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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"

31730 results found.

  1. EP240918a: GMG Optical Upper Limit
  2. GRB 240916A: GRBAlpha detection
  3. GRB 240914B: GRBAlpha detection
  4. GRB 240916A: NOT optical observation
  5. GRB 240912A: Swift-BAT refined analysis
  6. IPN triangulation of GRB 240913C / EP 240913a
  7. GRB 240825A: INTEGRAL SPI ACS LIGHT CURVE
  8. GRB 240825A: The nature of the afterglow motivates the search of the associated supernova
  9. GRB 240916A: Fermi GBM Observation
  10. LIGO/Virgo/KAGRA S240917cb: Identification of a GW compact binary merger candidate
  11. GRB 240821A: radio observation with the VLA
  12. GRB 240916A (AT 2024vlp / GOTO24fzn): VLT/X-shooter redshift
  13. GRB 240916A: Swift-XRT afterglow detection
  14. LIGO/Virgo/KAGRA S240916ar: Identification of a GW compact binary merger candidate
  15. GRB 240916A: Swift ToO observations
  16. GRB 240916A: JinShan optical decay in one of the two GOTO candidates
  17. GRB 240916A: GOTO identification of two new optical sources within the GBM localisation region
  18. EP EP240913a: Global MASTER-Net observations report
  19. LIGO/Virgo/KAGRA S240915b: Coverage and upper limits from MAXI/GSC observations
  20. GRB 240916A INTEGRAL SPI ACS LIGHT CURVE
  21. LIGO/Virgo/KAGRA S240915bd: Updated Sky localization
  22. EP240913a: VLT/HAWK-I near-infrared upper limits
  23. LIGO/Virgo/KAGRA S240915bd: Identification of a GW compact binary merger candidate
  24. LIGO/Virgo/KAGRA S240915b: Updated Sky localization and EM Bright Classification
  25. LIGO/Virgo/KAGRA S240915b: Identification of a GW compact binary merger candidate
  26. EP240913a/GRB 240913C: KAIT optical upper limit
  27. EP240913a / GRB 240913C INTEGRAL SPI ACS LIGHT CURVE
  28. GRB 240913C: Fermi GBM detection
  29. GRB 240913C: Joint location by ETJASMIN
  30. GRB 240914B: AstroSat CZTI detection
  31. EP240913A / GRB 240913C: AstroSat CZTI detection
  32. GRB 240914A: SVOM/GRM observation
  33. GRB 240910A: SVOM/VT optical observations
  34. GRB 240914A: Swift ToO observations
  35. EP240913a: NOT optical upper limits
  36. EP240913a: JinShan optical upper limits
  37. EP240913a: ESO-NTT optical observations
  38. GRB 240914A: ESO-NTT optical observations
  39. EP240913a: Swift/XRT detection of an X-ray source within the EP/WXT error circle
  40. GRB 240905E: further NOT optical observations
  41. EP240913a: A GRB Event
  42. GRB 240911A: LCO optical observations
  43. GRB 240911A: JinShan optical upper limits on two Swift/XRT candidates
  44. Fermi Gamma-ray Burst Monitor trigger 747837485/240912526 is not a GRB
  45. GRB 240912A: Swift/UVOT Detection
  46. GRB 240911A: GOTO optical limits on Swift/XRT candidates
  47. GRB 240912A: SVOM/GRM observation
  48. Fermi GRB 240913A: Global MASTER-Net observations report
  49. GRB 240912A: J-band observations with WINTER
  50. GRB 240912A: Fermi GBM Observation
  51. Swift GRB 240912A: Global MASTER-Net observations report
  52. GRB 240912A: LCOGT detection and Legacy Surveys likely host galaxy
  53. GRB 240911A: Tiled Swift observations
  54. GRB 240912A : INTEGRAL SPI ACS LIGHT CURVE
  55. GRB 240912A: NOT optical spectroscopy
  56. GRB 240912A: Redshift from OSIRIS+/GTC
  57. Fast X-ray Transient EP240801a: GMRT radio observations
  58. GRB 240910A: Redshift from OSIRIS+/GTC
  59. GRB 240910A: Fermi GBM Observation
  60. GRB 240910A: NOT optical observations
  61. GRB 240910A: Swift-XRT detection of GOTO24fvl/AT2024vfp
  62. GRB 240910A: JinShan optical observations
  63. GRB 240910A: GOTO candidate optical counterpart
  64. EP240908a: Optical afterglow confirmation
  65. GRB 240710A: SVOM/GRM observation
  66. GRB 240910A: Swift ToO observations
  67. IPN triangulation of GRB 240905B (short)
  68. GRB 240825A: 7DT Optical Upper Limit
  69. GRB 240905E: SVOM/VT optical observations
  70. GRB 240905E: SVOM/VT optical observations (duplicate submission of GCN 37453)
  71. GRB 240910A: GRBAlpha detection
  72. LIGO/Virgo/KAGRA S240910ci: Coverage and upper limits from MAXI/GSC observations
  73. LIGO/Virgo/KAGRA S240910ci: Updated Sky localization and EM Bright Classification
  74. LIGO/Virgo/KAGRA S240910ci: Identification of a GW compact binary merger candidate
  75. GRB 240910A: SVOM/GRM observation
  76. EP240908a: Mondy and AbAO follow-up observations
  77. EP240908a: Updates on the WXT detection result around the trigger time
  78. Fermi GRB 240910A: Global MASTER-Net observations report
  79. EP240908a: optical afterglow candidate
  80. EP EP240908a: Global MASTER-Net observations report
  81. GRB 240905B: Fermi GBM Observation
  82. EP240908a: TRT optical upper limit
  83. GRB 240905B: GOTO optical upper limits
  84. Fermi GRB 240908A: Global MASTER-Net observations report
  85. LIGO/Virgo/KAGRA S240908dg: Updated Sky localization
  86. LIGO/Virgo/KAGRA S240908bs: Updated Sky localization
  87. LIGO/Virgo/KAGRA S240908dg: Identification of a GW compact binary merger candidate
  88. LIGO/Virgo/KAGRA S240908bs: Identification of a GW compact binary merger candidate
  89. LIGO/Virgo/KAGRA S240907cg: Updated Sky localization
  90. GRB 240801A: SVOM/GRM observation
  91. LIGO/Virgo/KAGRA S240907cg: Identification of a GW compact binary merger candidate
  92. GRB 240905E: GIT optical upper limit
  93. GRB 240905E: Gaoyazi/GOT optical upper limits
  94. GRB 240905E: NUTTelA-TAO / BSTI Optical Limits
  95. GRB 240905B: Fermi-LAT detection
  96. GRB 240905B: Swift ToO observations
  97. GRB 240905E: J-band observations with WINTER
  98. GRB 240905E: CrAO Optical Afterglow observations, possible OT candidate
  99. GRB 240905E: AKO Optical Upper Limit
  100. GRB 240905E: SVOM/C-GFT optical upper limit

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