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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"

11756 results found.

  1. GRB 241002B: Swift/BAT-GUANO localization skymap of a burst
  2. Konus-Wind detection of GRB 240926A
  3. LIGO/Virgo/KAGRA S240925n: NED Galaxies in the Localization Volume
  4. GRB 241002B: GOTO24gpc/AT 2024xbg follow-up observations update
  5. EP240930a: Liverpool Telescope observations
  6. GRB 241002A: Swift-XRT refined Analysis
  7. GRB 241002B: GOTO optical counterpart candidate
  8. GRB 241002C : Detection of a long soft transient by SVOM/ECLAIRs
  9. Fermi GRB 241002B: Global MASTER-Net observations report
  10. GRB 241002A: Swift detection of a burst
  11. GRB 240930B: Swift/BAT-GUANO localization skymap of a burst
  12. Fermi-LAT Gamma-ray Observations of IceCube-240929A
  13. EP240930a: GOTO optical upper limits
  14. EP EP240930a: Global MASTER-Net observations report
  15. SVOM/GRM detection of a burst from SGR Swift J1818.0-1607
  16. GRB 240929A : Leavitt Observatory optical upper limit
  17. Fermi GRB 240930B: Global MASTER-Net observations report
  18. Fermi GRB 240930A: Global MASTER-Net observations report
  19. GRB 240929A long GRB detected by INTEGRAL
  20. Fermi GRB 240929A: Global MASTER-Net observations report
  21. Konus-Wind detection of GRB 240912A
  22. LIGO/Virgo/KAGRA S240921cw: Upper limits from Swift/BAT-GUANO
  23. LIGO/Virgo/KAGRA S240920dw: Upper limits from Swift/BAT-GUANO
  24. LIGO/Virgo/KAGRA S240919bn: Upper limits from Swift/BAT-GUANO
  25. EP trigger ID 01709061302: the X-ray transient is likely a stellar flare event
  26. Konus-Wind detection of GRB 240905B
  27. LIGO/Virgo/KAGRA S240925n: NED Galaxies in the Localization Volume
  28. EP240918b and EP240918c: EP-FXT follow-up observations
  29. Insight-HXMT ToO observations of X-ray bursts from SGR 1E 1841-045 / Kes 73
  30. GRB 240716A: Swift/BAT-GUANO localization skymap of a long burst
  31. LIGO/Virgo/KAGRA S240925n: Identification of a GW compact binary merger candidate
  32. Konus-Wind detection of GRB 240918B
  33. IPN triangulation of GRB 240918B
  34. EP trigger ID 01709059262: the X-ray transient is likely a stellar flare event
  35. LIGO/Virgo/KAGRA S240923ct: Identification of a GW compact binary merger candidate
  36. LIGO/Virgo S240919bn: GOTO optical upper limits
  37. LIGO/Virgo S240919bn: Swift XRT observations, 10 X-ray sources
  38. GRB 240918B: AstroSat CZTI detection
  39. LIGO/Virgo/KAGRA S240921cw: Identification of a GW compact binary merger candidate
  40. EP240919a: EP-FXT follow-up observation update
  41. EP240919a / GRB 240919A: Mondy optical upper limit
  42. EP240919a: Optical upper limit with Kinder observations
  43. GRB 240919A / EP240919a: SVOM/GRM observation
  44. EP240919a: INTEGRAL SPI-ACS confirmation of reported high-energy counterpart
  45. EP240919a: INTEGRAL SPI-ACS confirmation of reported high-energy counterpart
  46. LIGO/Virgo/KAGRA S240920dw: Identification of a GW compact binary merger candidate
  47. EP EP240919a: Global MASTER-Net observations report
  48. EP240918a: 1.6m Mephisto multi-band Optical Upper Limit
  49. EP240919a: NOT and Gemini optical observations
  50. LIGO/Virgo/KAGRA S240920bz: Identification of a GW compact binary merger candidate
  51. EP240919a: EP-WXT detection of a fast X-ray transient
  52. GRB 240918B: Fermi GBM Detection
  53. EP240918a: EP observation update
  54. LIGO/Virgo/KAGRA S240919bn: Identification of a GW compact binary merger candidate
  55. Fermi GRB 240918A: Global MASTER-Net observations report
  56. GRB 240918A: Fermi GBM Final Real-time Localization
  57. EP EP240918a: Global MASTER-Net observations report
  58. EP240918a: YAHPT Optical Upper Limit
  59. EP240918a: Optical upper limits with Kinder observations
  60. EP240918a: an X-ray transient detected by Einstein Probe
  61. GRB 240916A: NOT optical observation
  62. LIGO/Virgo/KAGRA S240915b: NED Galaxies in the Localization Volume
  63. LIGO/Virgo S240915b: Swift XRT observations, 8 X-ray sources
  64. EP EP240913a: Global MASTER-Net observations report
  65. LIGO/Virgo/KAGRA S240915b: Coverage and upper limits from MAXI/GSC observations
  66. Fermi Gamma-ray Burst Monitor trigger 748124309/240915846 is not a GRB
  67. GRB 240914B: AstroSat CZTI detection
  68. EP240913A / GRB 240913C: AstroSat CZTI detection
  69. EP240913a: Swift/XRT detection of an X-ray source within the EP/WXT error circle
  70. EP240913a: EP-WXT detection of a fast X-ray transient
  71. GRB 240913B: Fermi GBM Final Real-time Localization
  72. GRB 240912A: Swift-XRT refined Analysis
  73. GRB 240912A: NOT optical spectroscopy
  74. GRB 240912A: Swift detection of a burst with an optical counterpart
  75. GRB 240911A : a likely weak GRB detected by SVOM/ECLAIRs
  76. GRB 240825A: 7DT Optical Upper Limit
  77. LIGO/Virgo/KAGRA S240910ci: NED Galaxies in the Localization Volume
  78. LIGO/Virgo/KAGRA S240910ci: Coverage and upper limits from MAXI/GSC observations
  79. EP240908a: Updates on the WXT detection result around the trigger time
  80. Fermi GRB 240910A: Global MASTER-Net observations report
  81. LIGO/Virgo/KAGRA S240908bs: Upper limits from Swift/BAT-GUANO
  82. LIGO/Virgo/KAGRA S240907cg: Upper limits from Swift/BAT-GUANO
  83. GRB 240905E: GIT optical upper limit
  84. GRB 240905E: NUTTelA-TAO / BSTI Optical Limits
  85. GRB 240905B: Fermi-LAT detection
  86. GRB 240905E: SVOM/C-GFT optical upper limit
  87. GRB 240902B: AstroSat CZTI detection of a long burst
  88. GRB 240905E: Swift-XRT refined Analysis
  89. GRB 240902A: AstroSat CZTI detection of a long burst
  90. GRB 240905D: AstroSat CZTI detection
  91. GRB 240905B: AstroSat CZTI detection and localization
  92. LIGO/Virgo/KAGRA S240825ar: Upper limits from Swift/BAT-GUANO
  93. LIGO/Virgo/KAGRA S240807h: Upper limits from Swift/BAT-GUANO
  94. GRB 240825A: MeerLICHT afterglow detection
  95. Fermi trigger No 746923430: Global MASTER-Net observations report
  96. GRB 240828B: Mephisto optical upper limit
  97. LIGO/Virgo/KAGRA S240830gn: Coverage and upper limits from MAXI/GSC observations
  98. GRB 240825A: MeerKAT detection
  99. GRB 240828B: J-band upper limit from WINTER
  100. GRB 240828B: GWAC-F50A optical upper limit

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