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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"

25026 results found.

  1. GRB 240929A: SAO RAS, Mondy, and CrAO optical observations
  2. GRB 241002C : MITSuME Akeno optical upper limits
  3. LIGO/Virgo/KAGRA S240925n: Updated Sky localization
  4. NuEm-240926A: Upper limits from a search for coincident neutrino events in IceCube
  5. GRB241001A: REM optical/NIR upper limits
  6. LIGO/Virgo/KAGRA S241002e: Updated Sky localization
  7. GRB 241002A: Swift/UVOT Upper Limits
  8. EP240930a: Liverpool Telescope observations
  9. GRB 241002A: Swift-XRT refined Analysis
  10. GRB 241002A: LCOGT Optical Upper Limits
  11. GRB 241001A: GRANDMA and Kilonova-Catcher optical afterglow detection and upper limits
  12. GRB 241001A: Swift/UVOT Detection
  13. GRB 240929A: Liverpool Telescope prompt followup observations
  14. GRB 241001A: Swift-XRT observations
  15. GRB241001A: optical afterglow candidate
  16. GRB 241002A: Enhanced Swift-XRT position
  17. GRB 241001A: BOOTES-6/DPRT optical upper limit
  18. LIGO/Virgo/KAGRA S241002e: Identification of a GW compact binary merger candidate
  19. GRB 241002A: Swift detection of a burst
  20. LIGO/Virgo/KAGRA S240930du: Updated Sky localization
  21. GRB 240930B: Fermi GBM Observation
  22. GRB 240930B: Swift/BAT-GUANO localization skymap of a burst
  23. Fermi-LAT Gamma-ray Observations of IceCube-240929A
  24. EP240930a: EP-WXT detection of a fast X-ray transient
  25. SVOM/GRM detection of a burst from SGR Swift J1818.0-1607
  26. LIGO/Virgo/KAGRA S240930du: Identification of a GW compact binary merger candidate
  27. IceCube-240929A: Upper limits from a search for additional neutrino events in IceCube
  28. LIGO/Virgo/KAGRA S240930df: 1 counterpart neutrino candidate event from an IceCube neutrino search
  29. AMON NuEM 240926A: Swift XRT Follow-up
  30. GRB 240929A : Leavitt Observatory optical upper limit
  31. GRB 240825A: LBT optical observations
  32. GRB 240928A: SVOM/GRM observation
  33. LIGO/Virgo/KAGRA S240930aa: Identification of a GW compact binary merger candidate
  34. Fermi trigger No 749339671: Global MASTER-Net observations report
  35. GRB 240929A long GRB detected by INTEGRAL
  36. GRB 240929A: BALROG localization (Fermi Trigger 749332209 / GRB 240929826)
  37. Swift Trigger 1256950 is probably not a GRB
  38. LIGO/Virgo/KAGRA S240921cw: Upper limits from Swift/BAT-GUANO
  39. LIGO/Virgo/KAGRA S240920dw: Upper limits from Swift/BAT-GUANO
  40. LIGO/Virgo/KAGRA S240919bn: Upper limits from Swift/BAT-GUANO
  41. NuEm-240926A / IC240926A: BZQJ0955+4532 ~0.6m optical decay and rebrightening detection by MASTER
  42. GRB 240926A: SVOM/GRM observation
  43. Konus-Wind detection of GRB 240905B
  44. EP240919a / GRB 240919A: SVOM/VT upper limit
  45. LIGO/Virgo/KAGRA S240925n: NED Galaxies in the Localization Volume
  46. EP240918b and EP240918c: EP-FXT follow-up observations
  47. LIGO/Virgo/KAGRA S240925n: Updated Sky localization and Source Classification
  48. Insight-HXMT ToO observations of X-ray bursts from SGR 1E 1841-045 / Kes 73
  49. GRB 240716A: Swift/BAT-GUANO localization skymap of a long burst
  50. LIGO/Virgo/KAGRA S240925n: Identification of a GW compact binary merger candidate
  51. GRB 240905B: VZLUSAT-2 detection
  52. LIGO/Virgo/KAGRA S240922df: Updated Sky localization
  53. LIGO/Virgo/KAGRA S240920dw: Updated Sky localization
  54. LIGO/Virgo/KAGRA S240921cw: Updated Sky localization
  55. LIGO/Virgo/KAGRA S240924a: Updated Sky localization
  56. LIGO/Virgo/KAGRA S240920bz: Updated Sky localization and Source Classification
  57. LIGO/Virgo/KAGRA S240923ct: Updated Sky localization and Source Classification
  58. LIGO/Virgo/KAGRA S240924a: Identification of a GW compact binary merger candidate
  59. LIGO/Virgo/KAGRA S240923ct: Identification of a GW compact binary merger candidate
  60. LIGO/Virgo S240919bn: Swift XRT observations, 10 X-ray sources
  61. GRB 240918B: AstroSat CZTI detection
  62. LIGO/Virgo/KAGRA S240922df: Identification of a GW compact binary merger candidate
  63. LIGO/Virgo/KAGRA S240921cw: Identification of a GW compact binary merger candidate
  64. EP240913A/GRB 240913C: AbAO optical upper limit
  65. EP240919a / GRB 240919A: Mondy optical upper limit
  66. EP240913a/GRB 240913C: 1.6m Mephisto observations
  67. EP240918a: SVOM/VT upper limit
  68. Fermi GBM Sub-Threshold Detection of GRB240919A / EP240919a
  69. EP240919a / GRB 240919A: REM optical and NIR upper limits
  70. EP240918b and EP240918c: Optical upper limits with Kinder observations
  71. GRB 240414A: further radio observations with the VLA
  72. EP240919a: Optical upper limit with Kinder observations
  73. LIGO/Virgo/KAGRA S240920dw: Identification of a GW compact binary merger candidate
  74. GRB 240910A: radio detection with the VLA
  75. EP240918a: 1.6m Mephisto multi-band Optical Upper Limit
  76. EP240919a: NOT and Gemini optical observations
  77. EP240919a: GOTO optical upper limits
  78. EP240919a: JinShan optical upper limits
  79. LIGO/Virgo/KAGRA S240920bz: Identification of a GW compact binary merger candidate
  80. LIGO/Virgo/KAGRA S240919bn: Updated Sky localization
  81. GRB 240918B: Fermi GBM Detection
  82. LIGO/Virgo/KAGRA S240917cb: Updated Sky localization and EM Bright Classification
  83. LIGO/Virgo/KAGRA S240916ar: Updated Sky localization and EM Bright Classification
  84. EP240918b and EP240918c: EP-WXT detection of two fast X-ray transients
  85. GRB 240910A: further Swift observations and confirmation of afterglow
  86. LIGO/Virgo/KAGRA S240919bn: Identification of a GW compact binary merger candidate
  87. EP240918a: Swift-XRT observation
  88. EP240918a: JinShan optical upper limits
  89. EP240918a: Optical upper limits with Kinder observations
  90. EP240918a: GMG Optical Upper Limit
  91. EP240918a: an X-ray transient detected by Einstein Probe
  92. GRB 240912A: Swift-BAT refined analysis
  93. IPN triangulation of GRB 240913C / EP 240913a
  94. GRB 240916A: Fermi GBM Observation
  95. LIGO/Virgo/KAGRA S240917cb: Identification of a GW compact binary merger candidate
  96. GRB 240821A: radio observation with the VLA
  97. GRB 240916A: Swift-XRT afterglow detection
  98. LIGO/Virgo/KAGRA S240916ar: Identification of a GW compact binary merger candidate
  99. LIGO/Virgo/KAGRA S240915b: NED Galaxies in the Localization Volume
  100. LIGO/Virgo S240915b: Swift XRT observations, 8 X-ray sources

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