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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"

28059 results found.

  1. GRB030227 localized by INTEGRAL
  2. GRB 030226 : Predicted light curve
  3. GRB030226: ESI spectroscopy
  4. GRB030226 (=U10893): A Long GRB Localized by the HETE WXM and SXC
  5. GRB 030226 simultaneous optical observations
  6. GRB 030226, optical observations
  7. GRB030226: Optical decay index
  8. GRB 030226 Optical Spectra and R,I,z' Imaging
  9. GRB: Non-Referencing of GCN Circulars.
  10. IPN triangulation of GRB030217 (small error box)
  11. GRB 030131: marginal optical detection
  12. GRB 030204: Optical Observations
  13. GRB030204 field photometry
  14. GRB020819: Kiso R and I band observations
  15. GRB030131: Candidate Optical Afterglow
  16. IPN triangulation of GRB030204 (small error box)
  17. GRB 030131, optical observations
  18. GRB 030131: afterglow candidate
  19. GRB 030115, late-time optical observations
  20. GRB030131: corrected INTEGRAL position
  21. GRB 020819: Host galaxy at Radio Position
  22. IPN triangulation of GRB030131
  23. GRB 030131 optical observations
  24. GRB 030131 optical observations
  25. A long GRB detected by INTEGRAL
  26. GRB030115: 1.2 mm upper limits with MAMBO @ IRAM 30m
  27. GRB 030115, simultaneous observations by BOOTES-1
  28. GRB 030115: IR observations with IRSF/SIRIUS
  29. IPN triangulation of GRB030115C (large error box)
  30. GRB030115, afterglow candidate
  31. GRB 021211: R-band observations at late-time
  32. GRB030115: Optical Observations, Swiss Telescope at La Silla (ESO, Chile)
  33. GRB 030115 : Possible IR counterpart
  34. GRB030115 (=H2533): A Long GRB Localized by the HETE WXM and SXC
  35. Distribution of INTEGRAL SPI-ACS triggers for GRB bursts
  36. GRB 030115: APO Optical Observations
  37. Information about where HETE will be pointing
  38. VLT spectroscopy of the probable host of GRB 021211
  39. IPN triangulation of GRB030101 (two large error boxes)
  40. GRB 021211: Probable Host and Underlying Supernova
  41. GRB 021112: Evidence for Another Dark Optical Afterglow
  42. GRB 021219: OSN optical observations
  43. GRB021219, optical observations
  44. GRB021219, optical observation by MASTER
  45. VLT spectra of GRB 021211 revisited
  46. GRB021219: a long GRB localized by INTEGRAL
  47. GRB021211: APO optical observations
  48. XRF 020903 : HST observations
  49. GRB 021201: Optical Observations
  50. GRB 021211: CTIO observations
  51. GRB021211, BVRI field photometry
  52. GRB021211: Optical observations in CrAO
  53. GRB 021211, optical observations
  54. GRB021211: Kiso Observations
  55. GRB 021201, optical observations
  56. GRB021211: Optical observations
  57. GRB 021201 (short/hard), NOT observations
  58. SUB-MM SEARCH FOR GRB 021211
  59. Chandra observation of the IPN error box of GRB021201 (short/hard)
  60. GRB 021211, R- and I-band observations
  61. GRB021211 - Upper limits from recent and historical observations
  62. GRB021211 (=H2493): A Bright, Long GRB Localized by HETE-2 in Near-Real Time
  63. IPN triangulation of GRB021206 (small error box)
  64. IPN triangulation of GRB021205 (large error box)
  65. GRB021201, BVRcIc field photometry
  66. GRB 021201: BOOTES simultaneous optical observations
  67. IPN triangulation of GRB021201 (short/hard burst, small error box)
  68. GRB021004, late time optical observations
  69. GRB021004 Chandra Observation
  70. IPN detection of continued SGR1900+14 activity
  71. Improved IPN error box for GRB021125
  72. IPN BURST POSITION
  73. IPN triangulation of GRB021125 (INTEGRAL BURST)
  74. GRB021125 : A long GRB localized by INTEGRAL
  75. IPN confirmation of the reactivation of SGR1900+14
  76. GRB021113, SPI ACS observation
  77. GRB 021112: Afterglow or Variable Star?
  78. GRB021113: optical observations at Bisei
  79. GRB 021113: Evidence for a Dark Optical Afterglow
  80. GRB021112, BVRI field photometry
  81. GRB 021112: Variable Source in R-band search
  82. GRB021112: Optical Observations
  83. IPN triangulation of GRB021113 (=H2449; annulus)
  84. GRB 021113: Optical observations
  85. GRB 021112: RAPTOR Observations
  86. GRB021113 (=H2449): A Long GRB Localized by HETE
  87. GRB021112 (=H2448): A Long GRB Localized by HETE
  88. GRB 021016: Optical Observations
  89. GRB021104(=H2434): A Long, X-Ray-Rich GRB Localized by HETE
  90. IPN triangulation of bursts from SGR1900+14, November 1-2, 2002
  91. SGR1900+14 activity, November 2-4, 2002
  92. GRB021104: optical observations
  93. Detection of activity from SGR 1900+14 with the RXTE/PCA
  94. IPN triangulation of GRB021027 (single large error box)
  95. IPN triangulation of GRB021027 (two large error boxes)
  96. GRB 021023: Curious K-band Source(s) Just Outside of IPN Localization
  97. GRB 021004: optical observations
  98. IPN triangulation of GRB021023 (small error boc)
  99. GRB 020813; likely host galaxy.
  100. IPN triangulation of GRB021020 (smaller error box)

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