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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"

7422 results found.

  1. GRB 240910A: Swift ToO observations
  2. GRB 240905E: SVOM/VT optical observations
  3. LIGO/Virgo/KAGRA S240910ci: NED Galaxies in the Localization Volume
  4. LIGO/Virgo/KAGRA S240910ci: Coverage and upper limits from MAXI/GSC observations
  5. LIGO/Virgo/KAGRA S240910ci: Updated Sky localization and EM Bright Classification
  6. LIGO/Virgo/KAGRA S240910ci: Identification of a GW compact binary merger candidate
  7. EP240908a: Updates on the WXT detection result around the trigger time
  8. LIGO/Virgo/KAGRA S240908bs: Upper limits from Swift/BAT-GUANO
  9. LIGO/Virgo/KAGRA S240907cg: Upper limits from Swift/BAT-GUANO
  10. EP240908a: optical afterglow candidate
  11. GRB 240905B: GOTO optical upper limits
  12. LIGO/Virgo/KAGRA S240908dg: Updated Sky localization
  13. LIGO/Virgo/KAGRA S240908bs: Updated Sky localization
  14. LIGO/Virgo/KAGRA S240908dg: Identification of a GW compact binary merger candidate
  15. LIGO/Virgo/KAGRA S240908bs: Identification of a GW compact binary merger candidate
  16. LIGO/Virgo/KAGRA S240907cg: Updated Sky localization
  17. LIGO/Virgo/KAGRA S240907cg: Identification of a GW compact binary merger candidate
  18. GRB 240905E: GIT optical upper limit
  19. GRB 240905B: Swift ToO observations
  20. GRB 240905E: J-band observations with WINTER
  21. GRB 240905E: CrAO Optical Afterglow observations, possible OT candidate
  22. GRB 240905E: AKO Optical Upper Limit
  23. GRB 240905E: Swift detection of a burst
  24. LIGO/Virgo/KAGRA S240825ar: Upper limits from Swift/BAT-GUANO
  25. LIGO/Virgo/KAGRA S240807h: Upper limits from Swift/BAT-GUANO
  26. LIGO/Virgo/KAGRA S240902bq: Updated Sky localization
  27. LIGO/Virgo/KAGRA S240902bq: Identification of a GW compact binary merger candidate
  28. LIGO/Virgo/KAGRA S240830gn: Coverage and upper limits from MAXI/GSC observations
  29. LIGO/Virgo/KAGRA S240830gn: Updated Sky localization and EM Bright Classification
  30. LIGO/Virgo/KAGRA S240830gn: Identification of a GW compact binary merger candidate
  31. GRB 240828B: SVOM/C-GFT optical upper limit
  32. GRB 240828B: KAIT optical upper limit
  33. GRB 240828A: KAIT Optical Afterglow Candidate
  34. GRB 240828A: Tiled Swift observations
  35. GRB 240825A: Upper limits from a neutrino search with IceCube
  36. GRB 240828B: Swift ToO observations
  37. GRB 240821A: PRIME near-infrared observations
  38. SVOM GRB 240821A: optical afterglow discovery
  39. GRB 240821A: the second and third EP-FXT follow-up observations and afterglow candidates
  40. LIGO/Virgo/KAGRA S240825ar: Updated Sky localization
  41. LIGO/Virgo/KAGRA S240825ar: Updated Sky localization
  42. GRB 240824B: KAIT optical upper limit
  43. GRB 240824B: NOT optical upper limit
  44. GRB 240825A: Skynet Optical Afterglow observations
  45. GRB 240825A: Swift detection of a burst with a bright optical counterpart
  46. GRB 240824A: SVOM/C-GFT optical upper limit
  47. LIGO/Virgo/KAGRA S240825ar: Identification of a GW compact binary merger candidate
  48. GRB 240824B: Swift ToO observations
  49. GRB240824A: GRANDMA/TAROT-TCA Upper Limit
  50. GRB 240824A: Swift detection of a burst
  51. SGR 1E 1841-045 / Kes 73: Montarrenti Observatory optical upper limits
  52. EP240820a: PRIME J-band Observations
  53. GRB 240821A: GMG Optical Upper Limit
  54. GRB 240821A: Swift ToO observations
  55. GRB 240821A: EP-FXT follow-up observation and afterglow candidates
  56. GRB 240819A: JinShan optical upper limits on one Swift/XRT source
  57. GRB 240819A: KAIT optical upper limit
  58. EP240816a: PRIME upper limits
  59. GRB 240819A: Swift ToO observations
  60. EP240816b: KAIT optical upper limit
  61. LIGO/Virgo/KAGRA S240813d: Updated Sky localization
  62. LIGO/Virgo/KAGRA S240813d: Identification of a GW compact binary merger candidate
  63. LIGO/Virgo/KAGRA S240813c: Updated Sky localization
  64. LIGO/Virgo/KAGRA S240813c: Identification of a GW compact binary merger candidate
  65. GRB 240811A: Swift detection of a burst
  66. LIGO/Virgo/KAGRA S240807h: Updated Sky localization and EM Bright Classification
  67. GRB 240809A: Swift detection of a burst with a bright optical counterpart
  68. IceCube-240808A - IceCube observation of a high-energy neutrino candidate track-like event
  69. S240807h: Identification of a GW compact binary merger candidate
  70. The EP-WXT trigger 01709018832 on August 7th is likely a flaring star
  71. GRB 240626B: VZLUSAT-2 detection
  72. EP240806a: GSP optical counterpart detection
  73. GRB 240805B: Optical detection with 1.6m Mephisto
  74. GRB 240805B: BTA optical afterglow candidate
  75. EP240804a: GSP detects optical candidate counterpart
  76. GRB 240805B: Swift detection of a burst
  77. EP240804a: NOT optical counterpart detection
  78. EP240802a: Montarrenti Observatory optical upper limit
  79. EP240801a: GSP follow-up observations of the candidate counterpart
  80. EP240801a: Kinder follow-up observations of the candidate counterpart
  81. EP240708a: Kinder follow-up observations of the candidate counterpart (duplicate submission of GCN 37002)
  82. GRB 240730A: KAIT Optical Upper Limit
  83. GRB 240730A: Swift detection of a burst
  84. LIGO/Virgo/KAGRA S240615dg: GRAWITA wide-field optical observations
  85. GRB 240727A: observations of optical counterpart.
  86. GRB 240727B: Swift ToO observations
  87. GRB 240727A: KAIT Optical Afterglow Candidate
  88. IceCube-240725A - IceCube observation of a high-energy neutrino candidate track-like event
  89. Swift Trigger 1244778 is not a GRB
  90. LIGO/Virgo/KAGRA S240716b: Upper limits from Swift/BAT-GUANO
  91. LIGO/Virgo/KAGRA S240703ad: Upper limits from Swift/BAT-GUANO
  92. IceCube-240721A - IceCube observation of a high-energy neutrino candidate track-like event
  93. LIGO/Virgo/KAGRA S240716b: Updated Sky localization
  94. GRB 240715A: TRT optical upper limit on one Swift/XRT candidate
  95. LIGO/Virgo/KAGRA S240716b: Identification of a GW compact binary merger candidate
  96. GRB 240715A: Swift ToO observations
  97. GRB 240713A: optical upper limits from the INAF Asiago Observatory
  98. The EP-WXT source triggered on July 14th is likely a flaring star
  99. GRB 240713A: Tiled Swift observations
  100. GRB 240712A: Swift detection of a burst

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