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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"

7417 results found.

  1. LIGO/Virgo/KAGRA S240910ci: Identification of a GW compact binary merger candidate
  2. EP240908a: Updates on the WXT detection result around the trigger time
  3. LIGO/Virgo/KAGRA S240908bs: Upper limits from Swift/BAT-GUANO
  4. LIGO/Virgo/KAGRA S240907cg: Upper limits from Swift/BAT-GUANO
  5. EP240908a: optical afterglow candidate
  6. GRB 240905B: GOTO optical upper limits
  7. LIGO/Virgo/KAGRA S240908dg: Updated Sky localization
  8. LIGO/Virgo/KAGRA S240908bs: Updated Sky localization
  9. LIGO/Virgo/KAGRA S240908dg: Identification of a GW compact binary merger candidate
  10. LIGO/Virgo/KAGRA S240908bs: Identification of a GW compact binary merger candidate
  11. LIGO/Virgo/KAGRA S240907cg: Updated Sky localization
  12. LIGO/Virgo/KAGRA S240907cg: Identification of a GW compact binary merger candidate
  13. GRB 240905E: GIT optical upper limit
  14. GRB 240905B: Swift ToO observations
  15. GRB 240905E: J-band observations with WINTER
  16. GRB 240905E: CrAO Optical Afterglow observations, possible OT candidate
  17. GRB 240905E: AKO Optical Upper Limit
  18. GRB 240905E: Swift detection of a burst
  19. LIGO/Virgo/KAGRA S240825ar: Upper limits from Swift/BAT-GUANO
  20. LIGO/Virgo/KAGRA S240807h: Upper limits from Swift/BAT-GUANO
  21. LIGO/Virgo/KAGRA S240902bq: Updated Sky localization
  22. LIGO/Virgo/KAGRA S240902bq: Identification of a GW compact binary merger candidate
  23. LIGO/Virgo/KAGRA S240830gn: Coverage and upper limits from MAXI/GSC observations
  24. LIGO/Virgo/KAGRA S240830gn: Updated Sky localization and EM Bright Classification
  25. LIGO/Virgo/KAGRA S240830gn: Identification of a GW compact binary merger candidate
  26. GRB 240828B: SVOM/C-GFT optical upper limit
  27. GRB 240828B: KAIT optical upper limit
  28. GRB 240828A: KAIT Optical Afterglow Candidate
  29. GRB 240828A: Tiled Swift observations
  30. GRB 240825A: Upper limits from a neutrino search with IceCube
  31. GRB 240828B: Swift ToO observations
  32. GRB 240821A: PRIME near-infrared observations
  33. SVOM GRB 240821A: optical afterglow discovery
  34. GRB 240821A: the second and third EP-FXT follow-up observations and afterglow candidates
  35. LIGO/Virgo/KAGRA S240825ar: Updated Sky localization
  36. LIGO/Virgo/KAGRA S240825ar: Updated Sky localization
  37. GRB 240824B: KAIT optical upper limit
  38. GRB 240824B: NOT optical upper limit
  39. GRB 240825A: Skynet Optical Afterglow observations
  40. GRB 240825A: Swift detection of a burst with a bright optical counterpart
  41. GRB 240824A: SVOM/C-GFT optical upper limit
  42. LIGO/Virgo/KAGRA S240825ar: Identification of a GW compact binary merger candidate
  43. GRB 240824B: Swift ToO observations
  44. GRB240824A: GRANDMA/TAROT-TCA Upper Limit
  45. GRB 240824A: Swift detection of a burst
  46. SGR 1E 1841-045 / Kes 73: Montarrenti Observatory optical upper limits
  47. EP240820a: PRIME J-band Observations
  48. GRB 240821A: GMG Optical Upper Limit
  49. GRB 240821A: Swift ToO observations
  50. GRB 240821A: EP-FXT follow-up observation and afterglow candidates
  51. GRB 240819A: JinShan optical upper limits on one Swift/XRT source
  52. GRB 240819A: KAIT optical upper limit
  53. EP240816a: PRIME upper limits
  54. GRB 240819A: Swift ToO observations
  55. EP240816b: KAIT optical upper limit
  56. LIGO/Virgo/KAGRA S240813d: Updated Sky localization
  57. LIGO/Virgo/KAGRA S240813d: Identification of a GW compact binary merger candidate
  58. LIGO/Virgo/KAGRA S240813c: Updated Sky localization
  59. LIGO/Virgo/KAGRA S240813c: Identification of a GW compact binary merger candidate
  60. GRB 240811A: Swift detection of a burst
  61. LIGO/Virgo/KAGRA S240807h: Updated Sky localization and EM Bright Classification
  62. GRB 240809A: Swift detection of a burst with a bright optical counterpart
  63. IceCube-240808A - IceCube observation of a high-energy neutrino candidate track-like event
  64. S240807h: Identification of a GW compact binary merger candidate
  65. The EP-WXT trigger 01709018832 on August 7th is likely a flaring star
  66. GRB 240626B: VZLUSAT-2 detection
  67. EP240806a: GSP optical counterpart detection
  68. GRB 240805B: Optical detection with 1.6m Mephisto
  69. GRB 240805B: BTA optical afterglow candidate
  70. EP240804a: GSP detects optical candidate counterpart
  71. GRB 240805B: Swift detection of a burst
  72. EP240804a: NOT optical counterpart detection
  73. EP240802a: Montarrenti Observatory optical upper limit
  74. EP240801a: GSP follow-up observations of the candidate counterpart
  75. EP240801a: Kinder follow-up observations of the candidate counterpart
  76. EP240708a: Kinder follow-up observations of the candidate counterpart (duplicate submission of GCN 37002)
  77. GRB 240730A: KAIT Optical Upper Limit
  78. GRB 240730A: Swift detection of a burst
  79. LIGO/Virgo/KAGRA S240615dg: GRAWITA wide-field optical observations
  80. GRB 240727A: observations of optical counterpart.
  81. GRB 240727B: Swift ToO observations
  82. GRB 240727A: KAIT Optical Afterglow Candidate
  83. IceCube-240725A - IceCube observation of a high-energy neutrino candidate track-like event
  84. Swift Trigger 1244778 is not a GRB
  85. LIGO/Virgo/KAGRA S240716b: Upper limits from Swift/BAT-GUANO
  86. LIGO/Virgo/KAGRA S240703ad: Upper limits from Swift/BAT-GUANO
  87. IceCube-240721A - IceCube observation of a high-energy neutrino candidate track-like event
  88. LIGO/Virgo/KAGRA S240716b: Updated Sky localization
  89. GRB 240715A: TRT optical upper limit on one Swift/XRT candidate
  90. LIGO/Virgo/KAGRA S240716b: Identification of a GW compact binary merger candidate
  91. GRB 240715A: Swift ToO observations
  92. GRB 240713A: optical upper limits from the INAF Asiago Observatory
  93. The EP-WXT source triggered on July 14th is likely a flaring star
  94. GRB 240713A: Tiled Swift observations
  95. GRB 240712A: Swift detection of a burst
  96. LIGO/Virgo/KAGRA S240711cm: Coverage and upper limits from MAXI/GSC observations
  97. LIGO/Virgo/KAGRA S240627by: Updated Sky localization and EM Bright Classification
  98. EP240708a: KAIT optical upper limit
  99. LIGO/Virgo/KAGRA S240705at: Updated Sky localization
  100. LIGO/Virgo/KAGRA S240705at: Identification of a GW compact binary merger candidate

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