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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"

3344 results found.

  1. GRB 200715A: Swift-XRT afterglow detection
  2. GRB 200714E: Swift-XRT observations
  3. GRB 200713A: Swift-XRT refined Analysis
  4. GRB 200711A: Swift-XRT refined Analysis
  5. GRB 200709B/HAWC-200907A: Swift-XRT further observations
  6. GRB 200709B: Swift-XRT observations
  7. GRB 200630A: Swift-XRT refined Analysis
  8. GRB 200623A: Swift XRT further observations
  9. GRB 200623A: Swift-XRT observations
  10. Swift-XRT observations of IceCube 200615A
  11. Fermi GRB 200616A: Global MASTER-Net observations report
  12. GRB 200613A: Swift-XRT afterglow detection
  13. GRB 200613A: Fermi-LAT detection
  14. GRB 200612A: Swift-XRT refined Analysis
  15. GRB 200529A: Swift-XRT refined Analysis
  16. GRB 200528A: Swift-XRT refined Analysis
  17. GRB 200528A: Swift/UVOT Upper Limits
  18. GRB 200524A: Swift-XRT afterglow detection
  19. GRB 200522A: Swift-XRT refined Analysis
  20. GRB 200517A: Swift-XRT Confirmation of afterglow
  21. GRB 200519A: Swift-XRT refined Analysis
  22. GRB 200517A: Swift-XRT afterglow detection
  23. GRB 200512A: Swift-XRT refined Analysis
  24. GRB 200509A: Swift-XRT refined Analysis
  25. GRB 200424A: Swift-XRT afterglow detection
  26. SGR 1935+2154 the Insight-HXMT observation plan
  27. GRB 200424A: Swift/UVOT Upper Limits
  28. GRB 200425A: Swift-XRT refined Analysis
  29. GRB 200424A: Swift-XRT observations
  30. GRB 200412B: Swift XRT confirmation of afterglow and UVOT upper limits
  31. GRB 200405B: Further Swift-XRT observations
  32. GRB 200412B: Swift-XRT afterglow detection
  33. GRB 200411A: Swift-XRT refined Analysis
  34. LIGO/Virgo S200225q: Swift XRT observations, 1 X-ray sources
  35. LIGO/Virgo S200224ca: Swift XRT observations, 8 X-ray sources
  36. GRB 200410A: Swift-XRT refined Analysis
  37. GRB 200409A: Swift-XRT refined Analysis
  38. GRB 200405B: Swift-XRT observations
  39. GRB 200325B: further Swift-XRT observations
  40. GRB 200325B: Swift-XRT and UVOT observations
  41. GRB 200324A: Swift-XRT refined Analysis
  42. Chandra observations of GW170817 at 2.5 years since merger (All epochs 4 of 4)
  43. GW170817: Continued X-ray emission detected with Chandra at 940 days post-merger
  44. LIGO/Virgo S200316bj: No counterpart candidates in Fermi-LAT observations
  45. LIGO/Virgo S200213t: Continued Swift UVOT and XRT observations of ZTF20aamvmzj (AT2020cja)
  46. LIGO/Virgo S200311bg: No significant counterpart candidates in Fermi-LAT observations
  47. Chandra observations of GW170817 ~ 2.5 years since merger (epoch 1 of 4)
  48. GRB 200306C: Swift-XRT refined Analysis
  49. GRB 200306A: Swift-XRT refined Analysis
  50. GRB 200303A: Swift-XRT refined Analysis
  51. LIGO/Virgo S200302c: No significant counterpart candidates in Fermi-LAT observations
  52. GRB 200228B: Swift-XRT refined Analysis
  53. GRB 200227A: Swift-XRT refined Analysis
  54. LIGO/Virgo S200225q: No counterpart candidates in Fermi-LAT observations
  55. LIGO/Virgo S200224ca: No counterpart candidates in Fermi-LAT observations
  56. GRB 200219C: Swift-XRT afterglow confirmation
  57. GRB 200224A: Swift-XRT refined Analysis
  58. GRB 200219C: Swift-XRT afterglow detection
  59. LIGO/Virgo S200213t: Swift UVOT and XRT observations of ZTF20aamvmzj (AT2020cja)
  60. LIGO/Virgo S200219ac: No counterpart candidates in Fermi-LAT observations
  61. GRB 200219A: Swift-XRT refined Analysis correction
  62. GRB 200219A: Swift-XRT refined Analysis
  63. GRB 200216B: Swift-XRT refined Analysis
  64. Further Swift-XRT observations of Swift J0840.7-3516
  65. GRB 200215A: Swift-XRT refined Analysis
  66. LIGO/Virgo S200213t: No candidates found in J-GEM follow-up observations
  67. LIGO/Virgo S200213t: No counterpart candidates in Fermi-LAT observations
  68. LIGO/Virgo S200208q: No counterpart candidates in Fermi-LAT observations
  69. GRB 200205B: ESO/NTT near-infrared imaging
  70. GRB 200205B: Swift-XRT refined Analysis
  71. GRB 200131A: Swift-XRT refined Analysis
  72. LIGO/Virgo S200129m: No counterpart candidates in Fermi-LAT observations
  73. LIGO/Virgo S200128d: No counterpart candidates in Fermi-LAT observations
  74. GRB 200127A: Swift-XRT refined Analysis
  75. GRB 200125A: Further Swift-XRT observations
  76. GRB 200125A: TNG detection of a NIR counterpart candidate
  77. Correction to GRB 200125A: Swift-XRT refined analysis
  78. GRB 200125A: Swift-XRT refined Analysis
  79. LIGO/Virgo S200115j: Further Swift-XRT sources
  80. GRB 200122A: Swift-XRT refined Analysis
  81. GRB 191031D: XMM-Newton upper limit
  82. LIGO/Virgo S200115j: NIR upper limits for ZTF20aafqvyc/AT2020yq from the Palomar 200-inch telescope
  83. LIGO/Virgo S200114f: No transients found in J-GEM observations of nearby galaxies
  84. LIGO/Virgo S200115j: Swift-XRT sources
  85. LIGO/Virgo S200114f: Swift-XRT sources and observations
  86. LIGO/Virgo S200115j: No counterpart candidates in Fermi-LAT observations
  87. LIGO/Virgo S200114f: No counterpart candidates in Fermi-LAT observations
  88. LIGO/Virgo 200112r: No counterpart candidates in Fermi-LAT observations
  89. GRB 200107B: Swift-XRT refined Analysis
  90. GRB 200109A: Swift-XRT refined Analysis
  91. LIGO/Virgo 200105ae: No counterpart candidates in Fermi-LAT observations
  92. Fermi trigger No 599954133: Global MASTER-Net observations report
  93. GRB 191228A: Swift-XRT refined Analysis
  94. GRB 191227A: Marginal detection by Fermi-LAT
  95. GRB 191221B: Swift-XRT refined Analysis
  96. LIGO/Virgo S191222n: No counterpart candidates in Fermi-LAT observations
  97. GRB 191220A: Swift-XRT refined Analysis
  98. LIGO/Virgo S191213g: Swift UVOT/XRT observations of Pan-STARRS1 candidate: PS19hgw
  99. LIGO/Virgo S191216ap: No candidates found in J-GEM follow-up observations of HAWC error region
  100. LIGO/Virgo S191213g: No candidates found in J-GEM follow-up observations

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