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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"

25045 results found.

  1. GRB 021004: Optical/NIR Observations
  2. GRB 021004: Additional V-band Polarimetric Observations
  3. GRB021004: optical observation
  4. GRB 021004: Host Galaxy Star Formation Rate
  5. GRB 021004 submm observations
  6. GRB 021004: WC wind?
  7. GRB021004: NIR and Optical observations
  8. GRB 021004: Optical observations, AUDE network
  9. GRB 021004 - VLA Radio Observations
  10. GRB 021004 - Unusual Radio-to-Submm Spectrum
  11. GRB 021004: optical spectroscopy
  12. IPN triangulation of GRB021007 (annulus)
  13. GRB021004: optical observations and predicted break time
  14. GRB021004: BVRc photometry
  15. GRB021004 radio observation
  16. HETE fluences for GRB021004
  17. GRB 021004: Optical Photometry at 2.5 Days
  18. GRB 021004: polarimetric observations
  19. GRB 021004: V-band Polarimetric Observations
  20. GRB021004: Update Bisei photometric data
  21. IRAM Millimeter detection of GRB 021004
  22. GRB 021004 radio observation
  23. GRB 021004: Optical Photometry at 1.5 Days
  24. GRB021004, BVRcIc field photometry
  25. GRB021004: Optical Spectroscopy
  26. GRB 021004 radio search
  27. XRF020903, BVRI field photometry
  28. XRF020903: TNG and Asiago photometry
  29. GRB 020903: Optical observations at RIKEN
  30. XRF 020903: Correction to GCN 1560
  31. XRF 020903: VRI observations
  32. XRF 020903: R band observations
  33. XRF 020903: Archival Optical Images
  34. Radio Observations of XRF 020903: The Missing Link
  35. XRF 020903: Supernova
  36. IPN triangulation of GRB020923 (two error boxes)
  37. IPN triangulation of GRB020914B
  38. IPN triangulation of GRB020911 (2 large error boxes)
  39. GRB 020305: HST/STIS observations
  40. Confirmation of IPN error box for GRB020910
  41. IPN triangulation of GRB020910
  42. IPN GCN Circulars now to be issued without restriction
  43. Single IPN error box for GRB020904
  44. XRF 020903: optical observation at Kyoto
  45. GRB020322 : HST/STIS observations
  46. XRF 020903: Optical observations
  47. IPN triangulation of GRB020904
  48. INTEGRAL GRBs added to GCN
  49. SGR1900+14 burst localized by HETE
  50. GRB020813: High-resolution optical spectroscopy
  51. GRB020812: negative optical observations
  52. GRB 020812: optical observation at Kyoto University
  53. Second epoch K band imaging of GRB 020819
  54. GRB 020813 : HST observations
  55. GRB 020812: early time optical observation at Ouda Station
  56. GRB020813: Magellan BVRI Photometry
  57. GRB 020819: Optical observations
  58. K band observation of GRB 020819
  59. GRB020813: optical and NIR observations
  60. GRB020813: Fading X-ray Afterglow Observed with Chandra
  61. GRB020813, UBVRI field calibration
  62. GRB020812: NIR observations
  63. Polarimetry of GRB020813: evidence for variability
  64. GRB020813 IRAM millimeter observations
  65. GRB020812: optical observations
  66. GRB020813: High-Resolution Optical Observations
  67. GRB 020812: optical observation at Bisei
  68. GRB020813: Early Time Magnitude
  69. Millimeter observation of GRB 020813
  70. GRB020812: optical observations
  71. GRB 020813 : KISO multiband optical observations
  72. GRB020813, optical observations
  73. IPN error box for GRB020813
  74. GRB020813, astrometric position
  75. Spectropolarimetry of GRB 020813
  76. GRB 020812 optical observation
  77. GRB020812(=H2257): A Long Burst Localized by HETE in Near-Real Time
  78. GRB020801: Imaging of Suggested OT Counterpart at the Magellan
  79. HST Imaging of the Host of GRB 011121
  80. GRB020801, optical afterglow candidate
  81. GRB020331: Late-time Optical Light Curve (re-submission)
  82. GRB020331: Late-time Optical Light Curve
  83. IPN triangulation of GRB020714
  84. IPN triangulation of GRB020715 (=GRB150702)
  85. IPN triangulation of GRB020714
  86. IPN triangulation of GRB150702
  87. GRB 020410: Discovery of Probable OT by HST
  88. GRB 020124, HST observations of the fading afterglow
  89. IPN triangulation of GRB020708
  90. IPN triangulation of GRB020708
  91. Correction to IPN error box for GRB020706
  92. IPN triangulation of GRB020706
  93. GRB 020705: Optical observations
  94. GRB 020625, optical observations
  95. GRB 020625: Optical observations
  96. GRB 020531: optical photometry of Chandra sources
  97. GRB020625 (=H2081): A Long Burst Localized by HETE
  98. The Probable Host Galaxy of GRB/XRF 020427
  99. GRB/XRF 020427, detection of an underlying system with the VLT
  100. Gemini IR Detection of AXP 1E 2259+586 Post-Burst

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