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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"
  1. LIGO/Virgo/KAGRA S240915bd: Updated Sky localization
  2. EP240913a: VLT/HAWK-I near-infrared upper limits
  3. LIGO/Virgo/KAGRA S240915bd: Identification of a GW compact binary merger candidate
  4. LIGO/Virgo/KAGRA S240915b: Updated Sky localization and EM Bright Classification
  5. LIGO/Virgo/KAGRA S240915b: Identification of a GW compact binary merger candidate
  6. EP240913a/GRB 240913C: KAIT optical upper limit
  7. EP240913a / GRB 240913C INTEGRAL SPI ACS LIGHT CURVE
  8. GRB 240913C: Fermi GBM detection
  9. GRB 240914A: Swift-XRT observations
  10. GRB 240913C: Joint location by ETJASMIN
  11. GRB 240914B: AstroSat CZTI detection
  12. EP240913A / GRB 240913C: AstroSat CZTI detection
  13. GRB 240914A: SVOM/GRM observation
  14. GRB 240910A: SVOM/VT optical observations
  15. GRB 240914A: Swift ToO observations
  16. EP240913a: NOT optical upper limits
  17. EP240913a: JinShan optical upper limits
  18. EP240913a: ESO-NTT optical observations
  19. GRB 240914A: ESO-NTT optical observations
  20. EP240913a: Swift/XRT detection of an X-ray source within the EP/WXT error circle
  21. GRB 240914B: BALROG localization (Fermi Trigger 747990592 / GRB 240914298)
  22. GRB 240914A : An intermediate duration GRB located on-board by SVOM/ECLAIRs.
  23. GRB 240905E: further NOT optical observations
  24. EP240913a: A GRB Event
  25. EP240913a: EP-WXT detection of a fast X-ray transient
  26. GRB 240913B: Fermi GBM Final Real-time Localization
  27. GRB 240911A: LCO optical observations
  28. GRB 240911A: JinShan optical upper limits on two Swift/XRT candidates
  29. Fermi Gamma-ray Burst Monitor trigger 747837485/240912526 is not a GRB
  30. GRB 240912A: Swift/UVOT Detection
  31. GRB 240911A: GOTO optical limits on Swift/XRT candidates
  32. Fermi trigger No 747920561: Global MASTER-Net observations report
  33. GRB 240912A: SVOM/GRM observation
  34. GRB 240911A: Swift-XRT observations
  35. Fermi GRB 240913A: Global MASTER-Net observations report
  36. GRB 240913A: Fermi GBM Final Real-time Localization
  37. GRB 240912A: J-band observations with WINTER
  38. GRB 240912A: Swift-XRT refined Analysis
  39. GRB 240912A: Fermi GBM Observation
  40. Swift GRB 240912A: Global MASTER-Net observations report
  41. GRB 240912A: LCOGT detection and Legacy Surveys likely host galaxy
  42. GRB 240911A: Tiled Swift observations
  43. Fermi Gamma-ray Burst Monitor trigger 747839931/240912555 is not a GRB
  44. GRB 240912A : INTEGRAL SPI ACS LIGHT CURVE
  45. GRB 240912B: Fermi GBM Final Real-time Localization
  46. GRB 240912A: NOT optical spectroscopy
  47. GRB 240912A: Enhanced Swift-XRT position
  48. GRB 240912A: Redshift from OSIRIS+/GTC
  49. Fast X-ray Transient EP240801a: GMRT radio observations
  50. GRB 240910A: Redshift from OSIRIS+/GTC
  51. GRB 240912A: Swift detection of a burst with an optical counterpart
  52. GRB 240912A: Fermi GBM Final Real-time Localization
  53. GRB 240910A: Fermi GBM Observation
  54. GRB 240910A: NOT optical observations
  55. GRB 240911A : a likely weak GRB detected by SVOM/ECLAIRs
  56. GRB 240910A: Swift-XRT detection of GOTO24fvl/AT2024vfp
  57. GRB 240910A: JinShan optical observations
  58. GRB 240910A: GOTO candidate optical counterpart
  59. EP240908a: Optical afterglow confirmation
  60. GRB 240710A: SVOM/GRM observation
  61. GRB 240910A: Swift ToO observations
  62. IPN triangulation of GRB 240905B (short)
  63. GRB 240825A: 7DT Optical Upper Limit
  64. GRB 240905E: SVOM/VT optical observations
  65. GRB 240905E: SVOM/VT optical observations (duplicate submission of GCN 37453)
  66. LIGO/Virgo/KAGRA S240910ci: NED Galaxies in the Localization Volume
  67. GRB 240910A: GRBAlpha detection
  68. GRB 240910B: Fermi GBM Final Real-time Localization
  69. LIGO/Virgo/KAGRA S240910ci: Coverage and upper limits from MAXI/GSC observations
  70. LIGO/Virgo/KAGRA S240910ci: Updated Sky localization and EM Bright Classification
  71. LIGO/Virgo/KAGRA S240910ci: Identification of a GW compact binary merger candidate
  72. GRB 240910A: SVOM/GRM observation
  73. EP240908a: Mondy and AbAO follow-up observations
  74. EP240908a: Updates on the WXT detection result around the trigger time
  75. Fermi GRB 240910A: Global MASTER-Net observations report
  76. GRB 240910A: Fermi GBM Final Real-time Localization
  77. LIGO/Virgo/KAGRA S240908bs: Upper limits from Swift/BAT-GUANO
  78. LIGO/Virgo/KAGRA S240907cg: Upper limits from Swift/BAT-GUANO
  79. EP240908a: optical afterglow candidate
  80. EP EP240908a: Global MASTER-Net observations report
  81. GRB 240905B: Fermi GBM Observation
  82. Fermi trigger No 747553301: Global MASTER-Net observations report
  83. EP240908a: TRT optical upper limit
  84. GRB 240905B: GOTO optical upper limits
  85. EP240908a: EP detection of a fast X-ray transient
  86. Fermi GRB 240908A: Global MASTER-Net observations report
  87. LIGO/Virgo/KAGRA S240908dg: Updated Sky localization
  88. LIGO/Virgo/KAGRA S240908bs: Updated Sky localization
  89. GRB 240908A: Fermi GBM Final Real-time Localization
  90. LIGO/Virgo/KAGRA S240908dg: Identification of a GW compact binary merger candidate
  91. LIGO/Virgo/KAGRA S240908bs: Identification of a GW compact binary merger candidate
  92. LIGO/Virgo/KAGRA S240907cg: Updated Sky localization
  93. GRB 240801A: SVOM/GRM observation
  94. LIGO/Virgo/KAGRA S240907cg: Identification of a GW compact binary merger candidate
  95. GRB 240905E: GIT optical upper limit
  96. GRB 240905B: Swift-XRT observations
  97. GRB 240905E: Gaoyazi/GOT optical upper limits
  98. GRB 240905E: NUTTelA-TAO / BSTI Optical Limits
  99. GRB 240905B: Fermi-LAT detection
  100. GRB 240905B: Swift ToO observations

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