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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. EP240913a / GRB 240913C INTEGRAL SPI ACS LIGHT CURVE
  2. GRB 240913C: Fermi GBM detection
  3. GRB 240914A: Swift-XRT observations
  4. GRB 240913C: Joint location by ETJASMIN
  5. GRB 240914B: AstroSat CZTI detection
  6. EP240913A / GRB 240913C: AstroSat CZTI detection
  7. GRB 240914A: SVOM/GRM observation
  8. GRB 240910A: SVOM/VT optical observations
  9. GRB 240914A: Swift ToO observations
  10. EP240913a: NOT optical upper limits
  11. EP240913a: JinShan optical upper limits
  12. EP240913a: ESO-NTT optical observations
  13. GRB 240914A: ESO-NTT optical observations
  14. EP240913a: Swift/XRT detection of an X-ray source within the EP/WXT error circle
  15. GRB 240914B: BALROG localization (Fermi Trigger 747990592 / GRB 240914298)
  16. GRB 240914A : An intermediate duration GRB located on-board by SVOM/ECLAIRs.
  17. GRB 240905E: further NOT optical observations
  18. EP240913a: A GRB Event
  19. EP240913a: EP-WXT detection of a fast X-ray transient
  20. GRB 240913B: Fermi GBM Final Real-time Localization
  21. GRB 240911A: LCO optical observations
  22. GRB 240911A: JinShan optical upper limits on two Swift/XRT candidates
  23. Fermi Gamma-ray Burst Monitor trigger 747837485/240912526 is not a GRB
  24. GRB 240912A: Swift/UVOT Detection
  25. GRB 240911A: GOTO optical limits on Swift/XRT candidates
  26. Fermi trigger No 747920561: Global MASTER-Net observations report
  27. GRB 240912A: SVOM/GRM observation
  28. GRB 240911A: Swift-XRT observations
  29. Fermi GRB 240913A: Global MASTER-Net observations report
  30. GRB 240913A: Fermi GBM Final Real-time Localization
  31. GRB 240912A: J-band observations with WINTER
  32. GRB 240912A: Swift-XRT refined Analysis
  33. GRB 240912A: Fermi GBM Observation
  34. Swift GRB 240912A: Global MASTER-Net observations report
  35. GRB 240912A: LCOGT detection and Legacy Surveys likely host galaxy
  36. GRB 240911A: Tiled Swift observations
  37. Fermi Gamma-ray Burst Monitor trigger 747839931/240912555 is not a GRB
  38. GRB 240912A : INTEGRAL SPI ACS LIGHT CURVE
  39. GRB 240912B: Fermi GBM Final Real-time Localization
  40. GRB 240912A: NOT optical spectroscopy
  41. GRB 240912A: Enhanced Swift-XRT position
  42. GRB 240912A: Redshift from OSIRIS+/GTC
  43. Fast X-ray Transient EP240801a: GMRT radio observations
  44. GRB 240910A: Redshift from OSIRIS+/GTC
  45. GRB 240912A: Swift detection of a burst with an optical counterpart
  46. GRB 240912A: Fermi GBM Final Real-time Localization
  47. GRB 240910A: Fermi GBM Observation
  48. GRB 240910A: NOT optical observations
  49. GRB 240911A : a likely weak GRB detected by SVOM/ECLAIRs
  50. GRB 240910A: Swift-XRT detection of GOTO24fvl/AT2024vfp
  51. GRB 240910A: JinShan optical observations
  52. GRB 240910A: GOTO candidate optical counterpart
  53. EP240908a: Optical afterglow confirmation
  54. GRB 240710A: SVOM/GRM observation
  55. GRB 240910A: Swift ToO observations
  56. IPN triangulation of GRB 240905B (short)
  57. GRB 240825A: 7DT Optical Upper Limit
  58. GRB 240905E: SVOM/VT optical observations
  59. GRB 240905E: SVOM/VT optical observations (duplicate submission of GCN 37453)
  60. LIGO/Virgo/KAGRA S240910ci: NED Galaxies in the Localization Volume
  61. GRB 240910A: GRBAlpha detection
  62. GRB 240910B: Fermi GBM Final Real-time Localization
  63. LIGO/Virgo/KAGRA S240910ci: Coverage and upper limits from MAXI/GSC observations
  64. LIGO/Virgo/KAGRA S240910ci: Updated Sky localization and EM Bright Classification
  65. LIGO/Virgo/KAGRA S240910ci: Identification of a GW compact binary merger candidate
  66. GRB 240910A: SVOM/GRM observation
  67. EP240908a: Mondy and AbAO follow-up observations
  68. EP240908a: Updates on the WXT detection result around the trigger time
  69. Fermi GRB 240910A: Global MASTER-Net observations report
  70. GRB 240910A: Fermi GBM Final Real-time Localization
  71. LIGO/Virgo/KAGRA S240908bs: Upper limits from Swift/BAT-GUANO
  72. LIGO/Virgo/KAGRA S240907cg: Upper limits from Swift/BAT-GUANO
  73. EP240908a: optical afterglow candidate
  74. EP EP240908a: Global MASTER-Net observations report
  75. GRB 240905B: Fermi GBM Observation
  76. Fermi trigger No 747553301: Global MASTER-Net observations report
  77. EP240908a: TRT optical upper limit
  78. GRB 240905B: GOTO optical upper limits
  79. EP240908a: EP detection of a fast X-ray transient
  80. Fermi GRB 240908A: Global MASTER-Net observations report
  81. LIGO/Virgo/KAGRA S240908dg: Updated Sky localization
  82. LIGO/Virgo/KAGRA S240908bs: Updated Sky localization
  83. GRB 240908A: Fermi GBM Final Real-time Localization
  84. LIGO/Virgo/KAGRA S240908dg: Identification of a GW compact binary merger candidate
  85. LIGO/Virgo/KAGRA S240908bs: Identification of a GW compact binary merger candidate
  86. LIGO/Virgo/KAGRA S240907cg: Updated Sky localization
  87. GRB 240801A: SVOM/GRM observation
  88. LIGO/Virgo/KAGRA S240907cg: Identification of a GW compact binary merger candidate
  89. GRB 240905E: GIT optical upper limit
  90. GRB 240905B: Swift-XRT observations
  91. GRB 240905E: Gaoyazi/GOT optical upper limits
  92. GRB 240905E: NUTTelA-TAO / BSTI Optical Limits
  93. GRB 240905B: Fermi-LAT detection
  94. GRB 240905B: Swift ToO observations
  95. GRB 240905E: J-band observations with WINTER
  96. GRB 240905E: CrAO Optical Afterglow observations, possible OT candidate
  97. GRB 240905E: AKO Optical Upper Limit
  98. GRB 240905E: SVOM/C-GFT optical upper limit
  99. GRB 240905E: OHP/MISTRAL T193 optical upper limit
  100. Fermi GRB 240905D: Global MASTER-Net observations report

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