  11. IPN triangulation of GRB030204 (small error box)
  12. GRB 030131, optical observations
  13. GRB 030131: afterglow candidate
  14. GRB 030115, late-time optical observations
  15. GRB030131: corrected INTEGRAL position
  16. GRB 020819: Host galaxy at Radio Position
  17. IPN triangulation of GRB030131
  18. GRB 030131 optical observations
  19. GRB 030131 optical observations
  20. A long GRB detected by INTEGRAL
  21. GRB030115: 1.2 mm upper limits with MAMBO @ IRAM 30m
  22. GRB 030115, simultaneous observations by BOOTES-1
  23. GRB 030115: IR observations with IRSF/SIRIUS
  24. IPN triangulation of GRB030115C (large error box)
  25. GRB030115, afterglow candidate
  26. GRB 021211: R-band observations at late-time
  27. GRB030115: Optical Observations, Swiss Telescope at La Silla (ESO, Chile)
  28. GRB 030115 : Possible IR counterpart
  29. GRB030115 (=H2533): A Long GRB Localized by the HETE WXM and SXC
  30. Distribution of INTEGRAL SPI-ACS triggers for GRB bursts
  31. GRB 030115: APO Optical Observations
  32. Information about where HETE will be pointing
  33. VLT spectroscopy of the probable host of GRB 021211
  34. IPN triangulation of GRB030101 (two large error boxes)
  35. GRB 021211: Probable Host and Underlying Supernova
  36. GRB 021112: Evidence for Another Dark Optical Afterglow
  37. GRB 021219: OSN optical observations
  38. GRB021219, optical observations
  39. GRB021219, optical observation by MASTER
  40. VLT spectra of GRB 021211 revisited
  41. GRB021219: a long GRB localized by INTEGRAL
  42. GRB021211: APO optical observations
  43. XRF 020903 : HST observations
  44. GRB 021201: Optical Observations
  45. GRB 021211: CTIO observations
  46. GRB021211, BVRI field photometry
  47. GRB021211: Optical observations in CrAO
  48. GRB 021211, optical observations
  49. GRB021211: Kiso Observations
  50. GRB 021201, optical observations
  51. GRB021211: Optical observations
  52. GRB 021201 (short/hard), NOT observations
  53. SUB-MM SEARCH FOR GRB 021211
  54. Chandra observation of the IPN error box of GRB021201 (short/hard)
  55. GRB 021211, R- and I-band observations
  56. GRB021211 - Upper limits from recent and historical observations
  57. GRB021211 (=H2493): A Bright, Long GRB Localized by HETE-2 in Near-Real Time
  58. IPN triangulation of GRB021206 (small error box)
  59. IPN triangulation of GRB021205 (large error box)
  60. GRB021201, BVRcIc field photometry
  61. GRB 021201: BOOTES simultaneous optical observations
  62. IPN triangulation of GRB021201 (short/hard burst, small error box)
  63. GRB021004, late time optical observations
  64. GRB021004 Chandra Observation
  65. IPN detection of continued SGR1900+14 activity
  66. Improved IPN error box for GRB021125
  67. IPN BURST POSITION
  68. IPN triangulation of GRB021125 (INTEGRAL BURST)
  69. GRB021125 : A long GRB localized by INTEGRAL
  70. IPN confirmation of the reactivation of SGR1900+14
  71. GRB021113, SPI ACS observation
  72. GRB 021112: Afterglow or Variable Star?
  73. GRB021113: optical observations at Bisei
  74. GRB 021113: Evidence for a Dark Optical Afterglow
  75. GRB021112, BVRI field photometry
  76. GRB 021112: Variable Source in R-band search
  77. GRB021112: Optical Observations
  78. IPN triangulation of GRB021113 (=H2449; annulus)
  79. GRB 021113: Optical observations
  80. GRB 021112: RAPTOR Observations
  81. GRB021113 (=H2449): A Long GRB Localized by HETE
  82. GRB021112 (=H2448): A Long GRB Localized by HETE
  83. GRB 021016: Optical Observations
  84. GRB021104(=H2434): A Long, X-Ray-Rich GRB Localized by HETE
  85. IPN triangulation of bursts from SGR1900+14, November 1-2, 2002
  86. SGR1900+14 activity, November 2-4, 2002
  87. GRB021104: optical observations
  88. Detection of activity from SGR 1900+14 with the RXTE/PCA
  89. IPN triangulation of GRB021027 (single large error box)
  90. IPN triangulation of GRB021027 (two large error boxes)
  91. GRB 021023: Curious K-band Source(s) Just Outside of IPN Localization
  92. GRB 021004: optical observations
  93. IPN triangulation of GRB021023 (small error boc)
  94. GRB 020813; likely host galaxy.
  95. IPN triangulation of GRB021020 (smaller error box)
  96. IPN triangulation of GRB021020
  97. GRB 021008, optical observations
  98. IPN triangulation of GRB021016 (small error box)
  99. IPN triangulation of GRB021014 (large error box)
  100. IPN triangulation of GRB021013 (single error box)

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